The bioluminescent marine bacterium,Vibrio fischeri, exists in a symbiotic relationship with the Hawaiian bobtail squid. In order to study the strain diversity of the symbiosis, specifically the diversity within a single animal, various strains of V. fischeri were isolated from a wild-caught adult squid. This project uses a bioinformatic approach to study diversity in terms of the type VI secretion system, a contact-dependent, interbacterial, killing mechanism.