THE ANTIMICROBIAL ACTIVITY AND EFFECT OF HEAVY METALS ON THE BIOLUMINESCENCE OF BIOLUMINESCENT BACTERIA FROM THE GASTROINTESTINAL TRACTS OF PHILIPPINE MARINE FISHES

摘要

Bioluminescent bacteria isolated from the gastrointestinal tracts of fresh marine fishes locally known as alumahan (Rastrelliger sp.), matambaka (Selar crumenopthalmus), besugo (Nemipteris sp.), tamban (Sardinella sp.) and sap-sap (Leiognathus bindus)obtained from the Baclaran Seaside Market in Pasay City, Philippines were tested for the presence of antimicrobial activities. Twenty-one of the 34 isolates studied inhibited the growth of at least one of the test pathogens used in the study. Isolates that inhibited the growth of Candida albicans, Klebsiella sp. and Pseudomonas aeruginosa were catalase positive, facultatively anaerobic, Gram negative bacilli. Some isolates exhibited unstained inclusion bodies in their cytoplasm in Gram-stained smears.No isolate was able to inhibit the growth of Escheri-chia co/i, Salmonella typhi and Staphylococcus aureus. T316, a bioluminescent isolate from besugo, a local fish, was used to determine the light-quenching effect of the heavy metals mercury, cadmium and lead. The concentrations of each of these heavy metals ranged from 0.001 to 10 ppm. In the assay, the bacteria showed inhibition of light emission at minimum concentrations of 0.5 ppm mercury, 10 ppm of cadmium and 5 ppm of lead at different times of exposure.