Xie Bing-Ke, Zhang Yu, Wang Xiao-Wei, Sun Chao-Yue, Zhou Ji-Ti
Key Laboratory of Industrial Ecology and Environmental Engineering (MOE), School of Environmental Science and Technology, Dalian University of Technology, Dalian 116024, China.
Huan Jing Ke Xue. 2016 Oct 8;37(10):3955-3962. doi: 10.13227/j.hjkx.2016.10.038.
The process of dissimilatory nitrate reduction to ammonium (DNRA) plays an important role in the presence and conversion of ammonium ions in nature. However, the influencing factors and mechanisms of DNRA process in sulfate-reducing bacteria (SRB) have not yet been identified. The ability, influencing factors and mechanisms of DNRA was investigated in sp. CMX isolated previously in our laboratory. The results showed that the production rate of ammonium reached 85.8% and 97.3% respectively with NO and NO (10 mmol·L) as the sole electron donor and nitrogen source. Meanwhile, there was no by-products such as N and NO. Then the effects of different extra nitrogen sources and initial concentrations of sulfate and sulfide on DNRA process were also investigated. As a result, extra nitrogen, yeast extract, could promote DNRA process by improving both growth and metabolism of the strain. In another study, sulfate promoted the nitrate reduction stage while inhibited the nitrite reduction. Overall, the DNRA process by sp. CMX was inhibited by sulfate. In addition, both the growth and two stages of the DNRA process were inhibited in the presence of sulfide. Dose effect of sulfide was observed. Inhibition was enhanced with the increase of sulfide concentration. It's noticeable that the inhibition on nitrate reduction was stronger than the inhibition on nitrite reduction with 6 mmol·L of sulfide, leading to the lower reduction rate of nitrate than that of nitrite. In this condition, no accumulation of nitrite was observed in the system.
异化硝酸盐还原为铵（DNRA）过程在自然界铵离子的存在和转化中起着重要作用。然而，硫酸盐还原菌（SRB）中DNRA过程的影响因素和机制尚未明确。本研究以本实验室先前分离的菌株CMX为研究对象，对其DNRA能力、影响因素及机制进行了研究。结果表明，以NO和NO（10 mmol·L）作为唯一电子供体和氮源时，铵的产生率分别达到85.8%和97.3%。同时，未产生N和NO等副产物。随后，研究了不同额外氮源以及硫酸盐和硫化物初始浓度对DNRA过程的影响。结果表明，额外氮源酵母提取物可通过促进菌株生长和代谢来推动DNRA过程。另一项研究表明，硫酸盐促进了硝酸盐还原阶段，但抑制了亚硝酸盐还原。总体而言，菌株CMX的DNRA过程受到硫酸盐的抑制。此外，硫化物的存在抑制了菌株生长以及DNRA过程的两个阶段。观察到了硫化物的剂量效应。随着硫化物浓度的增加，抑制作用增强。值得注意的是，当硫化物浓度为6 mmol·L时，对硝酸盐还原的抑制作用强于对亚硝酸盐还原的抑制作用，导致硝酸盐的还原率低于亚硝酸盐。在此条件下，系统中未观察到亚硝酸盐的积累。
