Research Interests

My training and research interests have followed an odd trajectory. I was initially trained as a biochemist, but upon graduation I couldn’t imagine continuing on such a reductionist path. In grad school this rebellion resulted in my asking increasingly ultimate-causation questions—the most overt consequences being my Ph.D. minor (Ecology and Evolutionary Biology) and, subsequently, the emphasis of my dissertation (“The Ecology of Bacteriophage T4”). My early training, however, has never completely left my blood and I have come to see myself as an individual with a deep interest especially in ecological questions but who nevertheless sees the world through the eyes of a chemist. Such a perspective is not necessarily a bad thing in the study of viral ecology.

My reductionist training is what led me both to bacteriophages—the viruses of bacteria—and to my research style. Unlike phage ecologists with stronger ecological rather than molecular training, I almost always begin with questions that come out of my understanding of the organism. In particular, I am deeply interested in the evolution and ecological impact of variance in the basic phage growth parameters: the eclipse period (which is the post-adsorption pre-replicative phase), the latent period (which is the infection phase), the burst size (which is equivalent to per-infection fecundity), and the adsorption rate (a function of phage diffusion rates, bacterial size and numbers, and the likelihood of phage attachment given bacterial collision). Added to these basic parameters are such things as phage generation time (a function of phage adsorption rate and latent period) and, for temperate phages, the likelihoods of reduction to lysogeny or of prophage induction. This organismal approach essentially represents an amalgam of phage evolutionary, physiological, and population ecologies. By contrast, much of phage ecology research instead tends more toward community or ecosystem ecology.

The bulk of my research has involved working out the theory and experimental details of the evolution of phage lysis timing. For T-even bacteriophages, which for nearly two decades have been my model organisms of choice, the evolution of lysis timing is absurdly complicated. There even is interesting game theory that may be applied to T-even phage lysis timing, particularly in terms of the phenomenon known as lysis inhibition. Phage avoid what I describe as a virulence Prisoner’s Dilemma-like situation by delaying their lysis, but this fix only serves to create a second dilemma. The latter results from a conflict between the requirement for eventual dissemination of phage progeny (starting with host lysis) and the fact that released free-phage progeny are killed upon their ready adsorption to unlysed phage-infected bacteria. Lately I have begun to extend these studies to spatially structured environments. Much of this work is done employing macroscopic bacterial cultures, but it also lends itself to the creation of phage (and bacterial) constructs using molecular techniques.

The above serves as a backdrop to my more recent interests. Escaping my own campus—with its limited space and facilities—I have begun to dabble again in molecular techniques. I additionally have acquired a number of collaborators who have pushed me in new directions. As a consequence my interests now go well beyond T-even phage lysis timing and include consideration of the ecological (and evolutionary) interactions between phages and bacterial pathogens (especially Escherichia coli O157 and, increasingly, mycobacteria) plus the application of phages as anti-bacterial therapeutics (phage therapy) or as identifiers of bacteria. In conclusion, I see myself as a researcher who uses molecular and traditional microbiological techniques to increase our ecological understanding of what may very well be the world’s most numerous organisms (viruses). I hope to employ what I learn to refine both phage-based applications (i.e., IDing and therapy) and our understanding of bacterial pathology. Furthermore, I am strongly interested in collaborating with ecologists with whom I can apply my well-honed “feel for the organism” to experimentally address more-basic ecological questions. Finally, I am actively involved in defining the field of phage ecology including assembling the definitive collection of phage references and resources within the context of the definitive phage ecology web site (www.phage.org).

(click here for a list of my bacteriophage publications)
(click here for a list of my bacteriophage web pages)
(click here for a TIFF chart that outlines my research interests)
(click here for definition of evolutionary ecology)