Syntrophic acetate oxidation replaces acetoclastic methanogenesis during thermophilic digestion of biowaste
Syntrophic acetate oxidation replaces acetoclastic methanogenesis during thermophilic digestion of biowaste
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DOI：
10.1186/s40168-020-00862-5
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发表时间：
2020-07-03
期刊：
影响因子：
15.5
通讯作者：
Gallert, Claudia
中科院分区：
文献类型：
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作者：
Dyksma, Stefan;Jansen, Lukas;Gallert, Claudia
背景厌氧消化(AD)是一种有效管理废物和废水的全球重要技术。在AD中，微生物在一个复杂的食物网中相互作用，以产生沼气。在这里，乙酰裂解产甲烷菌和合养醋酸盐氧化细菌(SAOB)争夺醋酸盐，醋酸盐是有机质矿化的主要中间体。尽管越来越多的证据表明，合养醋酸盐氧化是甲烷产生的重要途径，但对SAOB的了解仍然非常有限。结果从高温固态生物废弃物消化器中重建的超基因组(MAG)涵盖了沼气微生物群落的基本功能。在超基因组中最丰富的类群(53%)中含有多种功能的物种，从聚合物的水解到合养的醋酸酯氧化。在一个与已知SAOB有亲缘关系的脱硫杆菌MAG中发现了Wood-Ljugdahl的合养醋酸酯氧化途径和相应的节能基因。16S rRNA基因扩增序列测定和浓缩培养一致地将未培养的脱硫杆菌与合胞杆菌、弧形厌氧杆菌和未分类的梭状芽孢杆菌在9个全惊吓消化器中鉴定为潜在的醋酸盐氧化核心群落的成员，而几乎没有检测到乙酰破碎型产甲烷菌。结论本研究结果为进一步研究厌氧消化生态系统提供了新的思路，在厌氧消化系统中，醋酸盐的分解主要由细菌实现。元基因组学和富集化培养揭示了一个不同的和新的未培养醋酸盐氧化细菌的核心群落，并指出了它们在生物垃圾干发酵中的特定生态位。它们的基因组图谱表明，除了具有合养醋酸酯氧化的可能性外，还具有代谢可塑性。
Background 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. Results A metabolic reconstruction of metagenome-assembled genomes (MAGs) from a thermophilic solid state biowaste digester covered the basic functions of the biogas microbial community.Firmicuteswas 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 aDethiobacteraceaeMAG that is phylogenetically related to known SAOB. 16S rRNA gene amplicon sequencing and enrichment cultivation consistently identified the unculturedDethiobacteraceaetogether withSyntrophaceticus,Tepidanaerobacter, and unclassifiedClostridiaas members of a potential acetate-oxidizing core community in nine full-scare digesters, whereas acetoclastic methanogens were barely detected. Conclusions Results presented here provide new insights into a remarkable anaerobic digestion ecosystem where acetate catabolism is mainly realized byBacteria. 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.