Zn(II)对好氧反硝化菌Acinetobacter sp. JR-142的代谢活性影响

Effects of Zn(II) on metabolic activity of aerobic denitrifier Acinetobacter sp. JR-142

摘要:

【目的】研究不同Zn（II）浓度对好氧反硝化菌Acinetobacter sp.JR-142生理活性，尤其是反硝化代谢特性的影响。【方法】筛选一株好氧反硝化菌，优化了最佳活性条件；分析了不同Zn（II）浓度对生长曲线和反硝化效率的影响以及对细胞形态的影响；明晰了不同Zn（II）浓度条件下，细胞特征活性酶-硝酸盐还原酶和亚硝酸盐还原酶的活性变化情况，分析了不同活性同关键酶的编码基因napA和nirS的相对表达量之间的规律。【结果】获得一株具有好氧反硝化功能的菌株，命名为JR-142，经鉴定为不动杆菌Acinetobacter sp.。在以琥珀酸钠为碳源，C/N为6，pH为7.0，温度30℃，转速为180 r/min的条件下，好氧反硝化活性最高。结果表明当Zn（II）浓度为3.25 mg/L时，对菌株的生长及好氧反硝化速率有促进作用；当Zn（II）浓度为52 mg/L以上浓度时，菌株的生长及反硝化速率均受到抑制。酶活及关键基因napA、nirS的定量分析结果显示，对照组及JR+0.05处理组的硝酸盐还原酶NR、亚硝酸盐还原酶NiR活性均高于JR+0.8处理组，在24 h时，JR+0.05 Zn（II）处理组中，细胞的关键好氧反硝化基因napA及nirS的相对表达量显著高于对照组，这进一步说明3.25 mg/L Zn（II）可以促进好氧反硝化过程，而在24 h及32 h时对照组及JR+0.05处理组的基因相对表达量远高于JR+0.8处理组，也说明52 mg/L Zn（II）则会对反应产生抑制。【结论】探究并系统分析了不同Zn（II）浓度对不动杆菌Acinetobacter sp.JR-142生长繁殖以及和在重金属锌离子存在的情况下影响好氧反硝化生理活性的影响，为后续硝酸盐-重金属复合污染废水的生物处理技术提供了数据指导。

Abstract:

[Objective] To study the effects of different concentrations of Zn(II) on the metabolic activities, especially the denitrification of the aerobic denitrifier Acinetobacter sp. JR-142.[Methods] An aerobic denitrifier was screened out and its growth conditions were optimized. The growth curve, denitrifying efficiency, and cell morphology of the strain were measured in the presence of Zn(II) at different concentrations. We measured the activities of cell characteristic enzymes (nitrate reductase and nitrite reductase) exposed to different concentrations of Zn(II), and then analyzed the relationship between napA & nirS expression levels and enzyme activities.[Results] An aerobic denitrifying strain was obtained and identified as Acinetobacter sp. JR-142. Under the conditions of sodium succinate as carbon source, C/N ratio of 6, pH 7.0, temperature at 30℃, shaking speed of 180 r/min, the aerobic denitrifier showed the highest activity. Zn(II) at the concentration of 3.25 mg/L promoted the cell growth and aerobic denitrification, while that at the concentration higher than 52 mg/L showed inhibitory effects. The nitrate reductase and nitrite reductase activities in the control group and JR+0.05 treatment group were higher than those in the JR+0.8 treatment group. At the time point of 24 h, the relative expression levels of aerobic denitrifying genes napA and nirS in JR+0.05 treatment group were significantly higher than those in control group, which further indicated that 3.25 mg/L Zn(II) can promote aerobic denitrification. At the time points of 24 h and 32 h, the relative expression levels of the two genes in the control group and JR+0.05 treatment group were much higher than those in the JR+0.8 treatment group, which indicated that 52 mg/L Zn(II) can inhibit the reaction.[Conclusion] This study systematically analyzed the effects of Zn(II) at different concentrations on the growth and aerobic denitrification of Acinetobacter sp. JR-142 for the first time. It provides a data basis for the biological treatment of wastewater with nitrate-heavy metal combined pollution.