多个环境因素对嗜水气单胞菌感染团头鲂致病力的影响

Effects of environmental factors on the virulence of Megalobrama amblycephala infected with Aeromonas hydrophila

采用正交试验L16(4×213)设计检验了养殖环境中多种理化因子(温度、p H、分子氨、亚硝酸盐)对嗜水气单胞菌感染团头鲂致病力的影响。试验设立温度(A)4个水平(20、24、28、32℃);p H(B)2个水平(6.5、8.0);分子氨(C)2个水平(0.02、0.04 mg·L-1)和亚硝酸盐(D)2个水平(0.1、0.3 mg·L-1),每组试验鱼分别注射嗜水气单胞菌106CFU·m L-1;以试验鱼存活时间的长短判断嗜水气单胞菌对团头鲂致病力的大小。结果表明:分子氨与p H的交互作用(B×C)和温度(A)因素分别对嗜水气单胞菌致病力影响极其显著(F>F0.01),p H(B)对嗜水气单胞菌致病力影响显著(F>F0.05),而亚硝酸盐(D)和分子氨(C)对嗜水气单胞菌致病力的影响不显著;团头鲂存活时间y(单位为h)与环境因子间的多元线性回归方程为y=164.713-6.399A+14.367B-11.914(B×C);根据该线性回归方程,当温度为20℃、p H=8.0、分子氨浓度为0.02 mg·L-1时,嗜水气单胞菌对团头鲂的致病力最弱,鱼体的存活时间最长(149.76 h)。本实验结果可为团头鲂养殖中的嗜水气单胞菌出血病防控预警提供一定的参考。

To detect the effects of environmental factors （temperature, pH, ammonia, and ni- trite） on the virulence of Megalobrama amblycephala infected with pathogen Aeromonas hydrophi- la, an experiment was conducted based on the orthogonal design L16（4x213）. The water tempera- ture （A） was designed with four levels, 20, 24, 28, and 32 ℃; pH （B）, ammonia （C） and nitrite （D） were set with two levels respectively： 6.5 and 8.0 for pH, 0.02 and 0.04 mg · L-1 for ammonia, and 0.1 and 0.3 mg· L-1 for nitrite. The virulence strength of M. amblycephala infec- ted with A. hydrophila was determined by the fish survival time. The results showed that the inter- active effect of pH and ammonia nitrogen （BxC）, as well as temperature （A） significantly im- pacted the virulence of M. amblycephala infected with A. hydrophila （ F〉F0.01 ）, the effect of pH （B） was significant （ F〉F0.05 ） , while the effects of ammonia nitrogen （C） and nitrite （D） were not significant. Based on the statistical analysis, the fish survival time y （h） presented a signifi- cant linear correlation with environmental factors （temperature, pH and ammonia nitrogen ）, i.e., y = 164.713-6.399A＋ 14.367B- 11.914（BXC）. Accordinz to the eauation. M. amblycephala