Data_Sheet_2_Hydrogen-Fueled Microbial Pathways in Biogas Upgrading Systems Revealed by Genome-Centric Metagenomics.XLSX

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 H2 addition distinctively alternated the abundance of the taxa. Two different Methanoculleus species (one mesophilic and one thermophilic) were identified as the main responsible ones for methane metabolism. Finally, it was demonstrated that the addition of H2 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., Tepidanaerobacter sp. DTU063), while the addition of H2 favored the proliferation of potential homoacetogens (e.g., Clostridia 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.

依托二氧化碳加氢的沼气提质（biogas upgrading）技术是一类新兴的电燃料生产路径。生物甲烷化效率（biomethanation efficiency）高度依赖于结构平衡的微生物群落（microbial consortium），对其开展高分辨率表征并解析其功能潜力与种间相互作用，对于工艺优化至关重要。本研究是首个针对中温与高温沼气提质反应器的以基因组为中心的宏基因组学（genome-centric metagenomics）研究，旨在明确200余种参与氢辅助甲烷化的未培养微生物（uncultivated microbes）的代谢谱（metabolic profile）。研究将预测功能分析所得结果与微生物丰度变化进行关联，以阐明工艺参数对群落结构的影响。运行温度显著影响反应器的微生物丰富度，而氢气（H₂）投加则显著改变了各分类单元（taxa）的丰度分布。两种不同的产甲烷管形菌属（Methanoculleus）物种（分别为中温型与高温型）被确定为驱动甲烷代谢的核心功能菌群。研究证实，氢气投加对功能与固碳、丙酸（propionate）及丁酸（butanoate）代谢相关的特定微生物的协同或互营相互作用（syntrophic interactions）施加了选择性压力。新型细菌被鉴定为潜在的互营乙酸氧化菌（如Tepidanaerobacter sp. DTU063），而氢气投加则促进了潜在同型产乙酸菌（homoacetogens，如Clostridia sp. DTU183）的增殖。携带Wood-Ljungdahl途径（Wood-Ljungdahl pathway）功能基因的种群基因组主要为嗜热型类群，而丙酸降解菌则多在中温条件下被检出。最终，研究明确了兼具多功能代谢能力的微生物与专性/兼性互营菌之间的潜在互营相互作用。