Lactobacillus rhamnosus CY-1의 분리와 배양학적 특성에 따른 항균물질 생산; Probiotc의 영향

Abstract

The purpose of this experiment was to select useful probiotic strains with antibacterial activity and acid resistance against a broad range of bacteria causing fish diseases to prevent bacterial diseases of fishes or improve their immune system for the efficiency of farming industry. Five kinds of strains extracted from olive flounder intestine were used to study their antibacterial activity, bile resistance, and acid resistance, and Lactobacillus rhamnosus CY-1 was finally selected to examine their cultural, morphological, genetic, and physiological characteristics. In result of identification, Lactobacillus rhamnosus CY-1 was identified as Lactobacillus rhamnosus and named Lactobacillus rhamnosus CY-1. In result of reviewing the optimal culturing conditions for maximum production of antibacterial materials, the source of carbon was 3% Rhamnose; the source of nitrogen was 3% Yeast extract; the inorganic salt was 3% FeSO4·7H2O; the culturing temperature was 35℃; the initial pH of culture medium was 8; and the culturing time was 96 hours. The strains were added to the feed in the concentration of 103, 105, and 107 CFU/kg and 2% of fishes were given the feed twice a day (9 AM and 5 PM) for 4 weeks. The mortality test performed by artificial infection using S.parauberis, a pathogenic bacterium, after the completion of this study also showed over 40% greater survival rate in all test samples. Based on the above findings, it was concluded that Lactobacillus rhamnosus CY-1 in the feed improved farmed flatfish's immune system and resistance against diseases as the probiotic. Also, the physiological indicators discovered by this study would be useful for identifying the mechanisms of probiotics.