Bacteriophage Ecology Group - Reference Abstracts (1994)

	Bacteriophage Ecology Group Reference Abstracts (1994)
	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

The Evolutionary Biology of Viruses. Anonymous (1994). Raven Press, Ltd., New York.[TOP OF PAGE]
Survival of enteric viruses on environmental fomites. Abad, F.X., Pinto, R.M., Bosch, A. (1994). Appl. Environ. Microbiol. 60:3704-3710. The survival of human enteric viruses on several porous (paper and cotton cloth) and nonporous (aluminum, china, glazed tile, latex, and polystyrene) environmental surfaces has been evaluated. Viruses persisted for extended periods on several types of materials commonly found in institutions and domestic environments. The stability of the viruses was generally influenced by environmental factors such as relative humidity (RH), temperature, and the type of surface contaminated. Overall, hepatitis A virus (HAV) and human rotavirus (HRV) were more resistant to inactivation than enteric adenovirus (ADV) and poliovirus (PV). The resistance to the desiccation step appears to be of major significance in determining the survival of a virus dried on fomites. ADV and PV showed a pronounced decrease in titer at this stage, whereas HAV and HRV displayed little decay at the desiccation step. HAV and HRV persistence was not affected by the presence of fecal material. On nonporous surfaces, PV and ADV persisted better in the presence of feces. However, on porous fomites the presence of fecal material had a negative influence on the survival of PV and ADV. Except for HRV, greater virus survival was observed at 4 degree than at 20 degree C. PV and HAV survival was enhanced at high RH; the survival of the latter was enhanced at least for nonporous materials. When dried on porous materials, HRV also exhibited greater persistence at high RH. The survival of ADV was not affected by RH. The validity of using bacteriophages of Bacteroides fragilis as indicators of human viruses dried on fomites was evaluated. B. fragilis phages persisted consistently longer than PV and ADV and sometimes survived as long as HAV and HRV. [TOP OF PAGE]
Disinfection of human enteric viruses in water by copper and silver in combination with low levels of chlorine. Abad, F.X., Pinto, R.M., Diez, J.M., Bosch, A. (1994). Appl. Environ. Microbiol. 60:2377-2383. The efficacy of copper and silver ions, in combination with low levels of free chlorine (FC), was evaluated for the disinfection of hepatitis A virus (HAV), human rotavirus (HRV), human adenovirus, and poliovirus (PV) in water. HAV and HRV showed little inactivation in all conditions. PV showed more than a 4 log-10 titer reduction in the presence of copper and silver combined with 0.5 mg of FC per liter or in the presence of 1 mg of FC per liter alone. Human adenovirus persisted longer than PV with the same treatments, although it persisted significantly less than HRV or HAV. The addition of 700 mu-g of copper and 70 mu-g of silver per liter did not enhance the inactivation rates after the exposure to 0.5 or 0.2 mg of FC per liter, although on sonic occasions it produced a level of inactivation similar to that induced by a higher dose of FC alone. Virus aggregates were observed in the presence of copper and silver ions, although not in the presence of FC alone. Our data indicate that the use of copper and silver ions in water systems may not provide a reliable alternative to high levels of FC for the disinfection of viral pathogens. Gene probe-based procedures were not adequate to monitor the presence of infectious HAV after disinfection. PV does not appear to be an adequate model viral strain to be used in disinfection studies. Bacteroides fragilis bacteriophages were consistently more resistant to disinfection than PV, suggesting that they would be more suitable indicators, although they survived significantly less than HAV or HRV. [TOP OF PAGE]
Specificity of bacteriophages of Pseudomonas solanacearum. Abdullah, H. (1994). Phytopathology 84:1069 [TOP OF PAGE]
Lysis and the interaction between free phages and infected cells. Abedon, S.T. (1994). pp. 397-405. In In Karam, J.D. (ed.), The Molecular Biology of Bacteriophage T4. ASM Press, Washington, DC. The envelope of T4-infected cells undergoes a complex set of changes that affect its stability, its susceptibility to lysozyme-induced degradation, and the fate of other incoming phage. Particularly, superinfection exclusion, resistance to lysis from without, lysis inhibition, and lysis inhibition collapse are all mechanisms involving the interaction between T4-infected cells and subsequently adsorbing T4 phage. This chapter reviews the normal T4 lysis process and, for the first time, what is known of the complex molecular biology of free phage-infected cell interactions. [TOP OF PAGE]
PID, a new member of the P1 bacteriophage group. Ackermann, H.-W., Reynaud, A., Gayerie, M.C. (1994). Can. J. Microbiol. 40:63-67. Phage PID produces particles of essentially uniform head size and differs from P1 in its range and tail length. The dimensions of phage P1 are reassessed. The P1 phage group shows signs of morphological evolution. [TOP OF PAGE]
Classification of Acinetobacter phages. Ackermann, H.-W., Brochu, G., Emadi Konjin, H.P. (1994). Arch. Virol. 135:345-354. Eight phage species and type viruses are proposed. They below to the Myoviridae, Siphoviridae, and Podoviridae families of tailed phages and are characterized by a combination of morphological and physiochemical properties. An unusual siphovirus species has an elongated head and transverse tail disks. [TOP OF PAGE]
New Bacillus bacteriophage species. Ackermann, H.-W., Azizbekyan, R.R., Emadi Konjin, H.P., Lecadet, M.-M., Seldin, L., Yu, M.X. (1994). Arch. Virol. 135:333-344. Nine new species of tailed Bacillus phages, based on morphological and physiochemical properties, are defined. Phage P10 is one of the largest viruses known. The total number of tailed Bacillus phage species is presently 33. [TOP OF PAGE]
Bacteriophages from Bombyx mori. Ackermann, H.-W., Auclair, P., Basavarajappa, S., Emadi Konjin, H.P., Savanurmath, C. (1994). Arch. Virol. 137:185-190. Preparations of silkworm larvae contained two large phages with contractile tails (Myoviridae). One phage was active on Pseudomonas paucimobilis. The other, not cultured, was one of the largest viruses known. [TOP OF PAGE]
Evolutionary factors influencing the nature of parasite specificity. Adamson, M.L., Caira, J.N. (1994). Parasitology 109(SUPPL.):S85-S95 This article considers how specificity patterns are shaped during the course of parasite evolution. Parasites are first and foremost specific to site, or microhabitat; host ranges are far more subject to change than is microhabitat. Specificity results from a number of convergent phenomena starting with habits (microhabitat and feeding styles) of free-living progenitors and the way in which the parasitic association arises (e.g., passive oral contamination as opposed to intrusive entry). These bias the types of interaction parasites have with the host, and, through this, the way specificity develops. Host ecology acts as an external factor affecting specificity and predominates in parasites that interact minimally with the hosts physiological and immune systems. Coevolutionary factors are more important in parasites that feed on host tissues or occur in extraintestinal sites. Here, parasites must present the right cues, and respond appropriately to the host defense system. The ability to generalize these cues and responses across host boundaries may act as a constraint on host range. The functional role of the host in the parasite life history also affects the degree of specificity; thus, parasites may act as host generalists in hosts that act as trophic channels to the final host. The role of competition in determining specificity is difficult to assess. However, competition has been reported to influence microhabitat and host distribution through interactive site selection and/or competitive seclusion. [TOP OF PAGE]
Characterization of a cowpea (Vigna unguiculata) rhizobiophage and its effects on cowpea nodulation and growth. Ahamd, M.H., Morgan, V. (1994). Biology and Fertility of Soils 18:297-301. A cowpea rhizobiophage (JRW 3 phage) from Jamaican soil was isolated and characterized. The phage has a polyhedral head and a non-contractile tail; maximum adsorption of the phage to the host occurred after 5 min. A one-step growth experiment revealed that the latent period, rise period and burst size of JRW3 phage were 12 h, 16 h, and 28 plaque-forming units/cell, respectively. The JRW3 phage was highly sensitive to heat, but survived well between pH 5 and 8. The phage was stable in EDTA, though completely inactivated in sodium citrate. Host range analysis showed that 7 of the 40 Rhizobium and Bradyrhizobium strains tested were sensitive to phage infection. The phage significantly reduced nodule numbers and shoot dry weight of cowpea plants when inoculated with rhizobia in combination with the phage. [TOP OF PAGE]
Period dependent selection in continuous culture of viruses in a periodic environment. Aita, T., Husimi, Y. (1994). J. Theor. Biol. 168:281-289. Selection in a cellstat culture of two mutant strains of a bacteriophage under periodically fluctuating temperature was analyzed mathematically and numerically. Each of the two viral strains (P-1 and P-2) was assumed to have a different Arrhenius activation energy for its reproduction reaction. A phase diagram of the final state in the continuous culture was drawn. The most noticeable was that there were both P-1-only and P-2-only phases of competitive exclusion depending on the period of oscillation and the dilution rate. The period-dependent selection was proved that it was based on the feedback effect via the host-population change. At a short period of oscillation, the strain with larger arithmetic average fitness ultimately dominated in the population; on the other hand, at a long period of oscillation, the strain with larger geometric average fitness ultimately dominated. There was a co-existence phase between the two exclusion phases. The results suggest the feasibility of a method to escape from trapping at local optima on a fitness landscape in evolutionary molecular engineering. [TOP OF PAGE]
Adsorption and growth characteristics of some lactic phages. Akcelik, M. (1994). Turkish Journal of Biology 18:155-160. The phage-host interactions of strains of lactococci, which were isolated in Turkey, and the phages active on them were studied under three different incubation temperatures, 28 degree C, 32 degree C and 37 degree C. While being quite similar at 28 degree C and 32 degree C, the percentages of adsorption, the latent periods and rise periods of lactic phages were decreased at 37 degree C. Average burst sizes of these phages were not varied by incubation temperature. A heat-sensitive phage resistance system, active at 28 degree C and 32 degree C, but not at 37 degree C, was also determined in two strains of lactococci. [TOP OF PAGE]
Recovery of somatic coliphages in shellfish. Albert, M., Vannesson, C., Schwartzbrod, L. (1994). Water Science and Technology 31:453-456. A phage recovery technique is described that is shown to be easy to perform and sensitive. It is efficient in detecting somatic coliphages in mussels artificially contaminated, even at every low levels. Good results are also reported for detection and enumeration of naturally occurring coliphages in mussels and cockles from the French Atlantic coast. [TOP OF PAGE]
A direct membrane filter method for enumerating somatic coliphages in drinking water. Alonso, M.C., Sanchez, J.M., Morinigo, M.A., Borrego, J.J. (1994). Microbiologia (Madrid) 10:285-296. The application of a simple membrane filter method to enumerate specific somatic bacteriophages of Escherichia coli, using E. coli C as host strain, from drinking water samples was studied. The efficiency of the method using cellulosic membrane filters, samples pretreated with magnesium ions and Tween 80 added to agar medium-host cell lawns ranged from 68.9 to over 112%, depending on the phage content of the sample. To avoid the pre-treatment of the sample with magnesium salts, electropositive-charged filters of cellulosic ester (HA-PEI and HA-Nalco) and Virosorb-IMDS filters were tested in conjunction with the simple membrane filter method. The electropositive filters showed wide bacteriophage recovery rate intervals depending on the sample treatment, ranging between 31.4 and 96.2% for ester-type filters. and a mean recovery lower than 2.2% for Virosorb filters. On the other hand, it was proved that the use of Tween 80 as an eluent improved somatic coliphage recovery rates for all the filters tested. In short, this methodology provides a rapid analysis (6-8 h) of the somatic coliphages from drinking water using the membrane filtration technique. [TOP OF PAGE]
Bacteriophage-like particle of Rochalimaea henselae. Anderson, B., Goldsmith, C., Johnson, A., Padmalayam, I., Baumstark, B. (1994). Molecular Microbiology 13:67-73. An extracellular particle approximately 40 nM in diameter was detected in culture supernatant from the fastidious bacterium Rochalimaea henselae. This particle has at least three associated proteins and contains 14 kbp linear DNA segments that are heterogeneous in sequence. The 14 kbp DNA was also present in R. henselae cells as an extrachromosomal element for all 14 strains tested. Despite attempts to induce lysis of R. henselae, plaque formation was not observed. A similar particle, also containing 14 kbp DNA, was observed in Bartonella bacilliformis, and may be analogous to a bacteriophage that has been described elsewhere for B. bacilliformis. [TOP OF PAGE]
On the generation of genetic diversity in microorganisms. Arber, W. (1994). Proceedings of the Indian National Science Academy Part B Biological Sciences 60:357-363. Bacterial genetics strongly influenced the development of molecular genetic strategies and techniques now available to study gene structure and functions of practically any living organisms. It also revealed natural processes of horizontal gene transfer (transformation, conjugation, phage-mediated transduction) as well as systems (e.g. restriction-modification systems) to hold such gene transfer in tolerably low frequencies to ensure a certain degree of genetic stability. Work with bacterial and bacteriophage systems has helped to unravel both homologous and non-homologous enzyme-mediated recombination processes at the molecular level. The acquired knowledge now helps to understand molecular processes contributing to the generation of genetic variation. especially DNA rearrangements resulting from transposition and from site-specific recombination which sometimes occurs at secondary crossing-over sites. Present knowledge on genetic plasticity of haploid microorganisms offers insights into the molecular basis for the natural interplay between mutagenesis and selection. This approach greatly profits from the short generation times and relatively small genome sizes of haploid microorganisms which allows one to investigate population genetic questions and to draw conclusions on the mechanisms of evolutionary processes. [TOP OF PAGE]
Stand der Forschung bei der Untersuchung der Phagen Problematik in biotechnologischen Prozessen der Lebensmittelfermentation. Arendt, E.K., Fitzgerald, G.F., Coffey, A., Hammes, W.P. (1994). Lebensmitteltechnik 6:40-44. [TOP OF PAGE]
Cultivation of Leishmania braziliensis in an economical serum-free medium containing human urine. Armstrong, T.C., Patterson, J.L. (1994). Journal of Parasitology 80:1030-1032. Leishmania braziliensis cells are difficult to culture in vitro and usually require media supplemented with serum for sustained cell division. Fresh, sterile urine is an inexpensive substitute for serum in the culture of 2 strains of L. braziliensis, 1 infected with Leishmania RNA virus 1, and 1 uninfected. In the presence of urine, both the infected and the uninfected strains grew to the same final cell density as the same strains grown in the presence of serum. One strain of Leishmania major was also successfully cultured in urine-supplemented media. [TOP OF PAGE]
Modeling the role of viral disease in recurrent phytoplankton blooms. Beltrami, E., Carroll, T.O. (1994). Journal of Mathematical Biology 32:857-863. The recurrent pattern of some phytoplankton species can vary considerably from year to year. Recent experimental work suggests that the contamination of algal cells by viruses can serve as a regulatory mechanism in bloom dynamics. A simple trophic model is proposed that includes virus-induced mortality, and it mimics the actual bloom patterns of several species. The model results are compared to actual data by a combination of nonlinear forecasting techniques. [TOP OF PAGE]
Characterization of thirteen Staphylococcus epidermidis and S. saprophyticus bacteriophages. Bes, M. (1994). Research in Virology 145:111-121. Thirteen bacteriophages of coagulase-negative staphylococci belonging to the Siphoviridae family (morphotype B1) were compared by seroneutralization kinetics, protein profiles, G + C content, DNA size and DNA/DNA hybridization. A previous classification into three morphological groups was confirmed. The Staphylococcus epidermidis phage group, although morphologically homogeneous, was heterogeneous by DNA/DNA hybridization (27 to 100% homology) and seroneutralization kinetics. Two new phage "species", STA1139 (STA for Staphylococcus) and STA1154A, corresponding to two morphological types of S. saprophyticus phages, were identified. Species STA1154A was particularly interesting because the size of its capsid, only 46 nm in diameter, and of its DNA, evaluated as 13 kbp, were smaller than those of other staphylococcal phages. [TOP OF PAGE]
New pyruvylated, glycosylated acyltrehaloses from Mycobacterium smegmatis strains, and their implications for phage resistance in mycobacteria. Besra, G.S., Khoo, K.H., Belisle, J.T., McNeil, M.R., Morris, H.R., Dell, A., Brennan, PJ (1994). Carbohydrate Research 251:99-114. Phage resistance and apparent lysogenization of Mycobacterium smegmatis due to infection with mycobacteriophage D29 results in the emergence of new variations of the pyruvylated, acylated trehaloses described by Saadat and Ballou, J. Biol. Chem. 258 (1983) 1813-1818. Thin-layer chromatography of the glycolipids from two strains of phage-resistant M. smegmatis (mc(2)22 and mc(2)11) and comparison with those from phage-sensitive strains revealed a new, more mobile glycolipid in each case. The structures of these acyltrehalose-containing lipooligosaccharides were elucidated by a combination of gas-liquid chromatography-mass spectrometry, methylation analysis, 1H and 13C NMR spectroscopy, and fast-atom bombardment mass spectrometry. The glycolipid from M. smegmatis mc(2)22 is beta-D-Glcp-(1-->3)-4,6-O-(1-methoxycarbonylethylidene)-beta-D-Glc p-(1-->4)- beta-D-Glcp-(1-->6)-2-O-acyl-alpha-D-Glcp-(<==>1)-3,4-O-acyl-alpha-D-Glc p and that from M. smegmatis mc(2)11 is 4,6-O-(1-methoxycarbonylethylidene)-3-O-Me-beta-D-Glcp-(1-->3)-4,6 -O- (1-methoxycarbonylethylidene)-beta-D-Glcp-(1-->4)-beta-D-Glcp-(1-- >6)-2-O-acyl- alpha-D-Glcp-(1<==>1)-3,4-di-O-acyl-alpha-D-Glcp. These differ from the original pyruvylated glycolipids of Saadat and Ballou in the extent of their O-acylation and O-methylation. The findings are the first example of the definition of a chemical basis for phage resistance and presumed lysogeny in mycobacteria, and show parallels to related changes in gram-negative enteric bacteria. [TOP OF PAGE]
Bacterial and Bacteriophage Genetics. Birge, E.A. (1994). Springer-Verlag, New York.[TOP OF PAGE]
Phage F-116 transduction of antibiotic resistance from a clinical isolate of Pseudomonas aeruginosa. Blahova, J., Hupkova, M., Krcmery, V.S. (1994). JOURNAL OF CHEMOTHERAPY 6:184-188. The lysate of phage F-116, propagated in a multiple drug resistant clinical isolate of Pseudomonas aeruginosa No. 131 was used to transduce determinants of antibiotic resistance to susceptible auxotrophic laboratory strains of the same species. The phage preparation, designated F-116/131 was found to transduce four determinants of resistance, i.e. to imipenem, cefotaxime, kanamycin and carbenicillin, but not to streptomycin, gentamicin, ceftazidime nor ciprofloxacin/ofloxacin. No conjugal transfer of any resistance determinants could be demonstrated in mating experiments using strain No. 131 and two rifampicin-resistant strains of P. aeruginosa which were highly susceptible to all antibiotics studied. These results might suggest that transduction could be an additional way to conjugational transfer of antibiotic resistance among P. aeruginosa. [TOP OF PAGE]
Viruses and the microbial loop. Bratbak, G., Thingstad, T.F., Heldal, M. (1994). Microb. Ecol. 28:209-221. The abundance of viral-like particles in marine ecosystems ranges from lt 10-4 ml-1 to gt 10-8 ml-1. Their distribution in time and space parallels that of other biological parameters such as bacterial abundance and chlorophyll a. There is a lack of consensus between methods used to assess viral activity, i.e., rate of change in viral abundance (increase or decrease). The highest rates, 10-100 days-1, are observed in experiments with short sampling intervals (0.2-2 h), while lower rates, on the order of 1 day-1, are observed in experiments with longer sampling intervals (days). Few studies have been carried out, but viruses appear, at least in some cases, to have a significant impact on carbon and nutrient flow in microbial food webs. Viruses have also been demonstrated to exert a species specific control of both bacteria and phytoplankton populations in natural waters. [TOP OF PAGE]
Distinct Streptococcus thermophilus bacteriophages share an extremely conserved DNA fragment. Brussow, H., Probst, A., Fremont, M., Sidoti, J. (1994). Virology 200:854-857. A cross-hybridizing 2.2-kb EcoRI fragment was cloned from two lytic Streptococcus thermophilus bacteriophages with distinct phenotypes. The DNA fragments, which contained two unidentified open reading frames, differed at only 3 of 2207 nucleotide positions. Partial sequencing of a temperate S. thermophilus phage and of a further lytic phage belonging to a different lytic group isolated 20 years earlier from a different geographical area confirmed this extreme sequence conservation. Hybridization of this phage DNA with bacterial host DNA was not observed. The evolutionary implications of these observations are briefly discussed. [TOP OF PAGE]
Detection and classification of Streptococcus thermophilus bacteriophages isolated from industrial milk fermentation. Brussow, H., Fremont, M., Bruttin, A., Sidoti, J., Constable, A., Fryder, V. (1994). Appl. Environ. Microbiol. 60:4537-4543. In the last 30 years, 81 Streptococcus thermophilus bacteriophage isolates were collected from industrial yogurt (n = 40) and cheese (n = 41) fermentation. Forty-six distinct restriction patterns of phage DNA (11 in yogurt and 35 in cheese) were observed. The phages were investigated for host range, serological properties, and DNA homology to study whether these three independent techniques can be used to classify the phages into taxonomic groups. Yogurt factory-derived phages were classified into the same two subgroups by serology, host range analysis, and hybridization with subgroup-specific DNA sequences. Cheese factory-derived phages, however, could not be classified: the 35 cheese phage isolates with distinct restriction patterns showed 34 different host ranges. All but one cheese phage isolate showed serological cross-reactivity with yogurt phages. A phage DNA fragment that hybridized with all phage DNA samples was cloned, establishing the genetic relatedness of all S. thermophilus phages from our collection. With the sequence information from an unusually conserved S. thermophilus phage DNA element (H. Brussow, A. Probst, M. Fremont, and J. Sidoti, Virology 200:854-857, 1994), a PCR-based phage detection method was developed for cheese whey from a factory that produced mozzarella cheese with complex undefined starter mixes. PCR allowed the detection of phages in cheese whey (detection limit, 10(3) PFU/ml) which could not be detected by dot blot hybridization techniques (detection limit, 10(7) PFU/ml). [TOP OF PAGE]
Comparative molecular biology of lambdoid phages. Campbell, A. (1994). Ann. Rev. Microbiol. 48:193-222. [TOP OF PAGE]
Enumerating phage. Carlson, K., Miller, E.S. (1994). pp. 427-429. In In Karam, J.D. (ed.), Molecular Biology of Bacteriophage T4. ASM Press, Washington, DC. The plaque assay is based on the fact that when a single phage particle encounters a permissive bacterium it will infect it and a while later lyse it, with the concomitant release of newly formed phage particles. When about 100 to 500 phage are mixed with about 10⁸ sensitive cells and poured in a layer of soft agar on the surface of a nutrient agar plate supporting bacterial growth, the cells will resume growth. Each phage soon comes into contact with a bacterium, which it infects; in areas where no phage are present the bacteria will grow to stationary phase, forming a smoot opaque layer or lawn in the overlay. The progeny phge from each infected bacterium will infect neighboring bacteria, resulting in a growing zone of lysis, full of liberated phage, which eventually becomes visible to the naked eye as a "plaque" in the otherwise smooth lawn. Growth of plaque is limited by slow diffusion of phage in the semi-solid soft agar and by the fact that the host cells support phage growth only as long as they metabolize actively; when cell growth stops, phage growth also ceases. A production of about 10 to 15 phage per infected cell is sufficient for plaque formation; each phage giving rise to a plaque can be assayed as a plaque-forming unit. [TOP OF PAGE]
Working with T4. Carlson, K., Miller, E.S. (1994). pp. 421-426. In In Karam, J.D. (ed.), Molecular Biology of Bacteriophage T4. ASM Press, Washington, DC. [TOP OF PAGE]
General procedures. Carlson, K., Miller, E.S. (1994). pp. 427-437. In In Karam, J.D. (ed.), Molecular Biology of Bacteriophage T4. ASM Press, Washington, DC. [TOP OF PAGE]
On the specificity of a bacteriophage-borne endoglycanase for the native capsular polysaccharide produced by Klebsiella pneumoniae SK1 and its derived polymers. Cescutti, P., Paoletti, S. (1994). Biochemical & Biophysical Research Communications 198:1128-1134. The specificity of the endoglycanase associated with the bacteriophage phi SK1 particles was tested on the native capsular polysaccharide produced by Klebsiella pneumoniae serotype SK1 and on three chemically modified polymers derived from it. The primary structure of the SK1 capsular polysaccharide is: [formula: see text] and the beta 1-3 linkage between the glucose and the galactose residues is the one cleaved by the phage enzyme. The enzyme activity was assayed on the deacetylated polysaccharide and on two derivatives obtained by removal of both the side-chain sugars and of only the alpha-D-galactosyl unit, respectively. The endoglycanase was more active on the deacetylated polysaccharide than on the native one, suggesting that the presence of the acetyl groups interferes with the enzyme-polysaccharide interaction. A possible role of the acetyl groups in the control of the polysaccharide chain length and hence on the rheological behaviour of the capsule cannot be ruled out, as already indicated for other bacterial polysaccharides. On the contrary, the removal of the side chains, either complete or selective, caused the modification of the recognition site in such a way that the enzymatic depolymerization no longer occurred. Therefore, it can be inferred that the phi SK1 endoglycanase requires the presence of both the side chain sugars to exhibit its cleaving activity, although this latter is in the main chain. [TOP OF PAGE]
Microbiological quality of shellfish-growing waters in Chesapeake Bay. Chai, T.-J., Han, T.-J., Cockey, R.R. (1994). Journal of Food Protection 57:229-234. A total of 338 water samples were collected at 20 stations from three geographically shellfish-growing areas in Chesapeake Bay from May to September 1989. Samples were examined for standard plate count, total coliforms, fecal coliforms, Escherichia coli and coliphages. Salinity, dissolved oxygen and temperature varied slightly with the depth, season, and geographic area of water samples. The geometric means of standard plate count for the three areas were 135, 355 and 275/ml, respectively. The range of means of fecal coliform for these areas was from lt 3 to 93/100 ml. Escherichia coli counts were also low with a range of lt 3 to 93/100 ml and a mean of lt 3/100 ml. The growing water area adjacent to cropland was found to have higher bacterial counts than those of the other two areas. Levels of male-specific phages were very low. Results indicate that shellfish-growing waters in all three areas were of satisfactory bacteriological quality. [TOP OF PAGE]
Growth of Legionella pneumophila in Acanthamoeba castellanii enhances invasion. Cirillo, J.D., Falkow, S., Tompkins, L.S. (1994). Infect. Immun. 62:3254-3261. Legionella pneumophila is considered to be a facultative intracellular parasite. Therefore, the ability of these bacteria to enter, i.e., invade, eukaryotic cells is expected to be a key pathogenic determinant. We compared the invasive ability of bacteria grown under standard laboratory conditions with that of bacteria grown in Acanthamoeba castellanii, one of the protozoan species that serves as a natural host for L. pneumophila in the environment. Amoeba-grown L. pneumophila cells were found to be at least 100-fold more invasive for epithelial cells and 10-fold more invasive for macrophages and A. castellanii than were L. pneumophila cells grown on agar. Comparison of agar- and amoeba-grown L. pneumophila cells by light and electron microscopy demonstrated dramatic differences in the morphology and structure of the bacteria. Analyses of protein expression in the two strains of bacteria suggest that these phenotypic differences may be due to the expression of new proteins in amoeba-grown L. pneumophila cells. In addition, the amoeba-grown bacteria were found to enter macrophages via coiling phagocytosis at a higher frequency than agar-grown bacteria did. Replication of L. pneumophila in protozoans present in domestic water supplies may be necessary to produce bacteria that are competent to enter mammalian cells and produce human disease. [TOP OF PAGE]
??? Cirillo, M.R., Trigg, M.E., Merril, C.R. (1994). Infect. Immun. 62:3254-3261. [this is cited in Lederberg, 1996 (PNAS 93:3167-3168): ". . . perhaps in the soil amoebae that harbor Legionella and other bacteria (ref)"]. [TOP OF PAGE]
The red queen reigns in the kingdom of RNA viruses. Clarke, D.K., Duarte, E.A., Elena, S.F., Moya, A., Domingo, E., Holland, J. (1994). Proc. Natl. Acad. Sci. USA 91:4821-4824. Two clonal populations of vesicular stomatitis virus of approximately equal relative fitness were mixed together and allowed to compete during many transfers in vitro as large virus populations. Eventually, one or the other population suddenly excluded its competitor population, yet both the winners and losers exhibited absolute gains in fitness. Our results agree with the predictions of two major theories of classical population biology; the Competitive Exclusion Principle and the Red Queen's Hypothesis, where (in Lewis Carroll's words) ''it takes all the running you can do to keep in the same place.''. [TOP OF PAGE]
A comparison between the Most Probable Number (MPN) method and direct counting for the determination of anti-E. coli bacteriophages. Contato, E., Mirolo, G., Garasto, G., Tampieri, M.L., Tuffanelli, A., Sartea, A., Bucci, G. (1994). Igiene Moderna 101:801-808. At present coliphages are considered good indicators of water viral pollution. In our laboratory (P.M.P. U.S.L. 31, Ferrara) a comparison between two analytical methods has been carried out. Both methods ("Direct Count" and "MPN") were applied to measure the quantity of bacteriophages in 102 samples of river water (survey period: from 29-08-89 to 18-02-92). "Direct Count" has proved better than "MPN", because it is rapid (saving of 24 hours), simple (saving of an analytical step) and accurate. Measures confirm higher number of coliphages in cold months. [TOP OF PAGE]
T4 phage evolution data in terms of a time-dependent topal- fresco mechanism. Cooper, W.G. (1994). Biochemical Genetics 32:383-395. A physical interpretation of the Topal-Fresco (Nature 263, 285 (1976)) model for spontaneous base substitutions suggests that hydrogen-bonded DNA protons satisfy the criteria for a classical noninteracting isolated system. Accessible states for duplex G sbd C protons include the keto-amino state and the six complementary enol-imine isomers. Hydrogen-bonded enol and imine protons occupy symmetric double-minima created by the two sets of indistinguishable electron lone pairs and a single proton belonging to each enol-imine end group. These protons will consequently participate in coupled quantum mechanical flip-flop, tunneling back and forth between symmetric energy wells. This results in a quantum mixing of proton energy states where the lowest energy state will be a linear combination of available G sbd C isomers. The resulting conclusion is that metastable keto- amino G sbd C protons will populate accessible enol-imine stationary states at rates governed by quantum laws of statistical equilibrium, consistent with achieving the lowest energy condition for duplex G sbd C protons. Enol-imine G sbd C stationary states are bound more tightly, of the order of 3 to 12 kcal/mol, which requires a modified mode of Topal-Fresco replication that will inhibit reequilibration of enol and imine G and C template isomers and, thus, promote the formation of complementary mispairs. The model is demonstrated on time- dependent base substitutions expressed by T4 phage DNA systems where data are consistent with model explanations, including the prediction that time-dependent evolutionary transversion sites will exhibit both G sbd C-to-T sbd A and G sbd C-to-C sbd G transversions at replication, due to proton flip-flop alteration of G template genetic specificity. The observation that A sbd T sites are resistant to time-dependent evolutionary base substitutions, expressed exclusively at G sbd C sites, allows codons to be classified as either evolutionary sensitive (16 codons) or evolutionary resistant (8 codons). These criteria provide possible explanations for expansion properties of the CGG fragile X sequences. Enol-imine G sbd C stationary states appear to have been misdiagnosed as deamination of cytosine and oxidation of guanine to 8-hydroxy-guanine. [TOP OF PAGE]
Bacteriophages presence in human faeces of healthy subjects and patients with gastrointestinal disturbances. Cornax, R., Morinigo, M.A., Gonzalez-Jaen, F., Carmen, A., Borrego, J.J. (1994). Zentralblatt Fuer Bakteriologie 281:214-224. The variation of the content of enteric bacteria and their bacteriophages in faeces from the different types of diarrhoeal processes has been studied. A total of 122 samples of human faeces from both healthy individuals and patients with diarrhoeal diseases of functional or infectious origin were tested. Detection rates for all microbial parameters tested decreased in the faeces of individuals with functional gastrointestinal disturbances. On the contrary, no significant differences of the microbial detection frequency was observed in faeces containing pathogenic microorganisms compared to faeces of healthy subjects. Human faeces were a poor source of F-specific, Salmonella, and Bacteroides bacteriophages, whereas specific Escherichia coli phages were isolated in most samples tested. Coliphage concentrations in faeces of healthy individuals were not directly correlated with levels of faecal coliforms. On the basis of their high correlation, faecal streptococci and coliphages were the most adequate indicators of the intestinal ecosystem variations ill subjects with diarrhoeal processes. [TOP OF PAGE]
Synergistic action of near-UV and phenylalanine, tyrosine or tryptophan on the inactivation of phage T7: role of superoxide radicals and hydrogen peroxide. Craggs, J., Kirk, S.H., Ahmad, S.I. (1994). JOURNAL OF PHOTOCHEMISTRY AND PHOTOBIOLOGY. B, BIOLOGY 24:123-128. Near ultraviolet (NUV) light can cause a variety of damage to biological systems. The effects of NUV are significantly enhanced in the presence of sensitizers. One of the most important targets of such synergistic effects is DNA. Cellular DNA exposed to NUV plus sensitizers is damaged in a variety of ways, DNA strand breaks and interstrand cross-links being the most common effects. In this study, phenylalanine, tyrosine and tryptophan are shown to act as sensitizers for NUV action of phage T7; superoxide anions are produced. The reactive species probably interacts with phage DNA causing damage responsible for phage inactivation. Superoxide dismutase reverses the synergistic activities of phenylalanine and tyrosine on NUV-induced phage inactivation, but catalase is additionally required to reverse the effect of tryptophan. Therefore, it is probable that NUV photolysis of tryptophan causes the production of superoxide ions and hydrogen peroxide, both of which contribute to phage inactivation. The ubiquitous nature of NUV in our environment and the presence of amino acids in skin cells suggests that an important mechanism for the induction of skin cancer in humans by solar exposure is amino acid photolysis by NUV. [TOP OF PAGE]
New technologies in the diagnosis of tuberculosis. Crawford, J.T. (1994). SEMINARS IN RESPIRATORY INFECTIONS 9:62-70. Classic methods for laboratory diagnosis of tuberculosis are time consuming, and resulting delays can adversely affect patient care and tuberculosis control. Newer radiometric culture methods can significantly reduce the time required for detection of Mycobacterium tuberculosis. DNA probe assays and high-performance liquid chromatography of mycolic acids allow identification of isolates in a few hours, and use of these methods is strongly encouraged. A new generation of rapid methods based on techniques of molecular biology will eventually allow direct detection and identification of mycobacteria in clinical samples. These methods use rapid nucleic acid amplification techniques, such as the polymerase chain reaction (PCR), rather than growth of cultures to increase the sensitivity of detection. Assays of this type are currently being evaluated in formal trails. Recent analysis of the mechanisms of drug resistance in M tuberculosis may allow the development of assays for direct detection of drug resistant strains at the genetic level. A luciferase reporter mycobacteriophage assay offers an alternate means for rapidly assessing drug resistance. This assay measures the activity of the drug rather than the genetic basis for resistance. DNA fingerprinting methods have provided the means for distinguishing strains for epidemiological purposes. These new approaches will have a dramatic impact on our ability to rapidly and accurately diagnose tuberculosis. [TOP OF PAGE]
Phenotypic consequences of altering the copy number of abiA, a gene responsible for aborting bacteriophage infections in Lactococcus lactis. Dinsmore, P.K., Klaenhammer, T.R. (1994). Appl. Environ. Microbiol. 60:1129-1136. The abiA gene (formerly hsp) encodes an abortive phage infection mechanism which inhibits phage DNA replication. To analyze the effects of varying the abiA gene dosage on bacteriophage resistance in Lactococcus lactis, various genetic constructions were made. An IS946-based integration vector, pTRK75, was used to integrate a single copy of abiA into the chromosomes of two lactococcal strains, MG1363 and NCK203. In both strains, a single copy of abiA did not confer any significant phage resistance on the host except for one of the MG1363 integrants, NCK625, which exhibited a slightly higher level of resistance to phages sk1 and p2. Hybridization of the total cellular RNA from NCK625 to an abiA-specific probe indicated that the integration took place downstream of a promoter causing stronger expression of abiA in this integrant. Three abiA-containing plasmids of various copy numbers were introduced into both strains, and the recombinants were evaluated for resistance to phages c2, p2, sk1, and vphi-31. Plasmid pTRK18 has a copy number of approximately six (cn = 6) and caused a decreased plaque size for all phages evaluated. Integration of pTRK75 into a native plasmid of NCK203 generated pTRK362 (cn = 13), which caused a reduced efficiency of plaquing (EOP = 10-2) and reduced plaque size. A high-copy-number abiA plasmid (pTRK363), based on the pAM-beta-1 origin of replication, was also constructed (cn = 100). Plasmid pTRK363 caused a significant reduction in EOP (10-4 to 10-8) and plaque size for all phages tested, although in some cases, this plasmid caused the evolution of AbiA-resistant phage derivatives. Altering the gene dosage or expression level of abiA significantly affects the phage resistance levels. [TOP OF PAGE]
Bacteriophage: A smart alternative to antibiotics? Dixon, B. (1994). pp. 190-192. In AnonymousThe Power Unseen. W.H.Freeman/Spektrum, Oxford, UK. [TOP OF PAGE]
Reduction of some bacteria and bacteriophages in secondary effluent by microfiltration in a pilot plant. Dizer, H., Althoff, W., Bartocha, W., Dorau, W., Grohmann, A., Lopez-Pila, J.M., Seidel, K. (1994). Zentralblatt fuer Hygiene und Umweltmedizin 196:23-37. Microfiltration through a membrane matrix of a nominal pore size of 0.2 mu-m has been applied for advanced treatment of mechanically and biologically treated wastewater. Elimination of bacteria and coliphages as well as the decrease in some chemical constituents were studied at a flow rate of 80 1/h. Microfiltration resulted in a reduction of E. coli, coliform bacteria, fecal streptococci and of coliphages by more than 4 logs in the filtrate. Thus, the quality requirements of EC Directives for bathing water (EC, 76/160) could be maintained. As a result of microfiltration, a 43 +- 13% removing of the total phosphorous compounds (P-t) in the pre-filtrated secondary effluent from 11 +- 2 mmol/m-3 (0.34 +- 0.06 mg/1) to 6 +- 2 mmol/m-3 (0.19 +- 0.06 mg/l) was measured. The dosage of FeCl-3 (between 30 and 150 mmol/m-3) as coagulant before microfiltration improved the reduction of P-t to result in an average volue of 75 +- 16%. After adding FeCl-3, orthophosphates (PO-4-P) could be efficiently reduced by microfiltration. Thus, PO-4-P concentrations in effluent samples were, in most cases, below the detection limit (0.01 mmol/m-3). [TOP OF PAGE]
The evaluation of the hygienic and sanitary quality of water from private shallow wells situated in an urban area of south-eastern Brazil: A comparison between the use of coliphages and bacterial indicators of fecal pollution. Do Amaral, L.A., Rossi, O.D.Jr., Nader Filho, A., Alexandre, A.V. (1994). Revista de Saude Publica 28:345-348. One hundred and four water samples from eight private shallow wells situated in the urban area of Jaboticabal city, State of S. Paulo, Brazil, were submitted to coliphage, total coliform, fecal coliform and fecal streptococcus counts, for the purpose of discovering their hygienic and sanitary quality and of verifying the correlations between the coliphage numbers and the fecal pollution indicator bacteria. Ninety-six (92.3%) of the samples were not up to the microbiological potability standards. This result demonstrates the unsatisfactory hygienic and sanitary quality of the water samples. The results show also the absence of correlations among coliphages, and the fecal pollution indicator bacteria. [TOP OF PAGE]
Subclonal component of consensus fitness in an RNA virus clone. Duarte, E.A., Novella, I.S., Ledesma, S., Clarke, D.K., Elena, S.F., Domingo, E., Holland, J.J. (1994). J. Virol. 68:4295-4301. Most RNA virus populations exhibit extremely high mutation frequencies which generate complex, genetically heterogeneous populations referred to as quasispecies. Previous work has shown that when a large spectrum of the quasispecies is transferred, natural selection operates, leading to elimination of noncompetitive (inferior) genomes and rapid gains in fitness. However, whenever the population is repeatedly reduced to a single virion, variable declines in fitness occur as predicted by the Muller's ratchet hypothesis. Here, we quantitated the fitness of 98 subclones isolated from an RNA virus clonal population. We found a normal distribution around a lower fitness, with the average subclone being less fit than the parental clonal population. This finding demonstrates the phenotypic diversity in RNA virus populations and shows that, as expected, a large fraction of mutations generated during virus replication is deleterious, This clarifies the operation of Muller's ratchet and illustrates why a large number of virions must be transferred for rapid fitness gains to occur. We also found that repeated genetic bottleneck passages can cause irregular stochastic declines in fitness, emphasizing again the phenotypic heterogeneity present in RNA virus populations. Finally, we found that following only 60 h of selection (15 passages in which virus yields were harvested after 4 h), RNA virus populations can undergo a 250% average increase in fitness, even on a host cell type to which they were already well adapted. This is a remarkable ability; in population biology, even a much lower fitness gain (e.g., 1 to 2%) can represent a highly significant reproductive advantage. We discuss the biological implications of these findings for the natural transmission and pathogenesis of RNA viruses. [TOP OF PAGE]
[Bacteriophage lambda:lux: design and expression of bioluminescence in E. coli cells]. Duzhii, D.E., Zavil'gel'skii, G.B. (1994). Molekuliarnaia Genetika, Mikrobiologia, i Virusologa 36-38. The bacteriophages lambda:lux and lambda:luxAB have been constructed by ligation of phage arms generated by BamHI or SalGI restriction endonucleases digestion of EMBL4 to BamHI digested plasmid pF1 lux+ or to SalGI digested plasmid pF2 lambda:luxA+B+. Cells of Escherichia coli prototrophic strain Cs were infected with lambda:lux or lambda:luxAB and intensity of bioluminiscence of the samples registered at different time intervals determined. The signal of bioluminiscence was first detected 15 min after infection and its level increased exponentially thereafter demonstrating replication of the lambda:lux bacteriophages. We have used the recombinant lambda:luxAB bacteriophage to detect the enteric indicator bacteria without enrichment in 15 min, provided that they are present at levels higher than 10(4). [TOP OF PAGE]
Evolution of Infectious Disease. Ewald, P.W. (1994). Oxford University Press, New York.[TOP OF PAGE]
Genetic variation and evolution of bacteriophages of lactobacilli. Forsman, P. (1994). Acta Universitatis Ouluensis Series a Scientiae Rerum Naturalium 1-39. Three Lactobacillus casei and seven Lactobacillus delbrueckii bacteriophages were compared phenotypically and at the DNA level. In general the phages are very similar in morphology but the prolate-headed phage JCL1032 differs from the others. The structural proteins were similar only in very closely related phages. On the basis of DNA homology the Lb. delbrueckii phages were divided into three groups. The phage JCL1032 represents a novel type of prolate-headed phage. It has short DNA regions that are highly homologous ( gt 74%) with the isometric-headed phages. The isometric-headed phages belonging to two different homology groups (groups a and b) had no high DNA homology ( gt 74%) with each other. The other major differences between the groups a and b are in the packaging of phage DNAs (pac- and cos-types) and in the host ranges. The different homology groups correspond to different incompatibility groups in superinfection immunity. The degree of homology among Lb. casei phages is larger than the homology among the Lb. delbrueckii phages. Prophages or defective prophages, which are highly homologous to the studied Lb. casei phages were found from all of the studied Lb. casei bacteria strains. Thus, the variability among Lb. casei phages seems to be very restricted. Genetic recombination have played a central role in evolution of the studied lactobacilli phages. The two putative transposable elements found from the Lb. delbrueckii phages LL-K and mv4 represent an extreme example of recombination. The KIS- element of LL-K contained further clusters of repated sequences as recombination hotspots. [TOP OF PAGE]
Use of bacteriophage for identification of Xanthomonas campestris pv. translucens. Forster, R.L., Strausbaugh, C.A., Lemattre, M., Freigoun, S., Rudolph, K., Swings, J.G. (1994). Colloques de l'INRA 421 [TOP OF PAGE]
Polymorphism of bacterial restriction-modification systems: The advantage of diversity. Frank, S.A. (1994). Evolution 48:1470-1477. Bacterial restriction-modification systems provide defense against foreign DNA by using a. self versus nonself recognition mechanism. A great diversity of recognition motifs is maintained in natural populations. Circumstantial evidence suggests that defense against bacteriophage viruses favors this diversity. (1) Bacterial restriction enzymes can destroy invading phage DNA. (2) Phage DNA can mimic the host's self-recognition mechanism. The ability of the virus to pose as a mimic favors diversification of the host's recognition motif. Other observations suggest that restriction modification (RM) does not provide any significant defensive advantages in mature communities. (1) In laboratory experiments, bacteria evolve resistance to phage by mutation and selection of the receptors to which phage adsorb. The outcome of these experiments is a community dominated by bacteria with receptor-based resistance, with a low abundance of phage and susceptible bacteria. (2) Phage are rare and receptor-based resistance is common in samples from natural communities. I present a model that shows two factors determine community composition: resources and RM diversity. Communities in resource- rich habitats are dominated by receptor-based resistance and support few phage; communities in poor habitats are dominated by restriction-modification defense and relatively abundant phage. RM diversity is itself a direct cause of community composition. As diversity increases from a low level, the abundance of phage increases and the relative abundance of receptor-based resistance declines. Further increases in diversity cause a crash in phage abundance, yielding a stable community of diverse RM types but an absence of the selective pressure - the phage - that drove the diversification. Empirical studies must sample a range of resource levels and RM diversity to analyze the forces that determine community composition. [TOP OF PAGE]
Phage sensitivity in relation to pathogenicity and virulence of the cotton bacterial blight pathogen of Sudan. Freigoun, S.O., El Faki, H.I., Gelie, B., Schirmer, M., Lemattre, M. (1994). Plant Pathology (Oxford) 43:493-499. At least two pathotypes of Xanthomonas campestris pv. malvacearum are now known to exist in Sudan. The pre-Barakat (race 1) and post-Barakat (race 2) pathogens have been shown to exhibit different host specificity. The former is pathogenic and highly aggressive on only cultivars with no resistance genes or with the B-2 and/or B-3 resistance factors, while the latter can infect the B-6 cultivars also. Race 2 in Sudan, which was previously reported to infect all the standard differentials, produced milder angular leaf spot symptoms and occasionally restricted vein infection. Moreover, it exhibited reduced growth in planta compared with race 1. Bacteriophage studies revealed that the two races are quite distinct in their phage sensitivity. Race 1 can be lysed by only three, or rarely four, of the six phages used for typing, while race 2 is sensitive to all of them. The present study suggests that phage 7 may be the type-determining phage for race 2. Race 2 strain mutants resistant to phage 3 or 4 were found to be sensitive to phage 7 and pathogenic to both Acala and Barakat, although showing marked attenuation of virulence. However, mutants resistant to phage 2 or 7 were insensitive to all the phages and although they retained their pathogenicity to Acala, they either lost the ability to infect Barakat or produced a hypersensitive reaction. The resistance of all mutants was found to be due to failure to adsorb the homologous phage, indicating a change in the cell wall. The association of this with the attenuation of virulence suggests that bacterial wall components may function as virulence determinants in Xanthomonas campestris pv. malvacearum. [TOP OF PAGE]
Relationship between phage sensitivity and pathogenicity in Xanthomonas campestris pv. malvacearum. Freigoun, S.O., Abdel, R., Elfaki, H.I., Omer, M.E., Lemattre, M., Freigoun, S., Rudolph, K., Swings, J.G. (1994). Colloques de l'INRA 109 [TOP OF PAGE]
Population biology of virus-host interactions. Garnett, G.P., Antia, R. (1994). pp. 51-73. In In Morse, S.S. (ed.), The Evolutionary Biology of Viruses. Raven Press, Ltd., New York. [TOP OF PAGE]
New developments in fungal virology. Ghabrial, S.A. (1994). Adv. Virus Res. 43:303-388. [TOP OF PAGE]
Gene transfer among bacteria under conditions of nutrient depletion in simulated and natural aquatic environments. Goodman, A.E., Marshall, K.C., Hermansson, M. (1994). FEMS Microbiol. Ecol. 15:55-60. Gene transfer among microorganisms has been well demonstrated in laboratory microcosms and in situ, under non-limiting nutrient conditions. The literature contains conflicting opinions, however, as to whether such processes could occur in the absence of nutrients. This review summarises the evidence for the occurrence of gene transfer by conjugation, transformation and transduction among non-growing bacteria in nutrient depleted environments. Conjugation by selftransmissible, or by non-selftransmissible but mobilisable, plasmids has been shown to occur among environmental isolates of Escherichia coli, Enterobacter cloacae, Pseudomonas aeruginosa and marine Vibrio strains. Transduction and transformation have been demonstrated in isolates of P. aeruginosa and marine Vibrio strains, respectively. It is possible that the mechanisms of these processes may be different in non-growing cells in nutrient depleted conditions, compared to those occurring in cells growing in rich media. [TOP OF PAGE]
Virus coagulation in aqueous environments. Grant, S.B. (1994). Environmental Science & Technology 28:928-933. A mathematical model is presented for the temporal decline in total infectious units caused by simultaneous first-order inactivation and Brownian coagulation of viruses in an aqueous environment. On the basis of published physicochemical and biological constants for poliovirus, human immunodeficiency virus, and indigenous marine and freshwater bacteriophage, the model predicts that virion-virion coagulation is negligible in most aquatic systems. This analysis provides a framework for investigating the effect of coagulation and inactivation on viral infectivity and for developing more sophisticated models of virus survival outside the host cell. [TOP OF PAGE]
Effect of gamma irradiation on shelf life and bacterial and viral loads in hard-shelled clams (Mercenaria mercenaria). Harewood, P., Rippey, S., Montesalvo, M. (1994). Appl. Environ. Microbiol. 60:2666-2670. The feasibility of using 60Co gamma irradiation to inactivate total coliforms, fecal coliforms, Escherichia coli, Clostridium perfringens, and F-coliphage in hard-shelled clams, Mercenaria mercenaria, was investigated. The results of three trials indicated average D-10 values of 1.32 kGy for total coliforms, 1.39 kGy for fecal coliforms, 1.54 kGy for E. coli, 2.71 kGy for C. perfringens, and 13.50 kGy for F-coliphage. Irradiation doses of gt 0.5 kGy were significantly lethal to the shellfish. [TOP OF PAGE]
Receptor recognition by T-even type coliphages. Henning, U., Hashemolhosseini, S. (1994). pp. 291-298. In In Karam, J.D. (ed.), The Molecular Biology of Bacteriophage T4. ASM Press, Washington, DC. [TOP OF PAGE]
Gene transfer in the marine environment. Hermansson, M., Linberg, C. (1994). FEMS Microbiol. Ecol. 15:47-54. This review summarises the literature on bacterial gene transfer in marine ecosystems. Relevant experiments carried out in model systems are also included. Prerequisites for the main gene transfer mechanisms, transformation, transduction and conjugation are discussed, such as concentrations of extracellular DNA in marine waters, numbers of bacteriophages in sea water and frequency of plasmids in marine bacteria. Transfer of chromosomal genes as well as plasmids are considered. We also discuss the possibility that gene transfer is more frequent in surface- associated bacterial communities. Examples of relevant studies using various solid surfaces and from the air-water interface are summarised. We suggest that there is a higher 'flow-rate' of genetic information through surface-associated communities compared to bulk water communities. [TOP OF PAGE]
In situ replication studies of somatic and male-specific coliphages in a tropical pristine river. Hernandez-Delgado, E.A., Toranzos, G.A. (1994). Water Science and Technology 247-250. The present study was carried out in order to evaluate coliphage survival and their ability to replicate in tropical aquatic environments. Results showed that coliphages survived for extended periods of time, however, neither sewage isolates nor laboratory phage strains replicated in the environment. Neither one of the bacterial strains tested were permissive to phage replication of "fecal coliphages" does not occur in the tropical aquatic environment and suggest that somatic or male-specific coliphages may be considered as potential indicators of fecal contamination in tropical aquatic environments. [TOP OF PAGE]
Population dynamics of phage-host interactions and phage conversion of streptomycetes in soil. Herron, P.R., Wellington, E.M.H. (1994). FEMS Microbiol. Ecol. 14:25-32. The fate of Streptomyces lividans lysogens was studied in sterile and nonsterile soil microcosms. It was found that in sterile soil lysogens grew as well as the parental strain. However, in nonsterile soil, numbers of the lysogen decreased rapidly, indicating a decreased fitness when compared to the original organism. In addition, the release of this phage from a lysogen and its subsequent infection and lysogenization of a recipient strain was demonstrated in sterile soil. [TOP OF PAGE]
Population and persistence of Zag-1 phage and cowpea Rhizobium in two sterile soils. Hussein, M.E., El-Hawa, M.E.A., El Dydamony, G. (1994). Egyptian Journal of Microbiology 29:271-283. ZAG-1 phage was isolated from the rhizosphere of cowpea plants grown in fields in Sharkiyia, Egypt. The existence and propagation of cowpea Rhizobium and its Zag-1 phage were studied in clay and sandy soils. The maximum bacterial counts were recorded in clay soil after 7 weeks of incubation compared with 8 weeks for sandy soil. The infectivity of Zag-1 phage persisted for 5 and 10 weeks in clay and sandy soils respectively. Testing the roles of Zag-1 phage on nodulation and growth of cowpea showed significant alterations. Zag-1 phage inhibited nodule formation in plants grown in sterile potted clay soils but with only a reduction for those grown in sandy soils. [TOP OF PAGE]
Field evaluation of two colorimetric coliphage detection methods. Ijzerman, M.M., Falkinhami, J.O.L., Reneau, R.B.Jr., Hagedom, C. (1994). Appl. Environ. Microbiol. 60:826-830. Two new methods for coliphage detection, a colorimetric agar-based (CAB) method and a liquid colorimetric presence-absence (LCPA) method, were compared to the coliphage method proposed by the American Public Health Association (APRA; Standard Methods for the Examination of Water and Wastewater, 18th ed., American Public Health Association, Washington, D.C., 1992). Both new methods are based on the induction of beta-galactosidase in Escherichia coli and the release of the enzyme through a lytic cell infection. The released enzyme then cleaves a chromogenic substrate which produces a colored reaction product. Ninety split water samples from four different sources were tested. A total of 52 samples were positive by the CAB method, 52 were positive by the LCPA method, and 53 were positive by the APRA method. Results indicated that (i) the CAB and LCPA methods were as sensitive in coliphage detection as the APHA method, (ii) both the CAB and LCPA methods were easier to read and interpret than the APHA method, and (iii) the CAB method detected more coliphages in a positive sample than the APRA method in two of the four types of water sources. Importantly, the rapid and simple LCPA method was as reliable and sensitive as either of the two agar-based methods in coliphage detection. [TOP OF PAGE]
Development and evaluation of a colorimetric coliphage assay detection system. Ijzerman, M.M., Hagedorni, C.I., Reneau, R.B., Jr. (1994). Virginia Polytechnic Institute and State University Water Resources Research Center Bulletin I-VII A colorimetric coliphage assay detection system (CCADS), composed of a liquid colorimetric presence-absence (LCPA) method and a colorimetric agar-based (CAB) method, was developed to overcome the limitations imposed by the Standard Methods for the Examination of Water and Wastewater agar-based coliphage method (APHA method). Both CCADS methods are based on the induction of beta-galactosidase in Escherichia coli and the release of the enzyme through a lytic cell infection. The released enzyme then cleaves a chromogenic substrate, which produces a colored reaction product. The CCADS was evaluated against the APHA method under laboratory conditions using a common sewage coliphage strain as a model (American Type Culture Collection-13706-B2), and under field conditions using water samples collected from four different sources. During the laboratory evaluation, both the LCPA and CAB methods were found to be superior to the APHA method in coliphage detection because: 1) the LCPA and CAB methods were easier to read and interpret than the APHA method, 2) the LCPA and CAB methods were not subject to false positive results, 3) the LCPA method theoretically detected fewer coliphage particles than the APHA method, and 4) the CAB method detected roughly twice the number of coliphage particles detected with the APHA method. During the field evaluation, the results indicated: 1) the LCPA method was as reliable as either the CAB or APHA method in coliphage detection; 2) the LCPA and CAB methods were easier to read and interpret than the APHA method; 3) neither the LCPA method nor the CAB method were subject to false positive results; 4) the CAB method detected more coliphages than the APHA method under conditions of high fecal pollution, but both methods performed equally well in coliphage detection under conditions of low fecal contamination; and 5) the LCPA and CAB methods were equally as sensitive in coliphage detection as the APHA method. Finally, the coliphage group proved to be a useful indicator of fecal pollution in nonpotable water supplies exhibiting a high degee of fecal pollution, whereas they were not shown to be useful indicators in potable water supplies exhibiting low levels of fecal contamination. The lack of coliphage detection sensitivity under conditions of low fecal contamination does not appear to be method-limited, but the result of inefficiencies in processing environmental samples using the concentration methods currently available. [TOP OF PAGE]
Seasonal and diel abundance of viruses and occurrence of lysogeny/bacteriocinogeny in the marine environment. Jiang, S.C., Paul, J.H. (1994). Mar. Ecol. Prog. Ser. 104:163-172. To understand the role of viruses in the marine environment, it is important to know the factors affecting their temporal distribution and the abundance of lysogens. We therefore performed a seasonal and a diel study on viral distribution in Tampa Bay, Florida, USA, and detected the abundance of lysogens and bacteriocinogens amongst marine bacterial isolates from diverse marine environments. We investigated the distribution of viruses, bacterial direct counts, chlorophyll a (chl a), salinity and temperature during a 13 mo period in the Tampa Bay estuary. The results indicated that the viral population had a strong seasonal pattern with the highest concentrations (2.0 +- 0.8 times 10-7) in the summer and lowest (4.8 +- 1.4 times 10-6) in the winter. Viral abundance was negatively correlated with salinity (r = -0.803), and positively correlated with chl a concentration (r = 0.725). A diel study in a seawater mesocosm indicated that viral abundance did not vary on a diel rhythm, but rather peaked after a maximum in bacterial abundance and chl a. Dissolved DNA concentrations displayed diel rhythmicity, suggesting that viruses were not the main source of dissolved DNA. An estimation of the percentage of the bacterial standing stock lysed by viruses based on 4 h intervals ranged from 3.0 to 53.3% per day. Screening bacterial isolates for the presence of inducible prophages indicated that 43% were lysogens or bacteriocinogens, suggesting that lysogeny and bacteriocinogeny are common in the marine environment. [TOP OF PAGE]
Isolation and characterization of V. furnissii phage [Korean]. Ju, J.W. (1994). Journal of the Korean Society for Microbiology 29:685-697. The study of bacteriophage began by F.W. Twort in 1915 and the lytic cycle recognized by d'Herelle in 1917. It repeated about the marine bacteriophage containg Vibrio phage by Smithand Spencers. V. furnissii and V. fluvialis are very close phenotypically. Gas production is the only key differential test in most clinical laboratories. V. furnissii is a new Vibro species which was formerly known as "V. fluvialis biovar II", "V. fluvialis aero genic", "V. fluvialis gas⁺". The majority of the V. furnissii group isolated from patients with diarrhea and acute gastroenteritis but the role of V. furnissii was not clear. Much resaerch concerning V. furnissii and V. furnissii phage remains unknown. Thus, author isolated two virulent phage from marine products. These 2 phages were examined the ultrastrucrure by electron microscopy and investigated temperature stability, pH stability, inactivation by UV irradiation, antibody production and structural protein analysis. VF phages formed plaques, 2-3mm in diameter, and VF5 formed turbid plaques. VF3 had only head whereas VF5 had tail and head. Although temperature, pH, and UV sensitivity were phage specific, all phages almost inactivated above 70 degree C, and was stable in wide pH range, pH 6.0-pH 10.0 and mostly inactivated by UV irradiation for 100 seconds. Latent period was 60-80 minutes and burst size was 300 PFU/cell in VF3, 400 PFU/cell in VF5. Serologically, antiserum of VF5 neutralized the VF3. Phage DNAs were about 23kb and two all phages were digested with BamHI, Bgl III. Structural protein analysis represented that VF phages have specific structural protein and several common major protein. [TOP OF PAGE]
Some characteristics of virulent bacteriophages isolated from Pseudomonas solanacearum-infested soil [Japanese]. Kakutani, K., Toyoda, H., Goto, S., Ouchi, S. (1994). Annals of the Phytopathological Society of Japan 60:531-534. Virulent bacteriophages (phages) were isolated from a field soil infested with the host bacterium, Pseudomonas solanaccarum (strain K-101) and examined for their physical and chemical properties. The phages were classified into two types on the basis of their plaque morphologies (small obscure or large clear plaques against the indicator bacterium K-101), and the phages were isolated and purified through a series of plaque isolation. An electron microscopic observation indicated that the phage isolate forming a small plaque had a polygonal head with three tails and the other a smaller head with two tails. The electrophoretic patterns of DNA fragments obtained by the digestion with some restriction endonucleases were completely different between these two types of isolated phages. The RFLP was detected among the small plaque-forming phage isolates, although there was no difference in morphology of phage particle and infectivity against some different strains of the host bacterium. [TOP OF PAGE]
Host range, morphology and DNA restriction patterns of bacteriophage isolates infecting Rhizobium leguminosarum Bv. trifolii. Kankila, J., Lindstrom, K. (1994). Soil Biol. Biochem. 26:429-437. 11 bacteriophages infecting Rhizobium leguminosarum bv. trifolii were isolated from Finnish field soils. Their host range was determined using 32 Rhizobium strains. Some of the phage isolates were further characterized by restriction analysis of phage DNA and by electron microscopy. Three morphological types were found among the isolates. Type 1 included several isolates belonging to Bradley's morphological group A. Type 1 phages were able to lyse all of the R. leguminosarum strains and their DNA was not cleaved by any of the 13 restriction enzymes tested. Types 2 and 3, each represented by one isolate, belonged to morphological groups A and C, respectively, and had a more narrow host range and DNA susceptible to cleavage by several restriction enzymes. The host range of all three types was inversely related to the level of susceptibility of phage DNA to restriction enzymes. [TOP OF PAGE]
Molecular Biology of Bacteriophage T4. Karam, J.D. (1994). ASM Press, Washington, DC.[TOP OF PAGE]
Inactivation of Q by potasium ferrate. Kazama, F. (1994). FEMS Microbiol. Let. 118:345-350. [TOP OF PAGE]
Trichomonas vaginalis with a double-stranded RNA virus has upregulated levels of phenotypically variable immunogen mRNA. Khoshnan, A., Alderete, J.F. (1994). J. Virol. 68:4035-4038. Some isolates of Trichomonas vaginalis carry a double-stranded RNA virus (TVV) and undergo phenotypic variation between surface expression and cytoplasmic expression of a prominent immunogen (P270). Only trichomonads with TVV express P270 on the surface. Northern (RNA) blots using a specific cDNA encoding the repeat element of the phenotypically varying P270 immunogen as a probe showed accumulation of P270 transcript only in isolates with TVV (V+) in contrast to isolates without the virus (V-). To test further the influence of virus infection on P270 mRNA expression, V- progeny, derived from the parental V+ isolates, were tested. Trichomonads of V- progeny, like the fresh clinical V- isolates, also showed no accumulation of P270 mRNA. By immunoblotting with a monoclonal antibody to the key repeated epitope of P270, it was found that V- organisms had quantitatively less immunoreactive protein than the parental V+ isolates. Although V+ and V- isolates contained proteins immunoreactive with the monoclonal antibody to P270, it was necessary to test for the presence of the P270 gene among all the isolates. As expected, Southern blots demonstrated that V+ and V- trichomonads possessed the gene encoding P270. These data suggest that the double-stranded RNA virus of T. vaginalis is involved in the regulation of P270 mRNA accumulation. [TOP OF PAGE]
Evidence for phage-mediated gene transfer among Pseudomonas aeruginosa strains on the phylloplane. Kidambi, S.P., Ripp, S., Miller, R.V. (1994). Appl. Environ. Microbiol. 60:496-500. [TOP OF PAGE]
Host determination of viral evolution: A variable tautology. Kilbourne, E.D. (1994). pp. 253-271. In In Morse, S.S. (ed.), The Evolutionary Biology of Viruses. Raven Press, Ltd., New York. [TOP OF PAGE]
A New Synechococcus Cyanophage from a Reservoir in Korea. Kim, M., Choi, Y.-K. (1994). Virology 204:338-342. A unicellular cyanobacterium (Synechococcus) and its cyanophage were both isolated from a reservoir in Korea. Although morphologically similar to AS-1, the cyanophage differs from cyanophage AS-1 in some respects. The burst size in the light is approximately 100 plaque-forming units (PFU)/cell. Replication of the virus also occurs in the dark, releasing about 10% of the virus particles observed in the light. Na+ is not necessary for adsorption. [TOP OF PAGE]
Measurements of UV-B radiation in two freshwater lakes: An instrument intercomparison. Kirk, J.T.O., Hargreaves, B.R., Morris, D.P., Coffin, R.B., David, B., Frederickson, D., Karentz, D., Lean, D.R.S., Lesser, M.P. (1994). Ergebnisse der Limnologie/Advances in limnology 43:71-99. Instruments and biological dosimeters were used to measure solar spectral irradiance in two lakes, one clear and the other moderately coloured, with emphasis on the ozone-sensitive UV-B wavelengths. An atmospheric model provided an approximate standard against which were compared commercial instruments from Biospherical Instruments, Inc., International Light, Inc., LI-COR Inc., and Optronic Laboratories, Inc. Comparisons of irradiance in air, and irradiance and attenuation coefficients at several depths, revealed differences in spectral resolution, accuracy, sensitivity to low light energy, and convenience in generating depth-specific profiles. Broadband instruments trade off resolution for simplicity and, in some cases, greater sensitivity, but are subject to errors when the solar spectrum is modified by sun angle, atmospheric column ozone, and the inherent optical properties of the water. For UV-B measurement in lakes, an ideal instrument should have a narrow bandwidth, sensitive and temperature-stable light detector and wavelength filter/selector with high rejection of stray light, well-characterized cosine response and immersion coefficients in both air and water, and an integral sensor for precise measurement of depth. None of the instruments tested matched the ideal, but each had useful characteristics as well as limitations that in some cases could be minimized by coupling their use with an atmospheric model. Analysis of results from bacterial and phage dosimeters using a new "biological attenuation coefficient", K*, yielded values corresponding to instrument-derived attenuation coefficients in the range of 320-340 nm, suggesting that UV-B and UV-A irradiance contributed to the damaging effects of sunlight. A several-fold reduction in mortality by Mylar super( registered )-screening of dosimeters argues for a significant effect of UV-B light. Bacteria (DNA repair-defective) were consistently more susceptible to light than were phage under matched conditions. [TOP OF PAGE]
Inducible cell lysis system for the study of natural transformation and environmental fate of DNA released by cell death. Kloos, D.U., Stratz, M., Guttler, A., Steffan, R.J., Timmis, K.N., phenom: lysis (1994). J. Bacteriol. 176:7352-7361. Two novel conditional broad-host-range cell lysis systems have been developed for the study of natural transformation in bacteria and the environmental fate of DNA released by cell death. Plasmid pDKL02 consists of lysis genes S, R, and Rz from bacteriophage lambda under the control of the Ptac promoter. The addition of inducer to Escherichia coli, Acinetobacter calcoaceticus, or Pseudomonas stutzeri containing plasmid pDKL02 resulted in cell lysis coincident with the release of high amounts of nucleic acids into the surrounding medium. The utility of this lysis system for the study of natural transformation with DNA released from lysed cells was assessed with differentially marked but otherwise isogenic donor-recipient pairs of P. stutzeri JM300 and A. calcoaceticus BD4. Transformation frequencies obtained with lysis-released DNA and DNA purified by conventional methods and assessed by the use of antibiotic resistance (P. stutzeri) or amino acid prototrophy (A. calcoaceticus) for markers were comparable. A second cell lysis plasmid, pDKL01, contains the lysis gene E from bacteriophage phi X174 and causes lysis of E. coli and P. stutzeri bacteria by activating cellular autolysins. Whereas DNA released from pDKL02-containing bacteria persists in the culture broth for days, that from induced pDKL01-containing bacteria is degraded immediately after release. The lysis system involving pDKL02 is thus useful for the study of both the fate of DNA released naturally into the environment by dead cells and gene transfer by natural transformation in the environment in that biochemically unmanipulated DNA containing defined sequences and coding for selective phenotypes can be released into a selected environment at a specific time point. This will allow kinetic measurements that will answer some of the current ecological questions about the fate and biological potential of environmental DNA to be made. [TOP OF PAGE]
A long lytic cycle in filamentous phage Cf1tv infecting Xanthomonas campestris pv. citri. Kuo, T.-T., Chiang, C.-C., Chen, S.-Y., Lin, J.-H., Kuo, J.-L. (1994). Archives of Virology 135:253-264. In this study the lytic cycle of a filamentous phage is reported. Under normal laboratory cultivation conditions a virulent form could spontaneously and easily arise from a temperate phage. The virulent one could superinfect cells containing Cflt lysogen. Therefore, we have named it Cfltv. In a colony formation assay using cells from an infected culture, two types of colonies were observed, small and large. It could be proven that the formation of small colonies is the result of killing during Cfltv infection. The number of small colony forming units (cfu) increased with infection time and reached a maximum at 16 h after infection, then dropped to the initial cell concentration at 28 h after infection; 28 h were required to kill all infected cells. Large colonies contained uninfected or phage- resistant cells, but no lysogenic cells. Bacterial death was further confirmed by a microculture assay. At 2 h after infection, normal-dividing cells (cfu giving large colonies) contained about 40% of Cfltv-infected cells, then the percentage decreased with infection time. Slow-dividing cells (infected cfu giving small colonies) initially contained 55% of cells; this percentage increased slightly at 4 h after infection, then decreased at 8 h after infection. Non-dividing cells initially contained 5% of infected cells, then their numbers rapidly increased with time after infection. The cell division was seriously affected and finally stopped. During one-step growth, the latent period was 30 min and there was no burst; phages were released at 30 min after infection and the rate of release increased gradually with time after infection. Phage DNA integration into host chromosome could not be observed. [TOP OF PAGE]
Rapid detection of Clavibacter toxicus and of its bacteriophage responsible for annual ryegrass toxicity in Australia and the effect of selected herbicides on toxin production. Kurtboke, D.I. (1994). Actinomycetes 5:31-39. [TOP OF PAGE]
Effects of bacterial growth conditions and physiology on T4 infection. Kutter, E., Kellenberger, E., Carlson, K., Eddy, S., Neitzel, J., Messinger, L., North, J., Guttman, B. (1994). pp. 406-418. In In Karam, J.D. (ed.), The Molecular Biology of Bacteriophage T4. ASM Press, Washington, DC. Most studies of T4 development have been carried out under conditions that appear to be optimal, at least for the commonly used laboratory strains: rich media, highly aerated, at 37&#176C. However, there is a growing interest in understanding the ability of phage to grow under conditions more like those they meet in nature. This interest parallels the growing number of studies of Escherichia coli in more natural environments, along with an increased understanding of how bacteria respond to altered growth conditions, such as lack of oxygen, nutrient deprivation, and environmental stress (Freter, 1983, 1992; Matin et al., 1989; Roszak and Colwell, 1987; Bohannon et al., 1991; Spiro and Guest, 1991). The interest is further stimulated by the finding that, in addition to approximately 150 genes of known function, T4 has nearly 150 apparent open reading frames (ORFs) whose functions are not yet known (see the Appendix of this volume). Most of them appear likely to endode proteins and are in regions that are deletable under standard laboratory conditions. Many may have functions that are relevant only in natural environmental conditions, while others are clearly involved in the transition from host to phage metabolism. Efforts to understand the infection process and evolutionary pressures in the natural habitat(s) of T-even phages need to take into account bacterial metabolism and intracellular environments under such conditions. Thus, in this chapter we explore the evidence regarding the probable origins of T4 and examine the effects on the composition of E. coli of various environmental factors that may affect T4 growth. We review the limited number of studies of phage growth under conditions approaching those in its native habitats: low oxygen tension, nutrient limitation, exposure to nongrowing ("stationary") host cells, and temperature variations. None of these topics has been reviewed previously. [TOP OF PAGE]
[Bacteriophage therapy in the treatment of recurrent subphrenic and subhepatic abscess with jejunal fistula after stomach resection]. [Polish]. Kwarcinski, W., Lazarkiewicz, B., Weber-Dabrowska, B., Rudnicki, J., Kaminski, K., Sciebura, M. (1994). Polski Tygodnik Lekarski 49:535-535. The case of recurrent subphrenic abscess with the jejunal fistula after stomach resection in 41-years old male is presented. In microbiological examination E. coli antibiotic-resisted was discovered. The bacteriophages were prepared and administered to the patient. The operation was performed without any antibiotics. During the whole stay at hospital the patient had got bacteriophages. He left the hospital in 33rd day of stay without any abscesses. [TOP OF PAGE]
Vphi-AAU2, a temperate bacteriophage specific for 'Arthrobacter aureus', whose integrative functions work in other corynebacteria. Le Marrec, C., Michotey, V., Blanco, C., Trautwetter, A. (1994). Microbiology (Reading) 140:3071-3077. The temperate bacteriophage AAU2 of 'Arthrobacter aureus' C70, isolated from a soil sample, has been purified and characterized. The phage belongs morphologically to the Siphoviridae family. Its genome consists of a linear double-stranded DNA of 45.4 kb with cohesive ends. The attP site and the phage-encoded functions essential for integration were cloned in Escherichia coli as a 5-25 kb BglII-EcoRV fragment. The resulting plasmid vector, nonreplicating in 'A. aureus', is able to integrate at high frequency into the chromosomes of 'A. aureus' and the industrially used coryneform bacteria Brevibacterium lactofermentum and Corynebacterium glutamicum. [TOP OF PAGE]
The evolution of virulence in parasites and pathogens reconciliation between two competing hypotheses. Lenski, R.E., May, R.M. (1994). J. Theor. Biol. 169:253-265. [TOP OF PAGE]
F-specific bacteria as an indicator of human viruses in natural waters and sewage effluent in northern New Zealand. Lewis, G.D. (1994). Water Science and Technology 31:231-234. To assess the F-specific bacteriophage as an indicator of pathogenic viruses, a comparative study has been of the occurrence of F-phage and human enteroviruses in sewage wastes and the marine environment. Although F-phage seemed in several respects to much pathogen behaviour, its low abundance in bathing beach water, uncertainty as to its source and other detection irregularities makes its use as an indicator problematical. [TOP OF PAGE]
Taxonomical classification of 20 newly isolated Listeria bacteriophage by electron microscopy and protein analysis. Loessner, M.J., Estela, L.A., Zink, R., Scherer, S. (1994). Intervirology 37:31-35. [TOP OF PAGE]
Effect of distance from the polluting focus on relative concentrations of Bacteroides fragilis phages and coliphages in mussels. Lucena, F., Lasobras, J., McIntosh, D., Forcadell, M., Jofre, J. (1994). Appl. Environ. Microbiol. 60:2272-2277. Concentrations of fecal bacteria, somatic and F-specific coliphages, and phages infecting Bacteroides fragilis in naturally occurring black mussels (Mytilus edulis) were determined. Mussels were collected over a 7-month period at four sampling sites with different levels of fecal pollution. Concentrations of both fecal bacteria and bacteriophages in mussel meat paralleled the concentration of fecal bacteria in the overlying waters. Mussels bioaccumulated efficiently, although with different efficiencies, all of the microorganisms studied. Ratios comparing the levels of microorganisms in mussels were determined. These ratios changed in mussels collected at the different sites. They suggest that bacteriophages infecting B. fragilis and somatic coliphages have the lowest decay rates among the microorganisms studied, with the exception of Clostridium perfringens. On the contrary, concentrations of F-specific coliphages showed a greater rate of decay than the other bacteriophages at sites more distant from the focus of contamination. Additionally, levels of enteroviruses were studied in number of samples, and in these samples, the B. fragilis bacteriophages clearly outnumbered the enteroviruses The results of this study indicate that, under the environmental conditions studied, the fate of phages infecting B. fragilis released into the marine environment resembles that of human viruses more than any other microorganism examined. [TOP OF PAGE]
Effects of biocides on MS2 and K coliphages. Maillard, J.-Y., Beggs, T.S., Day, M.J., Hudson, R.A., Russell, A.D. (1994). Appl. Environ. Microbiol. 3:849-853. [TOP OF PAGE]
Viral and bacterial dynamics in Arctic sea ice during the spring algal bloom near Resolute, N.W.T., Canada. Maranger, R., Bird, D.F., Juniper, S.K. (1994). Mar. Ecol. Prog. Ser. 111:121-127. High virus counts were found in Arctic sea ice samples taken during the spring ice algal bloom near Resolute, Northwest Territories, Canada. Viral abundances in the sea ice ranged from 3.7 x 10 super(11) viruses/m super(2) (or 9.0 x 10 super(6)/ml) to 4.9 x 10 super(12)/m super(2) (1.3 x 10 super(8)/m) which is 10- to 100-fold greater than the concentration of viruses in the underlying water column (1.1 x 10 super(6)/ml). This increase in viral abundance corresponds with the 10- to 100-fold increase in bacterial abundance in sea ice as compared with the water column. Bacterial abundances ranged from 6.1 x 10 super(9) bacteria/m super(2) (1.5 x 10 super(5)/ml) to 4.2 x 10 super(11)/m super(2) (1.0 x 10 super(7)/ml) from early to late spring respectively. The virus-to-bacteria ratios (VBR) were among the highest reported in natural samples. The greatest viral abundances occurred in the 0.5 to 1.5 cm layer of the ice profile, where the bacteria were most active. The VBR generally decreased during the spring although viruses were increasing in abundance. The disequilibrium between phage and bacterial growth and abundance maxima during the spring bloom is suggested to be due to (1) a change in the makeup of the bacterial community, such that phage-resistant bacteria proliferated later in the spring, or (2) an increase in viral lytic activity with higher bacterial cell-specific growth rates; both viral lytic activity and bacterial growth rates declined later in the spring as the bacterial population reached its peak. [TOP OF PAGE]
Phage-host interactions in soil. Marsh, P., Wellingron, E.M.H. (1994). FEMS Microbiol. Ecol. 15:99-108. [TOP OF PAGE]
Isolation of virus capable of lysing the Brown Tide microalga, Aureococcus anophagefferens. Milligan, K.L.D., Cosper, E.M. (1994). Science 266:805-807. Viruses have been hypothesized to control blooms of Aureococcus anophagefferens gen. et sp. nov. (Chrysophyceae), a marine phytoplankton that since 1985 has caused devastating summer blooms called "brown tide." By means of ultrafiltration methods, viruses specific to this alga were isolated from both the Great South Bay and Peconic Bay systems of Long Island, New York, during the summer bloom period of 1992. Cell lysis of healthy algal cultures was demonstrated, as well as continuing reinfection with serial transfers of cultures. Electron microscope surveys yielded images of phage-like virus particles with tails that could attach to A. anophagefferens cells within minutes of exposure. The isolation and cultivation of this virus highlights the need for further study of viral infection of eukaryotic algae and the potential for a better understanding of algal bloom control by viral infection. [TOP OF PAGE]
Evolution of a lytic bacteriophage via DNA acquisition from the Lactococcus lactis chromosome. Moineau, S., Pandian, S., Klaenhammer, T.R. (1994). Appl. Environ. Microbiol. 60:1832-1841. We discovered a phage-host interaction in which the lytic phage ul36, in response to pressure exerted by an abortive phage resistance mechanism, acquired a large DNA fragment from the chromosome of Lactococcus lactis NCK203 to form a new phage, ul37. Phage ul37 was characterized at morphological, phenotypic, and genotypic levels and was found to be a member of the P335 species. Although it exhibits a high level of DNA homology with ul36, phage ul37 is resistant to the abortive mechanism and has a longer tail, a different base plate, and apparently a different origin of replication. The chromosomal DNA implicated in the formation of new phage ul37 was disrupted by site-specific integration in NCK203. This strategy prevented the appearance of ul37 during subsequent infections with ul36. [TOP OF PAGE]
Toward an evolutionary biology of viruses. Morse, S.S. (1994). pp. 1-28. In In Morse, S.S. (ed.), The Evolutionary Biology of Viruses. Raven Press, Ltd., New York. [TOP OF PAGE]
Marine viral ecology: Incorporation of bacteriophage into the microbial planktonic food web paradigm. Murray, A.G., Eldridge, P.M. (1994). Journal of Plankton Research 16:627-641. In the decade since the microbial loop was defined by Azam et al. (Mar. Ecol. Prog. Ser., 59, 1-17, 1983), the importance of the interaction between microbial organisms and the larger planktonic animals has been a subject of controversy. Until recently, grazing was considered to be the major fate of bacterial production. Now, however, viruses are seen to have an important role in microbial processes. We describe how growth and recycling parameters affect the transfer of bacterial production through a microbial loop model that includes viruses. The loop is very inefficient for all reasonable conditions, but its relative importance as a source of mesozooplankton nutrition is variable. The model demonstrates that in mesotrophic coastal waters, the microbial loop is unlikely to supply more than a minor component of mesozooplankton nutrition, a proposition that is supported by accumulating evidence. For oligotrophic pelagic waters, the model indicates that in the absence of viruses the microbial loop, despite its low efficiency, may provide an important resource for mesozooplankton. Bacterial production, without viral mortality, is also relatively important in the case of direct exploitation by salps. Under these conditions, bacteria account for 10-30% of mesozooplankton nutrition. With high levels of bacteriophage activity, zooplankton production is generally reduced by 5-15%. We thus conclude that bacteriophages could significantly affect mesozooplanktonic and, hence, exploitable marine production. [TOP OF PAGE]
Virus-like particles in Heterosigma akashiwo (Raphidophyceae): a possible red tide disintegration mechanism. Nagasaki, K., Ando, M., Imai, I., Itakura, S., Ishida, Y. (1994). Mar. Biol. 119:307-312. [TOP OF PAGE]
Viral mortality in the final stage of Heterosigma akashiwo (Raphidophyceae) red tide. Nagasaki, K., Ando, M., Itakura, S., Imai, I., Ishida, Y. (1994). J. Plankton Res. 16:1595-1599. [TOP OF PAGE]
Experiments on the possible role of leeches as vectors of animal and human pathogens: a light and electron microscopy study. Nehili, M., Ilk, C., Mehlhorn, H., Ruhnau, K., Dick, W., Njayou, M. (1994). Parasitology Research 80:277-290. The presence and survival of pathogens inside the gut of leeches were studied by means of light and electron microscopy. In African leeches from Cameroon, blood was serologically positive for human immunodeficiency virus (HIV) and hepatitis B; blood of Hirudo medicinalis bought in German pharmacies contained up to 11 different species of bacteria. In experiments done at low (3 degrees C) and high (22 degrees, 32 degrees C) temperatures, it was shown that ingested red and white blood cells survive for long periods. The time was prolonged to at least 6 months in cases in which the leeches were stored at 3 degrees C. The same effect occurred with pathogens. Bacteriophages (viruses of bacteria) and bacteria persisted in large numbers for at least 6 months in the gut of experimentally infected leeches. Protozoan parasites such as Toxoplasma gondii, Trypanosoma brucei brucei, or Plasmodium berghei were even capable of reproducing inside the gut of the leech. In the case of Plasmodium parasites, this proceeded at low (3 degrees C) and high (22 degrees C) temperatures until all erythrocytes were used up. These parasites survived as long as the erythrocytes and lymphocytes were of good shape, i.e., around 5-6 weeks p.i. Single stages survived longer, especially at low temperatures. However, electron microscopy studies gave no hint of penetration of such pathogens into the unicellular salivary glands, which would initiate a direct transmission. Such transmission, however, is possible--many fish leeches directly transmit several blood parasites--when the leeches are squeezed during skin attachment or when they are manipulated by dropping salt solution on their backs while they are sucking. Consequently, the leech is a potential vector of many pathogens, especially in regions with an endemic spread of human and/or animal pathogens. [TOP OF PAGE]
The Kinetics of Batch Ultraviolet Inactivation of Bacteriophage MS2 and Microbiological Calibration of an UV Pilot Plant. Nieuwstad, T.J., Havelaar, A.H. (1994). Journal of Environmental Science and Health Part A Environmental Science and Engineering 29:1993-2007. Batch ultraviolet (UV) inactivation of bacteriophage MS2 in water or wastewater effluent using low pressure mercury lamps exhibits a tailing effect, which could be modeled by assuming that the rate constant, k, decreases with the logarithmic reduction, LR, according to the relation: k = aLR + b with a = 0.00044 +- 0.00012 m-2/J and b = 0.0152 +- 0.0010 m-2/J. It is not clear why k decreases with the LR. Possibilities are differences in sensitivity between individual phages within the population or the formation of clusters of organisms by aggregation with each other or with suspended solids present in the water. A full scale pilot plant could be characterized hydraulically by microbiological calibration using the batch kinetic constants. Ultraviolet disinfection units must be modeled as a number of completely mixed tanks in series. [TOP OF PAGE]
Subtidal volume fluxes, nutrient inputs and the brown tide – an alternative hypothesis. Nixon, S.W., Granger, S.L., Taylor, D.I., Johnson, P.W., Buckley, B.A. (1994). Estuar. Coast Shelf Sci. 39:303-312. [TOP OF PAGE]
Polyagglutinable Pseudomonas aeruginosa from cystic fibrosis patients. A survey. [Review] [233 refs]. Ojeniyi, B. (1994). APMIS Supplementum. 46:1-44. Chronic Pseudomonas aeruginosa lung infection is responsible for most of the mortallity and morbility observed in cystic fibrosis patients. During the course of the disease, the bacteria change from being O-serogroup typable (monoagglutinable), non-mucoid, resistant to normal human serum and motile, to become O-serogroup non-typable (polyagglutinable), serum-sensitive and non-motile. In spite of high levels of antibodies produced by the patient, and intensive antibiotic therapy it is not possible to eradiate the polyagglutinable bacteria from the lungs of the patients. The bacteria will reappear and it is not fully understood if it is the same strain which reappears, or it is a super-infection with a new strain which takes place. A reliable and stable typing method is needed to clarify this question. In the present study, the conventional typing methods, such as serotyping, phage typing and pyocin typing were compared with the newer DNA typing methods, such as, restriction fragment length polymorphism (RFLP) in combination with pulsed field gel electrophoresis (PFGE) and typing with a specific DNA probe. Typability, reproducibility and discriminatory power using the different typing methods were investigated. The conventional typing methods have proved to be adequate when typing P. aeruginosa isolates from non cystic fibrosis sources, but because the majority of cystic fibrosis P. aeruginosa isolates are polyagglutinable or non typable, serotyping is not useful. Phage typing also lacks discriminatory power as it lumps up to 40% of the isolates in the same phage group. Pyocin typing has the disadvantage of low reproducibility. Most of the conventional typing methods are based on receptors on the bacterial surface, which on exposure to the environmental conditions in the lung, are likely to provoke phenotypic changes of the bacteria. The obvious advantage of the newer DNA typing methods is that these methods are based on internal properties of the bacteria, as part of the bacterial genome is investigated. The present study has revealed that for the time being, restriction fragment length polymorphism (RFLP) and pulsed field gel electrophoresis (PFGE) in combination with phage typing is the best method of typing P. aeruginosa isolates from cystic fibrosis patients for epidemiological purposes. [References: 233]. [TOP OF PAGE]
Removal of influenza a virus, phage T1, and PP7 from fluids with a Nylon 0.04-mu-M membrane filter. Oshima, K.H., Highsmith, A.K., Ades, E.W. (1994). Environmental Toxicology and Water Quality 9:165-170. We tested the ability of a 0.04-mu-m nylon membrane filter to remove viral agents (influenza A virus, 80-120 nm; phage T1, 50-150 nm; and phage PP7, 25 nm) from the following media: ultrapure water (UPW), Dulbecco's modified Eagle minimum essential medium (DMEM), gelatin phosphate (GP), DMEM with 10% (DMEM-10) fetal bovine serum (FBS), and 100% FBS. When challenged with at least 3.0 times 10-7 plaque-forming units/mL, no influenza A virus was detected downstream of the filter with any of the fluids tested. The titer reduction (Tr) was determined using the equation: Tr = Concentration Input (PFU/mL)/ Concentration Filtrate (PFU/mL). Higher concentrations of phage T1 were removed from UPW (Tr = 1.6 times 10-6) and DMEM (Tr = 1.1 times 10-6) than from GP (Tr = 9.3 times 10-3), DMEM-10 (Tr = 1.5 times 10-2), and 100% FBS (Tr = 2.4 times 10-2). Phage PP7 was removed in significant numbers only in ultrapure water (Tr = 8.5 times 10-4). The results indicate that adsorption enhanced the titer reduction in fluids containing low levels of protein. The titer reduction in DMEM-10 and 100% FBS may reflect the sieving properties of the 0.04-mu-m filter. As expected, a much smaller Tr was observed in the filtrate of the 0.2-mu-m filters, compared to the 0.04 mu-m filters. In contrast to the 0.04-mu-m filter, no increase in Tr was detected when the 0.2-mu-m filters were challenged with virus diluted in UPW compared with virus diluted in GP. These results suggest that the 0.04-mu-m filter has greater adsorptive properties than the 0.2-mu-m filter. [TOP OF PAGE]
Response to phage infection of immobilized lactococci during continuous acidification and inoculation of skim milk. Passos, F.M.L., Klaenhammer, T.R., Swaisgood, H.E. (1994). Journal of Dairy Research 61:537-544. A laboratory scale bioreactor was used for continuous acidification and inoculation of milk with a proteinase-negative, lactose-fermenting strain, Lactococcus lactis subsp. lactis C2S. Calcium alginate-entrapped cells were immobilized on a spiral stainless steel mesh incorporated into a column bioreactor and used to acidify and inoculate reconstituted skim milk. Characteristics of the immobilized cell bioreactor (TCB) were compared with those of a free cell bioreactor (FCB) during challenge with a virulent phage. Steady state biomass and lactate productivities were respectively 25-fold and 12-fold larger with the ICB than with the FCB. The ICB and the FCB were inoculated with the prolate phage c2 at multiplicities of infection of 0.25 and 0.02 respectively. Within 90 min of the infection, the FCB viable cell concentration dropped by five orders of magnitude and never recovered, while the plaque forming units/ml increased dramatically. In the ICB, released cells decreased immediately after infection, but subsequently increased, while the plaque forming units/ml steadily declined, indicating that phage were being washed out of the bioreactor. Productivity of FCB decreased to zero, whereas productivity of the ICB only decreased apprx 60% and subsequently recovered to its initial steady state value. [TOP OF PAGE]
Virsuses and DNA in marine environments. Paul, J.H., Kellogg, C.A., Jiang, S.C. (1994). pp. 119-128. In In Colwell, R.R., Simidu, U., and Ohwada, K. (eds.), Microbial Diversity in Space and Time. Plenum Press, New York, N.Y. [TOP OF PAGE]
Significance of the virus-rich 2-200 nm size fraction of seawater for heterotrophic flagellates: I. Impact on growth. Pesan, B.F., Weinbauer, M.G., Peduzzi, P. (1994). P. S. Z. N. I. : Mar. Ecol. 15:281-290. [TOP OF PAGE]
Monitoring of bacterial and viral indicators in a drinking-water treatment plant. Poda, G., Cesaroni, D., Bucci, M.A., Chetti, L., Rossi, L., Illice, M., Turtura, G.C., Bianchi, G.C., Bianchi, G., Minelli, L., et al. (1994). Aqua (Oxford) 43:127-132. The compared trends of bacterial indicators (coliforms, faecal streptococci and sulphite-reducing clostridia) and of the anti-E. coli bacteriophage throughout the treatment stages at a drinking-water plant are reported and discussed. The coliphages were tested using tangential-flow ultrafiltration. The findings indicate that in the final treatment stages the correlation of bacterial indicators to coliphages is lost, and that the latter are more resistant than the former to the physical treatments of sedimentation and filtration and more susceptible to the combined action of ozonation-flocculation. [TOP OF PAGE]
Genetic enhancement of phage resistance in a commercial cheese starter. Powell, I.B., Romano, G.M., Hillier, A.J., Davidson, B.E. (1994). Australian Journal of Dairy Technology 49:30-33. Lactococcus lactis subsp. lactis strain DRC1 has been shown to carry genes that diminish the susceptibility of lactococci to phage infection. Conjugation, a naturally-occurring form of mating between bacteria, allows these genes to be transferred between lactococcal strains. The genes were introduced into a commercial cheese starter strain (L. lactis strain HID92) by conjugation, producing transconjugants of HID92 with diminished sensitivity to phage infection. One transconjugant (designated MUTS59) was evaluated in commercial cheese manufacture. The phage-resistance genes were stably maintained in this strain during propagation, bulk starter preparation and cheese manufacture. [TOP OF PAGE]
??? Powelson, D.K., Gerba, C.P. (1994). Water Res. 28:2175-2181. [TOP OF PAGE]
Isolation and characterization of large lactococcal phage resistance plasmids by pulsed-field gel electrophoresis. Prevots, F., Remy, E., Mata, M., Ritzenthaler, P. (1994). FEMS Microbiol. Let. 117:7-13. Five phage-resistant Lactococcus lactis strains were able to transfer by conjugation the lactose-fermenting ability (Lac+) to a plasmid-free Lac- L. lactis strain. In each case, some Lac+ transconjugants were phage-resistant and contained one or two additional plasmids of high molecular mass, as demonstrated by pulsed-field gel electrophoresis. Plasmids pPF144 (144 kb), pPF107 (107 kb), pPF118 (118 kb), pPF72 (72 kb) and pPF66 (66 kb) were characterized: they are conjugative (Tra+), they confer a phage-resistant phenotype and they bear lactose-fermenting ability (Lactose plasmid) except for the last two. Plasmids pPF144, pPF107 and pPF118 resulted probably from a cointegrate formation between the Lactose plasmid and another plasmid of the donor strain, whereas pPF72, pPF66 and the Lactose plasmid were distinct in the corresponding transconjugants. Plasmids pPF72 and pPF66 produced a bacteriocin. At 30 degree C, the phage resistance conferred by the plasmids was complete against small isometric-headed phage and partial against prolate-headed phage, except for pPF107 whose phage resistance mechanism was totally effective against both types of phages, but was completely inactivated at 40 degree C. Restriction maps of four of the plasmids were constructed using pulsed-field get electrophoresis. [TOP OF PAGE]
Sensitivity of host strains and host range of coliphages isolated from Finnish and Nicaraguan wastewater. Rajala-Mustonen, R.L., Heinonen-Tanski, H. (1994). Water Res. 28:1811-1815. Coliphages are regarded as possible indicators of enteric viruses in drinking water and waters used for recreational purposes. They can be detected in water by a rapid, simple and inexpensive method, which does not require special equipment or specially skilled personnel. In spite of extensive studies of coliphages any agreement about a standard method has not yet been reached. One of the questions that has delayed the decision is the choice of a good host strain. In the present study, the ability of more than 40 Escherichia coli strains to detect phages in effluents of several wastewater treatment plants in Finland was tested. The 12 most sensitive strains were selected for a study of sensitivity to pure cultures of coliphages isolated from Finnish and Nicaraguan wastewaters. The sensitivity of the host strains was found to be similar to phages isolated from both countries. Two strains were sensitive to 20 of the 25 somatic coliphages tested. Three strains had almost identical patterns of sensitivity to male-specific RNA-phages, two of the strain were sensitive to all of the 13 and one strain to 12 phages tested. According to the results the same host strains can be used in countries where the climate is very different. [TOP OF PAGE]
Genomic polymorphism in the T-even bacteriophages. Repoila, F., Tétart, F., Bouet, J.Y., Krisch, H.M. (1994). EMBO Journal 13:4181-4192. We have compared the genomes of 49 bacteriophages related to T4. PCR analysis of six chromosomal regions reveals two types of local sequence variation. In four loci, we found only two alternative configurations in all the genomes that could be analyzed. In contrast, two highly polymorphic loci exhibit variations in the number, the order and the identity of the sequences present. In phage T4, both highly polymorphic loci encode internal proteins (IPs) that are encapsidated in the phage particle and injected with the viral DNA. Among the various T4- related phages, 10 different ORFs have been identified in the IP loci; their amino acid sequences have the characteristics of internal proteins. At the beginning of each of these coding sequences is a highly conserved 11 amino acid leader motif. In addition, both 5' and 3' to most of these ORFs, there is a approximately 70 bp sequence that contains a T4 early promoter sequence with an overlapping inversely repeated sequence. The homologies within these flanking sequences may mediate the recombinational shuffling of the IP sequences within the locus. A role for the new IP-like sequences in determining the phage host range is proposed since such a role has been previously demonstrated for the IP1 gene of T4. [TOP OF PAGE]
Transduction of a freshwater microbial community by a new Pseudomonas aeruginosa generalized transducing phage, UT1. Ripp, S., Ogunseitan, O., Miller, R.V. (1994). Moleculear Ecology 3:121-126. [TOP OF PAGE]
Virus-like particles in Eimeria nieschulzi are associated with multiple RNA segments. Roditi, I., Wyler, T., Smith, N., Braun, R. (1994). MOLECULAR AND BIOCHEMICAL PARASITOLOGY 63:275-282. RNA preparations from sporulated oocysts of Eimeria nieschulzi were found to contain 2 double-stranded RNA segments of 5.0 kb and 5.7 kb that were not present in other species of Eimeria. Treatment of crude lysates with RNase A revealed that in addition to these two segments, 3 other segments of 0.57 kb, 0.72 kb and 11.5 kb were protected from digestion, suggesting that they were enclosed within particles. Virus-like particles with a diameter of approximately 39 nm were purified by caesium chloride buoyant density centrifugation. Four of the five RNA segments copurified with these particles. In keeping with the nomenclature generally adopted for protozoan viruses, we have named this new isolate ENV 1. The largest RNA segment does not cosediment with ENV 1 particles and may be derived from another RNA-protein complex that is unstable under the conditions used. The particle size and genome structure of ENV 1 both differ from that of the Eimeria stiedae virus (ESV), which is the only other virus to have been isolated from Eimeria to date. Short cDNA clones derived from ENV 1 show significant homology to a region of the Leishmania virus (LRV 1) genome that encodes an RNA-dependent RNA polymerase. The polymerase sequences from ENV 1 and LRV 1 are more closely related to each other than to any other protein sequences in the GenEMBL Database. This raises intriguing questions about the origins of the two viruses, since Eimeria and Leishmania normally infect different hosts and also show different cell tropisms within these hosts. [TOP OF PAGE]
Comparative tracing experiments in a porous aquifer using bacteriophages and fluorescent dye on a test field located at Wilerwald (Switzerland) and simultaneously surveyed in detail on a local scale by radio-magneto-tellury (12-240 kHz). Rossi, P., De Carvalho-Dill, A., Mueller, I., Aragno, M. (1994). Environmental Geology 23:192-200. [TOP OF PAGE]
The pilE gene product of Pseudomonas aeruginosa, required for pilus biogenesis, shares amino acid sequence identity with the N-termini of type 4 prepilin proteins. Russell, M.A., Darzins, A. (1994). Molecular Microbiology 13:973-985. A new locus required for type 4 pilus biogenesis by Pseudomonas aeruginosa has been identified. A pilE mutant, designated MJ-6, was broadly resistant to pili-specific phages and unable to translocate across solid surfaces by the pilus-dependent mechanism of twitching motility (Twt-). Immunoblot analysis demonstrated that MJ-6 was devoid of pili (Pil-) but was unaffected in the production of unassembled pilin pools. Genetic studies aimed at localizing the pilE mutation on the P. aeruginosa PAO chromosome demonstrated a strong co-linkage between MJ-6 phage resistance and the proB marker located at 71 min. Cloning of the pilE gene was facilitated by the isolation and identification of a pro(B+)-containing plasmid from a PAO1 cosmid library. Upon introduction of the PAO1 proB+ cosmid clone into MJ-6, sensitivity to pili-specific phage, twitching motility and pilus production were restored. The nucleotide sequence of a 1 kb EcoRV-ClaI fragment containing the pilE region revealed a single complete open reading frame with characteristic P. aeruginosa codon bias. PilE, a protein with a molecular weight of 15,278, showed significant sequence identity to the pilin precursors of P. aeruginosa and to other type 4 prepilin proteins. The region of highest homology was localized to the N-terminal 40 amino acid residues. The putative PilE N-terminus contained a seven-residue basic leader sequence followed by a consensus cleavage site for prepilin peptidase and a largely hydrophobic region which contained tyrosine residues (Tyr-24 and Tyr-27) previously implicated in maintaining pilin subunit-subunit interactions. The requirement of PilE in pilus biogenesis was confirmed by demonstrating that chromosomal pilE insertion mutants were pilus- and twitching-motility deficient. [TOP OF PAGE]
Principles of population ecology [German]. Rutschke, E. (1994). Berichte Ueber Landwirtschaft Sonderheft 37-53. The paper deals with some theoretical aspects of the population ecology important for the understanding of the dynamics of ecosystems. Regulation processes and the evolution of populations are the main subjects of the paper. After a short description of types of the abundance dynamics, the adaption of populations in the environment is explained by the concept of r- and K- selection. The theories of the causes of the abundance dynamics are discussed in detail. The environment theory is confronted with the regulation theories. The theory of self regulation is criticized. Further subjects are the description of regulation processes with terms of the cybernetics, the position of populations in ecosystems and interactions between populations (f. e. predator-prey-relations, host-parasite-relations). [TOP OF PAGE]
Correlation between phage-resistance and fructose-tolerance in Lactococcus lactic subsp. lactis 4513-5. Sandberg, S., Laux, P., Suessmuth, R. (1994). Milchwissenschaft 49:552-555. Differences between phage-sensitive and phage-resistant cultures of Lactococcus lactis subsp. lactis 4513-5 could be found, when the cells were grown in M17 medium in which lactose was replaced by fructose. Phage-sensitive cells lysed in fructose M17 broth. Long-time culture in fructose M17 medium of phage-sensitive cells caused the selection of fructose tolerant and phage-resistant variants, which became phage-sensitive and fructose sensitive again, if they grew in the generally used M17 medium with lactose. As a consequence, we assume that the formation of phage receptors for phage 4513-K12 depends on sugar metabolism. [TOP OF PAGE]
Acquisition and rearrangement of sequence motifs in the evolution of bacteriophage tail fibres. Sandmeier, H. (1994). Molecular Microbiology 12:343-350. Molecular analysis reveals a surprising sharing of short gene segments among a variety of large double-stranded DNA bacteriophages of enteric bacteria. Ancestral genomes from otherwise unrelated phages, including lambda, Mu, P1, P2 and T4, must have exchanged parts of their tail-fibre genes. Individual genes appear as mosaics with parts derived from a common gene pool. Therefore, horizontal gene transfer emerges as a major factor in the evolution of a specific part of phage genomes. Current concepts of homologous recombination cannot account for the formation of such chimeric genes and the recombinational mechanisms responsible are not known. However, recombination sites for DNA invertases and recombination site-like sequences are present at the boundaries of gene segments conferring the specificity for the host receptor. This, together with the properties of the DNA inversion mechanism, suggests that these site-specific recombination enzymes could be responsible for the exchange of host-range determinants. [TOP OF PAGE]
Bacteriophages in industrial fermentations. Saunders, M.E. (1994). pp. 116-121. In In Webster, R. and Granoff, A. (eds.), Encyclopedia of Virology. Academic Press, ??? [TOP OF PAGE]
Ingested foreign (phage M13) DNA survives transiently in the gastrointestinal tract and enters the bloodstream of mice. Schubbert, R., Lettmann, C., Doerfler, W. (1994). Mol. Gen. Genet. 242:495-504. [TOP OF PAGE]
A new phage typing scheme for Proteus mirabilis and Proteus vulgaris strains. Sekaninová, G., Hofer, M., Rychlík, I., Pillich, J., Kolárová, M., Zajíková, D. (1994). Folia Microbiol. 39:381-386. [TOP OF PAGE]
Giardiavirus-resistant Giardia lamblia lacks a virus receptor on the cell membrane surface. Sepp, T., Wang, A.L., Wang, C.C. (1994). J. Virol. 68:1426-1431. Giardia lamblia virus (GLV) is a small nonenveloped double-stranded RNA virus that infects specifically the parasitic protozoan G. lamblia. Among the many collected strains of G. lamblia, a few turn out to be highly resistant to the virus infection. Two of these strains, Ac and JH, were subjected to electroporation with the RNA from GLV-infected G. lamblia WB strain. Subsequent studies indicated the presence of GLV double-stranded RNA and GLV protein in the electroporated and propagated cells. Virus particles, released by the transfected cells into the culture medium, were capable of infecting the virus-sensitive G. lamblia WB strain. When the WB cells were incubated with GLV at 4 degrees C and treated with the bifunctional cross-linking reagent disuccinimidyl suberate, little GLV protein was detectable inside the cells by immunofluorescent staining. However, patches of fluorescent granules were found on the membrane surface of the cells, suggesting cross-linking of the viruses with a certain membrane component(s). Similar treatment of the resistant strains Ac and JH showed no fluorescence either inside or outside of the cells. Two other closely related parasitic protozoa, Tritrichomonas foetus and Trichomonas vaginalis, cannot be infected by GLV via either viral infection or RNA transfection. The [35S]cysteine-labeled protein profiles in Triton X-114 extracts of G. lamblia WB, Ac, and JH were compared. The profile of the WB strain differs clearly from that of Ac and JH. It remains to be seen, however, whether this difference is related at all to the different susceptibilities to GLV infection. [TOP OF PAGE]
Bacterial viruses. Bacterial altruism? Shub, D.S. (1994). Current Biology 4:555-556. Some strains of Escherichia coli harbor genes that trigger cell death upon infection by bacteriophage T4; these may provide examples of the evolution of altruistic behavior in bacteria. [TOP OF PAGE]
Energetics of cyanophage N-1 multiplication in the diazotrophic cyanobacterium Nostoc muscorum. Singh, S., Bhatnagar, A., Kashyap, A.K. (1994). Microbios 78:259-265. Cyanophage N-1 multiplication was investigated during the latent period of the virus, when super(14)CO sub(2) fixation was inhibited whereas respiratory O sub(2) uptake increased similar to 67% at 4 h after infection. A simultaneous decrease (70%) in the glycogen content of infected cells indicated its catabolic involvement. A chloramphenicol-sensitive rise in glucose-6-phosphate dehydrogenase activity as a result of N-1 infection partly explained the increase in aerobic respiration. The total ATP pool declined to 53% of the control while Ca super(2+)-dependent ATPase activity also declined (25%). In contrast, Mg super(2+)-dependent ATPase activity increased (80%) in comparison with uninfected