Bacteriophage Ecology Group
Reference Abstracts (1992)
Dedicated to the ecology and evolutionary biology of the parasites of unicellular organisms (UOPs)
© Stephen T. Abedon
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© Phage et al. last updated on Wednesday, December 26, 2001
  1. Lysogeny in Bradyrhizobium japonicum and its effect on soybean nodulation. Abebe, H.M., Sadowsky, M.J., Kinkle, B.K., Schmidt, E.L. (1992). Appl. Environ. Microbiol. 58:3360-3366. Rhizobiophage V, isolated from soil in the vicinity of soybean roots, was strongly lytic on Bradyrhizobium japonicum 123B (USDA 123) but only mildly lytic on strain L4-4, a chemically induced small-colony mutant of 123. Numerous bacteriophage-resistant variants were isolated from L4-4 infected with phage V; two were studied in detail and shown to be lysogenic. The two, L4-4 (V5) and L4-4 (V12), are the first reported examples of temperate-phage infection in B. japonicum. Phage V and its derivative phages V5 and V12 were closely related on the basis of common sensitivity to 0.01 M sodium citrate and phage V antiserum, phage immunity tests, and apparently identical morphology when examined by electron microscopy. However, the three phages differed in host range and in virulence. Lysogens L4-4 (V5) and L4-4 (V12) were immune to infection by phages V and V5 but not to infection by V12. Southern hybridization analysis confirmed the incorporation of phage V into the genomes of strains L4-4(V5) and L4-4(V12) and also demonstrated the incorporation of phage V into the genome of a phage V-resistant derivative of USDA 123 designated 123 (V2). None of the three lysogens, L4-4(V5), L4-4(V12), or 123B(V2), was able to nodulate soybean plants. However, Southern hybridization profile data indicated that phage V had not incorporated into any of the known B. japonicum nodulation genes. [TOP OF PAGE]

  2. Lysis of lysis inhibited bacteriophage T4 infected cells. Abedon, S.T. (1992). J. Bacteriol. 174:8073-8080. T4 bacteriophage (phage)-infected cells show a marked increase in latent-period length, called lysis inhibition, upon adsorption of additional T4 phages (secondary adsorption). Lysis inhibition is a complex phenotype requiring the activity of at least six T4 genes. Two basic mysteries surround our understanding of the expression of lysis inhibition: (i) the mechanism of initiation (i.e., how secondary adsorption leads to the expression of lysis inhibition) and (ii) the mechanism of lysis (i.e., how this signal not to lyse is reversed). This study first covers the basic biology of the expression of lysis inhibition and lysis of T4-infected cells at high culture densities. Then evidence is presented which implies that, as with the initiation of lysis inhibition, sudden, lysis-associated clearing of these cultures is likely caused by T4 secondary adsorption. For example, such clearing is often observed for lysis-inhibited T4-infected cells grown in batch culture during T4 stock preparation. The significance of this secondary adsorption-induced lysis to wild T4 populations is discussed. The study concludes with a logical argument suggesting that the lytic nature of the T4 phage particle evolved as a novel mechanism of phage-induced lysis. [TOP OF PAGE]

  3. Phage susceptibility and enterotoxin production by Staphylococcus aureus strains isolated from Nigerian foods. Adesiyun, A.A., Lenz, W., Schaal, K.P. (1992). Journal of Food Protection 55:871-873. The sensitivity of Staphylococcus aureus strains isolated from Nigerian foods to phages in the international phage sets for typing human and bovine strains of staphylococci was determined. The enterotoxigenicity of the strains was also determined using the avidin-biotin enzyme-linked immunosorbent assay and the reversed passive latex agglutination test (for staphylococcal enterotoxin D only). One hundred and five (67.7%) of 155 stains tested were susceptible to phages in both typing sets. Phages for staphylococci of human origin lysed all 105 typeable strains while those for staphylococci of bovine origin were responsible for the lysis of 92 strains. Phages in the different phage groups (mixed) were most frequently responsible for lysis, 29 (27.6%), followed by group III phages with 26 (24.8%) strains susceptible. Of the 155 strains tested, 122 (78.7%) were enterotoxigenic producing staphylococcal enterotoxins A, B, C, D, or a combination. Dried beef isolates were most enterotoxigenic (100.0%) and those from fermented milk least 968.8%). Staphylococcal enterotoxins C, B, and A were elaborated either singly or in combination by 71 (58.2%). 69 (56.6%), and 62 (50.8%) strains, respectively. It was concluded that a majority of staphylococcal strains isolated form Nigerian foods originated from humans and their high enterotoxigenicity could be a health risk to consumers. [TOP OF PAGE]

  4. Isolation and characterization of Leuconostoc oenos phages from German wines. Arendt, E.K., Hammes, W.P. (1992). Applied Microbiology and Biotechnology 37:643-646. Thirty-four wines that showed problems during malolactic fermentation were obtained from five different German wineries and were examined for the presence of phages using electron microscopy and the agar spot-test. Phages were discovered in 11 of the wines and host strains were found for ten of these phages. The phages were characterized on the basis of their morphology, host range and protein profiles. Furthermore the ten phages could be divided into four groups by restriction enzyme analysis of the phage DNA. This grouping was consistent with results based on morphology, protein composition and host range analysis. [TOP OF PAGE]

  5. Phage coating of soybean seed reduces nodulation by indigenous soil bradyrhizobia. Basit, H.A., Angle, J.S., Salem, S., Gewaily, E.M. (1992). Canadian Journal of Microbiology 38:1264-1269. Inoculation of soybean with Bradyrhizobium japonicum is often unsuccessful owing to the failure of inoculum strains to nodulate soybeans (Glycine max (L.) Merr.) in the presence of indigenous strains of rhizobia in soil. Previous studies have shown that it is possible to reduce nodulation with indigenous strains of rhizobia by amending the soil with a bacteriophage specific for the indigenous strain. The objective of the current study was to determine whether the coating of seed with phage affected nodule occupancy and soybean growth. A phage specific for B. japonicum USDA 469 and a symbiotically superior strain of rhizobium (B. japonicum USDA 110) were coated together onto soybean seed and planted into both greenhouse and field soil previously inoculated with B. japonicum USDA 469. The phage coated onto seed reduced nodulation by B. japonicum USDA 469 to 48% occupancy, compared with 64% for the untreated control value. Nodulation by the superior inoculum strain was increased from 48 to 82% occupancy by coating seed with the homologous phage and B. japonicum USDA 110. The rate of nitrogenase activity (on a per plant basis) was increased by coating seed with the phage and B. japonicum USDA 110. No other plant or symbiotic parameters were affected by phage coating of seed. These results indicate that the nodulation of soybeans can be significantly affected by the coating of seed with phage specific for undesirable strains of rhizobia in soil and the concurrent coating of seed with desirable strains of rhizobia. [TOP OF PAGE]

  6. Effect of the method of preparing monochloramine upon inactivation of MS2 coliphage, Escherichia coli, and Klebsiella pneumoniae. Berman, D., Sullivan, R., Hurst, C.J. (1992). Canadian Journal of Microbiology 38:28-33. Monochloramine prepared in situ by first adding chlorine to a suspension of microorganisms, followed by subsequent addition of ammonia, inactivated the MS2 coliphage more rapidly than did exposure of phage to monochloramine prepared either by adding chlorine to ammonia or by adding chlorine and ammonia simultaneously. The rapid viral inactivation was apparently due to the exposure of MS2 to free chlorine before the addition of ammonia. The average 99% CT value of MS2 when exposed to free chlorine was 1.3 and 1.1 at 5 and 15 degrees C, respectively. The average 99% CT values of MS2 briefly exposed to the combined action of free chlorine followed by the addition of ammonia to form monochloramine in situ were 19.3 and 1.5 at 5 and 15 degrees C, respectively. No 99% CT values were calculated for the inactivation of MS2 with preformed monochloramine because less than 1 log (90%) of inactivation occurred during a 4-h contact time. Inactivation of MS2 by monochloramine was more rapid at 15 than at 5 degrees C and when the chlorine to nitrogen weight ratio was 5:1 compared with 3:1. Monochloramine was a more efficient inactivating agent for the coliforms Escherichia coli and Klebsiella pneumoniae than it was for the MS2 coliphage. [TOP OF PAGE]

  7. Comparative electron microscopic study of Bacillus thuringiensis cells grown in chemostat. Blokhina, T.P., Kostrikina, N.A., Sakharova, Z.V., Biryuzova, V.I. (1992). Mikrobiologiya 61:672-677. It has been shown that the culture of Bacillus thuringiensis subsp. gall. 69-6 dissociates into R- and S-variants in chemostat. Although under some conditions the sporogenesis and the synthesis of S-variant toxin began two hours earlier than these processes in R-variant cells which were observed, respectively, after 10 or 12 hours from the beginning of the experiment, the intensities of sporogenesis and toxin production as well as the exit of spores and toxin excretion from cells were similar after 24 hours. The resistance to the bacteriophage present in chemostat was the advantage of S-variant cells. The data obtained by electron microscopy indicate that the phage resistance is caused by the structural organization of the S-variant cell wall. Its peptidoglycan can component is thin and is distinguished by crumb structure. By means of negative contrast microscopy it was found that the surface T-layer of R-variant cell wall was characterized by the tetragonal packaging of protein subunits indicating the regular orientation of phage receptors in it. The redistribution of protein subunits in the T-layer of S-variant cell wall prevented from the adsorbance of bacteriophages on the cell surface. The adsorbance of phages on the surface of R-variant cells was observed rather often. It led to the degradation of peptidoglycan, the formation of protoplasts and lysis. [TOP OF PAGE]

  8. [Immunobiological properties and therapeutic effectiveness of preparations from Klebsiella bacteriophages]. [Russian]. Bogovazova, G.G., Voroshilova, N.N., Bondarenko, V.M., Gorbatkova, G.A., Afanas'eva, EV, Kazakova, T.B., Smirnov, V.D., Mamleeva, A.G., Glukharev, I., Erastova, E.I. (1992). Zhurnal Mikrobiologii, Epidemiologii i Immunobiologii 30-33. The purified preparations of Klebsiella bacteriophages, viz. the monovalent preparation of K. pneumoniae bacteriophage and the polyvalent bacteriophage preparation for the treatment of infections caused by K. ozaenae, K. rhinoscleromatis scleromatis and K. pneumoniae sensu lato, have been obtained. The bacteriophage preparations have proved to be nontoxic and safe for laboratory animals after the intraperitoneal injection of these preparations followed by the pathomorphological study of the internal organs of the animals. The clinical study of the newly developed bacteriophage preparations in the course of the treatment of purulent inflammatory diseases in 109 patients has revealed that the preparations are not reactogenic and exhibit sufficient effectiveness in the therapy of ozena, rhinoscleroma and Klebsiella infections with different localization of the infectious process. [TOP OF PAGE]

  9. Giant marine viruses? Bratbak, G., Haslund, O.H., Heldal, M., Noess, A., Røeggen, T. (1992). Mar. Ecol. Prog. Ser. 85:201-202. [TOP OF PAGE]

  10. Incorporation of viruses into the budget of microbial C-transfer. A first approach. Bratbak, G., Heldal, M., Thingstad, T.F., Riemann, B., Haslund, O.H. (1992). Mar. Ecol. Prog. Ser. 83:273-280. Viral lysis of bacteria has been suggested to be a quantitatively important process in the removal of bacteria, and potentially also in the production of DOC, in the ocean. In order to investigate the quantitative role of viruses in the pelagic microbial ecosystem, a diel study was undertaken, comprising measurements of particulate and dissolved primary production, bacterial production, bacterial grazing by flagellates, bacterial lysis by viruses, and production of viruses. Estimates of algal excretion (4.7-mu-mol Cl-1 d-1)and bacterial carbon consumption (3.0-mu-mol Cl-1 d-1) estimates by a balance. Predation (2.9-mu-mol Cl-1 d-1) exceeded bacterial production (1.5-mu-mol Cl-1 d-1) estimates by a factor of 2. Major difficulties in balancing the budget emerged however, from the estimates of viral lysis of bacteria (9.2-mu-mol Cl-1 d-1), which exceeded bacterial production by a factor of 6. Despite these problems, results support the idea that viral lysis may be a quantitatively significant process that needs to be incorporated into budgets of microbial C-transfer. [TOP OF PAGE]

  11. Inactivation of phage tracers by exposure to liquid-air interfaces. Bricelj, M., Sisko, M. (1992). International Symposium on Water Tracing. [TOP OF PAGE]

  12. Staphylococcus carnosus bacteriophages isolated from salami factories in Germany and Italy. Bruttin, A., Marchesini, B., Moreton, R.S., Sozzi, T. (1992). J. Appl. Bacteriol. 73:401-406. Two phages lysing strains of Staphylococcus carnosus, an organism used as a starter culture for salami production, were isolated from factories in Germany and Italy. Morphologically they show the C1 morphotype and are unrelated to the only other known Staph. carnosus phage. The phages were physiologically and morphologically similar but showed differences in their structural proteins and DNA restriction patterns. Their genomes consisted of linear double stranded DNA with a genome size of 19 kb. The phages lysed a wide range of Staph. carnosus strains from commercial meat starter cultures as well as the DSM type strain. Despite the presence of these phages, the products were normal from the point of view of colour, texture and flavour. [TOP OF PAGE]

  13. Molecular genetics of adaptation in an experimental model of cooperation. Bull, J.J., Molineux, I.J. (1992). Evolution 46:882-895. The evolution of cooperation was studied in an empirical system utilizing a parasitic bacteriophage (fl) and a bacterial host. Infected cells were propagated by serial passage so that a phage could increase its representation among infected hosts only by enhancing the rate of growth of its host. Loss of infectivity was therefore without selective penalty, and phage benevolence could potentially evolve through a variety of genetic changes. The infected hosts evolved to grow faster over the course of the study, but the genetic bases of this phenotypic change were more difficult to anticipate. Two fundamentally different types of genetic changes in the phage were revealed. One involved the loss of some phage genes, resulting in a noninfectious plasmid that continued to replicate via the parental phage replicon. The second change involved integration of the phage to genome into host DNA by a process that, at low frequency, could be reversed to produce infectious phage particles. Integration is a previously known property of wild-type fl, and in the system studied, may have resulted from the use of a phage bearing an insert containing nonfunctional DNA. The evolution of this novel function apparently depended only on the presence of a small region in the phage genome that provided some homology to the host DNA, with the host providing all necessary functions. Although fl is one of the simplest phages known, these observations suggest that host-parasite interactions of the filamentous phages are more complicated than previously thought. More generally, the fl system offers a useful model for many problems concerning the genetic basis of adaptation. [TOP OF PAGE]

  14. Efficiency of crossflow ultrafiltration in the recovery of bacteriophage from water samples. Burrini, D., Pollicino, G., Lupi, E. (1992). Igiene Moderna 98:541-554. The production of water for human consumption, especially when such water is taken from superficial sources, must be virus-free in compliance with the existing safety requisites. Traditional virologic testing is normally carried out by highly specialized laboratories, whereas the evaluation of anti-E. coli bacteriophage is an easily detected and very reliable parameter that can frequently be performed by laboratories of water quality control. On this basis the Biological-Chemical Laboratory of the Acquedotto of Florence, in cooperation with Sartorius S.p.A., Florence, has studied a method to verify the efficiency of crossflow technology in the concentration of anti-E. coli phages, by means of the Sartorius Sartocon Mini System (SM 17521) with a 100.000 NMWCO polysulfone ultrafiltration module, filtration area 0.1 m-2 (SM 3031466901E). Prior to the test, the system was chemically sanitized and rinsed with deionized water, the membranes were conditioned with a 3% beef extract solution (Difco) to prevent the adhesion of the phage particles to the module surface, and finally the samples were concentrated to 200 ml volumes, starting from 5- and 10-litre lots. In order to quantify the percentage of phages recovered, the samples were infected with water from the Arno River with a known value determined on a 100 ml sample by means of the Grabow method on E. coli K 12 Hfr phagosensitive strain. The residual volume in the system was recovered using a 3% beef extract solution pH9. After pH correction to 7.2, the phages in the 500 ml sample were counted with the same method. The percentage recoveries verified so far have varied from 8% to 117%. Further tests, still under way, will explain the mechanisms by which phage particle recovery, sometimes higher than 100%, occurs, in order to optimize this promising method that can be integrated into routine water quality control testing. [TOP OF PAGE]

  15. The autoradiography of DNA. Cairns, J. (1992). pp. 252-257. In In Cairns, J., Stent, G.S., and Watson, J.D. (eds.), Phage and the Origins of Molecular Biology (expanded edition). Cold Spring Harbor Laboratory Press, Cold Spring Harbor, NY. "I embarked on a search for RNA viruses infecting certain soil amoebae that have simple nutritional requirements. At the end of a year of futile search…" p. 254. [TOP OF PAGE]

  16. Phage and the Origins of Molecular Biology (expanded edition). Cairns, J., Stent, G., Watson, J.D. (1992). Cold Spring Harbor Laboratory Press, Cold Spring Harbor, NY.[TOP OF PAGE]

  17. Evidence and characterization of temperate bacteriophage in Streptococcus salivarius spp thermophilus st18. Carminati, D., Giraffa, G. (1992). Journal of Dairy Research 59:71-79. Lysogenic strains of Streptococcus salivarius subsp. thermophilus were studied using induction with mitomycin C (MC). The induction and presence of temperatre phage were investigated carrying out tests on sensitive strains, electron microscopy and phage DNA analysis. Forty-five Str. salivarius subsp. thermophilus strains were subjected to induction with MC and growth of the various cultures was evaluated. Only one strain of those tested showed lysis after adding MC, thus indicating a possible lysogenic state, 0.5 .mu.g MC/ml being the optimal dose. Two .PHI. 18 phage-sensitive strains out of 45 were isolated in which this phage behaved as virulent, causing lysis of the culture in broth, but no lysis plaques on agar medium were detected. The St 18 strain was cured by u.v. irradiation but no mutants sensitive to the .PHI. 18 phage were found among the clones non-inducible by MC. The presence of phages having a hexagonal isometric head and a long non-contractile tail in the lysate obtained after including the St18 strain was confirmed by examination under the electron microscope. Study of the phage DNA showed a genome size of 40.9.+-. 0.5 kb without cohesive end fragments. In addition, the restriction map of the phage genome was constructed. This study has demonstrated lysogeny in Str. salivarius subsp. thermophilus and also that several phage infections of Str. salivarius subsp. thermophilus starters may have an 'endogenous' origin. [TOP OF PAGE]

  18. Evolution of dsDNA tailed-bacteriophage genomes. Casjens, S., Hatfull, G., Hendrix, R.W. (1992). Semin. Virol. 3:383-397. [TOP OF PAGE]

  19. The potential of immobilized cell technology to produce freeze-dried, phage-protected cultures of Lactococcus lactis. Champagne, C.P., Morin, N., Couture, R., Gagnon, C., Jelen, P., Lacroix, C. (1992). Food Research International 25:419-427. Lactococcus lactis cells were immobilized in calcium alginate beads and added to growth media to enable biomass production in the gel. The immobilized population was then freeze-dried. Survival during freeze-drying (FD), stability upon high-temperature storage and residual humidity were evaluated. This culture was compared to a classical liquid starter and fresh beads of immobilized L. lactis in simulated quarg manufacture. Acidifying characteristics, proteolytic activity, sensitivity to bacteriophage and sensory properties of quarg products were evaluated. The population in the beads prior to FD was 7 times 10-10 CFU/g. The best survival rate to FD (62-79%) was obtained when the beads were mixed with a milk-based protective solution. In the absence of protective ingredients (milk solids, sucrose and vitamin C) the alginate beads had high water content following FD. Survival of the immobilized cells during FD was as high for immobilized cells as that of free cells. Stability of the immobilized cells at high-temperature storage (45-55 degree C) was higher than for the free cells. Quarg cheese was successfully produced in 5 h with the immobilized freeze-dried (IFD) culture, but sensory evaluation confirmed a significant texture difference between cheeses made with free or IFD cultures. Higher inoculation rates were required with the IFD culture to obtain the same acidifying activity as classical fresh liquid starters. The IFD culture performed well under phage contamination; folowing a 6-h fermentation 30% of the cells remained viable and active in the phage-contaminated sample. Increase in non-protein amino compounds (0.2 g/100 g cheese) over a 30 day storage period at 4 degree C was similar in quarg cheeses made with fresh of IFD starters, despite the higher inoculation rate used with the IFD culture. [TOP OF PAGE]

  20. Muller's ratchet and the advantage of sex in the RNA virus Phi-6. Chao, L., Tran, T., Matthews, C. (1992). Evolution 46:289-299. Population genetic models have shown that if genetic drift is strong and the rate of deleterious mutations is high, Muller's ratchet provides an advantage to sex. A previous study tested for the possibility that Muller's ratchet could work in RNA viruses, which are known to have very high mutation rates. Muller's ratchet was found to operate when lineages of the RNA bacteriophage .vphi. 6 were subjected to intensified genetic drift. The study did not determine, however, whether sex is advantageous to these viruses. We have examined whether sex can reverse the effects of Muller's ratchet by crossing nine .vphi.6 lineages that were subjected to the ratchet in Chao's study. To determine whether there was a net advantage to sex, we analyzed the effect of crossing three lineages to all other lineages. Crossing increased significantly the fitness of two lineages, but it did not significantly affect the fitness of the third lineage. We argue that the minimal advantage of sex of these nine lineages is small, but positive. These results provide a possible scenario for the evolution of sex in an RNA phage like .vphi.6. [TOP OF PAGE]

  21. Bacteriocidal and mutagenic effects of ozone on shrimp (Penaeus monodon ) meat. Chen, H.C., Huang, S.H., Moody, M.W., Jiang, S.T. (1992). Journal of Food Science [J. FOOD SCI. ] 57:923-927. Among 9 bacterial strains tested, Salmonella typhimurium was more resistant to ozone in shrimp meat. Mutagen was not detected in shrimp meat when it was ozonated in saline. Ozone in saline (less than 5 mg-O sub(3)/L) could lyse M13 RF DNA in Escherichia coli) and single-stranded DNA In phage M13 outside bacterial cell, within 30 min. [TOP OF PAGE]

  22. Detection of genetic exchange in the terrestrial environment. Cresswell, N., Wellington, E.M.H. (1992). pp. 59-82. In In Wellington, E.M.H. and van Elsas, J.D. (eds.), Genetic Interactions among Microorganisms in the Natural Environment. Pergamon Press, Oxford. [TOP OF PAGE]

  23. The fate of introduced streptomyces, plasmid and phage populations in a dynamic soil system. Cresswell, N., Herron, P.R., Saunders, V.A., Wellington, E.M.H. (1992). Journal of General Microbiology 138:659-666. [TOP OF PAGE]

  24. Phages and phage resistance in lactococci. Actes du Colloque LACTIC 91. Daly, C., Coffey, A., Casey, C.N., Fitzgerald, G.F. (1992). In none (ed.), Les Bacteries Lactiques, Recherche et Applications Industrielles en Agro-Alimentaire. Adria Normandie, Villers Bocage, Cedex, France. [TOP OF PAGE]

  25. Rates of inactivation of waterborne coliphages by monochloramine. Dee, S.W., Fogleman, J.C. (1992). Appl. Environ. Microbiol. 58:3136-3141. A sophisticated water quality monitoring program was established to evaluate virus removal through Denver's 1-million-gal (ca. 4-million-liter)/day Direct Potable Reuse Demonstration Plant. As a comparison point for the reuse demonstration plant, Denver's main water treatment facility was also monitored for coliphage organisms. Through the routine monitoring of the main plant, it was discovered that coliphage organisms were escaping the water treatment processes. Monochloramine residuals and contact times (CT values) required to achieve 99% inactivation were determined for coliphage organisms entering and leaving this conventional water treatment plant. The coliphage tested in the effluent waters had higher CT values on the average than those of the influent waters. CT values established for some of these coliphages suggest that monochloramine alone is not capable of removing 2 orders of magnitude of these specific organisms in a typical water treatment facility. Electron micrographs revealed one distinct type of phage capable of escaping the water treatment processes and three distinct types of phages in all. [TOP OF PAGE]

  26. The eclipse in the bacteriophage life cycle. Doermann, A.H. (1992). pp. 79-87. In In Cairns, J., Stent, G.S., and Watson, J.D. (eds.), Phage and the Origins of Molecular Biology (expanded edition). Cold Spring Harbor Laboratory Press, Cold Spring Harbor, NY. [TOP OF PAGE]

  27. Tracing the origin of retroviruses. Doolittle, R.F., Feng, D.F. (1992). CURRENT TOPICS IN MICROBIOLOGY AND IMMUNOLOGY 176:195-211. Reverse transcriptase sequences, which are fundamental to retrovirus existence, are widely distributed in the living world. Phylogenies based on their sequences set vertebrate retroviruses apart as relatively modern creations. Their nearest evolutionary relatives are a large group of transposable elements that have all the standard retrovirus equipment except spliced envelope proteins. The distribution of these elements suggests a long-standing presence predating the radiation of plants, fungi, and animals. There is another large group of elements, LINEs, that also contain recognizable reverse transcriptase sequences and which likely diverged even earlier, as evidenced by their presence in trypanosomes and other protists. They lack tRNA priming sites--which they could have lost--but they do exhibit characteristic eukaryotic polyadenylation. These elements are problematic in that the sequences are so degenerate in most instances that it is not possible to identify the accessory enzymes or structural proteins with any confidence, leaving major gaps in our reconstruction of events. Even with these gaps, however, the historical beginnings of retroviruses can be traced back to events coincident with the prokaryotic invasion of primitive eukaryotes. [TOP OF PAGE]

  28. Rapid fitness losses in mammalian RNA virus clones due to Muller's ratchet. Duarte, E., Clarke, D., Moya, A., Domingo, E., Holland, J. (1992). Proc. Natl. Acad. Sci. USA 89:6015-6019. Muller's ratchet is an important concept in population genetics. It predicts that when mutation rates are high and a significant proportion of mutations are deleterious, a kind of irreversible ratchet mechanism will gradually decrease the mean fitness of small populations of asexual organisms. In contrast, sexual recombination may stop or reverse this mutational ratchet by recombinational repair of genetic damage. Experimental support for Muller's ratchet has previously been obtained in protozoa and in a tripartite RNA bacteriophage. We now show clear evidence that Muller's ratchet can operate on a nonsegmented nonrecombining pathogenic RNA virus of animals and humans. We did genetic bottleneck passages (plaque-to-plaque transfers) of vesicular somatitis virus (VSV) and then quantitated relative fitness of the bottleneck clones by allowing direct replication competition in mixed infections in cell culture. We document variable fitness drops (some severe) following only 20 plaque-to-plaque transfers of VSV. In some clones no fitness changes (or only insignificant changes) were observed. Surprisingly, the most regular and severe fitness losses occurred during virus passages on a new host cell type. These results again demonstrate the extreme genetic and biological variability of RNA virus populations. Muller's ratchet could have significant implications for variability of disease severity during virus outbreaks, since genetic bottlenecks must often occur during respiratory droplet transmissions and during spread of low-yield RNA viruses from one body site to another (as with human immunodeficiency virus). Likewise, the lower-probability generation of increased-fitness clones during repeated genetic bottleneck transfers of RNA viruses in nature might also affect disease pathogenesis in infected individuals and in host populations. Whenever genetic bottlenecks of RNA viruses occur, enhanced biological differences among viral subpopulations may result. [TOP OF PAGE]

  29. Molecular characterization of a second abortive phage resistance gene present in Lactococcus lactis lactis ME2. Durmaz, E., Higgins, D.L., Klaenhammer, T.R. (1992). J. Bacteriol. 174:7463-7469. The fifth resistance factor from the prototype phage-insensitive strain Lactococcus lactis subsp. lactis ME2 has been characterized and sequenced. The genetic determinant for Prf (phage resistance five) was subcloned from the conjugative plasmid pTN20, which also encodes a restriction and modification system. Typical of other abortive resistance mechanisms, Prf reduces the efficiency of plaquing to 10-2 to 10-3 and decreases the plaque size and burst size of the small isometric-headed phage p2 in L. lactis subsp. lactis LM0230. However, normal-size plaques occurred at a frequency of 10-4 and contained mutant phages that were resistant to Prf, even after repeated propagation through a sensitive host. Prf does not prevent phage adsorption or promote restriction and modification activities, but 90% of Prf+ cells infected with phage p2 die. Thus, phage infections in Prf+ cells are aborted. Prf is effective in both L. lactis subsp. lactis and L. lactis subsp. cremoris strains against several small isometric-headed phages but not against prolate-headed phages. The Prf determinant was localized by Tn5 mutagenesis and subcloning. DNA sequencing identified a 1,056-nucleotide structural gene designated abiC. Prf+ expression was obtained when abiC was subcloned into the lactococcal expression vector pMG36e. abiC is distinct from two other lactococcal abortive phage resistance genes, abiA (Hsp+, from L.lactis subsp. lactis ME2) and abi416 (Abi+, from L. lactis subsp. lactis IL416). Unlike abiA, the action of abiC does not appear to affect DNA replication. Thus, abiC represents a second abortive system found in ME2 that acts at a different point of the phage lytic cycle. [TOP OF PAGE]

  30. Introns in the T-Even Bacteriophages. Eddy, S.R. (1992). University of Colorado at Boulder. It is generally true that prokaryotic genes do not have introns. Because prokaryotic genomes tend to be smaller and replicate faster than eukaryotic genomes, it is thought that introns and other nonessential DNA sequences do not occur in prokaryotes because of selective pressure to streamline the genome. An exception is the occurrence of three group I introns in the E. coli bacteriophage T4. That these three introns occur in the space-efficient T4 genome suggests that there is an evolutionary pressure keeping them there. However, I found that an intronless T4 construct has no detectable phenotype relative to T4, under several different growth conditions. Furthermore, I found that the three introns occur variably and infrequently in wild T-even phage populations. Another laboratory then discovered that two of the three T4 introns are mobile ``infectious'' elements capable of duplicating themselves into homologous intronless genes. I subsequently found that the third T4 intron appears to be a defective copy of another mobile intron from a related wild phage isolate. The high efficiency of intron mobility seems sufficient to account for the occurrence of introns in T-even phage genomes. The mechanism proposed to account for intron mobility is relatively simple. I constructed an artificial mobile ``intron'' from the genes for the EcoRI restriction/modification system. Besides showing that the proposed model for intron mobility is likely to be correct, these experiments raise the possibility of harnessing the mechanism for targeted manipulation of genomes. [TOP OF PAGE]

  31. Bacteriophage: One-step growth. Ellis, E. (1992). pp. 56-62. In In Cairns, J., Stent, G.S., and Watson, J.D. (eds.), Phage and the Origins of Molecular Biology (Expanded Edition). Cold Spring Harbor Laboratory Press, Cold Spring Harbor, NY. [TOP OF PAGE]

  32. Bacteriophage typing of Listeria monocytogenes cultures isolated from seafoods. Estela, L.A., Sofos, J.N., Flores, B.B. (1992). Journal of Food Protection [J. FOOD PROT. ] 55:13-17. Listeria monocytogenes cultures isolated from a variety of seafoods were subjected to phage typing procedures utilizing the French International set of L. monocytogenes bacteriophages. These cultures were also subjected to the activity of newly isolated North American phages to L. monocytogenes . There were 147 serotype is equivalent and 80 serotype 4b L. monocytogenes cultures isolated from 16 varieties of marine products included in this study. L. monocytogenes was most frequently isolated from crab meat, salmon, and shrimp. Bacteriophages to serotype is equivalent isolates most frequently observed as single patterns were 575, 1967, 2685, and 19. Serotype 4b phages observed most frequently were 1317, 2425, and 52 as single phage patterns, and 52/340/110/108/2671/2425/2389 and the new North American phages 90861/910716/93253/90666 as one complete spectrum. The prevalence of L. monocytogenes and their respective phage spectra observed in the 16 varieties of seafoods studied is discussed. [TOP OF PAGE]

  33. Rates of experimental microbiological contamination of fish exposed to polluted water. Fattal, B., Dotan, A., Tchorsh, Y. (1992). Water Res. 26:1621-1627. Fish inhabiting fecally polluted bodies of water are often used for human consumption. Such fish can be contaminated by enteric human pathogens and may pose a potential risk to public health. Controlled experiments with 132 fish of 100 g average weight were conducted to evaluate the rate of contamination of various tissues of fish (tilapia hybrids). The fish were exposed to E. coli introduced into the ambient water at concentrations of up to 10-6 cfu/ml. Additional experiments were conducted with diluted wastewater containing Aeromonas, enterococci, fecal coliform and F + coliphages. In another experiment poliovirus 1 was also added. The highest bacterial concentrations were recovered from the digestive tract (DT), some 5-24 h following exposure, with DT levels essentially similar to those in the inoculated water. In the E. coli experiments, geometric mean levels of about 10-2 cfu/m-2 were recovered from the skin, 26 cfu/g in the spleen and 10-2 cfu/g in the liver. Most of the muscle samples were not contaminated. Greater contamination was not found under conditions of stress such as high organic load, a water temperature of 37 degree C or low levels of dissolved oxygen. [TOP OF PAGE]

  34. Bacterioplankton roles in cycling of organic matter: the microbial food web. Fuhrman, J.A. (1992). pp. 361-383. In In Falkowski, P.G. and Woodhead, A.D. (eds.), Primary Productivity and Biogeochemical Cycles in the Sea. Plenum, New York. [TOP OF PAGE]

  35. Biological properties of Serratia marcescens bacteriophages. Gabrilovich, I.M., Gairabekov, R.K. (1992). Zhurnal Mikrobiologii Epidemiologii i Immunobiologii 10-12. Sixteen phages active against bacteria of the genus Serratia have been divided into 4 groups on the basis of the study of their biological properties. As a result, 5 typing phages have been selected, which permitted the typing of 77.3% of S. marcescens cultures under study, divided into 13 phage types. [TOP OF PAGE]

  36. Wastewater renovation in buried and recirculating sand filters. Gold, A.J., Lamb, B.E., Loomis, G.W., Boyd, J.R., Cabelli, V.J., McKiel, C.G. (1992). Journal of Environmental Quality [J. ENVIRON. QUAL. ] 21:720-725. A replicated, multiyear field study was conducted to assess the reduction of N, P and microbial indicators by a recirculating sand filter (RSF) and a buried multilayer sand filter patterned after the RUCK filter. The RSF's received 38 L/m super(2)/d of septic tank effluent, while the buried sand filters were loaded at 76 L/m super(2)/d. The RSF's had significantly greater reductions of N and P (21 and 31%, respectively) than the buried filters (8 and 1%, respectively); however, N reduction was not significantly different per unit area. The lower daily loading rate and even distribution of effluent on the recirculating filters may have contributed to the elevated P reductions noted. Total Kjeldahl N (TKN) reductions in the RSF's were markedly lower during the cold season ( less than or equal to 10 degree C) than the warm season. In contrast, TKN reductions in the buried sand filters were relatively constant, except during the coldest periods of winter. Substantial TKN reductions occurred under acidic conditions. During warm weather sampling, both types of filters dramatically reduced levels of fecal coliform, enterococci, and F male-specific bacteriophage. During cold conditions, the buried sand filters produced greater reductions of fecal coliforms and enterococci levels, while neither filter consistently reduced the levels of Clostridium perfringens) or F phage. Increased reductions in fecal coliform, enterococci and F phage were associated with lower effluent pH for both sand filters. [TOP OF PAGE]

  37. DNA sequences of the tail fiber genes of bacteriophage P2 evidence for horizontal transfer of tail fiber genes among unrelated bacteriophages. Håggard-Ljungquist, E., Halling, C., Calendar, R. (1992). J. Bacteriol. 174:1462-1477. We have determined the DNA sequence of the bacteriophage P2 tail genes G and H, which code for polypeptides of 175 and 669 residues, respectively. Gene H probably codes for the distal part of the P2 tail fiber, since the deduced sequence of its product contains regions similar to tail fiber proteins from phages Mu, P1, .lambda., K3, and T2. The similarities of the carboxy- terminal portions of the P2, Mu, and P1 tail fiber proteins may explain the observation that these phages in general have the same host range. The P2 H gene product is similar to the products of both .lambda. open reading frame (ORF) 401-stf, side tail fiber) and its downstream ORF, ORF 314. If 1 bp is inserted near the end of ORF 401, this reading frame becomes fused with ORF 314, creating an ORF that may represent the complete stf gene that encodes a 774-amino-acid-long side tail fiber protein. Thus, a frameshift mutation seems to be present in the common laboratory strain of .lambda.. Gene G of P2 probably codes for a protein required for assembly of the tail fibers of the virion. The entire G gene product is very similar to the products of genes U and U' of phage Mu; a region of these poteins is also found in the tail fiber assembly proteins of phages TuIa, TuIb, T4, and .lambda.. The similarities in the tail fiber genes of phages of different families provide evidence that illegitimate recombination occurs at previously unappreciated levels and that phages are taking advantage of the gene pool available to them to alter their host ranges under selective pressures. [TOP OF PAGE]

  38. Molecular interactions between bacteriophage and the Gram-negative cell envelope. Heller, K.J. (1992). Archives of Microbiology 158:235-248. [TOP OF PAGE]

  39. Bacteriophage lamda PaPa: not the mother of all lambda phages. Hendrix, R.W., Duda, R.L. (1992). Science 258:1145-1148. The common laboratory strain of bacteriophage lambda--lambda wild type or lambda PaPa--carries a frameshift mutation relative to Ur-lambda, the original isolate. The Ur-lambda virions have thin, jointed tail fibers that are absent from lambda wild type. Two novel proteins of Ur-lambda constitute the fibers: the product of stf, the gene that is disrupted in lambda wild type by the frameshift mutation, and the product of gene tfa, a protein that is implicated in facilitating tail fiber assembly. Relative to lambda wild type, Ur-lambda has expanded receptor specificity and adsorbs to Escherichia coli cells more rapidly. [TOP OF PAGE]

  40. A persistent virus infection in Feldmannia phaeophyceae. Henry, E.C., Meints, R.H. (1992). Journal of Phycology 28:517-526. A virus infection is described within the unilocular sporangia of Feldmannia sp., a filamentous brown alga (Phaeophyceae). The alga is easily maintained in culture and vegetative growth is vigorous, but formation of icosahedral virious 150 nm in diameter completely displaces production of zoospores. The viruses, estimated at 1-5 x 10-6 per sporangium, are eventually released by rupture of the sprangial wall. Deoxyribonucleic acid (DNA) isolated from the viruses can be readily digested with restriction endonucleases and consists of ca. 170 kbp of double-stranded DNA. [TOP OF PAGE]

  41. Extraction of Streptomyces spores from soil and detection of rare gene transfer events. Herron, P.R., Wellington, E.M.H. (1992). pp. 91-103. In In Wellington, E.M.H. and van Elsas, J.D. (eds.), Genetic Interactions among Microorganisms in the Natural Environment. Pergammon Press, Oxford. [TOP OF PAGE]

  42. Experimental phylogenetics: generation of a known phylogeny. Hillis, D.M., Bull, J.J., White, M.E., Badgett, M.R., Molineux, I.J. (1992). Science 255:589-592. Although methods of phylogenetic estimation are used routinely in comparative biology, direct tests of these methods are hampered by the lack of known phylogenies. Here a system based on serial propagation of bacteriophage T7 in the presence of a mutagen was used to create the first completely known phylogeny. Restriction-site maps of the terminal lineages were used to infer the evolutionary history of the experimental lines for comparison to the known history and actual ancestors. The five methods used to reconstruct branching pattern all predicted the correct topology but varied in their predictions of branch lengths; one method also predicts ancestral restriction maps and was found to be greater than 98 percent accurate. [TOP OF PAGE]

  43. Improved method for coliphage detection based on beta-galactosidase induction. Ijzerman, M.M., Hagedorn, C. (1992). Journal of Virological Methods 40:31-36. An improved method for coliphage detection based on induction of beta-galactosidase in Escherichia coli is described. Upon infection by coliphages, the cells are lysed and a stable indolyl product that is dark blue becomes visible within each plaque. The improved method is compared to the proposed coliphage detection procedure described in Standard Methods for the Examination of Water and Wastewater. [TOP OF PAGE]

  44. Regulation of the BamHI restriction-modification system by a small intergenic open reading frame, bamHIC, in both Escherichia coli and Bacillus subtilis. Ives, C.L., Nathan, P.D., Brooks, J.E. (1992). J. Bacteriol. 174:7194-7201. BamHI, from Bacillus amylodiquefaciens, H, is a type II restriction-modification system recognizing and cleaving the sequence G-GATCC. The BamII restriction-modification system contains divergently transcribed endonuclease and methylase genes along with a small open reading frame oriented in the direction of the endonuclease gene. The small open reading frame has been designated bamIIC (for BamHI controlling element). It acts as both a positive activator of endonuclease expression and a negative repressor of methylase expression of BamHI clones in Escherichia coli. Methylase activity increased 15-fold and endonuclease activity decreased 100-fold when bamHIC was inactivated. The normal levels of activity for both methylase and endonuclease were restored by supplying bamHIC in trans. The BamHI restriction-modification system was transferred into Bacillus subtilis, where bamHIC also regulated endonuclease expression when present on multicopy plasmid vectors or integrated into the chromosome. In B. subtilis, disruption of bamHIC caused at least a 1,000-fold decrease in endonuclease activity; activity was partially restored by supplying bamHIC in trans. [TOP OF PAGE]

  45. Isolation and characterization of two temperate phages from Lactococcus lactis ssp cremoris C3. Jarvis, A.W., Parker, V.R., Bianchin, M.B. (1992). Canadian Journal of Microbiology 38:398-404. Lactococcus lactis ssp. cremoris C3 was shown to contain two prophages, C3-T1 and C3-T2, both inducible by mitomycin C. The phages were morphologically indistinguishable, having an isometric head (55 nm), a noncontractile tail (142 nm), and a distinctive base plate. The phages C3-T1 and C3-T2 were differentiated from one another by restriction endonuclease analysis of their DNA, and genome sizes of 37.8 ( C3-T1) and 22.5 kb (C3-T2). Southern blot DNA hybridization suggested a maximum homology between the phage genomes of 50%. Page C3-T1 was propagated and the phage obtained was designated C3-T1l. Phage C3- T2 was not propagated despite tests with a large number of possible indicator strains. Restriction enzyme analysis of phage C3-T1l genome yielded a 37.8-kb circular restriction map. The packaging site (pac) and site of intergration into the bacterial chromosome (att) were located and an EcoRI DNA fragment containing the att site was cloned. Only one C3-T1 att site was present in the C3 chromosome. No homology was detected between DNA from C3-T1l and DNA from lytic phages commonly isolated from cheese wheys. [TOP OF PAGE]

  46. Evaluation of a mechanical/chemical infectious waste disposal system [see comments]. Jette, L.P., Lapierre, S. (1992). INFECTION CONTROL AND HOSPITAL EPIDEMIOLOGY 13:387-393. OBJECTIVES: The mechanical/chemical infectious waste disposal system (IWDS), model Z-5000 HC, manufactured by Medical SafeTEC Inc. (Indianapolis, Indiana) was evaluated for its ability to disinfect biomedical waste. METHODS: The IWDS was operated with a sodium hypochlorite solution and tested with loads consisting of microbial cultures and blood. During and after processing, samples of liquid, milled solid waste, and leachate were collected to determine the efficacy of disinfection and the chemical by-products released. An inactivation factor was calculated. Aerosol emission was studied. All tests were done in triplicate. RESULTS: Our results showed the expected level of disinfection (inactivation factor greater than or equal to 5 log10) for all tests carried out with Bacillus subtilis, Enterococcus faecalis, Candida albicans, and Serratia marcescens, and for most of the tests with Mycobacterium fortuitum and bacteriophages OX174 and f2. Further tests performed in the absence of blood resulted in an inactivation factor greater than or equal to 5 log10 for all tests with M fortuitum, but not for those of the milled solids with bacteriophage f2. Aerosols were found to escape the apparatus when the IWDS was operated in the absence of chlorine. The liquid effluent contained an average of 17,600, and 15 mg/l of free chlorine, chloramines, and trihalomethanes (THM), respectively. The air effluent contained 1.1 mg/m3 of total chlorine and 1.4 micrograms/m3 of THM. CONCLUSIONS: Under our study conditions and except for certain tests with bacteriophage f2, the IWDS reduced the microbial populations tested by a factor of 5 log10. The aerosol dispersion problem remains to be solved, and the significance of the chemical by-products released will require further investigation. [TOP OF PAGE]

  47. High energy phosphate bonds: Optional or obligatory? Kalckar, H.M. (1992). pp. 43-49. In In Cairns, J., Stent, G.S., and Watson, J.D. (eds.), Phage and the Origins of Molecular Biology (expanded edition). Cold Spring Harbor Laboratory Press, Cold Spring Harbor, NY. "…5-hydroxymethylcytosine in the DNA of T-even phages (reference), a pyrimidine whose existance would indeed be difficult to explain by invoking chemical evolution based on structural chemical characteristics (cf. Hattmann and Fukasawa, 1963) made it evident, however, that it was what we would call 'social' incompatibilities betweeen phage and host which may have governed the evolutionary history of hydroxymethylcytosine and its glucosylated DNA derivatives… Although Salmonella mutants lacking 4-epimerase lose all the galactose of their polysaccharides, their generation time and general viability in galactose-free nutrient media are unaffected (Fukasawa and Nikaido, 1959). The galactose-free creatures are even protected from attack by the phage P-22 (Fukasawa and Nikaido, 1960), because they have lost the superficial phage receptor sites whose specificity depends on galactose and the deoxyhexoses which nest on galactose… One could ask why any cell should waste the 'high energy phosphate' resident in UTP for the sake of synthesizing a compound like UDP-galactose which seems superfluous, and even hazardous. One answer to this question may be that perhaps the hazards are outweighed by the prospects of novel biological combinations. Phage P-22 is a temperate phage which offers a chance to acquire new genetic information by grace of lysogeny to a small fraction of those potential host cells that contains accessory sugars like galactose or deoxyhexoses. Perhaps this innovation, or 'transfiguration' of the minority offers advantages that greatly outweigh the heavy toll of death—the fate of the majority of the population.¶ Finally we must bear in mind the possibility that the development of pathways for the biosynthesis of some of these accessory sugars may be completely optional and carry neither positive nor negative selective values." [quoted from pp. 46 and 47 of Kalckar]. [TOP OF PAGE]

  48. Inactivation of lambda phage with 658 nm light using a DNA binding porphyrin sensitizer. Kasturi, C., Platz, M.S. (1992). PHOTOCHEMISTRY AND PHOTOBIOLOGY 56:427-429. Exposure of lambda phage to 658 nm light in the presence of 5,10,15,20-tetrakis-(1-methyl-4-pyridyl)-21H,23H-porphine, tetra-p-tosylate leads to complete (greater than 7 logs) inactivation as measured by the plaque assay. The sensitizer without light and 658 nm photolysis of lambda phage in the absence of sensitizer do not lead to a measurable decrease in viral inactivity. Viral inactivation is not dependent upon the presence of oxygen. [TOP OF PAGE]

  49. Bacteriophage resistance in Lactococcus lactis ssp. lactis using antisense ribonucleic acid. Kim, S.G., Bor, Y.C., Batt, C.A. (1992). Journal of Dairy Science 75:1761-1767. Antisense RNA against a conserved bacteriophage gene when expressed in a Lactococcus lactis ssp. lactis strain renders it resistant to bacteriophage infection. Two open reading frames have been identified in a L. lactis ssp. lactis bacteriophage that are conserved in a majority of isolates. They code for an 18-kDa (designated GP18C) protein and a 24-kDa (GP24C) protein, respectively, which are arranged along with previously identified open reading frames in a tandem motif similar to other bacteriophages. The presence of gp18C and gp24C in a number of bacteriophage isolates was confirmed by polymerase chain reaction using primers specific for these regions. Plasmids bearing various fragments of gp18C, gp24C, or both were constructed such that the respective open reading frames were positioned in the antisense direction relative to the Lactococcus lactis ssp. cremoris Wg2 promoter, p59. These antisense RNA-producing vectors inhibited the efficiency of plaquing of L. lactis ssp. lactis bacteriophage phi 7-9 up to 50%; the resulting plaques were extremely small and irregular in shape. The replication of the bacteriophage was severely inhibited, and the total number decreased over the first 3 h during infection in strains expressing antisense RNA compared with the host strain alone, in which the bacteriophage number increased 10(4)-fold. [TOP OF PAGE]

  50. Bakterienviren. Klaus, S., Krüger, W., Meyer, J. (1992). Gustav Fischer, Stuttgart.[TOP OF PAGE]

  51. Gene transfer in the environment: transduction. Kokjohn, T.A., Miller, R.V. (1992). pp. 54-81. In In Fry, J.C. and Day, M.J. (eds.), Release of Genetically Engineered and Other Microorganisms. Cambridge University Press, Cambridge, United Kingdom. [TOP OF PAGE]

  52. A natural mutant of plasmid RP4 that confers phage resistance and reduced conjugative transfer. Kornstein, L.B., Waters, V.L., Cooper, R.C. (1992). FEMS Microbiol. Let. 70:97-100. A natural isolate of RP4 (PRC:116) acquired from the Stanford University Plasmid Reference Center differed from the wild-type Incompatibility Group P plasmid in several respects. Cells of Escherichia coli harboring PRC:116 were resistant to the IncP pili-specific bacteriophage PRD1 and GU5, and transferred this plasmid at a lower efficiency than the wild-type RP4. Phage sensitivity was restored, and transfer considerably improved in PRC:116+ bacteria transformed with plasmid constructs containing the origin of transfer (oriT region) of RP4. Mutant RP4 plasmids equivalent to PRC:116 were selected at a high frequency from an RP4+ E. coli population infected with PRD1 indicating that this RP4 variant may be the product of a very common mutation of the wild-type plasmid. [TOP OF PAGE]

  53. Isolation and characteristics of phage-resistant mutants of Bacillus thuringiensis var thuringiensis. Koroleva Yu, V., Grigoreva, T.M., Azizbekyan, R.R. (1992). Biotekhnologiya 3-5. 34 phage-resistant mutants of the strain of B. thuringiensis H1-177-131-producing baterial insecticide - bitoxybacilline were isolated with the use of Tb-2-group of Bacillus thuringiensis phages. Phage-resistant mutants limited the growth of phages and maintained the main technological parameters - the level of exotoxin and endotoxin synthesis, spore titration. It was shown that the decreasing of the efficiency of phages development on phage-resistant mutants was not determined with the changes in their phage-receptor apparatus. On the bases of the analysis of the integral parameter- approximate harvest of the phage it was supposed that the phage- resistant might be determined with the internal mechanisms of phages development mechanisms-decreasing of the phages harvest. It was shown that phage-resistant strains might be used as the recipients for transduction, though it fully limited the lytic development of the transduction bacteriophage. The transduction bacteriophage CP-51 in phage resistant organisms helped to carry out the transduction of pBC-16-plasmid, determining tetracycline- resistance. [TOP OF PAGE]

  54. A bacteriological survey of cheese-making and starter practices in a South African cheese factory. Kotze, C.J., Jooste, P.J. (1992). South African Journal of Dairy Science 24:1-6. The quality of a biological product such as cheese, is greatly affected by the conditions under which it is produced. This reports on the activities in a South African cheese factory as determined per questionnaire and by bacteriological monitoring of starter- and cheese-making practices in the factory. Raw milk quality was satisfactory from a Standard Plate Count point on view and the absence of inhibitory substances. Coliform and Yeast Counts were unsatisfactorily high. Undesirable started practices included the use of the same starter on consecutive days and an extended rotation cycle of commercial mixed-strain starters from different supply companies. Low starter population levels in the final curd and young cheese may have been the result of phage activity. [TOP OF PAGE]

  55. Use of polyvalent phage for reduction of Streptomycetes on soil dilution plates. Kurtboke, D.I., Chen, C.F., Williams, S.T. (1992). J. Appl. Bacteriol. 72:103-111. An isolation method was developed in which prior to inoculation soil suspensions were exposed to suspensions of polyvalent phage isolated to Streptomyces spp. The phage susceptibility of streptomycetes provided a selective means of reducing streptomycetes on isolation plates subsequent to inoculation, and this reduction was persistent after long incubation periods. The efficiency and applicability of the method developed were checked with different samples from a range of sources. The increased chances of development of other genera after the reduction of streptomycetes on soil dilution plates were assessed. [TOP OF PAGE]

  56. Stimulation of bacterial cytokinesis by bacteriophage predation. Lammers, W.T. (1992). pp. 261-265. In In Hart, B.T. and Sly, P.G. (eds.), SEDIMENT/WATER INTERACTIONS. Bacteriophage (phage) are ubiquitous in the water column and in the sediments of most natural water. Because of their colloidal nature, they can either aggregate into clumps large enough to settle into the sediment or departing upon the physiochemical conditions or disassociate and reenter the water column. About 80% of the bacterial strains isolate from New River sediment have a virulent phage that can be isolated with them. Liquid cultures of a strain of Pseudomonas aeruginosa isolated from the New River along with its phage were set up. One was infected with the virulent phage and another kept as a control. Daily counts were made of bacterial numbers. After 10 days the control culture was infected and counted for 3 more days. Both cultures divided exponentially at first. The infected culture continued to divide at about half the initial rate. The uninfected culture nearly ceased division, but when phage were added it quickly began to divide. The virulent phage infection clearly stimulated host division. The effect was to establish itself as an endemic infection which did not outpace its host's division rate. Further, the enhanced division rate may act to increase the host's share of available nutrients and benefit its competitive position in the system. [TOP OF PAGE]

  57. Different bacteriophage resistance mechanisms in Streptococcus salivarius subsp. thermophilus. Larbi, D., Decaris, B., Simonet, J.M. (1992). Journal of Dairy Research 59:349-357. Streptococcus salivarius subsp. thermophilus strain NST5 exhibited a temperature-dependent defence mechanism against the virulent bacteriophages phi B1.2 and phi A1.1. It was active at 42 degrees C but not at 30 degrees C as demonstrated by a significant increase of both plaque size and efficiency of plaquing. This defence mechanism did not affect host-dependent phage replication and did not interfere with phage adsorption to NST5. These results suggest that it interfered with phage development. The phages phi T33, phi T58, phi D1, phi T21 and phi T9, belonging to the same phage type as phi B1.2, were examined for their ability to infect NST3 and NST5. Restriction modification systems of different specificity were detected in NST3 and NST5; host-dependent phage replication was detected at 30 and 42 degrees C; an abortive defence mechanism was detected in NST5 which was active at 42 degrees C, but not 30 degrees C, and was independent of restriction modification action or interference with phage adsorption. Our investigations of phage-host interactions showed that the two Str. salivarius subsp. thermophilus strains studied avoided attack by related bacteriophages by evolving at least three different resistance systems. [TOP OF PAGE]

  58. Bioluminescence detection system of mutagen using firefly luciferase genes introduced in Escherichia coli lysogenic strain. Lee, S.M., Suzuki, M., Kumagai, M., Ikeda, H., Tamiya, E., Karube, I. (1992). Analytical Chemistry 64:1755-1759. A rapid and convenient microbial sensing system for mutagens was developed based upon the induction of prophage from Escherichia coli lysogenic strain and bioluminescence. The system consisted of lysogenic E. coli encoding firefly luciferase genes and a photodetection system. Measurement of mutagen mitomycin C was achieved by measuring the luminescence intensity emitted from E. coli lysogenic strain for the recombinant phage in the presence of luminescence substrates. Approximately 1 h after addition of mitomycin C, the luminescence began to be observed, and 3 h after, it attained a level of 2 times greater than that of 1 h. Irradiation with ultraviolet light also produced light based on induction of phage from the E. coli lysogenic strain for the recombinant phage. On the other hand, when nonmutagenic toxic compounds like sodium azide were added to the reaction medium, luminescence was not observed. Mitomycin C could be detected within 1 h with this sensing system, at concentrations down to 10(2) ng/assay. [TOP OF PAGE]

  59. Information spiraling movement of bacteria and their genes in streams. Leff, L.G., Mcarthur, J.V., Shimkets, L.J. (1992). Microb. Ecol. 24:11-24. Bacteria in transport in streams are largely derived from other parts of the ecosystem. Here we review factors that influence transport of bacteria and their movement between habitats (such as sediment, water column, rocks, wood, and leaves) and consider the role of these movements in ecosystem processes. Bacteria enter the water column by sloughing, scouring, as a consequence of changes in morphology or hydrophobicity, or dislodgment by invertebrates and fish or other aquatic vertebrates. Transported cells (which may be planktonic or particle-associated) that colonize surfaces may establish new gene pools through cell division (vertical transfer) or genetic exchange (lateral transfer). Genetic information is also transported in streams as free or protected DNA or in bacteriophages. Movement of these vectors causes genetic information to spiral along a stream in a manner analogous to that of nutrients and organic carbon. Spiraling refers to the pattern of transport, uptake or attachment, and release of a molecule or cell. The flow of water in streams causes this cycle of attachment and release to be displaced downstream resulting in a spiral rather than a closed, stationary loop. [TOP OF PAGE]

  60. The Antibiogic Paradox: How Miracle Drugs are Destroying the Miracle. Levy, S.B. (1992). Plenum Publishers, [TOP OF PAGE]

  61. Cross-contamination potential with dental equipment. Lewis, D.L., Arens, M., Appelton, S.S., Nakashima, K., Ryu, J., Boe, R.K., Patrick, J.B., Watanabe, D.T., Suzuki, M. (1992). Lancet (North American Edition) 340:1252-1254. Some types of reused dental equipment, especially handpieces and their attachments for drilling and cleaning teeth, might be responsible for cross-contamination if patient material were to lodge temporarily in difficult-to-disinfect internal mechanisms. This possibility is worrisome with respect to transmission of hepatitis B and human immunodeficiency viruses (HBV, HIV). Previous cross-contamination studies have relied on laboratory experiments with bacteria or dye tracers. To assess possible risks more thoroughly, we tested 30 new prophylaxis angles and 12 new high-speed handpieces to see whether they would take up and expel contaminants in laboratory and clinical trials. In treatments of three patients, including two infected with HIV, human-specific DNA (beta-globin, HLA DQ-alpha) and HIV proviral DNA were detected inside or coming back from the devices. Similarly, when handpieces were operated in contact with blood pooled from HBV-infected patients, HBV DNA was detected in samples taken from inside the equipment and from their attached air/water hoses. When we used bacteriophage phi-174 as a model virus in laboratory tests, many infective viral particles were recovered from internal mechanisms of handpieces, their connecting air/water hoses, and from water spray expelled when the equipment was reused. We recommend that reused high-speed, air-driven handpieces and prophylaxis angles should be cleaned and heat-treated between patients. Further studies are needed to determine ways of elimating the risks associated with exhaust hoses and air/water input lines. [TOP OF PAGE]

  62. Phage-inactivating effect of iron(II)-ascorbate complex. Lho, I.-H., Miyake, H., Morita, K. (1992). TEMP 99/06/16 56:720-724. [TOP OF PAGE]

  63. Origin of phage particles in culture fluids during the industrial production of fodder protein with the use of methanotrophic bacteria: The role of the bacteria in the discontinuing the fermentation process. Lobanov, A.O., Turin, V.S., Krylov, V.N. (1992). Biotekhnologiya 4-8. There is a direct confirmation of the possibility that the phage lysis of the attending cultures may cause the death of the main culture in the article. Besides reviewed are the properties as follows: data received during electronic-microscope observations of bacteria during continous fermentation proving the existing phages, specific for bacteria, which are in the special physiological state caused probable by the continuous character of fermentation. [TOP OF PAGE]

  64. Partial characterization of coliphage WPK and a comparison with coliphage T3. Loeffelholz, L., Maier, S. (1992). Microbiology and Immunology 36:173-189. Coliphage WPK was originally isolated from sewage in Kiel, Germany, because its plaque diameter continued to expand for days. Electron microscopy revealed an isometric capsid with dimensions of 54 nm between opposite apices, and a short, noncontractile tail 16 nm long, placing phage WPK into morphogroup C1. The nucleic acid of phage WPK was linear double stranded DNA. The host ranges of phages WPK and T3 were identical. Of ten E. coli strains tested for host range, two were resistant and of eighteen other Enterobacteriaceae only four were susceptible. Seven gram-negative species which are not members of the Enterobacteriaceae were refractory. However, there were differences in plaque morphology and plaque expansion between the two phages. Phage T3 plaques expanded for at least seven days on E. coli B only, while phage WPK plaques expanded for at least seven days on four strains of E. coli. The buoyant density of WPK, determined by isopycnic density gradient centrifugation in CsCl, was 1,508 g/ml which was significantly different than that of T3 at 1.493 g/ml (P less than 0.05). Phage-encoded proteins were examined for each phage using [35S]methionine incorporation, SDS-PAGE, and autoradiography. Of thirty proteins identified in phage WPK and twenty-eight in phage T3, only fourteen were of the same size in both. We concluded that phage WPK was distinct, but related to T3. [TOP OF PAGE]

  65. Mutations of bacteria and of bacteriophage. Luria, S.E. (1992). pp. 173-179. In In Cairns, J., Stent, G.S., and Watson, J.D. (eds.), Phage and the Origins of Molecular Biology (expanded edition). Cold Spring Harbor Laboratory Press, Cold Spring Harbor, NY. [TOP OF PAGE]

  66. Etude moléculaire comparative de 18 bacteriophages appartenant au morphospecies T-pair. Maftahi, M. (1992). Unité des Entérobactéries, U199 INSERM, Institut Pasteur, Paris, France. [TOP OF PAGE]

  67. Differences in the production of tempered bacteriophages in lysogenic Salmonella typhimurium and Pseudomonas aeruginosa strains. Majtanova, L.'U. (1992). Biologia (Bratislava) 47:503-506. The examined lysogenic strains of two bacterial species, pathogenic S. typhimurium and conditionally pathogenic P. aeruginosa, showed differences in the production of tempered bacteriophages. In the lysogenic strains of S. typhimurium, by the help of sensitive strains of the same species, the phage DNA replicated. The evidence of the replication wss given by the presence of mature phages in the nutrient solution. In the lysogenic strains of P. aeruginosa, at the same conditions, temperature were not isolated even after the induction of UV radiation. [TOP OF PAGE]

  68. Characterization, localization, and sequence of F transfer region products: the pilus assembly gene product TraW and a new product, TrbI. Maneewannakul, S., Maneewannakul, K., IPPEN-IHLER, K. (1992). J. Bacteriol. 174:5567-5574. The traW gene of the Escherichia coli K-12 sex factor, F, encodes one of the numerous proteins required for conjugative transfer of this plasmid. We have found that the nucleotide sequence of traW encodes a 210-amino-acid, 23,610-Da polypeptide with a characteristic amino-terminal signal peptide sequence; in DNA from the F lac traW546 amber mutant, the traW open reading frame is interrupted at codon 141. Studies of traW expression in maxicells in the presence and absence of ethanol demonstrate that the traW product does undergo signal sequence processing. Cell fractionation experiments additionally demonstrated that mature TraW is a periplasmic protein. Electron microscopy also showed that F lac traW546 hosts do not express F pili, confirming that TraW is required for F-pilus assembly. Our nucleotide sequence also revealed the existence of an additional gene, trbI, located between traC and traW. The trbI gene encodes a 128-amino-acid polypeptide which could be identified as a 14-kDa protein product. Fractionation experiments demonstrated that TrbI is an intrinsic inner-membrane protein. Hosts carrying the pOX38-trbI::kan insertion mutant plasmids that we constructed remained quite transfer proficient but exhibited increased resistance to F-pilus-specific phages. Mutant plasmids pOX38-trbI472 and pOX38-trbI473 expressed very long F pili, suggestive of a pilus retraction deficiency. Expression of an excess of TrbI in hosts carrying a wild-type pOX38 plasmid also caused F-pilus-specific phage resistance. The possibility that TrbI influences the kinetics of pilus outgrowth and/or retraction is discussed. [TOP OF PAGE]

  69. Enterobacterial and viral decay experimental models for anaerobic digestion of piggery waste. Mateu, A., Mata, A.J., Pares, R. (1992). Appl. Microbiol. Biotechnol. 38:291-296. A laboratory study was conducted to determine the effects of the continuous mesophilic anaerobic digestion of raw pig manure in two types of enteropathogenic microorganisms, bacterial and viral. Faecal coliforms (indigenous to pig manure) and coliphage f2 (ATCC 15766 B1) were used as a model for some indigenous enteropathogenic microorganisms. The study was completed with laboratory survival experiments in lagoon stabilization of raw pig manure, for both models. Experiments for f2 survival in cell- free synthetic medium were also carried out. The results show that the anaerobic digestion process is more effective in eliminating viral than bacterial particles. Some parameters related to the ultimate biogas yield and kinetics were also determined. Lagoon stabilization of raw pig manure provides a more suitable environment for the removal of faecal coliforms than does anaerobic digestion. Finally, it was concluded that volatile fatty acids appeared to be repsonsible for the elimination of faecal coliforms. The agent that causes f2 inactivation is not well identified, although in some cases it could be NH3 that seems to act as a viricidal agent. [TOP OF PAGE]

  70. A broad-host-range vibriophage, KVP40, isolated from seawater. Matsuzaki, S., Tanaka, S., Koga, T., Kawata, T. (1992). Microbiology and Immunology 36:93-97. [TOP OF PAGE]

  71. Repliction of chorella virus PBCV-1 and host karyotype determination studied with pulsed-field gel electrophoresis. Mccluskey, K., Graves, M., V, Mills, D., Meints, R.H. (1992). Journal of Phycology 28:846-850. We demonstrated the time-course of DNA replication of the 330-kbp Chlorella virus PBCV-1 by pulsed-field gel electrophoresis. Viral DNA replication began between 90 and 120 min postinfection in cell samples produced without first removing cell walls. The host nuclear genome was degraded beginning almost immediately after infection, but some host DNA remained even after 360 min postinfection. The karyotype of the host alga consisted of nine resolvable bands that we presume to represent 13 chromosomes based on band intensity. The chromosomes ranged in size from 1.1 to 6.5 megabase pairs (Mbp). A summation of the sizes of the bands predicts a genome size of 39-45 Mbp of DNA. [TOP OF PAGE]

  72. Effect of reproduction of cyanophages A-1, S-8K and LPP-3 on proteolysis processes in the cells of cyanobacteria. Mendzhul, M.I., Koltukova, N.V., Lysenko, T.G., Shainskaya, O.A. (1992). Mikrobiologichnyi Zhurnal [MIKROBIOL. ZH. ] 54:90-95. The dynamics of proteolytic activity and formation of protein metabolism products (free aminoacids and peptides) in three virus-cell systems (Anabaena variabilis - A-1, Synechococcus cedrorum-S-8K, Plectonema boryanum - LPP-3) have been studied as affected by cyanophage infection. Proteolytic activity of the cell-free extracts of cyanobacteria is established to considerably change during the cyanophage development. Preparations isolated from the cells 1h after infection are the most active ones. Proteolytic activity of the cells 3h after the infection (period of intensive morphogenesis of virions) is almost commensurable with that of the noninfected cells. The level of proteolytic activity and the content of free aminoacids and peptides well correlate only in the system LPP-3-P. boryanum. Such an agreement was not revealed in two other-virus-cellular systems and this is, probably, connected with different specificity of proteinases, which perform degradation of cell proteins, and with the differences in the processes of the de novo synthesis of amino acids and proteins. Various ways and mechanisms, including proteolysis-performed by virus-induced proteinases, may be involved in formation of a pool of free aminoacids in different virus-cellular systems. [TOP OF PAGE]

  73. Characterization of an O-antigen bacteriophage from Aeromonas hydrophila. Merino, S., Camprubi, S., Tomas, J.M. (1992). Canadian Journal of Microbiology 38:235-240. A unique bacteriophage of Aeromonas hydrophila serotype O:34 was isolated, purified, and characterized. The bacterial surface receptor was shown to be the O-antigen polysaccharide component of lipopolysaccharide specific to serotype O:34, which was chemically characterized. The high molecular weight lipopolysaccharide fraction (a fraction enriched in O antigen) was fully able to inactivate bacteriophage PM1. Phage-resistant mutants of A. hydrophila O:34 were isolated and found to be specifically devoid of lipopolysaccharide O antigen. No other cell-surface molecules were involved in phage binding. The host range of bacteriophage PM1 was found to be very narrow, producing plaques only on A. hydrophila strains from serotype O:34. [TOP OF PAGE]

  74. Virus-mediated gene transfer in freshwater environments. Miller, R.V., Ripp, S., Replicon, J., Ogunseitan, O.A., Kokjohn, T.A. (1992). pp. 50-62. In In Gauthier, M.J. (ed.), Gene Transfers and the Environment. SpringerVerlag, Berlin. [TOP OF PAGE]

  75. Bacteriophage-host interactions in aquatic systems. Miller, R.V., Sayler, G.S. (1992). pp. 176-193. In In Wellington, E.M.H. and van Elsas, J.D. (eds.), Genetic Interactions among Microorganisms in the Natural Environment. Pergamon Press, Oxford. Recently, bacterial virus (bacteriophage) concentrations in many aquatic environments have been reported to be one to two orders of magnitude higher than bacterioplankton (Bergh et al., 1989, B&#248rsheim et al., 1990; Bratbak et al., 1990; Proctor & Fuhrman, 1990). These observations have brought into question many of our conclusions about the ecology of aquatic microbial populations. Is bacterial abundance really controlled by viral infection and not by heterotrophic nanoplanktonic predators as has been previously thought? Is the make-up of bacterial communities controlled by bacteriophage susceptibility? Is gene transfer of chromosomal and extrachromosomal DNA by transduction a viable method for the reassortment of natural gene pools in aquatic microbial populations? Will alterations to the environment which alter the flux of solar UV radiation have an effect on interactions between aquatic bacteriophages and their bacterial host populations? Even though phage-host interactions have not been investigated in any great detail in aquatic environments, there are data that suggest each of these questions may be answered in the affirmative. In this review, we survey the available literature pertinent to assessing the roles of environmental viruses in determining microbial community structure and diversity in aquatic ecosystems. [TOP OF PAGE]

  76. Further investigations on the concentration of marine bacteriophages in the water around helgoland with reference to the phage-host systems encountered. Moebus, K. (1992). Helgol. Meeresunters. 46:275-292. Between April 3 and September 24, 1991, the concentrations of bacteriophages infecting bacterial strains, isolated in 1990 and during this investigations, were determined in 35 samples of seawater taken at station 'Kabeltonne' adjacent to Helgoland. Similar to the findings of 1990, phage concentrations of several hundred plaque forming units (PFU) ml-1 were observed with a number of indicator strains, the maximum concentration being at least 1.5 .times. 103 PFU ml-1. These high concentrations lasted for only a few days, generally decreasing at rates between 0.6 and 0.9 day-1. Phage concentrations of 0 to 2 PFU ml-1 were found to be prodominant until the end of June, occasionally attaining 5 PFU ml-1. From July through September, when high phage concentrations were observed with some indicator strains, between 0 and 10 PFU ml-1 were found in the majority of tests. As revealed by a final phage-host cross-reaction test, the greater part of 138 indicator bacteria is genetically related, and almost half of the 200 phage strains tested are propagated only by their original indicator bacterium. The possible importance of mutational events for the maintenance of phage-host systems in nature is discussed. [TOP OF PAGE]

  77. Laboratory investigations on the survival of marine bacteriophages in raw and treated seawater. Moebus, K. (1992). Helgol. Meeresunters. 46:251-273. Laboratory investigations were performed to gain insight into the mechanisms which govern the survival bacteriophages in nature. Samples collected in 1988 to 1990 at station "Kabeltonne" near Helgoland were used raw, membrane-filtered (0.15 .mu.m), and/or after inverse filtration through 10 .mu.m-mesh gauze to reduce or increase live and dead particles. The development of natural or artificial bacterial populations and the survival of 2 to 10 distinguishable strains of test phage were followed during incubation at 20.degree. C. The results obtained with most test phages point to the predominant role of indigenous bacteria for marine phage inactivation which was generally enhanced by sample managements leading to improved growth of bacteria. The virucidal properties of the samples differed greatly in total strength as well as in the changes taking place during incubation, the latter resulting in conspicuously differing inactivation curves. Generally, phage inactivation was slow during the first 2 to 3 days of incubation, followed by a peroid of very rapid inactivation which usually coincided with the die-away of colon- forming bacteria. This period lasted either only a few days or until the concentration of test phage was reduced to (near) zero. While the inactivation of most test phage is assumedly caused by proteolytic enzymes released during the die-away of bacteria, the survivability of one test phage (H7/2) was also markedly influenced by the bacteria sensitive to it. Survival rates of the test phages in the laboratory tests were generally of the same order of magnitude as those recently observed with natural phage populations. [TOP OF PAGE]

  78. Preliminary observations on the concentration of marine bacteriophages in the water around helgoland. Moebus, K. (1992). Helgol. Meeresunters. 45:411-422. In a preliminary survey, conducted between August 28 and October 9, 1990, the concentration of bacteriophages in seawater sampled at intervals of 1 to 4 days near Helgoland (station Kabeltonne) was determined by using indicator bacteria which had been isolated from seawater sampled only some weeks before. With a number of bacterial strains, phage concentrations ranging between 2 and 7 .times. 102 ml-1 were found. However, during the course of this investigation maximal concentrations lasted for a few days only. With most indicator bacteria employed, the concentration of plaque-forming units (PFU) varied in the range of < and 20-30 PFU ml-1. [TOP OF PAGE]

  79. Characterization of lactococcal bacteriophages from Quebec cheese plants. Moineau, S., Fortier, J., Ackermann, H.-W., Pandian, S. (1992). Canadian Journal of Microbiology 38:875-882. This is the first study on the characterization of lactococcal phages isolated in Canada. Thirty lactococcal phages were isolated from Quebec cheese plants reporting partial loss of starter activity. Phages were characterized by electron microscopy, DNA homology, protein profile, and host range. All phages belonged to the Siphoviridae family. Seventeen phages (57%) has prolate heads (60 times 40 nm) and 100 nm long, noncontractile tails (morphotype B2, species c2). They showed strong DNA homology with other prolate-headed phages isolated from other countries (Australia, United States). In addition to normal prolate phages, most lysates contained pairs of empty heads (no DNA) connected by a small bridge. Thirteen phages (43%) had small isometric heads (55 nm in diameter) and long, noncontractile tails (morphotype B1). Based on DNA homology, 11 of these phages were found related to phage species 936 despite differences in tail length (140 to 200 nm). The two other small isometric phages, UL36 and UL39, hybridized with phage P335 DNA, and therefore belong to this species. No DNA homology was observed between prolate and small isometric phages. Phages with prolate heads showed a broader host range than small isometric-headed phages. The DNA of phage UL36, which has a relatively narrow host range, has more restriction endonuclease sites than other lactococcal bacteriophages. [TOP OF PAGE]

  80. Evaluation of different bacteriophage groups as faecal indicators in contaminated natural waters in southern England. Morinigo, M.A., Wheeler, D., Berry, C., Jones, C., Munoz, M.A., Cornax, R., Borrego, J.J. (1992). Water Res. 26:267-271. [TOP OF PAGE]

  81. [Factors that affect transduction in microorganisms]. Mukvich, N.S., Romaniuk, L.V., Didyk, O.A. (1992). MIKROBIOLOGICHESKII ZHURNAL 54:75-86. Data from literature concerning general and specialized transduction in microorganisms are given in the paper. The process of exogenic DNA penetration to the cells of bacteria and participation of protein products of separate phage genes in this process are described. The so-called E-proteins in a set with DNA penetrate through a cell membrane. In phage P22 they are protein products of phage genes 7, 16, 20. In P22 mutants with an altered transducing frequencies (HFT and LFT) the due functions are also coded by the phage genes. It is shown that the process of DNA packing in phages P22, phi 80, lambda and others is genetically determined. The gene transfer frequency depends on UV radiation and the very nature of transducing phages itself. In virulent phages the UV radiation up to inactivation level 95-99% evokes a decrease of their "killer "ability, which is accompanied by an increase of survivability of the formed transductants and, as a result, by enhancement of the transduction transfer frequency. An important role of the transduction analysis for fine mapping of a genome of microorganisms and its significance for practice are shown. A mathematical analysis of the data on cotransduction of linkage markers is presented as such that may be used when determining the value of transduced fragment of a chromosome. [TOP OF PAGE]

  82. Viral dynamics: A model of the effects of size, shape, motion, and abundance of single-celled planktonic organisms and other particles. Murray, A.G., Jackson, G.A. (1992). Mar. Ecol. Prog. Ser. 89:103-116. The transport of aquatic viruses to particles can be described in terms of diffusive transport from solution. Such transport is influenced by motion of the water relative to the particle. Because transport rate is determined purely by physical factors it is independent of whether the particle is a host or non-host organism. The low viral diffusivity relative to that for dissolved nutrients makes transport enhancement from organism swimming more important for viruses. The virus contact rate with bacteria is relatively unaffected by such motions because of small bacterial sizes. Transport rates for phytoplankton and protozoa can increase over an order of magnitude when swimming motions are considered. Although larger organisms have much higher transport rates per individual, their far lower concentrations in sea water should make small organisms the preferred targets for viruses. Rates of host-virus interactions in culture are closely related to predictions from transport theory. There is a fairly close relationship between bacterial populations and virus disappearance rates in the marine environment, suggesting that non-host organisms are a major cause of viral mortality at the higher ionic strengths typical of sea water. Other factors, such as UV radiation, must also be included when estimating viral mortality in seawater. [TOP OF PAGE]

  83. Isolation and characterization of bacteriophages specific for capsular antigens K3, K7, K12, and, K13 of Escherichia coli. Nimmich, W., Krallmann Wenzel, U., Mueller, B., Schmidt, G. (1992). Zentralblatt Fuer Bakteriologie 276:213-220. Four bacteriophages recognizing the Escherichia coli capsular antigens K3, K7, K12, and K13, respectively, were isolated from pooled sewage samples. The nucleic acid of these phages was identified as double-stranded DNA of different size (.fK3, 71.3, .f.K7, 32.8; .f.K12, 42.9; .f.K13, 43.4 kbp). Three of these phages belonged to Bradley's morphology group C and were specific for K3, K7, and K12 antigens, respectively. The phage .f.K13 (Bradley's group A) attacked not only E. coli K13 strains but also E. coli producing the closely related K20 and K23 antigens. It is suggested that the common basic repeating units occurring in these capsular polysaccharides are the primary receptor of .phi.K13. It could be demonstrated that the four phages were able to depolymerize enzymatically the capsular polysaccharides isolated from the respective host strains. [TOP OF PAGE]

  84. The susceptibility of nodule bacteria with the unclear taxonomic position to bacteriophages of various Rhizobium genera. Novikova, N.I., Limeshchenko, E.V. (1992). Mikrobiologiya 61:484-489. Seven isolates of Rhizobium loti phages, three phages of R. leguminosarum biovar trifolii and a phage of R. galegae have been isolated from soil samples collected in locations where legumes grow. These bacteriophages, and also four phages of R. meliloti characterized previously and a phage of R. galegae werre used for phagotyping of nodule bacteria with unknown taxonomic position from a milk vetch (Astagalus), a liquorice (Glycirrhiza), a rest-harrow (Ononis), a French honeysuckle (Hedysarum) and a crown vetch (Coronilla). It was found that R. meliloti, R. leguminosarum and R. galegae lysed only bacterial strains of homologous species. Strains susceptible to R. loti bacteriophages were present among nodule bacteria from a milk vetch, a liquorice, a rest-harrow and a French honey-suckle, and the effectiveness of the inoculation of phages studied on these strains was near one. [TOP OF PAGE]

  85. Antibody response to bacteriophage phi X174 in patients with adenosine deaminase deficiency. Ochs, H.D., Buckley, R.H., Kobayashi, R.H., Kobayashi, A.L., Sorensen, R.U., Douglas, S.D., Hamilton, B.L., Hershfield, M.S. (1992). Blood 5:1163-1171. [TOP OF PAGE]

  86. Application of DNA probes to analysis of bacteriophage distribution patterns in the environment. Ogunseitan, O.A., Sayler, G.S., Miller, R.V. (1992). Appl. Environ. Microbiol. 58:2046-2052. Radiolabeled bacteriophage DNA probes have been used in this study to determine the distribution of Pseudomonas aeruginosa-infecting bacteriophages in natural samples of lake water, sediment, soil, and sewage. The sensitivity of detection of bacteriophage with the DNA probes was between 103 and 104 PFU and 106 to 107 CFU of lysogenized bacteria detectable with a homologous phage DNA probe. Analyses of environmental samples suggest that up to 40% of P. aeruginosa in natural ecosystems contain DNA sequences homologous to phage genomes. By using different bacteriophage DNA probes, the diversity of the bacteriophage population in sewage was estimated to be higher than that in other natural samples. The indication that transducing phages and prophages are widely distributed in the Pseudomonas populations investigated has considerable implications for the frequency of natural gene transfer by transduction and of lysogenic conversion of host bacteria in natural ecosystems. [TOP OF PAGE]

  87. Characterization of water quality in the Ukrainian part of the Danube (by general indices). Oksiyuk, O.P., Zhuravleva, L.A., Lyashenko, A.V., Bashmakova, I.K., Karpezo, Y.I., Ivanov, A.I. (1992). Gidrobiologicheskii Zhurnal 28:3-11. The quality of water in the Ukrainian part of the Danube has been characterized as to mineralization and ecological-sanitary indices. It is shown that the composition and properties of the Danube water flowing into the Ukrainian part are formed mainly in the territory of Bulgaria and Romania; as flowing on along the Bulgarian-Romanian part the quality of water decreases by most indices as a result of anthropogenic pollution. In the present period the prograssing eutrofication and deterioration of water quality in the Ukrainian part of the Danube are observed as compared to the indices of late 70s, that is greatly caused by intensification of phytoplankton vegetation because of water turbidity decrease (especially in low-water years) as a result of the Danube regulated flow. [TOP OF PAGE]

  88. Population dynamics of bacteriophage and Bacillus subtilis in soil. Pantastica-Caldas, M., Duncan, K.E., Istock, C.A., Bell, J.A. (1992). Ecology 73:1888-1902. The dynamics of the interaction of populations of Bacillus subtilis and a temperate bacteriophage in soil microorganisms were examined. The purpose of the study was to investigate these dynamics in a structured habitat approaching that of their natural habitat in soil, in contrast to previous investigations in broth or chemostats. We addressed three main questions. What are the population dynamics of a phage-bacteria interaction in soil. What role might the heterogeneity of the soil play in shaping the interaction. Are the dynamics controlled more by the population biology of the phage or of the bacteria. The phage used was isolated from Arizona USA desert soil in which B. subtilis is common. Phage and bacteria were grown separately or together in sterile soil microcosms consisting of autoclaved soil rich in organic material. Densities of phage and bacteria were estimated through repeated sterile sampling of the microsomes by spreading precise dilutions of sampled soil suspensions onto plates of microbiological media. The plates for estimation of phage densities contained in addition a lawn of host bacteria. While the principal focus is on temperate phage ecology, the dynamics of a single example of interaction between B. subtilis and virulent phage is also presented. In all cases an initial epidemic of phage occurred, followed by stable equilibria lasting weeks to months. A threshold host density for phage outbreak occurs at .apprxeq. 5 .times. 10^6 colony-forming units per gram of soil. At equilibrium the phage, both temperate and virulent, were much less abundant than the bacteria. The temperature phage did not depress the equilibrium host density, while the virulent phage lowered it by a factor of ten. The acidic soil of these experiments caused rapid and permanent inactivation of free phage, making the continuous interaction of phage and host essential for persistence of phage. Low levels of phage resistance (superimmunity or genetic) were typical of host populations. Most properties of the interaction between B. subtilis and phage in soil are quite different from those observed with chemostat populations of Escherichia coli and virulent phages. Potential doubling times and rates of increase in soil for phage and B. subtilis were calculated. At equilibrium, soil slows the interaction of phage and host relative to population growth in broth culture, and possibly also makes it heterogeneous in space and time. The life-history features of B. subtilis and temperature phage ae considerably more complex than those of non-sporeforming bacteria and virulent phage. The biotic relationship of temperate phage and host may be distinct from predation of parasitism. Patterns in the ecology and evolution of temperate and virulent phage were explored, leading to the expectation that temperate forms will be more common among the phages of soil bacteria. [TOP OF PAGE]

  89. The rex system of bacteriophage lambda: Tolerance and altruistic cell death. Parma, D.H., Snyder, M., Sobolevski, S., Nawroz, M., Brody, E., Gold, L. (1992). Genes. Dev. 6:497-510. The rexA and rexB genes of bacteriophage l encode a two-component system that aborts lytic growth of bacterial viruses. Rex exclusion is characterized by termination of macromolecular synthesis, loss of active transport, the hydrolysis of ATP, and cell death. By analogy to colicins E1 and K, these results can be explained by depolarization of the cytoplasmic membrane. We have fractionated cells to determine the intracellular location of the RexB protein and made RexB-alkaline phosphatase fusions to analyze its membrane topology. The RexB protein appears to be a polytopic transmembrane protein. We suggest that RexB proteins form ion channels that, in response to lytic growth of bacteriophages, depolarize the cytoplasmic membrane. The Rex system requires a mechanism to prevent l itself from being excluded during lytic growth. We have determined that overexpression of RexB in l lysogens prevents the exclusion of both T4 rII mutants and l ren mutants. We suspect that overexpression of RexB is the basis for preventing self-exclusion following the induction of a l lysogen and that RexB overexpression is accomplished through transcriptional regulation. [TOP OF PAGE]

  90. Differential activities of bacteriophage depolymerase on bacterial polysaccharide: binding is essential but degradation is inhibitory in phage infection of K1-defective Escherichia coli. Pelkonen, S., Aalto, J., Finne, J. (1992). J. Bacteriol. 174:7757-7761. Host range mutants were derived from bacteriophages PK1A and PK1E specific for the K1 polysialic acid capsule of Escherichia coli. The mutants were selected for their ability to infect E. coli bacteria with a low level of the K1 capsule. A specific loss of the cleaving activity of the phage endosialidase was observed in all the mutants, while the ability to bind specifically to the polysialic acid capsule was retained. The results indicate that the polysaccharide-binding activity of the bacteriophage enzyme is essential for the infection process. The cleaving activity, in contrast, is required for the penetration of the dense polysaccharide of wild-type bacteria but is inhibitory in the infection of bacteria with a sparse capsular polysaccharide. [TOP OF PAGE]

  91. Detection of gene transfer in aquatic environments. Pickup, R.W. (1992). pp. 145-164. In In Wellington, E.M.H. and van Elsas, J.D. (eds.), Genetic Interactions among Microorganisms in the Natural Environment. Pergamon Press, Oxford. [TOP OF PAGE]

  92. Bacteriophage phi X-174 as an aerobiological marker for surgical plume generated by the electromagnetic field focusing system. Price, J.A., Yamanashi, W., McGee, J.M. (1992). Journal of Hospital Infection 21:39-50. The aerosol of surgical plume could be measured effectively with the use of bacteriophage phi X-174 as a biological marker, in contrast to previous methodologies reported by others. Recovery of virus plaque-forming units was highest from hydrophobic polytetrafluoro-ethylene membranes compared to hydrophobic polycarbonate screen filters or polyvinylidene difluoride depth filters, indicating that the method of virus recovery strongly affects the utility of a virus as an aerobiological marker. With this new method, surgical plume was indeed found in significant amounts when cutting tissue phantoms made with agar containing virus. The Electromagnetic Field Focusing System was used, which is a new thermal surgical device. The nominal power setting did not appear to be a factor in the amount of virus recovered. However, when pulse modulating the power by adjusting the crest factor from 1.4 to 4.3, a measure of the duty cycle for power delivery which adjusted the device from its cutting to haemostatic mode, a nearly five-fold increase in surgical plume, as evidence by the recovery of phi X-174 plaque forming units, was seen. The data indicate that bacteriophage phi X-174 can be used effectively as an aerobiological marker for aerosols generated during clinical procedures, and reinforce the need to use a safety vacuum during aerosol generating procedures. The availability of a safe and economical biological marker for aerosols from clinical procedures, which may lead to acquired infections in hospital personnel, makes evaluation of procedures and containment systems markedly easier. The data also indicates that surgical plume biohazard may be present in other techniques that employ pulse modulation including surgical lasers and electrocauteries. [TOP OF PAGE]

  93. Mortality of marine bacteria in response to enrichments of the virus size fraction from seawater. Proctor, L.M., Fuhrman, J.A. (1992). Mar. Ecol. Prog. Ser. 87:283-293. The potential for viral lysis of marine bacteria in seawater enriched with the virus size fraction from seawater was investigated in seawater samples from Long Island Sound, USA, the eastern Pacific Ocean and the Caribbean Sea. Ultrafiltration was used to concentrate material from seawater in the > 0.05 .mu.m to <0.22 .mu.m size fraction. Electron microscopy counts of virus-like particles in the high molecular weight concentrate (HMWC) correlated closely to epifluorescence microscopy counts of <0.22 .mu.m DAPI-positive, DNase-resistant particles of the HMWC. Acridine orange direct counts of bacterial abundances significantly declined (often to 1/2 or less of controls) when seawater was incubated with 4- to 16-fold enrichnments of HMWC. Microwave treatment of the HMWC before addition to seawater virtually eliminated the declines in bacterial abundance. The combined evidence of the size range of particles, the heat lability of the HMWC and the presence of <0.22 .mu.m DAPI-fluorescent, DNase-resistant particles by epifluorescence microscopy and abundant virus particles by electron microscopy suggests that a dominant bacterial mortality agent in the seawater concentrate was bacteriophage, although we could not rule out an effect of high molecular weight proteins. [TOP OF PAGE]

  94. DNA as a solar dosimeter in the ocean. Regan, J.D., Carrier, W.L., Gucinski, H., Olla, B.L., Yoshida, H., Fujimura, R.K., Wicklund, R.I. (1992). Photochemistry & Photobiology 56:35-42. Stratospheric ozone depletion may result in increased solar UV-B radiation to the ocean's upper layers and may cause deleterious effects on marine organisms. The primary UV-B damage induced in biological systems is to DNA. While physical measurements of solar UV-B penetration into the sea have been made, the effective depth and magnitude of actual DNA damage have not been determined. In the experiments reported here, UV-B-induced photoproducts (cyclobutane pyrmidine dimers) have been quantified in DNA molecules exposed to solar UV at the surface and at various depths in clear, tropical marine waters off Lee Stocking Island (23.degree. 45' N, 76.degree. 0.7' W), Exuma Cays, Bahamas. 14Cthymidine-labeled DNA or unlabeled bacteriophage .vf.X174 DNA was placed in specially designed quartz tubes at various depths for up to five days. Following exposure, DNA samples were removed to the laboratory where UV-B-induced pyrimidine dimers were quantified using a radiochromatographic assay, and bacteriophage DNA inactivation by solar UV-B was assayed by plaque formation in spheroplasts of Escherichia coli. Pyrimidine dimer induction was linear with time but the accumulation of dimers in DNA with time varied greatly with depth. Attenuation of dimer formation with depth of water was exponential. DNA at 3 m depth had only 17% of the pyrimidine dimers found at the surface. Bacteriophage .vf.X174 DNA, while reduced 96% in plaque-forming ability by a one day exposure to solar UV at the surface of the water, showed no effect on plaque formation after a similar exposure at 3 m. The data collected at the water's surface showed a "surface-enhanced dose" in that DNA damages at the real surface were greater than at the imaginary surface, which was obtained by extrapolating the data at depth to the surface. These results show the sensitivity of both the biochemical (dimers) and biological (phage plaques) DNA dosimeters. DNA dosimeters offer a sensitive, convenient and relatively inexpensive monitoring system, having both biochemical and biological endpoints for monitoring the biologically effective UV-B flux in the marine environment. Unlike physical dosimeters, DNA dosimeters do not have to be adjusted for biological effectiveness since they are sensitive only to DNA- mediated biologically effective UV-B radiation. Results of pyrimidine dimer induction in DNA by soloar UV accurately predicted UV doses to the phage DNA. [TOP OF PAGE]

  95. Characteristics and diffusion in the rabbit of a phage for Escherichia coli 0103. Attempts to use this phage for therapy. Reynaud, A., Cloastre, L., Bernard, J., Laveran, H., Ackermann, H.W., Licois, D., Joly, B. (1992). Veterinary Microbiology 30:203-212. A bacteriophage for Escherichia coli 0103 was isolated during a study on E. coli diarrhoea in intensive breeding units of rabbits. The phage had an isometric head and a short tail and resembled coliphage N4 (Podoviridae). It had a very narrow host range and seemed to be specific for serogroup 0103, suggesting that it might be used for preliminary identification of E. coli strains of this serogroup instead of the usual slide agglutination. In view of its possible use as a therapeutic phage, we investigated its dissemination in rabbit organs after oral administration. The phage persisted in the spleen for at least 12 days. However, in vivo studies showed that this phage and a mixture of more virulent phages for E. coli 0103 were ineffective in preventing disease in rabbits inoculated with an enteropathogenic strain of E. coli 0103. [TOP OF PAGE]

  96. Virucidal effectiveness of some commercial disinfectants for chemothermal disinfection procedures tested against temperature resistant viruses and bacteriopahges—evaluation of a test model. Rheinbaben, F.V., Bansemir, K.-P., Heinzel, M. (1992). Zentralbatt für Hygiene 192:419-431. [TOP OF PAGE]

  97. Influence of soil type on the transfer of plasmid RP4p from Pseudomonas fluorescens to introduced recipient and to indigenous bacteria. Richaume, A., Smit, E., Faurie, G., Elsas, J.D.V. (1992). FEMS Microbiol. Ecol. 101:281-292. Transfer of plasmid RP4p from introduced Pseudomonas fluorescens to a co-introduced recipient strain or to members of the indigenous bacterial population was studied in four different soils of varying texture planted with wheat. Donor and recipient strains showed good survival in the four soils throughout the experiment. The numbers of transconjugants found in donor and recipient experiments in two soils, Ede loamy sand and Loss silt loam were significantly higher in the rhizosphere than in corresponding bulk soil. In the remaining two soils, Montrond and Flevo silt loam, transconjugant numbers were not significantly higher in the rhizosphere than in the bulk soil. The combined utilization of a specific bacteriophage to eliminate the donor strain and the pat sequence as a specific marker to detect RP4p was found to be very efficient in detecting indigenous transconjugants under various environmental conditions. The numbers of indigenous transconjugants were consistently higher in rhizosphere than bulk soil. A significant rhizosphere effect on transconjugant numbers was noticeable in Loss soil. Highest numbers of transconjugants were recovered from Flevo and Montrond silt loam; these soils possess characteristics such as clay of organic matter contents which may be favorable to conjugation. [TOP OF PAGE]

  98. Analysis of phagoresistance among pseudomonads. Romashko, A.M., Bylinski, A.F. (1992). Mikrobiologiya 61:478-483. Spontaneous mutants of four Pseudomonas syringae strains resistant to 24 bacteriophages have been received. The cross susceptibility of these mutants to each phage was tested. Formal schemes of phage receptors located on the surface of bacterial cells were drawn on the basis of the results obtained. It was shown that each strain of bacteria had some peculiarities in the construction of the adsorbance apparatus, and cells possessed from 3 to 5 phage receptors. Phages studied could be divided into 9 groups: in these groups they have identical sites of attachment to bacterium-host cells. [TOP OF PAGE]

  99. Phage T7 in biological UV dose measurement. Ronto, G., Gaspar, S., Berces, A. (1992). JOURNAL OF PHOTOCHEMISTRY AND PHOTOBIOLOGY. B, BIOLOGY 12:285-294. An experimental method complete with theoretical considerations is presented for the measurement of different biological UV doses. The method is based on the high sensitivity of phage T7 activity to UV light. A precisely determined T7 inactivation action spectrum is presented over a wide optical range (240-514 nm). Using the T7 spectral sensitivity in relation to the minimal erythema dose (MED) and the effective spectral irradiance from solar radiation for the MED, an example is given to determine the MED value based on the measurement of T7 inactivation for a given case. The advantages and applicability of the method are discussed. [TOP OF PAGE]

  100. Application of phage typing to the identification of sources of groundwater contamination. Rusin, P.A., Sinclair, N.A., Gerba, C.P., Gershman, M. (1992). Journal of Contaminant Hydrology [J. CONTAM. HYDROL. ] 11:173-188. Phage typing of Escherichia coli populations was used as a "fingerprinting" tool to identify the source(s) of fecal coliform contamination of a drinking water well, PW-12. Group discriminate analysis was used to evaluate the data and determine the relative distance of population centroids from the centroid of the PW-12 population. The phage typing patterns were compared to serological results and correlations noted. Phage typing patterns were shown to be stable following 32-days incubation of E. coli isolates in garden soil, tap water and neutralized tertiary effluent, with and without the presence of autochthonous flora. [TOP OF PAGE]

  101. DNA inversion regions min of plasmid P15B and cin of bacteriophage P1 evolution of bacteriophage tail fiber genes. Sandmeier, H., Iida, S., Arber, W. (1992). J. Bacteriol. 174:3936-3944. Plasmid p15B and the genome of bacteriophage P1 are closely related, but their site-specific DNA inversion systems, Min and Cin, respectively, do not have strict structural homology. Rather, the complex Min system represents a substitution of a Cin-like system to an ancestral p15B genome. The substituting sequences of both the min recombinase gene and the multiple invertible DNA segments of p15B are, respectively, homologous to the pin recombinase gene and to part of the invertible DNA of the Pin system on the defective viral element e14 of Escherichia coli K- 12. To map the sites of this substitution, the DNA sequence of a segment adjacent to the invertible segment in the P1 genome was determined. This, together with already available sequence data, indicated that both P1 and p15B had suffered various sequence acquisitions or deletions and sequence amplifications giving rise to mosaics of partially related repeated elements. Data base searches revealed segments of homology in the DNA inversion regions of p15B, e14, and P1 and in tail fiber genes of phages Mu, T4, P2, and .lambda.. This result suggests that the evolution of phage tail fiber genes involves horizontal gene transfer and that the Min and Pin regions encode tail fiber genes. A functional test proved that the p15B Min region carries a tail fiber operon and suggests that the alternative expression of six different gene variants by Min inversion offers extensive host range variation. [TOP OF PAGE]

  102. Experimental studies to modify the number of endocytic bacteria in Cryptomonas strain SAG 2580 (Cryptophyceae) and their lysis by bacteriophages. Schnepf, E., Feith, R. (1992). Archiv fuer Protistenkunde 142:95-100. Cryptomonas strain SAG 2580 contains three forms of endocytic bacteria (Schnepf & Melkonian 1990), those within peribacterial vacuoles as well as free (not surrounded by a membrane) ones in the ground cytoplasm. Some of the latter are crowded with virions. They do not completely lyse in the cytoplasm but are digested in lysosomes. In order to investigate the relationships between cryptomonads and bacteria and between the different forms of bacteria, cells at various growth conditions were studied by electron microscopy. In general, the total number of bacteria per cell is fairly constant. It is, however, low after treatment with 2 mg cntdot l-1 gentamycin and high in the stationary phase, mainly because the number of free bacteria without virions is then increased. Only the bacteria within peribacterial vacuoles are able to grow and to divide. It is concluded that they also contain virus genomes and represent a stock from which the other forms develop, controlled by the host. The lysis of the bacteria could not be increased by a temperature shock. Attempts to remove the endocytic bacteria failed. The cryptomonads did not grow in the absence of extracellualr bacteria. [TOP OF PAGE]

  103. Primary characterization of the bacteriophage BA-4 from a nitrogen-fixing Bacillus azotofixans strain. Seldin, L. (1992). Microbios 71:167-177. Bacillus azotofixans RBN4 is lysogenic and harbours an inducible prophage, BA-4. Bacteriophages were detected in cell lysates induced by treatment with mitomycin C or UV light. Electron microscopy of lysates revealed phage particles with an isometric head (55 nm) and a noncontractile, slightly flexible tail (140 nm). Phage BA-4 was classified within Bradley's B1 phage group. The BA-4 genome is a double-stranded DNA molecule of 38.4 kilobase pairs not showing cohesive ends. The DNA restriction endonuclease digestion pattern is presented. Hybridization experiments showed that the BA-4 genome was present in the RBN4 chromosome but no homology was detected between BA-4 and two B. polymyxa phages. Phage BA-4 is able to promote lysis of different B. azotofixans strains, and attempts are being made to find an indicator strain to propagate it. [TOP OF PAGE]

  104. Identification of a family of bacteriophage T4 genes encoding proteins similar to those present in group I introns of fungi and phage. Sharma, M., Ellis, R.L., Hinton, D.M. (1992). Proc. Natl. Acad. Sci. USA 89:6658-6662. [TOP OF PAGE]

  105. Virus and bacteria abundances in the Drake Passage during January and August 1991. Smith, D.C., Steward, G.F., Azam, F., Hollibaugh, J.T. (1992). Antarct. J. U. S. 27:125-126. no abstract. [TOP OF PAGE]

  106. Treatment of experimental infections of mice with bacteriophages. Soothill, J.S. (1992). J. Med. Microbiol. 37:258-262. Bacteriophages for Acinetobacter baumanii, Pseudomonas aeruginosa and Staphylococcus aureus were tested in experimental infections of mice to investigate their potential for the treatment of infections of man. As few as 10(2) particles of an acinetobacter phage protected mice against 5 LD50 (1 x 10(8)) of a virulent strain of A. baumanii, and phage was demonstrated to have multiplied in the mice. A pseudomonas phage protected mice against 5 LD50 of a virulent strain of P. aeruginosa, with a PD50 of 1.2 x 10(7) particles. A staphylococcal phage failed to protect mice infected with a strain of S. aureus. These studies support the view that bacteriophages could be useful in the treatment of human infections caused by antibiotic-resistant strains of bacteria. [TOP OF PAGE]

  107. Nucleotide sequence of the genome of the filamentous bacteriophage I2-2 module evolution of the filamentous phage genome. Stassen, A.P.M., Schoenmakers, E.F.P.M., Yu, M., Schoenmakers, J.G.G., Konings, R.N.H. (1992). J. Mol. Evol. 34:141-152. The nucleotide sequence of the circular single-stranded genome of the filamentous Escherichia coli phage I2-2 has been determined and compared with those of the filamentous E. coli phages Ff(M13, fl, or fd) and IKe. The I2-2 DNA sequence comprises 6744 nucleotides; 139 nucleotides less than that of the N- and I2-plasmid-specific phage IKe, and 337-336) nucleotides more than that of the F-plasmid-specific phage Ff. Nucleotide sequence comparisons have indicated that I2-2, IKe, and Ff have a similar genetic organization, and that the genomes of I2-2 and IKe are evolutionarily more closely related than those of I2-2 and Ff. The studies have further demonstrated that the I2-2 genome is a composite replicon, composed of only two-thirds of the ancestral genome of IKe. Only a contiguous I2-2 DNA sequence of 4615 nucleotides encompassing not only the coat protein and phage assembly genes, but also the signal required for efficient phage morphogenesis, was found to be significantly homologous to sequences in the genomes of IKe and Ff. No homology was observed between the consecutive DNA sequence that contains the origins for viral and complementary strand replication and the replication genes. Although other explanations cannot be ruled out, our data strongly suggest that the ancestor filamentous phage genome of phages I2-2 and IKe has exchanged its replication module during evolution with that of another replicon, e.g., a plasmid that also replicates via the so-called rolling circle mechanism. [TOP OF PAGE]

  108. Estimation of virus production in the sea: II. Field results. Steward, G.F., Wikner, J., Cochlan, W.P., Smith, D.C., Azam, F. (1992). Mar. Microb. Food Webs. 6:79-90. Virus production was estimated in samples from diverse marine environments by incorporation of super(32)P-orthophosphate ( super(32)P sub(i)) into viral DNA. Rates of virus production in the field were found to vary over three orders of magnitude (from < 1 x 10 super(8) to 2.3 x 10 super(11) viruses/l/d). Due to the possibility of intracellular isotope dilution and filtration losses, these rates should be considered minimum estimates. Virus production displayed a strong onshore-offshore gradient which covaried with bacteria abundance and chlorophyll a. Minimum estimates of mortality in two coastal samples (12 and 25% of bacteria production) suggest that viruses were a significant source of bacteria mortality in these environments. The apparent dependence of virus production on host density suggests that significant phage attack is spatially and temporally episodic in the open ocean (e.g. during phytoplankton blooms), but more persistent in the highly productive coastal waters. [TOP OF PAGE]

  109. Estimation of virus production in the sea. I. Method development. Steward, G.F., Wikner, J., Smith, D.C., Cochlan, W.P., Azam, F. (1992). Marine Microbial Food Webs 6:57-78. A method for estimating virus production in seawater was developed and tested in the field. The rates of virus production were determined on the basis of the rate of 32P-orthophosphate (32Pi) or 3H-thymidine (3H-TdR) incorporation specifically into the nucleic acid of the viruses released during the incubation period. The 3H-TdR-incorporation method was designed to specifically detect the production of DNA-containing bacterial viruses. The 32Pi-incorporation method has the potential to measure the production of DNA and RNA viruses of bacteria, algae and protozoa. The 32Pi-incorporation protocols developed in this study, however, measure only the production of DNA viruses. The method provides sensitive detection of virus production with high precision and low blanks. Conversion factors relating label incorporated to viruses produced were derived empirically from culture and field measurements. Due to variable and potentially biased losses of viruses, the accuracy of the method could not be determined in the present study. Virus production measured by this method must be considered minimum estimates at present. This method should be of value in studies of the ecology of viruses in the sea and the roles of viruses in the ocean's biogeochemical dynamics. [TOP OF PAGE]

  110. Mechanisms and rates of decay of marine viruses in seawater. Suttle, C.A., Chen, F. (1992). Appl. Environ. Microbiol. 58:3721-3729. Loss rates and loss processes for viruses in coastal seawater from the Gulf of Mexico were estimated using three different marine bacteriophages. Decay rates in the absence of sunlight ranged from 0.009 to 0.028 h-1, with different viruses decaying at different rates. In part, decay was attributed to adsorption by heat-labile particles, as viruses did not decay or decayed very slowly in 0.2-&micro;m-filtered, autoclaved or ultracentrifuged seawater, but continued to decay in cyanide-treated seawater. Cyanide did cause decay rates to decrease, however, indicating that biological processes were also involved. As decay rates were often greatly reduced in 0.8- or 1.0 &micro;m-filtered seawater, whereas bacteria numbers were not, it suggested that most bacteria were not responsible for the decay. Decay rates were also reduced in 3-&micro;m-filtered or cycloheximide-treated seawater, but not in 8-&micro;m-filtered water, implying that flagellates consumed viruses. Viruses added to flagellate cultures decayed at 0.15 h-1, corresponding to 3.3 viruses ingested flagellate-1 h-1. Infectivity was very sensitive to solar radiation and in full sunlight decay rates were 0.4-0.8 -1. Even when UV-B was blocked, rates were as high as 0.17 h-1. Calculations suggest that in clear oceanic waters exposed to full sunlight that most of the viral decay, averaged over a depth of 200 m, would be attributable to solar radiation. In coastal waters, when decay rates were averaged over 24 h and 10 m depth, loss rates of infectivity attributable to sunlight were similar to those resulting from all other pro