Treu Laura, Campanaro Stefano, Kougias Panagiotis G, Sartori Cristina, Bassani Ilaria, Angelidaki Irini
Department of Environmental Engineering, Technical University of Denmark, Kongens Lyngby, Denmark.
Department of Biology, University of Padova, Padova, Italy.
Front Microbiol. 2018 May 28;9:1079. doi: 10.3389/fmicb.2018.01079. eCollection 2018.
Biogas upgrading via carbon dioxide hydrogenation is an emerging technology for electrofuel production. The biomethanation efficiency is strongly dependent on a balanced microbial consortium, whose high- resolution characterization along with their functional potential and interactions are pivotal for process optimization. The present work is the first genome-centric metagenomic study on mesophilic and thermophilic biogas upgrading reactors aiming to define the metabolic profile of more than 200 uncultivated microbes involved in hydrogen assisted methanogenesis. The outcomes from predictive functional analyses were correlated with microbial abundance variations to clarify the effect of process parameters on the community. The operational temperature significantly influenced the microbial richness of the reactors, while the H addition distinctively alternated the abundance of the taxa. Two different species (one mesophilic and one thermophilic) were identified as the main responsible ones for methane metabolism. Finally, it was demonstrated that the addition of H exerted a selective pressure on the concerted or syntrophic interactions of specific microbes functionally related to carbon fixation, propionate and butanoate metabolisms. Novel bacteria were identified as candidate syntrophic acetate oxidizers (e.g., sp. DTU063), while the addition of H favored the proliferation of potential homoacetogens (e.g., sp. DTU183). Population genomes encoding genes of Wood-Ljungdahl pathway were mainly thermophilic, while propionate degraders were mostly identified at mesophilic conditions. Finally, putative syntrophic interactions were identified between microbes that have either versatile metabolic abilities or are obligate/facultative syntrophs.
通过二氧化碳加氢进行沼气升级是一种用于生产电燃料的新兴技术。生物甲烷化效率强烈依赖于平衡的微生物群落，对其进行高分辨率表征以及了解它们的功能潜力和相互作用对于工艺优化至关重要。目前的工作是首次以基因组为中心对中温及高温沼气升级反应器进行宏基因组研究，旨在确定参与氢辅助甲烷生成的200多种未培养微生物的代谢谱。预测功能分析的结果与微生物丰度变化相关联，以阐明工艺参数对群落的影响。操作温度显著影响反应器的微生物丰富度，而添加氢气则显著改变了分类群的丰度。两种不同的物种（一种中温菌和一种高温菌）被确定为甲烷代谢的主要责任菌。最后，结果表明添加氢气对与碳固定、丙酸盐和丁酸盐代谢功能相关的特定微生物的协同或互营相互作用施加了选择压力。新型细菌被鉴定为候选互营乙酸氧化菌（例如DTU063菌属），而添加氢气有利于潜在的同型产乙酸菌（例如DTU183菌属）的增殖。编码伍德-Ljungdahl途径基因的群体基因组主要是嗜热菌，而丙酸盐降解菌大多在中温条件下被鉴定出来。最后，在具有多种代谢能力或为专性/兼性互营菌的微生物之间鉴定出了假定的互营相互作用。
