State Key Joint Laboratory of Environment Simulation and Pollution Control, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, 18 Shuangqing Road, Haidian District, Beijing, 100085, China; School of Ecology and Environment, Zhengzhou University, Zhengzhou, 450001, China.
State Key Joint Laboratory of Environment Simulation and Pollution Control, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, 18 Shuangqing Road, Haidian District, Beijing, 100085, China; National Engineering Laboratory for VOCs Pollution Control Material & Technology, University of Chinese Academy of Sciences, Beijing, 101408, China.
Environ Res. 2023 Jul 15;229:115997. doi: 10.1016/j.envres.2023.115997. Epub 2023 Apr 25.
Denitrifying anaerobic methane-oxidizing (DAMO) processes, which link anaerobic methane oxidation (AMO) and denitrification, have a promising prospect in anaerobic wastewater treatment. In bioelectrochemical systems (BES), DAMO consortium presented potent metabolic activity. However, the extracellular electron transfer (EET) in BES was poorly understood. This study investigated the EET mechanisms and modes of electron transport in BES dominated by anaerobic methanotrophic bacteria. In the bioreactors with the auxiliary voltage of 0.5 and 1.1 V, named EMN-0.5 and EMN-1.1, respectively, biological voltages of 0.198 and 0.329 V were generated with power densities of 0.6 and 1.20 mW/m, after removing the voltage. High throughput and metagenome analyses demonstrated that main methanotrophs were DAMO bacteria and Methylocystis sp. The electroactive bacteria detected were Pseudomonas sp., Hypomicrobium sp., Thiobacillus sp, and Rhodococcus sp. The pil, cytochrome c, hdr, and he/fp genes related to EET were present on the electrode surfaces. Carbon 13 isotope tracing and chemicals analysis by GC-MS exhibited that methanol was an intermediate product released to extracellular environment and acted as the electronic carrier to drive the EET in methane oxidation. Extracellular electron transfer was achieved through the collaboration of DAMO bacteria, Methylocystis sp., and Pseudomonas sp. Anthraquinone 2-sulfonic acid ester (AQS) could improve the rate of electron transfer to the extracellular space, especially in the EMN-0.5 reaction system. This study provides a new understanding of AMO consortium metabolism in BES and may provide a scientific basis for developing methane control technology.
反硝化厌氧甲烷氧化（DAMO）过程将厌氧甲烷氧化（AMO）和反硝化联系起来，在厌氧废水处理中具有广阔的前景。在生物电化学系统（BES）中，DAMO 菌群表现出很强的代谢活性。然而，BES 中的胞外电子传递（EET）机制还不太清楚。本研究探讨了以厌氧甲烷氧化菌为主导的 BES 中 EET 机制和电子传递模式。在辅助电压为 0.5 和 1.1 V 的生物反应器 EMN-0.5 和 EMN-1.1 中，分别产生 0.198 和 0.329 V 的生物电压，去除电压后，功率密度分别为 0.6 和 1.20 mW/m。高通量和宏基因组分析表明，主要的甲烷氧化菌是 DAMO 细菌和甲基球菌。检测到的电活性细菌有假单胞菌、寡养单胞菌、硫杆菌和红球菌。与 EET 相关的 pil、细胞色素 c、hdr 和 he/fp 基因存在于电极表面。碳 13 同位素示踪和 GC-MS 化学分析表明，甲醇是一种释放到细胞外环境的中间产物，作为电子载体驱动甲烷氧化中的 EET。通过 DAMO 细菌、甲基球菌和假单胞菌的协同作用实现了胞外电子传递。蒽醌 2-磺酸酯（AQS）可以提高电子向细胞外空间的传递速率，特别是在 EMN-0.5 反应体系中。本研究为 BES 中 AMO 菌群代谢提供了新的认识，可能为开发甲烷控制技术提供科学依据。
