Centre Bioengineering of Russian Academy of Sciences, Moscow, Russia.
FEMS Microbiol Ecol. 2012 Feb;79(2):348-58. doi: 10.1111/j.1574-6941.2011.01221.x. Epub 2011 Nov 1.
Gas hydrates in marine sediments have been known for many years but recently hydrates were found in the sediments of Lake Baikal, the largest freshwater basin in the world. Marine gas hydrates are associated with complex microbial communities involved in methanogenesis, methane oxidation, sulfate reduction and other biotransformations. However, the contribution of microorganisms to the formation of gas hydrates remains poorly understood. We examined the microbial communities in the hydrate-bearing sediments and water column of Lake Baikal using pyrosequencing of 16S rRNA genes. Aerobic methanotrophic bacteria dominated the water sample collected at the lake floor in the hydrate-bearing site. The shallow sediments were dominated by Archaea. Methanogens of the orders Methanomicrobiales and Methanosarcinales were abundant, whereas representatives of archaeal lineages known to perform anaerobic oxidation of methane, as well as sulfate-reducing bacteria, were not found. Affiliation of archaea to methanogenic rather than methane-oxidizing lineages was supported by analysis of the sequences of the methyl coenzyme M reductase gene. The deeper sediments located at 85-90 cm depth close to the hydrate were dominated by Bacteria, mostly assigned to Chloroflexi, candidate division JS1 and Caldiserica. Overall, our results are consistent with the biological origin of methane hydrates in Lake Baikal.
多年来，海洋沉积物中的天然气水合物已经为人所知，但最近在世界上最大的淡水湖贝加尔湖中也发现了水合物。海洋天然气水合物与参与甲烷生成、甲烷氧化、硫酸盐还原和其他生物转化的复杂微生物群落有关。然而，微生物对水合物形成的贡献仍知之甚少。我们使用 16S rRNA 基因的焦磷酸测序技术研究了贝加尔湖含气水合物沉积物和水柱中的微生物群落。在含气水合物的湖底采集的水样中，好氧甲烷氧化菌占主导地位。浅层沉积物以古菌为主。产甲烷菌的目 Methanomicrobiales 和 Methanosarcinales 很丰富，而已知进行甲烷厌氧氧化以及硫酸盐还原菌的代表则没有发现。古菌与产甲烷菌而非甲烷氧化菌的亲缘关系得到了甲基辅酶 M 还原酶基因序列分析的支持。位于含气水合物附近 85-90 厘米深的深层沉积物以细菌为主，主要属于绿弯菌门、候选门 JS1 和 Caldiserica。总的来说，我们的结果与贝加尔湖甲烷水合物的生物学起源一致。
