STUDIES ON ISOLATION AND IDENTIFICATION OF BIOLUMINESCENT BACTERIA FROM MARINE FISHES AND SQUIDS AND EFFECT OF METALS PHENOLS PHENOLIC COMPOUNDS AND PESTICIDES ON BIOLUMINESCENCE AND GROWTH OF THE BACTERIA ISOLATED

Abstract

Bioluminescence, the phenomenon of light emission by living organisms, is widespread in the marine environment in all the trophic levels from bacteria to fish and is thought to play a crucial role in the general ecology of marine plants and animals. Being an ecologically versatile group, luminous bacteria have continued to interest microbial ecologists. This is for the reason that they offer extensive possibilities to investigate problems in wide-ranging fields, such as medicine, ecology and marine biology. Bacterial bioluminescence is very sensitive to toxic materials, and hence, several investigations have tested its application for determining the toxicity of several chemicals. newlineThe present study was conducted to isolate and identify bioluminescent bacteria from marine fishes and squids using standard microbiological techniques, to assess the effect of external factors on the luminescence of luminescent bacteria and to assess the effect of metals, phenol and phenolic compounds and chemical pesticides on the growth and bioluminescence of the bacteria. newlineA total of 50 samples, 40 from fishes of 4 varieties and 10 from squids were examined for the presence of bioluminescent bacteria. Among 50 samples, a total of 15 (60%) isolates of Vibrio fischeri were isolated of which 13 (32.5%) were from fishes and 2 (20%) were from squids. A total of 10 (40%) isolates of Photobacterium phosphoreum were isolated of which 9 (22.5%) were from fishes and 1 (10%) was from squids. newlineEvaluation of different media used for growth of bioluminescent bacteria was done. Sea water agar (SWA), Boss medium (BM), luminescenct medium (LM) and luminescent agar (LA) were evaluated. The sea water agar (SWA) media was found to be the best media. newlineThe effect of external factors on the luminescence of the bacteria was analyzed. The effect of varying concentrations of NaCl, different pH ranges and different concentrations of glycerol on the luminescence of the Vibrio fischeri and newlinePhotobacterium phosphoreum cultures was observed.