Methanotrophic bacteria mitigate emissions of the potent greenhouse gas methane (CH4) from a variety of anthropogenic and natural sources, including freshwater lakes, which are large sources of CH4 on a global scale. Despite a dependence on dioxygen (O2) for CH4 oxidation, abundant populations of putatively aerobic methanotrophs have been detected within microoxic and anoxic waters and sediments of lakes. Experimental work has demonstrated active aerobic methanotrophs under those conditions, but how they are able to persist and oxidize CH4 under O2 deficiency remains enigmatic. In this review, we discuss possible mechanisms that underpin the persistence and activity of aerobic methanotrophs under O2-limiting conditions in freshwater habitats, particularly lakes, summarize experimental evidence for microbial oxidation of CH4 by aerobic bacteria under low or no O2, and suggest future research directions to further explore the ecology and metabolism of aerobic methanotrophs in O2-limiting environments.

中文翻译：

---

需氧甲烷氧化菌在限氧淡水栖息地中的神秘持久性

甲烷营养菌可减少各种人为和自然来源的强效温室气体甲烷 (CH4) 的排放，其中包括淡水湖，淡水湖是全球范围内 CH4 的重要来源。尽管 CH4 氧化依赖双氧 (O2)，但在微氧和缺氧水域以及湖泊沉积物中仍检测到了大量的推定需氧甲烷氧化菌。实验工作已经证明了在这些条件下活跃的需氧甲烷氧化菌，但它们如何在缺氧条件下持续存在并氧化 CH4 仍然是个谜。在这篇综述中，我们讨论了淡水栖息地（特别是湖泊）限氧条件下好氧甲烷氧化菌持久性和活性的可能机制，总结了低氧或无氧条件下需氧细菌氧化 CH4 的实验证据，并提出了未来的研究建议进一步探索限氧环境中需氧甲烷氧化菌的生态学和代谢的方向。