不同条件下副溶血弧菌对墨吉明对虾致病性研究

Pathogenicity of Vibrio parahaemolyticus to Penaeus merguiensis Under Different Conditions

为研究墨吉明对虾的弧菌病防控措施，通过人工注射感染的方式，研究不同数量副溶血弧菌及在不同温度、盐度、pH、不同硝酸氮、亚硝酸氮和氨氮浓度条件下副溶血弧菌对墨吉明对虾的致病性的影响。结果表明：当人工感染副溶血弧菌数量为3．92×10^6CFU以上时，24h内对虾累计死亡率100％．副溶血弧菌数量为3．92×10^5CFU时，24h对虾累计死亡率为50％。温度为32clC时，对虾累计死亡率最高，在一定范围内，随着温度的升高对虾累计死亡率升高。在温度为（24±1）℃时，盐度为10‰时对虾的死亡率最高，盐度为30‰次之，盐度为20‰时最低；在温度为（24士1）℃，盐度为（22士1）‰时，对虾累计死亡率pH9时最高，pH7时次之，pH8时最低；温度为（24土1）℃，盐度为（22±1）‰，硝酸氮浓度为30．0mg／L时，对虾累计死亡率最高，浓度为20．0mg／L时次之，浓度为10．0mg／L时最低；亚硝酸氮浓度为10．0mg／L时死亡率最高，5．0mg／L时死亡率次之，1．0mg／L时死亡率最低；氨氮浓度为1．5mg／L时死亡率最高，1．0mg／L时死亡率次之，0．5mg／L时死亡率最低。实验证实：当副溶血弧菌数量为3．92×10^5CFU以上和数量为3．92×10^4CFU爆发72h之后，弧菌病难以控制；在26～32℃范围内，随着温度的升高对虾累计死亡率升高；盐度与pH对墨吉明对虾的致病性可能与噬菌体有关；硝酸氮对感染副溶血弧菌的墨吉明对虾有胁迫作用；一定范围内亚硝酸氮浓度（1．0～10．0rag／L）、氨氮浓度（O.5～1.5mg／L）越高，副溶血弧菌对墨吉明对虾的致病性的影响越强，对虾累计死亡率越高。该试验为墨吉明对虾的弧菌病防控提供了坚实的基础。

In order to provide theoretical foundation of Vibrio control for Fenneropenaeus merguiensis, pathogenicity of Vibrio parahaemolyticus to Fenneropenaeus merguiensis by different quantities, and under different temperatures, salinities, pH, and concentrations of nitrate nitrogen, nitrite nitrogen, ammonia nitrogen were studied. The results showed that the death rate of Fenneropenaeus merguiensis was 100% in 24 h when the quantity of Vibrio parahaemolyticus was beyond 3.92×10^6 CFU, and the death rate was 50% when the quantity of Vibrio prehaemolyticus was 3.92×10^5 CFU. When the temperature was 32℃, the accumulation death rate was the highest, and the death rate increased with the increase of temperature within a certain range. When thetemperature was （24±1）℃, the death rate was the highest when salinity was 10‰, followed by 30‰, and it was the lowest when salinity was 20‰. When the temperature was （24± 1）℃ and the salinity was （22±1）‰, the death rate was the highest when pH 9, and it decreased when pH 7, and it was the lowest when pH 8. When the temperature was （24±1）℃ and the salinity was （22±1）‰, the death rate was the highest when the concentration of nitrate nitrogen was 30.0 mg/L, followed by 20.0 mg/L, and it was the lowest when the concentration of nitrate nitrogen was 10.0 mg/L. Under the same temperature and salinity, the death rate was the highest when the concentration of nitrite nitrogen was 10.0 mg/L, followed by 5.0 mg/L, and it was the lowest when the concentration of nitrite nitrogen was 1.0 mg/L. The death rate was the highest when the concentration of ammonia nitrogen was 1.5 mg/L, followed by 1.0 mg/L, and it was the lowest when the concentration of ammonia nitrogen was 0.5 mg/L. The research indicated that when the quantity of Vibrio parahaemolyticus was up to 3.92 ×10^5 CFU or 3.92 × 10^4 CFU for 72 h, it was hard to control. The death rate of Fenneropenaeus merguiensis would rise with the increase of temperature when the temperature was from 26℃ to 32℃. The influence of salinity and pH to the pathogenicity for Fenneropenaeus merguiensis might be related to bacteriophage. The results indicated that nitrate nitrogen had stress effect on Fenneropenaeus merguiensis. In a certain range, pathogenicity of Vibrio parahaemolyticus to Fenneropenaeus merguiensis was more serious and the death ratio was higher with the increase concentration of nitrite nitrogen （1.0-10.0 rag/L） and ammonia nitrogen （0.5-1.5 mg/L）. The results lay a foundation for the Vibrio prevention of Fenneropenaeus merguiensis.