State Key Laboratory of Lake Science and Environment, Nanjing Institute of Geography and Limnology, Chinese Academy of Sciences, Nanjing 210008, China.
State Key Laboratory of Lake Science and Environment, Nanjing Institute of Geography and Limnology, Chinese Academy of Sciences, Nanjing 210008, China; University of Chinese Academy of Sciences, Beijing 100039, China.
Water Res. 2023 May 1;234:119833. doi: 10.1016/j.watres.2023.119833. Epub 2023 Mar 3.
Conventional aerobic CH-oxidizing bacteria (MOB) are frequently detected in anoxic environments, but their survival strategy and ecological contribution are still enigmatic. Here we explore the role of MOB in enrichment cultures under O gradients and an iron-rich lake sediment in situ by combining microbiological and geochemical techniques. We found that enriched MOB consortium used ferric oxides as alternative electron acceptors for oxidizing CH with the help of riboflavin when O was unavailable. Within the MOB consortium, MOB transformed CH to low molecular weight organic matter such as acetate for consortium bacteria as a carbon source, while the latter secrete riboflavin to facilitate extracellular electron transfer (EET). Iron reduction coupled to CH oxidation mediated by the MOB consortium was also demonstrated in situ, reducing 40.3% of the CH emission in the studied lake sediment. Our study indicates how MOBs survive under anoxia and expands the knowledge of this previously overlooked CH sink in iron-rich sediments.
传统的好氧 CH 氧化菌（MOB）经常在缺氧环境中被检测到，但它们的生存策略和生态贡献仍然是个谜。在这里，我们通过结合微生物学和地球化学技术，探索了 MOB 在 O 梯度和富铁湖泊沉积物原位富集培养中的作用。我们发现，当氧气不可用时，富含 MOB 的联合体在核黄素的帮助下，使用氧化铁作为替代电子受体来氧化 CH。在 MOB 联合体中，MOB 将 CH 转化为低分子量有机物，如乙酸盐，作为联合体细菌的碳源，而后者分泌核黄素以促进细胞外电子转移（EET）。MOB 联合体介导的铁还原耦合 CH 氧化也在原位得到证实，减少了研究湖泊沉积物中 40.3%的 CH 排放。我们的研究表明了 MOB 如何在缺氧条件下生存，并扩展了对富铁沉积物中这一先前被忽视的 CH 汇的认识。
