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.

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Verrucomicrobial 甲烷氧化菌：代谢多才多艺的嗜酸菌的生态生理学

甲烷氧化菌是一组重要的微生物，可以抵消向大气排放的甲烷。阿尔法和伽玛变形菌的甲烷氧化细菌已经研究了一个多世纪，而疣微菌门的甲烷氧化菌是最近才发现的。疣状微生物甲烷氧化菌是生活在酸性极强的地热生态系统中的极端微生物。目前已分离出十余株，属于甲基酸杆菌属和甲基酸杆菌属。. 最初，这些甲烷氧化菌被认为是代谢受限的。然而，过去几年的基因组分析和生理生化实验表明，疣状微生物甲烷氧化菌以及变形菌甲烷氧化菌在代谢方面比以前假设的要多得多。可以利用酸性地热生态系统中存在的几种无机气体和其他分子，例如甲烷、氢气、二氧化碳、铵、氮气，也许还有硫化氢。因此，疣状微生物甲烷氧化菌可以代表多个火山营养循环和减少地热生态系统温室气体排放的关键参与者。这里，我们总结了目前关于疣状微生物甲烷氧化菌代谢多功能性的知识，并讨论了决定它们在自然环境中多样性的因素。此外，还回顾了疣状微生物和变形菌甲烷氧化菌的关键代谢、形态和生态特征。