极端环境下嗜热酸甲烷营养细菌研究进展

甲烷营养细菌能够将温室气体甲烷(CH4)转化为CO2或生物质,在碳生物地球化学循环及缓解由温室气体导致的全球气候变化方面发挥着重要的作用.甲烷营养细菌生存的条件范围较为广泛,但在中性pH (5～8)和中温(20～35℃)范围内生长最佳.系统进化分析认为,它们均属于γ-或α-变形菌门(Proteobacteria).最近3项独立完成的研究从极端热酸(pH接近1,温度高于50℃)环境中分离获得了具有甲烷氧化(营养)功能的微生物,经鉴定均属于疣微菌门(Verrucomicrobia).这些全新的、不同于以往的研究结果不仅是对现有关于甲烷营养细菌生态学认知的进一步拓展,同时也暗示着可能存在着新型的、由微生物介导的CH4氧化途径与机制. 因此,特就极端环境中嗜热嗜酸甲烷营养细菌的最新研究进展作一概述.

Advances in thermoacidophilic methanotrophs from extreme environments

Methane-oxidizing bacteria (methanotrophs) play an important role in the biogeochemical carbon cycle and in controlling global climate change, by converting methane to carbon dioxide or biomass. Although these bacteria have been isolated from a variety of environments, most of which grow best at neutral pH (5-8) and moderate temperature ranges (20-35℃). Based on the phylogenetic analysis, methanotrophs are classified into type I and type II, which belong to the gamma- and alpha-Proteobacteria, respectively. Very recently, three independent studies have isolated methane-oxidizing microorganisms from extreme thermoacidophilic environments with pH values of approximately 1 and temperatures higher than 50℃, these nonproteobacterial strains were all identified as members of the phylum Verrucomicrobia. These new and unusual studies will undoubtedly expand the known phylogenetic and functional diversity of methanotrophs, also indicate that novel methane oxidizing pathways and mechanisms could exist in the methanotrophs. This review illustrates the latest advances in thermoacidophilic methanotrophs, based on the recent three reports on methane oxidation in the extreme environments.