Lights in the Philippines: Examination of the Bacterial Diversity within the Light Organ of Euprymna hyllebergi

Bioluminescent bacteria from the g-Proteobacterial family Vibrionaceae share mutualistic symbiosis with a variety of sepiolid and loliginid squids (Mollusca: Cephalopoda). The bacteria are housed in a bilobed light organ within the mantle cavity of the host squid . Although the association between squid hosts and Vibrio bacteria is specific, the diversity of vibrios in the light organ across the globe is not well characterized. The sepiolid squid-Vibrio mutualism allows for better examination of strain diversity and host specificity in this mutalistic symbiosis. By characterizing different strains of vibrios occupying certain areas of the ocean,we are better able to understand whether environment or host drives the diversity of the symbiosis. Therefore,  we identified various strains within the light organ of different Euprymna hyllebergi populations collected throughout the Philippine islands.  Light organ isolates collected between 2011-2012 were examined through total DNA extraction, polymerase chain reaction (PCR) amplification, followed by DNA sequencing of the 16S ribosomal RNA (for species identification).  The sequence data (16S ribosomal RNA) produced a haplotype network to determine the relationship of Philippian vibrios from four different locations: Banate Bay, San Juan Barotac Viejo, Guimaras Islands, and Atabayan. Analysis of the sequence data generated haplotypes that genera Photobacterium and Vibrio were found at all locations sampled, and a diversity of species can be found within each population of Euprymna sampled from 2011-2012.  Results indicate that a number of species from the Vibrionaceae are able to colonize populations of Euprymna within the Philippine Islands.

RESEARCH SUPPORTED BY GRANT R25 GM048998-13.