Methanonatronarchaeia represents a deep-branching phylogenetic lineage of extremely halo(alkali)philic and moderately thermophilic methyl-reducing methanogens belonging to the phylum Halobacteriota. It includes two genera, the alkaliphilic Methanonatronarchaeum and the neutrophilic Ca. Methanohalarchaeum. The former is represented by multiple closely related pure culture isolates from hypersaline soda lakes, while the knowledge about the latter is limited to a few mixed cultures with anaerobic haloarchaea. To get more insight into the distribution and ecophysiology of this enigmatic group of extremophilic methanogens, potential activity tests and enrichment cultivation with different substrates and at different conditions were performed with anaerobic sediment slurries from various hypersaline lakes in Russia. Methanonatronarchaeum proliferated exclusively in hypersaline soda lake samples mostly at elevated temperature, while at mesophilic conditions it coexisted with the extremely salt-tolerant methylotroph Methanosalsum natronophilum. Methanonatronarchaeum was also able to serve as a methylotrophic or hydrogenotrophic partner in several thermophilic enrichment cultures with fermentative bacteria. Ca. Methanohalarchaeum did not proliferate at mesophilic conditions and at thermophilic conditions it competed with extremely halophilic and moderately thermophilic methylotroph Methanohalobium, which it outcompeted at a combination of elevated temperature and methyl-reducing conditions. Overall, the results demonstrated that Methanonatronarchaeia are specialized extremophiles specifically proliferating in conditions of elevated temperature coupled with extreme salinity and simultaneous availability of a wide range of C₁-methylated compounds and H₂/formate.

中文翻译：

---

甲烷古菌生态学


Methanonatronarchaeia代表了属于盐杆菌门的极度嗜盐（碱）和中等嗜热甲基还原产甲烷菌的深分支系统发育谱系。它包括两个属，嗜碱Methanonatronarchaeum和嗜中性Ca。甲烷菌。前者以从高盐苏打湖中分离出的多种密切相关的纯培养物为代表，而对后者的了解仅限于少数与厌氧盐古菌混合的培养物。为了更深入地了解这一神秘的极端嗜极产甲烷菌群的分布和生态生理学，我们对来自俄罗斯各个高盐湖的厌氧沉积物进行了不同基质和不同条件下的潜在活性测试和富集培养。 Methanonatronarchaeum仅在高盐苏打湖样品中增殖，且大多在高温下进行，而在中温条件下，它与极其耐盐的甲基营养菌Methanosalsum natronophilum共存。古甲烷古菌还能够在几种具有发酵细菌的嗜热富集培养物中充当甲基营养型或氢营养型伙伴。约。甲烷卤古菌在中温条件下不增殖，在高温条件下，它与极度嗜盐和中度嗜热的甲基营养菌甲烷卤菌竞争，在高温和甲基还原条件的组合下，它击败了后者。 总体而言，结果表明Methanonatronarchaeia是专门的嗜极微生物，在高温加上极端盐度以及同时提供多种C ₁ -甲基化化合物和H ₂ /甲酸盐的条件下特异性增殖。