PNAS：北极泥炭微生物种群可适应暖温度并持续制造甲烷
研究发现，北极泥炭的微生物种群可能迅速适应变暖的温度从而以高速率持续制造甲烷。来自富含碳的北极永冻土的甲烷排放预计将在一个变暖的气候中增加，但是影响甲烷制造的微生物动态尚不清楚。Mette Marianne Svenning及其同事收集了来自挪威斯瓦尔巴特的永冻土样本，然后在1摄氏度到30摄氏度之间的温度孵化这些样本，同时对样本中的微生物群落的活动与基因表达进行分析。甲烷制造率随着温度而迅速上升，伴随着微生物群落结构与功能对不同温度范围的适应。这组作者说，甲烷制造的限速步骤在低于7摄氏度与高于7摄氏度的时候不同;不同的物种在低温而非高于7摄氏度的时候制造甲烷。这组作者报告说，微生物对温度的适应出现在30天内，而10摄氏度以下的北极泥炭的甲烷制造高于低纬度同样温度的生态系统的制造。这组作者说，这些结果提示，随着温度上升，北极泥炭微生物群调控代谢与营养相互作用，从而在各种温度下持续制造高浓度的甲烷，改造维持甲烷底物可用性所需的物种关系。
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原文摘要：
Arctic permafrost soils store large amounts of soil organic carbon (SOC) that could be released into the atmosphere as methane (CH4) in a future warmer climate. How warming affects the complex microbial network decomposing SOC is not understood. We studied CH4 production of Arctic peat soil microbiota in anoxic microcosms over a temperature gradient from 1 to 30 °C, combining metatranscriptomic, metagenomic, and targeted metabolic profiling. The CH4 production rate at 4 °C was 25% of that at 25 °C and increased rapidly with temperature, driven by fast adaptations of microbial community structure, metabolic network of SOC decomposition, and trophic interactions. Below 7 °C, syntrophic propionate oxidation was the rate-limiting step for CH4 production; above this threshold temperature, polysaccharide hydrolysis became rate limiting. This change was associated with a shift within the functional guild for syntrophic propionate oxidation, with Firmicutes being replaced by Bacteroidetes. Correspondingly, there was a shift from the formate- and H2-using Methanobacteriales to Methanomicrobiales and from the acetotrophic Methanosarcinaceae to Methanosaetaceae. Methanogenesis from methylamines, probably stemming from degradation of bacterial cells, became more important with increasing temperature and corresponded with an increased relative abundance of predatory protists of the phylum Cercozoa. We concluded that Arctic peat microbiota responds rapidly to increased temperatures by modulating metabolic and trophic interactions so that CH4 is always highly produced: The microbial community adapts through taxonomic shifts, and cascade effects of substrate availability cause replacement of functional guilds and functional changes within taxa.
doi: 10.1073/PNAS.1420797112
作者：Alexander Tøsdal Tve
