Metagenomic analysis of a permafrost microbial community reveals a rapid response to thaw
Metagenomic analysis of a permafrost microbial community reveals a rapid response to thaw
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DOI：
10.1038/nature10576
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发表时间：
2011-12-15
期刊：
影响因子：
64.8
通讯作者：
Jansson, Janet K.
中科院分区：
文献类型：
--
作者：
Mackelprang, Rachel;Waldrop, Mark P.;Jansson, Janet K.
永久冻土含有约1672 Pg碳（C），大致相当于目前陆地植物和大气中所含的总量（1-3）。随着全球气温上升导致永久冻土融化，这种C库很容易分解（2）。在解冻过程中，截留的有机物可能更容易被微生物降解，并导致温室气体排放（4，5）。尽管最近在使用分子工具研究冻土微生物群落方面取得了进展（6-9），但它们对解冻的反应仍然不清楚。在这里，我们使用深度宏基因组测序来确定解冻对微生物系统发育和功能基因的影响，并将这些数据与甲烷排放量的测量相关联。宏基因组学是对来自环境的DNA进行直接测序，它允许检查整个生化途径和相关过程，而不是代谢难题的单个部分。我们的宏基因组分析表明，在从冷冻到解冻状态的过渡过程中，许多微生物，系统发育和功能基因丰度和途径都发生了快速变化。在5摄氏度下孵育一周后，永冻层宏基因组比冷冻时更加相似。我们发现，多个基因参与循环的碳和氮迅速转移解冻过程中。我们还从一个复杂的土壤宏基因组中构建了第一个基因组草图，该基因组对应于一种新的产甲烷菌。以前积累在冻土中的甲烷在解冻过程中释放出来，随后被甲烷营养菌消耗。这些数据共同指出了甲烷和氮在融化的永久冻土中快速循环的重要性。
Permafrost contains an estimated 1672 Pg carbon (C), an amount roughly equivalent to the total currently contained within land plants and the atmosphere(1-3). This reservoir of C is vulnerable to decomposition as rising global temperatures cause the permafrost to thaw(2). During thaw, trapped organic matter may become more accessible for microbial degradation and result in greenhouse gas emissions(4,5). Despite recent advances in the use of molecular tools to study permafrost microbial communities(6-9), their response to thaw remains unclear. Here we use deep metagenomic sequencing to determine the impact of thaw on microbial phylogenetic and functional genes, and relate these data to measurements of methane emissions. Metagenomics, the direct sequencing of DNA from the environment, allows the examination of whole biochemical pathways and associated processes, as opposed to individual pieces of the metabolic puzzle. Our metagenome analyses reveal that during transition from a frozen to a thawed state there are rapid shifts in many microbial, phylogenetic and functional gene abundances and pathways. After one week of incubation at 5 degrees C, permafrost metagenomes converge to be more similar to each other than while they are frozen. We find that multiple genes involved in cycling of C and nitrogen shift rapidly during thaw. We also construct the first draft genome from a complex soil metagenome, which corresponds to a novel methanogen. Methane previously accumulated in permafrost is released during thaw and subsequently consumed by methanotrophic bacteria. Together these data point towards the importance of rapid cycling of methane and nitrogen in thawing permafrost.