Meeting Abstract

86.7  Monday, Jan. 6 11:30  Sublte genetic changes in the two-component regulatory system etk effects anti-predatory behavior in the symbiotic bacterium, Vibrio fischeri NAVA, A.*; NISHIGUCHI, M.K.; New Mexico State University; New Mexico State University nish@nmsu.edu

Biofilms are comprised of vast array of exopolysaccharides, channels, and bacteria that provide a stable environment for the consortium of bacteria to accommodate abiotic stresses. Formation of biofilms can be controlled by both biotic and abiotic stress, and involves different regulatory genes that sense as well as respond to such fluctuations. One strong selection pressure that effects biofilm formation is grazing by predatory protozoans. Biofilms have evolved certain mechanisms to prevent such destructive grazing from the strong selective pressure placed by protists. Previous research has demonstrated that different feeding modes of protists have driven the selection of these mechanisms. Biofilms can also change their morphology in response to the different types of predation, or produce noxious chemicals to deter or destroy their predators. We investigated the two-component regulatory locus, etk in the beneficial mutualist Vibrio fischeri, to determine if this locus is responsible for the anti-predatory behavior observed among strains of this bacterium. The etk locus is a protein-tyrosine kinase chain length regulator for capsular polysaccharide biosynthesis. Single nucleotide polymorphisms in the loci of various strains of V. fischeri enable these symbionts to resist predation by various protists or competitive bacteria by changing the morphological structure of the biofilm. Genetic diversity within the etk locus of a single species of V. fischeri demonstrates the large evolutionary and ecological benefits derived as a result of small subtle changes in genotype.