Isolation of bioluminescent bacteria from marine organisms

471-476Bioluminescence is an emission of cold light by enzyme driven reaction within certain living organisms. The most abundant and widely distributed light emitting organisms are luminescent bacteria. Such organisms are either found as free-living in the ocean or in symbiotic relationship with the marine host. To employ bioluminescence in environmental monitoring, isolation of bioluminescent bacteria from the two different marine samples (sea water sample and various organs of squid and fish) were collected from different sites of Veraval seashore and fish markets located nearby seashore respectively. The marine organisms used in the study were 20-25 days old. Cultivation media that were used for isolation were sea water agar (SWA), luminous agar (LA) and nutrient agar (NA); out of which SWA proved to be the most suitable medium for their growth and luminescence. No bioluminescent bacterium was found in water samples and total five bioluminescent bacteria were isolated from five different organs of fish and squid each. Out of these five isolates, two were selected based on their maximum light intensity. These two isolates, PBS1 and PBF1, were further characterized biochemically. PBS1 was able to utilize glucose, galactose, maltose and were tested positive for catalase and oxidase tests. Similar results were obtained in case of PBF1 except it was tested positive for urease urea but was unable to utilize glucose. Both isolates thrived at neutral pH and showed maximum bioluminescence. Effect of NaCl concentration on luminescence revealed that the two isolates were not able to grow in media devoid of NaCl and the luminescence was found to be maximum at 3 % (w/v) NaCl supplementation