Abstract—

The review summarizes the results of recent studies of microbial communities of the Lake Baikal sediments obtained using diverse techniques. In the sediments of the areas of stable sedimentation metabarcoding revealed predominance of members of the phyla Alpha- and Gammaproteobacteria (including Betaproteobacteriales), Bacteroidetes, Acidobacteria, Verrucomicrobia, and Thaumarchaeota, which are also common in other freshwater lakes. In the areas of discharge of gas-bearing mineralized fluids, the structure of microbial communities varied depending on the presence of electron acceptors and intensity and component composition of gas-bearing fluids responsible for microbial migration from the deep zone to the upper sediment layers and vice versa. Methanogenic archaea detected in Baikal sediments belonged to the groups capable of all four known catabolic pathways of methanogenesis: hydrogenotrophic, acetoclastic, methylotrophic, and hydrogen-dependent methylotrophic ones. Predominant members of the Baikal archaeal community, hydrogenotrophic methanogens of the family Methanoregulaceae (genera Methanoregula and Methano-sphaerula, as well as uncultured lineages), hydrogen-dependent methylotrophic archaea of the order Methanomassiliicoccales, and acetoclastic methanogens of the family Methanosaetaceae (genus Methanothrix (Methanosaeta)), were the same as in methanogenic communities of other freshwater lakes. Experimental evidence was obtained for anaerobic methane oxidation (AOM) via the nitrate- and nitrite-dependent pathways by archaea of the ANME-2d subcluster and bacteria of the phylum NC10. Structures of the 16S rRNA genes, mcrA, and pmoA exhibited high identity to those of the known freshwater organisms performing this process. Diversity of microbial communities at the sites of natural oil seepage differed at the order and family levels, as well as by the presence of alkane hydroxylases in the genes of the cultured species.

中文翻译：

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世界上最深、最古老的湖泊贝加尔湖沉积物中的微生物

摘要——

该综述总结了最近使用不同技术获得的贝加尔湖沉积物微生物群落研究的结果。在稳定沉降metabarcoding领域的沉积物揭示了门类成员的优势阿尔法-和γ-变形菌（包括Betaproteobacteriales），拟杆菌，酸杆菌门，疣微菌门，和Thaumarchaeota，这在其他淡水湖中也很常见。在含气矿化流体的排放区，微生物群落的结构因电子受体的存在以及负责微生物从深部迁移到上沉积层的含气流体的强度和组分组成而变化，反之亦然。反之。在贝加尔湖沉积物中检测到的产甲烷古菌属于能够进行所有四种已知的产甲烷分解代谢途径的组：氢营养型、乙酰碎屑型、甲基营养型和氢依赖型甲基营养型。贝加尔湖古细菌群落的主要成员，甲烷调节科（Methanoregulae和Methano-sphaerula属）的氢营养产甲烷菌，以及未培养的谱系），Methanomassiliicoccales目的氢依赖性甲基营养古细菌和Methanosaetaceae家族（Methanothrix ( Methanosaeta )）的乙酰碎屑产甲烷菌，与其他淡水湖泊的产甲烷群落相同。ANME-2d 亚群的古细菌和 NC10 门的细菌通过硝酸盐和亚硝酸盐依赖性途径获得了厌氧甲烷氧化 (AOM) 的实验证据。16S rRNA 基因、mcrA和pmoA 的结构表现出与执行此过程的已知淡水生物的高度同一性。天然石油渗漏位点的微生物群落多样性在顺序和家族水平上有所不同，并且在培养物种的基因中存在烷烃羟化酶。