ZnO-NPs对好氧反硝化细菌Zobellella sp. B307的致毒机制

本文以一株筛自胶州湾沉积物中的好氧反硝化细菌Zobellella sp.B307为研究对象，在短期暴露条件下，通过细菌的生长、脱氮能力，相关酶活以及代谢途径等指标的变化，研究纳米氧化锌（ZnO-NPs）对该菌株的毒性效应；结合锌离子溶出试验、CAT和ROS等氧化应激水平测定，探讨ZnO-NPs对该菌株的致毒机制.结果表明，200mg/L的ZnO-NPs会使菌株硝酸盐氮去除率降至57.53%，LDH升高至对照组的378%，ROS水平高达对照组的5.34倍，SOD活性比对照组升高了60.32%，NIR活性仅为对照组的14.46%；ZnO-NPs主要通过诱导菌株活性氧的生成使其膜通透性改变、相关酶活性下降，并使相关蛋白质、氨基酸的合成及基因表达等代谢通路受到影响，进而抑制该菌株的反硝化能力；游离锌离子的产生可能不是ZnO-NPs对菌株的主要致毒途径.

Toxicity and mechanism of ZnO-NPs on an aerobic denitrifying bacteria strain Zobellella sp.B307

In this paper, a strain of aerobic denitrifying bacteria Zobellellasp. B307screened from the sediment of Jiaozhou Bay was studied. Under short-term exposure condition, the toxic effect of ZnO-NPs on the bacterial strain was analysed through the changes in growth, denitrification ability, related enzyme activity and metabolic pathway of the bacteria. The toxicity mechanism of ZnO-NPs on the strain was discussed based on the dissolution test of zinc ions and the oxidative stress levels such as of CAT and ROS. The results showed that comparing with the control group, the addition of ZnO-NPs at 200mg/L could decrease the nitrate removal rate and NIR activity of the strain to 57.53% and 14.46%. Whereas it could increase the LDH、ROS level、SOD activity to 378%、534% and 60.32% respectively. ZnO-NPs could induce the formation of reactive oxygens species and through that, the membrane permeability of strain was changed, the enzyme activity was decreased, and the related pathway of protein, amino acid synthesis and gene expression were affected, which inhibited the denitrification ability of the strain. The production of free zinc ions is not the main cause of toxicity of ZnO-NPs on the bacterial strain.