Lickliter, C.L.*; Nishiguchi, M.K.: Phylogenetic characterization of the genus Vibrio based on morphological and molecular data.

Vibrio fischeri and Vibrio logei are two species of luminous bacteria (GAMMA-Proteobacteria) that reside as symbionts in the light organs of a variety of sepiolid squids (Cephalopoda: Family Sepiolidae). These squids include the genera Euprymna and Sepiola, which are capable of exhibiting specificity towards their symbiotic associates. In order to better understand the evolutionary relationships between symbiotic vibrios and other related species that are pathogenic or benign, we have examined both phenotypic and molecular data to determine the phylogenetic relationships among particular Vibrio species. Phenotypic data was obtained by analyzing several biochemical processes (based on enzymatic capabilities), as well as measuring the growth rates of various bacterial strains in culture at two different temperatures (20� or 28�C). We also amplified and sequenced both the 16S rDNA and glyceraldehyde phosphate dehydrogenase (gapA) loci to obtain molecular sequence data for each of the Vibrio species used in the study. Combining both the morphological and molecular data between the different Vibrio species has allowed us to determine which species are genetically similar or distant, as well as help predict the evolutionary radiation of the symbiotic, pathogenic, and free-living species of the genus Vibrio.