Screening，Identification and Properties of One Antagonistic Strain Against Aeromonas hydrophila from Hypophthalmichthys molitrix Intestinal Tract

Abstract:

In order to provide the theory basis for prevention and treatment the disease caused by Aeromonas hydrophila in the process of Hypophthalmichthys molitrix breeding，the strains which have the strong and stable abilities against A. hydrophila from H. molitrix intestinal tract were screened and their growth and culture conditions were studied. Antagonistic strains against A. hydrophila were separated and screened from H. molitrix intestinal tract. Then，the physiological and biochemical，molecular identification and the optimization of growth conditions of the stable antagonistic bacterium were determined. After many times of screening，15 antagonistic strains were got. Among them，the more stable antagonistic bacterium is number S4，which was an alkaline Gram-negative bacillus brevis bacteria and belonged to Aeromonas genus. Orthogonal test indicated that the optimal growth conditions were 1.5 g/dL starch，1.5 g/dL beef extract，1 g/dL CaCL2，32 ℃，pH 8.5 and inoculation quantity 3%. The results provide the theoretical basis for the prevention of A. hydrophila and the application of antagonistic bacterium S4.