微生物介导硝酸盐还原耦合亚铁氧化过程的动力学及其影响因素

Kinetics and influencing factors of microbially-mediated nitrate reduction coupled with Fe(II) oxidation process

摘要:

[目的] 探究不同菌浓度和亚铁浓度条件下，Acidovorax sp.strain BoFeN1介导的厌氧亚铁氧化耦合硝酸盐还原过程的动力学和次生矿物。[方法] 构建包含菌BoFeN1、硝酸盐、亚铁的厌氧培养体系，测试硝酸根、亚硝酸根、乙酸根、亚铁等浓度，并收集次生矿物，采用XRD、SEM进行矿物种类和形貌表征。[结果] 在微生物介导硝酸盐还原耦合亚铁氧化的体系中，高菌浓度促进硝酸盐还原，对亚铁氧化也有一定促进作用；高浓度亚铁在低菌浓度下氧化反应速率和程度降低，但是在高菌浓度下无明显影响；亚铁浓度越高次生矿物结晶度越高，但对硝酸盐还原具有一定抑制作用。在微生物介导亚硝酸盐还原耦合亚铁氧化的体系中，高的菌浓度和亚铁浓度都会促进亚硝酸盐还原，但亚铁氧化的次生矿物会对亚硝酸盐的微生物还原产生较强的抑制作用，次生矿物的种类和结晶度主要受亚铁浓度影响。[结论] 硝酸盐还原主要是生物反硝化作用，亚硝酸盐还原包含生物反硝化和化学反硝化两部分，在硝酸盐体系中亚铁氧化与次生矿物生成是受生物和化学反硝化作用的共同影响，但亚硝酸盐体系中亚铁氧化与次生矿物生成主要是受化学反硝化作用影响。该研究可为深入理解厌氧微生物介导铁氮耦合反应机制提供基础数据和理论支撑。

Abstract:

[Objective] This study aims to investigate the effects of cell density and Fe(II) concentrations on the kinetics and secondary minerals during nitrate reduction and Fe(II) oxidation by Acidovorax sp. strain BoFeN1 under anoxic condition. [Methods] The anaerobic culture system containing strain BoFeN1, nitrate and Fe(II) was set up; the concentrations of nitrate, nitrite, acetate, Fe(II) were determined with the use of ion chromatography and microplate reader; and the mineralogy and morphology of the secondary minerals were characterized by using XRD and SEM. [Results] In the system of microbially-mediated nitrate (NO₃^-) reduction coupled with Fe(II) oxidation, high cell density substantially promoted nitrate reduction and Fe(II) oxidation. With low cell density, the Fe(II) oxidation reaction rate and extent of reaction declined for the high concentrations of Fe(II), while no obvious effect was observed in the high cell density. The higher crystallinity of secondary minerals was generated and inhibited the nitrate reduction to some extent. In the system of microbially-mediated nitrite (NO₂^-) reduction coupled with Fe(II) oxidation, the high cell density and Fe(II) concentration promoted the nitrite reduction, but the Fe(II) oxidation had a strong inhibitory effect on the microbial reduction of nitrite, and the types and crystallinity of secondary minerals were mainly affected by the concentration of Fe(II). [Conclusion] Biological denitrification is the main process controlling nitrate reduction; nitrite reduction was contributed by both of the biological and chemical denitrification; biological and chemical denitrification are the main reasons for Fe(II) oxidation and secondary mineral formation in the nitrate system; but chemical denitrification is the main reason for Fe(II) oxidation and secondary mineral formation in the nitrite system. This study can provide basic data and theoretical support for the coupling reactions of iron and nitrogen mediated by anaerobic microorganisms.