The Response Characteristics Of Four Pathogenic Aeromonas Hydrophila Strains To Ammonia And Nitrite

The paper was aimed to explore the effects on the growth of four Aeromonas hydrophila(ZHYYZ-1、ZHYYZ-2、ZHYYZ-3、ZHYYZ-4) under the stress of single and combined ammonia and nitrit by spectrophotometry. The results showed that:(1)There was no significant effect on the growth of four strains at the concentration of ammonia of2g/L.With the increase of the concentration of ammonia, the inhibitory effect on the growth of four strains was increased as well as the delay period.(2) There was no significant effect on the growth of four strains at the concentration of nitrit of 0.2g/L.With the increase of the concentration of nitrit, the effect on the growth of four strains was the same as ammonia,however showing a less influence to delay period than ammonia.(3)Under the stress of combined ammonia and nitrit, different concentrations groups were set in the experiment according to the semi lethal concentration of ammonia(M) and nitrit(N). All four strains’ growth increasement reached maximum in 24 hours with high concentration of ammonia and low concentration of nitrit(0.8M+0.2N), howerer it reached minimum in 24 hours with low level concentration of ammonia and high level concentration of nitrit(0.2M+0.8N).PCR technique was used to detect four virulence genes(AHH, Aha, OMP and AerA).The results showed that the four virulence genes were distributed in this four strains.RT-PCR technique was used to detect the expression of the four virulence genes of semi quantitative.The results showed that: the virulence genes(AHH, OMP, and Aha) existed in this four strains under the stress of ammonia, nitrite, and ammonia-nitrite.There was a inhibitory effect on the expression of AHH, OMP and Aha with elevated concentrations under the stress of nitrite. There was hardly any expression of AerA under the stress of ammonia and ammonia-nitrit. It showed a weak expression in ZHYYZ-1 under the stress of high level concentration of nitrite..The AerA of ZHYYZ-1 was quantitatively detected under high level concentration of ammonia, nitrite, and ammonia-nitrite by using fluorescence quantitative PCR. The results showed that: the amount of gene expression in the group under the stress of ammonia was smaller than control group, however the amount of gene expression in the group under the stress of nitrite was bigger than the control group, and the amount of gene expression in the group under the stress of ammonia-nitrite reached maximum. And it was more conducive to the expression in combination with low concentration of ammonia and high concentrations of nitrite.