School of Environmental Sciences, University of East Anglia, Norwich Research Park, Norwich NR4 7TJ, UK.
Nature. 2014 Jun 5;510(7503):148-51. doi: 10.1038/nature13192. Epub 2014 Apr 28.
The climate-active gas methane is generated both by biological processes and by thermogenic decomposition of fossil organic material, which forms methane and short-chain alkanes, principally ethane, propane and butane. In addition to natural sources, environments are exposed to anthropogenic inputs of all these gases from oil and gas extraction and distribution. The gases provide carbon and/or energy for a diverse range of microorganisms that can metabolize them in both anoxic and oxic zones. Aerobic methanotrophs, which can assimilate methane, have been considered to be entirely distinct from utilizers of short-chain alkanes, and studies of environments exposed to mixtures of methane and multi-carbon alkanes have assumed that disparate groups of microorganisms are responsible for the metabolism of these gases. Here we describe the mechanism by which a single bacterial strain, Methylocella silvestris, can use methane or propane as a carbon and energy source, documenting a methanotroph that can utilize a short-chain alkane as an alternative to methane. Furthermore, during growth on a mixture of these gases, efficient consumption of both gases occurred at the same time. Two soluble di-iron centre monooxygenase (SDIMO) gene clusters were identified and were found to be differentially expressed during bacterial growth on these gases, although both were required for efficient propane utilization. This report of a methanotroph expressing an additional SDIMO that seems to be uniquely involved in short-chain alkane metabolism suggests that such metabolic flexibility may be important in many environments where methane and short-chain alkanes co-occur.
气候活性气体甲烷既可以通过生物过程产生，也可以通过化石有机物质的热成因分解产生，后者形成甲烷和短链烷烃，主要是乙烷、丙烷和丁烷。除了自然来源，环境还会受到石油和天然气开采和分配过程中所有这些气体的人为输入的影响。这些气体为各种微生物提供了碳和/或能量，使它们能够在缺氧和有氧区代谢这些气体。能够同化甲烷的好氧甲烷营养菌被认为与短链烷烃的利用者完全不同，而对暴露于甲烷和多碳烷烃混合物的环境的研究则假设，不同的微生物群体负责这些气体的代谢。在这里，我们描述了一种单一细菌菌株 Methylocella silvestris 可以将甲烷或丙烷作为碳和能源源的机制，证明了一种可以利用短链烷烃作为甲烷替代品的甲烷营养菌。此外，在这些气体的混合物上生长时，两种气体都能同时被有效消耗。鉴定出两个可溶性二铁中心单加氧酶 (SDIMO) 基因簇，并发现它们在细菌生长过程中对这些气体的表达存在差异，尽管两者都是有效利用丙烷所必需的。本报告描述了一种表达额外的 SDIMO 的甲烷营养菌，它似乎专门参与短链烷烃代谢，这表明这种代谢灵活性在许多甲烷和短链烷烃共存的环境中可能很重要。
