Abstract：
Coal seam microbes, as endogenous drivers of secondary biogenic gas production in coal seams, might be related to methane production in coal seams. In this study, we carried out anaerobic indoor culture experiments of microorganisms from three different depths of bituminous coal seams in Huainan mining area, and revealed the secondary biogas generation mechanism of bituminous coal seams by using the combined analysis of macro-genome and metabolism multi-omics. The results showed that the cumulative mass molar concentrations (Molality) of biomethane production increased with the increase of the coal seam depth in two consecutive cycles. At the genus level, there were significant differences in the bacterial and archaeal community structures corresponding to the three coal seams 1#, 6#, and 9#(p < 0.05). The volatile matter of air-dry basis (Vad) of coal was significantly correlated with differences in genus-level composition of bacteria and archaea, with correlations of R bacterial = 0.368 and R archaeal = 0.463, respectively. Functional gene analysis showed that the relative abundance of methanogenesis increased by 42% before and after anaerobic fermentation cultivation. Meanwhile, a total of 11 classes of carbon metabolism homologues closely related to methanogenesis were detected in the liquid metabolites of coal bed microbes after 60 days of incubation. Finally, the fatty acid, amino acid and carbohydrate synergistic methanogenic metabolic pathway was reconstructed based on the Kyoto Encyclopedia of Genes and Genomes (KEGG) database. The expression level of mcrA gene within the metabolic pathway of the 1# deep coal sample was significantly higher than that of the other two groups (p < 0.05 for significance), and the efficient expression of mcrA gene at the end of the methanogenic pathway promoted the conversion of bituminous coal organic matter to methane. Therefore, coal matrix compositions may be the key factors causing diversity in microbial community and metabolic function, which might be related to the different methane content in different coal seams.
摘要：
煤层微生物,作为煤层二次生物气生产的内生驱动因素，可能与煤层中甲烷的产生有关。在这项研究中,对淮南矿区三种不同深度烟煤层微生物进行室内厌氧培养实验,并利用宏基因组和代谢多组学的联合分析揭示了烟煤煤层的二次沼气生成机理。结果表明,在连续两个循环中,生物甲烷产量的累积质量摩尔浓度(Molality)随煤层深度的增加而增加。在属一级，1#三个煤层对应的细菌和古细菌群落结构存在显著差异，6#,和9#(p<0.05)。煤的风干基（Vad）的挥发性物质与细菌和古细菌的属水平组成差异显着相关，分别为R细菌=0.368和R古细菌=0.463。功能基因分析表明，厌氧发酵培养前后产甲烷的相对丰度增加了42％。同时,培养60天后，在煤层气微生物的液体代谢产物中共检测到11类与甲烷生成密切相关的碳代谢同源物。最后,脂肪酸，基于京都基因和基因组百科全书（KEGG）数据库，重建了氨基酸和碳水化合物协同产甲烷代谢途径。1#深煤样品代谢途径内mcrA基因表达水平显著高于其他两组(p<0.05为显著性),甲烷生成途径末端mcrA基因的高效表达促进了烟煤有机质向甲烷的转化。因此,煤基质组成可能是引起微生物群落和代谢功能多样性的关键因素，这可能与不同煤层中甲烷含量的不同有关。
