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The aim of study was to explore the antimicrobial activity and immunomodulatory effect of Bacillus velezensis on non-O1 Vibrio cholerae infection in Macrobrachium nipponense. The antibacterial test showed that B. velezensis CPA1–1 had antibacterial activity against non-O1 V. cholerae, and the minimum inhibitory concentration of B. velezensis CPA1–1 fermentation broth against non-O1 V. cholerae was 2.7 × 105 CFU/mL. Groups of M. nipponense were treated with 105, 106 and 107 CFU/mL of B. velezensis by immersion bath for 20 days, respectively, and various immune parameters and water quality indexes were examined at 5, 10, 15 and 20 d. Results indicated that the acid phosphatase (ACP), alkaline phosphatase (AKP), and superoxide dismutase (SOD) activity of M. nipponense were increased significantly in B. velezensis treated group, and the mRNA expression level of immune-related genes including Crustin, Dorsal, Hemocyanim, p38, Prophenoloxidase and Stat in M. nipponense was significantly up-regulated after treating with B. velezensis. Furthermore, the B. velezensis CPA1–1 could degrade ammonia nitrogen and nitrite in culture water. After challenge with non-O1 V. cholerae, it is higher of the survival rate of M. nipponense in B. velezensis treated group than that of the control group. These results indicate that B. velezensis CPA1–1 is a potential probiotic against non-O1 Vibrio cholerae infection in M. nipponense. |
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