Anaerobic digestion (AD) is a globally important technology for effective waste and wastewater management. In AD, microorganisms interact in a complex food web for the production of biogas. Here, acetoclastic methanogens and syntrophic acetate-oxidizing bacteria (SAOB) compete for acetate, a major intermediate in the mineralization of organic matter. Although evidence is emerging that syntrophic acetate oxidation is an important pathway for methane production, knowledge about the SAOB is still very limited. A metabolic reconstruction of metagenome-assembled genomes (MAGs) from a thermophilic solid state biowaste digester covered the basic functions of the biogas microbial community. Firmicutes was the most abundant phylum in the metagenome (53%) harboring species that take place in various functions ranging from the hydrolysis of polymers to syntrophic acetate oxidation. The Wood-Ljungdahl pathway for syntrophic acetate oxidation and corresponding genes for energy conservation were identified in a Dethiobacteraceae MAG that is phylogenetically related to known SAOB. 16S rRNA gene amplicon sequencing and enrichment cultivation consistently identified the uncultured Dethiobacteraceae together with Syntrophaceticus, Tepidanaerobacter, and unclassified Clostridia as members of a potential acetate-oxidizing core community in nine full-scare digesters, whereas acetoclastic methanogens were barely detected. Results presented here provide new insights into a remarkable anaerobic digestion ecosystem where acetate catabolism is mainly realized by Bacteria. Metagenomics and enrichment cultivation revealed a core community of diverse and novel uncultured acetate-oxidizing bacteria and point to a particular niche for them in dry fermentation of biowaste. Their genomic repertoire suggests metabolic plasticity besides the potential for syntrophic acetate oxidation.

中文翻译：

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在生物废物的高温消化过程中，互养乙酸盐氧化取代了乙酰分解产甲烷作用。


厌氧消化（AD）是有效废物和废水管理的全球重要技术。在 AD 中，微生物在复杂的食物网中相互作用以产生沼气。在这里，乙酸分解产甲烷菌和互养乙酸盐氧化细菌（SAOB）竞争乙酸盐，乙酸盐是有机物矿化的主要中间体。尽管越来越多的证据表明互养乙酸盐氧化是甲烷生产的重要途径，但有关 SAOB 的知识仍然非常有限。来自嗜热固态生物废物消化器的宏基因组组装基因组（MAG）的代谢重建涵盖了沼气微生物群落的基本功能。厚壁菌门是宏基因组中最丰富的门（53%），其物种具有从聚合物水解到互养乙酸盐氧化等各种功能。在与已知 SAOB 系统发育相关的脱硫杆菌科 MAG 中鉴定了用于互养乙酸氧化的 Wood-Ljungdahl 途径和相应的能量守恒基因。 16S rRNA 基因扩增子测序和富集培养一致地鉴定出未培养的脱硫杆菌科以及 Syn营乙酸菌、Tepidanaerobacter 和未分类的梭状芽胞杆菌是 9 个完全恐慌的消化池中潜在的乙酸氧化核心群落的成员，而几乎没有检测到乙酸破碎的产甲烷菌。这里提出的结果为非凡的厌氧消化生态系统提供了新的见解，其中乙酸分解代谢主要由细菌实现。宏基因组学和富集培养揭示了多种新型未培养的醋酸氧化细菌的核心群落，并指出了它们在生物废物干发酵中的特殊利基。 它们的基因组库表明，除了互养乙酸氧化的潜力之外，还具有代谢可塑性。