Dang Cheng-Cheng, Jin Yin-Zhu, Tan Xin, Nie Wen-Bo, Lu Yang, Liu Bing-Feng, Xing De-Feng, Ren Nan-Qi, Xie Guo-Jun
State Key Laboratory of Urban Water Resource and Environment, School of Environment, Harbin Institute of Technology, Harbin, 150090, China.
Key Laboratory of the Three Gorges Region's Eco-Environment, Ministry of Education, College of Environment and Ecology, Chongqing University, Chongqing, 400044, China.
Environ Sci Ecotechnol. 2024 Jun 13;21:100438. doi: 10.1016/j.ese.2024.100438. eCollection 2024 Sep.
Ethane, the second most abundant gaseous hydrocarbon in vast anoxic environments, is an overlooked greenhouse gas. Microbial anaerobic oxidation of ethane can be driven by available electron acceptors such as sulfate and nitrate. However, despite nitrite being a more thermodynamically feasible electron acceptor than sulfate or nitrate, little is known about nitrite-driven anaerobic ethane oxidation. In this study, a microbial culture capable of nitrite-driven anaerobic ethane oxidation was enriched through the long-term operation of a nitrite-and-ethane-fed bioreactor. During continuous operation, the nitrite removal rate and the theoretical ethane oxidation rate remained stable at approximately 25.0 mg NO N L d and 11.48 mg CH L d, respectively. Batch tests demonstrated that ethane is essential for nitrite removal in this microbial culture. Metabolic function analysis revealed that a species affiliated with a novel genus within the family Rhodocyclaceae, designated as ' Alkanivoras nitrosoreducens', may perform the nitrite-driven anaerobic ethane oxidation. In the proposed metabolic model, despite the absence of known genes for ethane conversion to ethyl-succinate and succinate-CoA ligase, '. A. nitrosoreducens' encodes a prospective fumarate addition pathway for anaerobic ethane oxidation and a complete denitrification pathway for nitrite reduction to nitrogen. These findings advance our understanding of nitrite-driven anaerobic ethane oxidation, highlighting the previously overlooked impact of anaerobic ethane oxidation in natural ecosystems.
乙烷是广阔缺氧环境中第二丰富的气态碳氢化合物，是一种被忽视的温室气体。乙烷的微生物厌氧氧化可由硫酸盐和硝酸盐等可用电子受体驱动。然而，尽管亚硝酸盐在热力学上比硫酸盐或硝酸盐更可行作为电子受体，但关于亚硝酸盐驱动的厌氧乙烷氧化却知之甚少。在本研究中，通过长期运行以亚硝酸盐和乙烷为进料的生物反应器，富集了一种能够进行亚硝酸盐驱动的厌氧乙烷氧化的微生物培养物。在连续运行期间，亚硝酸盐去除率和理论乙烷氧化率分别稳定在约25.0毫克氮/升·天和11.48毫克乙烷/升·天。批次试验表明，乙烷对于这种微生物培养物中的亚硝酸盐去除至关重要。代谢功能分析表明，一种隶属于红环菌科内一个新属的物种，命名为“亚硝酸盐还原烷食菌”，可能进行亚硝酸盐驱动的厌氧乙烷氧化。在所提出的代谢模型中，尽管缺乏将乙烷转化为琥珀酸乙酯和琥珀酸辅酶A连接酶的已知基因，但“亚硝酸盐还原烷食菌”编码了一条用于厌氧乙烷氧化的潜在富马酸加成途径和一条将亚硝酸盐还原为氮气的完整反硝化途径。这些发现推进了我们对亚硝酸盐驱动的厌氧乙烷氧化的理解，突出了厌氧乙烷氧化在自然生态系统中先前被忽视的影响。
