High Potential of Methane Production from Coal by Fungi and Hydrogenotrophic Methanogens from Produced Water
Hongguang Guo, Yixuan Zhang, Zaixing Huang, Weiguo Liang, Michael A. Urynowicz, Muhammad Ali
Abstract
Studying in situ microorganisms is essential to understand the formation of biogenic coalbed methane (CBM). Only a few studies have investigated the fungi community inhabiting in coal seams although fungi are found to degrade refractory compounds and solubilize coal and even work with methanogens to produce methane. In this study, produced water was collected from Qinshui Basin and used as the source of microflora to degrade coal. The function of fungi was analyzed by inhibition of bacteria with antibiotics. The results have shown that the inhibition of bacteria in the microcosms significantly increased the methane yield. Fungi were more favorable to cooperate with hydrogenotrophic methanogens when bacteria were inhibited as Methanobacterium were the predominant archaea accounting for 45.98–86.98% of the sequence reads. The relatively unchanged fungal community and high volatile fatty acids (VFAs) yields (48.70–85.72%) in the presence of antibiotics might contribute to H2 production to facilitate hydrogenotrophic methanogenesis. On the contrary, the dominant methanogens in microcosms without antibiotics gradually changed from Methanobacterium (89.85%) to Methanoceta (46.19%) and finally to Methanobacterium (87.72%). The bacterial community and organic intermediates have also changed greatly over time, which can be the reason for the succession of the methanogens. These results suggest that fungi in produced water can play an important role in coal biodegradation to produce VFAs and H2 that support hydrogenotrophic methanogenesis, which could be negatively impacted by the existence of bacteria.