固态腐殖质修饰生物阴极强化低温反硝化及分子生物学机制

The low temperature is always considered as one restriction factor for in situ bioremediation of nitrate contaminated groundwater. Currently used regulation measures for microbial denitrification system are costly and may introduce secondary pollution for groundwater. Our prior experiment results indicate an electrochemical system equipping with a solid-phase humin modified biocathode (SH-biocathode) could maintain high microbial denitrification efficiency even under 10℃. However, the response of electroactive biofilm formed on the SH-biocathode under 10℃ and molecular biology mechanism of such low temperature adaption remain unclear. A bioelectrochemical system equipped with a SH-biocathode will be set up in this research to assess the activity of such SH biocathode and optimize the operating conditions. Further, the micromorphology and electrochemical properties of the electroactive biofilm was analyzed to elucidate its low temperature responses. Finally, metagenomic and metaproteomic techniques will be employed for analyzing the dominant species and the corresponding functions (gene abundance/protein number). The changes of functions such as denitrification, electron transfer and cold adaption of the electroactive biofilm community and their possible interactions are investigated for revealing the molecular biology mechanism of the enhanced denitrification at low temperature. The results of this research will provide a new alternative for maintain the microbial denitrification efficiency at low temperature.

低温对生物反硝化的抑制，严重影响硝态氮污染地下水生物修复的效果。现有调控低温生物反硝化的措施成本较高，可能会对地下水造成二次污染。我们前期的研究表明固态腐殖质修饰生物阴极能在低温下提高反硝化效率，但固态腐殖质修饰生物阴极低温电活性生物膜的特征及其分子生物学机制尚不清楚。本项目通过建立固态腐殖质修饰生物阴极反硝化系统，进一步明确固态腐殖质修饰生物阴极强化低温反硝化的效果并优化运行条件。在此基础上，对固态腐殖质修饰生物阴极电活性生物膜进行微观形态和电化学表征，分析其低温响应特征。同时借助宏基因组结合宏蛋白质组学技术分析电活性生物膜群落的关键物种及其功能（基因丰度/蛋白数量），探索低温下生物膜群落的反硝化、电子传递、低温适应等功能的变化规律及可能的互作关系，揭示固态腐殖质修饰生物阴极强化低温反硝化的分子生物学机制。研究成果为强化低温地下水硝态氮污染生物修复提供新思路和手段。

低温对生物反硝化的抑制，严重影响硝态氮污染地下水生物修复的效果。现有调控低温生物反硝化的措施成本较高，可能会对地下水造成二次污染。我们前期的研究表明固态腐殖质修饰生物阴极能在低温下提高反硝化效率，但固态腐殖质修饰生物阴极低温电活性生物膜的特征及其分子生物学机制尚不清楚。本项目建立了固态腐殖质修饰生物阴极连续流反硝化反应器及其对照反应器，结果表明固态腐殖质修饰生物阴极在5℃条件下仍能进行反硝化而对照阴极无法进行反硝化。对固态腐殖质修饰生物阴极进行的微观形态和电化学分析表明固态腐殖质丰富了电活性微生物并增强了生物膜的电子传递活性。进一步对生物阴极的微生物群落分析表明Acidovorax可能是低温条件下利用固态腐殖质进行反硝化的优势菌，PICRUSt预测结果表明腐殖质促进了阴极生物膜的形成，并增强了低温下生物阴极的电子转移和反硝化功能。研究成果为强化低温地下水硝态氮污染生物修复提供新思路和手段。