Effect of new beneficial lactic acid bacteria on fish production

New beneficial lactic acid bacteria were isolated from fresh water fish and shrimp for the purpose of using as probiotic supplemented in the fish feed for culturing fish. From 48 samples of 14 species of fresh water fishes and shrimp, 118 strains of lactic acid bacteria were isolated by using MRS Agar, BL Agar and anaerobic condition. The newly isolated bacteria were screened for the beneficial properties of probiotics such as tolerance to salt, bile, low pH and ability to grow in aerobic condition, having also the antagonistic ability toward 7 indicator strains including fish pathogens. The three selected strains were Enterococcus E7, Enterococcus E26 and Lactobacillus F10. They were later identified to be Pediococcus acidilactici, Enterococcus faecium and Lactobacillus pentosus respectively. These three selected strains were cultured in MRS broth and harvested the cell for supplementation into the fish feed. The shelf-life of these feeds were determined for 42 days. Probiotic E7 and E26 supplemented feeds possessed higher cell count and declined very little while probiotic F10 showed drastic decrease of viable cells. Enterococcus E26 were selected and prepared to be probiotic by large scale culture in 300 litre fermentor. Defatted soybean meal was main substrate of the culture medium. The submerged batch type of cultivation was performed. At 48 hours culture time the viable cells of Enterococcus E26 was 2.9*10**(8) cells/ml. The final concentrated formulation or probiotic E26 had the viable cell count of 9.1*10**(9) cells/ml. Field trial of using probiotic E26 concentrated formulation as feed supplement to culture Tilapia nilotica was performed at fish farm in Surin Province. The three replicate caged of 2,000 fishes each were dipped into the separate ponds and cultured for 40 days. At the end of experiment, the probiotic E26 fed fish showed more average body weight but similar survival rate with controlled feed fed fish.