一株新型完全氨氧化菌适应缺氧和高氨氮环境的代谢机制

完全氨氧化菌驱动“一步硝化”的发现彻底打破了“两步硝化”理论的传统认识。前期研究结果表明，完全氨氧化菌广泛分布在污水处理体系中，尤其是在缺氧反应池中其丰度甚至超过典型氨氧化菌，但对其适应缺氧和高氨氮污水环境的机制尚不清楚。申请人前期报道了一个厌氧池中的硝化过程由完全氨氧化菌主导，基因组学分析发现，灵活的代谢途径可能极大地提高了它们的环境适应能力。近期申请人成功从此厌氧池中分离出一株新型完全氨氧化菌，本项目拟在前期研究的基础上，运用生理生化、稳定同位素示踪和基因组学分析的方法，探索新型完全氨氧化菌适应复杂缺氧污水环境的底物获取与代谢途径，进一步研究其在高氨氮环境中过量氨氧化积累的有毒中间产物的清除机制及副产物氧化亚氮的产生途径，最终阐明其适应缺氧和高氨氮污水环境的代谢机制。研究结果不仅可以提高对复杂污水环境中完全氨氧化菌代谢与环境适应机制的认识，还将为其在污水脱氮领域的高效应用提供理论基础。

The discovery of “one-step nitrification” catalyzed by complete ammonia oxidizers completely contradicts the traditional rule of “two-step nitrification”. Previous studies show that Comammox widely distribute in wastewater treatment systems, especially in anoxic reactors where their abundances are even higher than canonical nitrifiers. However, the mechanism of their adaption to the anoxic and ammonium-rich sewage environment is not clear. Our previous studies reported that Comammox dominated the nitrification process in an anaerobic tank. Based on the genomic analysis, we speculated that complex metabolic pathways encoded by Comammox could significantly improve their environmental adaptability. Recently, we successfully isolated a new type of Comammox strain from the anaerobic tank. Based on our preliminary results, physiology and biochemistry, isotopic tracing, and genomic analyses will be combined to investigate the substrate acquisition and metabolism pathways of the new Comammox strain adapted to the complex anoxic sewage environment. Furthermore, metabolic pathways in removing harmful substances produced by excessive ammonia oxidation in the ammonium-rich environment and the byproduct nitrous oxide production pathway will be further investigated. Finally, the metabolic mechanism of the new Comammox strain adapted to the anoxic and ammonium-rich environment will be expounded. The expected results from this project will not only advance our understanding of the metabolism and environmental adaptation mechanism of Comammox in the anoxic and ammonium-rich sewage environment but also provide a theoretical foundation for effective applications of Comammox in nitrogen removal from wastewater.