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a b s t r a c t a r t i c l e i n f oIt is generally believed that biogenic coal bed methane (CBM) is an end product of coal biodegradation by methanogenic archaea and syntrophic bacteria. In this work, the archaeal and bacterial communities of CBM reservoir associated with Ordos Basin in China were investigated using 454 pyrosequencing. Sampling produced water, coal and rock in the reservoir, a total of 46,598 sequence reads were obtained. All archaea were methanogens with the genus Methanolobus predominating. The genus consisted of 81.18% of pyrosequencing reads in water sample and > 99% in coal and rock samples. Although the phylum Proteobacteria was the main component of all samples, bacterial communities in coal and rock samples were similar at the genus level, which were distinctly separated with water sample. The results strongly suggested that methylotrophic methanogenesis governed the biogenic CBM formation. The separation of microbial communities between water and coal, rock samples should be considered when investigating the process of coal biodegradation and the generation of new biogenic CBM.

The activity of methanogens and related bacteria which inhabit the coal beds is essential for stimulating new biogenic coal bed methane (CBM) production from the coal matrix. In this study, the microbial community structure and methanogenesis were investigated in Southern Qinshui Basin in China, and the composition and stable isotopic ratios of CBM were also determined. Although geochemical analysis suggested a mainly thermogenic origin for CBM, the microbial community structure and activities strongly implied the presence of methanogens in situ. 454 pyrosequencing analysis combined with methyl coenzyme-M reductase (mcrA) gene clone library analysis revealed that the archaeal communities in the water samples from both coal seams were similar, with the dominance of hydrogenotrophic methanogen Methanobacterium. The activity and potential of these populations to produce methane were confirmed by the observation of methane production in enrichments supplemented with H2 + CO2 and formate, and the only archaea successfully propagated in the tested water samples was from the genus Methanobacterium. 454 pyrosequencing analysis also recovered the diverse bacterial communities in the water samples, which have the potential to play a role in the coal biodegradation fueling methanogens. These results suggest that the biogenic CBM was generated by coal degradation via the hydrogenotrophic methanogens and related bacteria, which also contribute to the huge CBM reserves in Southern Qinshui Basin, China.

It is commonly accepted that biogenic coalbed methane (CBM) is formed by anaerobic bacteria and methanogens via coal biodegradation. While the syntrophic cooperation between fungi and methanogens has been well-established in the production of methane from rumen, little is known about the role that fungi play in the formation of biogenic CBM. Miseq sequencing and mcrA gene library were employed to investigate the fungal, archaeal, and bacterial communities in produced water from Qinshui Basin, a major site for CBM exploitation in China. The syntrophic relationship between fungi degrading coal and methanogens producing methane was also investigated. A diversity of fungal communities was found in produced water from different coal seams with the dominance of Ascomycota and Basidiomycota. Hydrogenotrophic methanogens, Methanobacterium, were also found to be predominant in produced water as revealed by Miseq sequencing and mcrA gene library analysis. Bacterial communities with potential to degrade coal were also recovered in produced water. Large yields of methane were produced in incubations with produced water and coal. Incubations that included antibiotics achieved 62.24% to 97.53% of the methane production as compared to the incubations without antibiotics. These results confirmed that most of the biogenic gas was produced by hydrogenotrophic methanogens and demonstrated the important role that fungi play in the biodegradation of coal.