Vibriostastic bacteria isolated from black tiger prawns, Penaeus monodon (Fabricius), pond water and pond soil of some prawn farms in Negros Occidental [Philippines]
1998
Deriquito, F.R. (Philippines Univ. Los Banos, College, Laguna (Philippines). Microbiology Div.) Zamora, A.F. | Albaladejo, J.D.
Bacterial isolates from prawn forms monitored by the Negros Prawn Producers Marketing Cooperative, Inc. in Negros Occidental [Philippines] were screened for vibriostatic activity. Three screening methods were performed: parallel streak method, cylinder cup assay, and co-cultivation in broth. Through the cylinder-cup assay, none of the isolates with potential vibriostatic activity produced any inhibitory products to suppress growth of the shrimp pathogens, Vibrio harveyi. One isolate, coded 91A, was observed to have the highest potential as a vibriostat based on its consistent ability to reduce growth of V. harveyi through the parallel-streak method and co-cultivation method. The results suggest that this isolate has a very good potential to reduce or prevent occurence of the disease since prohibiting the proliferation of a pathogen is the initial step to disease prevention. The efficacy of isolate 91A to reduce or prevent luminous fibrosis in vivo, though, was not determined during the experiment since no bacterial LD50 was derived. Preliminary results of an on-going experiment at BFAR [Bureau of Fisheries and Aquatic Resources, Philippines] showed the potential of isolate 91A as a good probiotic and biocontrol agent in the hatchery. Survival and quality of fry were as good as when antibiotics were employed. The seeding of shrimp hatchery tanks with isolate 91A lessened the reliance on antibiotic up to 80%. Characterization of isolate 91A revealed very high similarity with Vibrio alginolyticus. Further studies on the pathogenicity of isolate 91A are needed since V. alginolyticus is a potential pathogen to shrimp and to man. Optimization and refinement in the use of application of this probiotic bacteria are still needed to maximize its potential
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