Cultivation and molecular approaches were used to study methanogenesis in saline aquatic system of the Lake Elton (southern Russia), the largest hypersaline lake in Europe. The potential rates of hydrogenotrophic, acetoclastic, methylotrophic and methyl-reducing methanogenesis and diversity of the growth-enriched for by adding electron donors methanogenic communities were studied in the sediment slurry incubations at salinity range from 7 to 275 g/L. The most active pathway detected at all salinities was methylotrophic with a dominance of Methanohalobium and Methanohalophilus genera, at salt saturation and moderately halophilic Methanolobus and Methanococcoides at lower salinity. The absence of methane production from acetate, formate and H₂/CO₂ under hypersaline conditions was most probably associated with the energy constraints. The contribution of hydrogenotrophic, acetoclastic, and methyl-reducing methanogens to the community increases with a decrease in salinity. Temperature might play an important regulatory function in hypersaline habitats; i.e. methylotrophic methanogens and hydrogenotrophic sulfate-reducing bacteria (SRB) outcompeting methyl-reducing methanogens under mesophilic conditions, and vice versa under thermophilic conditions. An active methane production together with negligible methane oxidation makes hypersaline environments a potential source of methane emission.

中文翻译：

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埃尔顿湖盐碱水生系统的甲烷生成。

耕种和分子方法被用于研究欧洲最大的高盐湖埃尔顿湖（俄罗斯南部）的盐碱水生系统中的甲烷生成。研究了在盐度为7至275 g / L的底泥培养中，通过添加电子供体产甲烷菌而增加了氢营养，乙酰碎裂，甲基营养和甲基还原的甲烷生成和增长的多样性。在所有盐度下，最活跃的途径是甲基营养，以甲烷卤代和嗜盐嗜盐杆菌属为主，在盐饱和度和中等嗜盐的甲醇嗜热菌和甲烷菌盐度较低。在高盐条件下不存在由乙酸盐，甲酸和H ₂ / CO ₂产生的甲烷，这很可能与能量限制有关。随着盐度的降低，氢营养型，乙酰碎裂性和甲基还原型产甲烷菌的贡献增加。在高盐生境中温度可能起着重要的调节功能。例如，在嗜温条件下，甲基营养型产甲烷菌和硫酸氢还原型细菌（SRB）的竞争优势胜过甲基还原性产甲烷菌，反之亦然。活跃的甲烷生产以及可忽略的甲烷氧化使高盐环境成为甲烷排放的潜在来源。