Korea Polar Research Institute, Incheon, Republic of Korea.
Max Planck Institute for Biogeochemistry, Jena, Germany.
Glob Chang Biol. 2021 Oct;27(20):5124-5140. doi: 10.1111/gcb.15785. Epub 2021 Jul 16.
Permafrost thaw induces soil hydrological changes which in turn affects carbon cycle processes in the Arctic terrestrial ecosystems. However, hydrological impacts of thawing permafrost on microbial processes and greenhouse gas (GHG) dynamics are poorly understood. This study examined changes in microbial communities using gene and genome-centric metagenomics on an Arctic floodplain subject to decadal drainage, and linked them to CO and CH flux and soil chemistry. Decadal drainage led to significant changes in the abundance, taxonomy, and functional potential of microbial communities, and these modifications well explained the changes in CO and CH fluxes between ecosystem and atmosphere-increased fungal abundances potentially increased net CO emission rates and highly reduced CH emissions in drained sites corroborated the marked decrease in the abundance of methanogens and methanotrophs. Interestingly, various microbial taxa disproportionately responded to drainage: Methanoregula, one of the key players in methanogenesis under saturated conditions, almost disappeared, and also Methylococcales methanotrophs were markedly reduced in response to drainage. Seven novel methanogen population genomes were recovered, and the metabolic reconstruction of highly correlated population genomes revealed novel syntrophic relationships between methanogenic archaea and syntrophic partners. These results provide a mechanistic view of microbial processes regulating GHG dynamics in the terrestrial carbon cycle, and disproportionate microbial responses to long-term drainage provide key information for understanding the effects of warming-induced soil drying on microbial processes in Arctic wetland ecosystems.
多年冻土融化会引起土壤水文变化，进而影响北极陆地生态系统的碳循环过程。然而，对于多年冻土融化对微生物过程和温室气体（GHG）动态的水文影响，人们了解甚少。本研究利用基因和基因组中心宏基因组学，对经历了数十年排水的北极泛滥平原上的微生物群落进行了研究，并将其与 CO 和 CH 通量和土壤化学联系起来。数十年来的排水导致了微生物群落的丰度、分类和功能潜力发生了显著变化，这些变化很好地解释了生态系统与大气之间 CO 和 CH 通量的变化——真菌丰度的增加可能会增加净 CO 排放速率，而排水区高度还原的 CH 排放证实了产甲烷菌和甲烷营养菌丰度的显著减少。有趣的是，各种微生物类群对排水的反应不成比例：在饱和条件下产甲烷的关键参与者之一 Methanoregula 几乎消失，而 Methylococcales 甲烷营养菌也因排水而明显减少。此外，还回收了七个新的产甲烷种群基因组，并对高度相关的种群基因组进行了代谢重建，揭示了产甲烷古菌和共生伙伴之间的新共生关系。这些结果提供了一个关于微生物过程调节陆地碳循环中 GHG 动态的机制性观点，并且对长期排水的不成比例的微生物反应为理解变暖引起的土壤干燥对北极湿地生态系统中微生物过程的影响提供了关键信息。
