铁对嗜水气单胞菌毒力因子的影响

Effect of iron on virulent factors of Aeromonas hydrophila

用含不同浓度铁离子的培养基培养嗜水气单胞菌Ｊ－１株，３６ｈ时检测细菌含量以及毒素、蛋白酶、载铁体的表达量。发现菌液的浓度随着Ｆｅ２＋浓度的升高而升高，而毒力因子的表达量则相反，当Ｆｅ２＋的加入浓度为０时，毒素、蛋白酶、载铁体的表达量达最大值。用ＳＤＳ－ＰＡＧＥ电泳及免疫转印分析细菌的外膜蛋白（ＯＭＰ），嗜水气单胞菌Ｊ－１株在表达载铁体的同时多表达一条ＯＭＰ，其相对分子质量为７１．７×１０３，应为载铁体的受体。此时，经ＥＬＩＳＡ检测细菌菌体及抽取物Ｓ蛋白为阴性；经超薄切片电镜观察，菌体无Ｓ层结构。随着铁离子浓度的降低，Ｊ－１株毒素、蛋白酶及载铁体的表达增多，菌体Ｓ蛋白消失，并产生相应的ＯＭＰ条带，显示铁对嗜水气单胞菌毒力因子的产生具有重要影响。

Aeromonas hydrophila J 1 strain was cultured in mediums containing different concentrations of iron,and virulent factors of toxin,protease and siderophore were detected at 36 h.It was shown that the bacteria concentration increased and expression of virulent factors decreased with the increase of iron concentration.If no iron was added,maximum expression of toxin,proteases and siderophore were obtained.When iron was added at 0 0 8 μg/mL,the expression of toxin,protease and siderophore varied negatively with the iron concentration.But further variation was not observed when iron was added at 0 8 3 2 μg/mL.SDS PAGE and immuno blotting demonstrated that J 1 strain expressed one outer membrane protein(OMP)band with MW of 71 7×10 3,which was considered as siderophore receptor.When J 1 expressed siderophore,S protein was not detected in J 1 cells by electron microscopy and ELISA.It suggested that iron is an important environment factor that affects the virulence of Aeromonas hydrophila .