A study of development of probiotics for fish

点击翻译按钮获取中文摘要

1.Ecology of a fish pathogen Listonella anguillarum in a seed production facility for the Japanese flounder was investigated for the better understanding of behavior of opportunistic pathogens in aquaculture environments. L.anguillarum associated with larvae and juvenile seems to be derived from live diets including rotifers and rearing waters. This result idicates the importance of probiotic practice for the prevention of opportunistic infections caused by bacteria such as L.anguillarum.2.The culturability of intestinal bacteria from eight coastal fish as determined by both the culture method and the direct count method using DAPI ranged from 0.00003 to 80.9%. Predominant intestinal bacteria in the mullet as determined by the FISH method were Alphaproteobacteria, Betaproteobacteria, Gammaproteobacteria, Deltaproteobacteria and Gram-positive bacteria. Taken together, it is found that the intestinal microflora of coastal fish is composed of different phyla of bacteria.3.Intestinal tracts of Japanese flounder were mainly colonized by Vibrio scophthalmi-V.ichthyoenteri group and V.fischeri, amost all of which digested the colloidal chitin. On the other hand, major intestinal bacteria in the production of antibacterial substances were V.harveyi, V.ichthyoenteri and V.fischeri.4.In the rainbow trout fed with live cells of probiotic Lactobacillus rhamnosus JCM 1136, the serum lysozyme and complement activity, and the phagocytic activity of head kidney leucocytes were significantly enhanced compared with control fish. These results strongly suggest that L.rhamnosus possesses the ability to immunomodulate the fish.5.These results obtained through the above experiments show that probiotic treatment is the important method to prevent the opportunistic infections in fish and aquatic animals.