Department of Microbiology, Institute for Water and Wetland Research, Radboud University, Heyendaalseweg 135, 6525 AJ, Nijmegen, The Netherlands.
FEMS Microbiol Rev. 2021 Sep 8;45(5). doi: 10.1093/femsre/fuab007.
Methanotrophs are an important group of microorganisms that counteract methane emissions to the atmosphere. Methane-oxidising bacteria of the Alpha- and Gammaproteobacteria have been studied for over a century, while methanotrophs of the phylum Verrucomicrobia are a more recent discovery. Verrucomicrobial methanotrophs are extremophiles that live in very acidic geothermal ecosystems. Currently, more than a dozen strains have been isolated, belonging to the genera Methylacidiphilum and Methylacidimicrobium. Initially, these methanotrophs were thought to be metabolically confined. However, genomic analyses and physiological and biochemical experiments over the past years revealed that verrucomicrobial methanotrophs, as well as proteobacterial methanotrophs, are much more metabolically versatile than previously assumed. Several inorganic gases and other molecules present in acidic geothermal ecosystems can be utilised, such as methane, hydrogen gas, carbon dioxide, ammonium, nitrogen gas and perhaps also hydrogen sulfide. Verrucomicrobial methanotrophs could therefore represent key players in multiple volcanic nutrient cycles and in the mitigation of greenhouse gas emissions from geothermal ecosystems. Here, we summarise the current knowledge on verrucomicrobial methanotrophs with respect to their metabolic versatility and discuss the factors that determine their diversity in their natural environment. In addition, key metabolic, morphological and ecological characteristics of verrucomicrobial and proteobacterial methanotrophs are reviewed.
产甲烷菌是一类能拮抗甲烷向大气排放的重要微生物。α-和γ-变形菌门的甲烷氧化细菌已经被研究了一个多世纪，而疣微菌门的产甲烷菌是最近才发现的。疣微菌产甲烷菌是生活在非常酸性地热生态系统中的极端微生物。目前，已经分离出十几种菌株，属于甲基酸菌属和甲基酸微菌属。最初，这些产甲烷菌被认为在代谢上受到限制。然而，近年来的基因组分析以及生理生化实验表明，疣微菌产甲烷菌和变形菌产甲烷菌在代谢上比之前认为的要多样得多。一些存在于酸性地热生态系统中的无机气体和其他分子，如甲烷、氢气、二氧化碳、铵、氮气，甚至可能还有硫化氢，可以被利用。因此，疣微菌产甲烷菌可能是多种火山养分循环和减轻地热生态系统温室气体排放的关键参与者。在这里，我们总结了目前关于疣微菌产甲烷菌在代谢多样性方面的知识，并讨论了决定它们在自然环境中多样性的因素。此外，还综述了疣微菌和变形菌产甲烷菌的关键代谢、形态和生态特征。
