Meeting Abstract
Understanding the combined effects of both environmental and host selection on the evolution of microbes to a specific host species has been difficult and confounding due to the various mechanisms that are responsible for a successful association. Phenotypic in vitro studies using experimental evolution and strain specific genomic approaches have been useful in deciphering which particular components are key to ensuring a successful symbiosis, yet the order in which specific adaptations to benefit both host and symbiont occur has been questionable. We set out to examine how environmental/biotic stresses lead to the adaptation and therefore selection of highly specific Vibrio cholerae biofilms that are more resistant to abiotic stresses. By experimentally evolving both wild-type and mutated strains of pathogenic V. cholerae, we assessed whether grazing by various protozoan predators promoted the evolution of less competitive and/or effective strains to more dominant isolates. We also measured whether the same grazing pressures have pleiotrophic effects upon other aspects of biofilm production (attachment, polysaccharide production). By comparing both early and late biofilms with two different types of grazers (Rhynchomonas nasuta and Acanthamoeba castellanii), we were able to determine whether predator-prey interactions outside the host caused increased biofilm production (and possibly virulence) in this human pathogenic bacterium.
