Lakes of meltwater in the Artic have become one of the transforming landscape changes under global warming. We herein compared microbial communities between sediments and bank soils at an arctic lake post land submergence using geochemistry, 16S rRNA amplicons, and metagenomes. The results obtained showed that each sample had approximately 2,609 OTUs on average and shared 1,716 OTUs based on the 16S rRNA gene V3–V4 region. Dominant phyla in sediments and soils included Proteobacteria, Acidobacteria, Actinobacteria, Gemmatimonadetes, and Nitrospirae; sediments contained a unique phylum, Euryarchaeota, with the phylum Thaumarchaeota being primarily present in bank soils. Among the top 35 genera across all sites, 17 were more abundant in sediments, while the remaining 18 were more abundant in bank soils; seven out of the top ten genera across all sites were only from sediments. A redundancy analysis separated sediment samples from soil samples based on the components of nitrite and ammonium. Metagenome results supported the role of nitrite because most of the genes for denitrification and methane metabolic genes were more abundant in sediments than in soils, while the abundance of phosphorus-utilizing genes was similar and, thus, was not a significant explanatory factor. We identified several modules from the global networks of OTUs that were closely related to some geochemical factors, such as pH and nitrite. Collectively, the present results showing consistent changes in geochemistry, microbiome compositions, and functional genes suggest an ecological mechanism across molecular and community levels that structures microbiomes post land submergence.

中文翻译：

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宏基因组学揭示陆地淹没后北极土壤微生物组的地球化学成分功能变化


北极融水湖已成为全球变暖带来的地貌变化之一。我们在本文中使用地球化学、16S rRNA 扩增子和宏基因组比较了陆地淹没后的北极湖沉积物和岸土之间的微生物群落。获得的结果显示，每个样本平均约有2,609个OTU，并且基于16S rRNA基因V3-V4区域共有1,716个OTU。沉积物和土壤中的优势门包括变形菌门、酸杆菌门、放线菌门、Gemmatimonadetes 和 Nitrospirae；沉积物中含有独特的广古菌门，其中奇古菌门主要存在于河岸土壤中。在所有地点的前 35 个属中，有 17 个属在沉积物中含量较高，而其余 18 个属在岸土中含量较高；所有地点的前十个属中有七个仅来自沉积物。冗余分析根据亚硝酸盐和铵的成分将沉积物样品与土壤样品分开。宏基因组结果支持亚硝酸盐的作用，因为大多数反硝化基因和甲烷代谢基因在沉积物中比在土壤中更丰富，而磷利用基因的丰度相似，因此不是一个重要的解释因素。我们从 OTU 全球网络中识别出几个与一些地球化学因素（例如 pH 和亚硝酸盐）密切相关的模块。总的来说，目前的结果显示地球化学、微生物组组成和功能基因的一致变化表明了跨分子和群落水平的生态机制，该机制在陆地淹没后构建了微生物组。