Distribution of Microbial Community in Coal Reservoir with Ability to Generate Methane by Anaerobically Degrading Coal

Abstract

The utilization of biogenic coalbed methane (CBM) can meet the increasing demand of energy and reduce the burden of fossil energy on the environment. The in situ microorganisms are the performers in the generation of biogenic CBM and the key to the formation of biogenic CBM and microbially enhanced CBM (MECBM). However, the variability of microbial community structure in different coal seams of one basin has still not been reported, and the reasons for the significant differences among coal, water, gas, and coalfield are not clear. Here, microbial communities in coal samples from coal seams 3^#, 9^#, and 15^# associated with Qinshui Basin in China were determined. The archaeal and bacterial diversities in coal seam 3^# were the largest, while the highest fungal diversity was observed in coal seam 15^#. Hydrogenotrophic methanogens, Methanobacterium and Methanocella, dominated in all samples. The bacterial communities varied while the fungal communities showed higher similarity among samples. Syntrophic relationship was found between bacteria, fungi and methanogen that the organics in coal would be degraded by bacteria and fungi to facilitate methanogenesis. The differences of microbial communities in various basins were further discussed to be caused by the diverse coal structures and hard migration of microorganisms which were respectively influenced by coal formation process and characteristics of porous media in strata. These results suggested that geological history coupled with biological migration contributed to the structure of existing microbial community which further determine the formation pathway of biogenic CBM.