The Phylogenetic Characterization of a Bioluminescent Bacterium Isolated From Shrimp

Bioluminescence, the biological production of light, is an unusual characteristic that is observed in certain members of the genera Vibrio, Photobacterium, Photorhabdus, and Shewanella. The bioluminescence system is composed of a group of proteins, including luciferase the main enzyme responsible for light production. I have isolated a bioluminescent strain of gram negative cocci from marine shrimp. All known bioluminescent bacteria are gram negative rods, so the different morphology of the isolate indicates that it has not been previously characterized. The isolate, designated strain BC1, is catalase and oxidase positive and is unable to utilize maltose as a sole carbon and energy source. A fragment of the luxA gene, which encodes for the enzyme luciferase, was amplified from the DNA of the unknown isolate using the polymerase chain reaction and primers specific for the Vibrio fischeri luxA gene. The 16S rRNA gene was sequenced to determine the phylogeny of the isolate. With sequence data containing approximately 1200 bases, strain BC1 was 83.5% similar to Photobacterium leiognathi, its closest relative. Based on this data, I conclude that strain BC1 is a new species in the genus Photobacterium.