Methanogenesis, a biological process mediated by complex microbial communities, has attracted great attention due to its contribution to global warming and potential in biotechnological applications. The current study unveiled the core microbial methanogenic metabolisms in anaerobic vessel ecosystems by applying combined genome-centric metagenomics and metatranscriptomics. Here, we demonstrate that an enriched natural system, fueled only with acetate, could support a bacteria-dominated microbiota employing a multi-trophic methanogenic process. Moreover, significant changes, in terms of microbial structure and function, were recorded after the system was supplemented with additional H2. Methanosarcina thermophila, the predominant methanogen prior to H2 addition, simultaneously performed acetoclastic, hydrogenotrophic, and methylotrophic methanogenesis. The methanogenic pattern changed after the addition of H2, which immediately stimulated Methanomicrobia-activity and was followed by a slow enrichment of Methanobacteria members. Interestingly, the essential genes involved in the Wood-Ljungdahl pathway were not expressed in bacterial members. The high expression of a glycine cleavage system indicated the activation of alternative metabolic pathways for acetate metabolism, which were reconstructed in the most abundant bacterial genomes. Moreover, as evidenced by predicted auxotrophies, we propose that specific microbes of the community were forming symbiotic relationships, thus reducing the biosynthetic burden of individual members. These results provide new information that will facilitate future microbial ecology studies of interspecies competition and symbiosis in methanogenic niches. Video abstract.

中文翻译：

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在厌氧消化生态系统的甲烷生成过程中，代谢依赖性控制着微生物的营养。

甲烷生成是由复杂的微生物群落介导的生物过程，由于其对全球变暖的贡献和在生物技术应用中的潜力，因此引起了极大的关注。当前的研究通过应用以基因组为中心的宏基因组学和元转录组学相结合的方法，揭示了厌氧血管生态系统中核心的微生物产甲烷代谢。在这里，我们证明了仅用乙酸盐提供燃料的丰富的自然系统，可以利用多营养甲烷生成过程来支持细菌为主的微生物群。此外，在系统中添加了额外的H2后，记录了微生物结构和功能方面的重大变化。嗜热甲烷菌（Methanosarcina thermophila）是添加H2之前的主要产甲烷菌，它同时进行了抗碎裂，氢营养，和甲基营养的甲烷生成。加入H2后产甲烷的模式发生了变化，立即刺激了甲烷微生物的活性，并随后缓慢富集了甲烷细菌成员。有趣的是，参与Wood-Ljungdahl途径的必需基因未在细菌成员中表达。甘氨酸裂解系统的高表达表明乙酸酯代谢的替代代谢途径的激活，该途径在最丰富的细菌基因组中得以重建。此外，正如预测的营养缺陷所证明的那样，我们提出该群落的特定微生物正在形成共生关系，从而减轻了单个成员的生物合成负担。这些结果提供了新的信息，将有助于未来的微生物生态学研究种间竞争和产甲烷生态位的共生。录像摘要。