Contribution of sulfate-reducing bacteria in the formation of hydrogen sulfide in coal seams of Hancheng mining area, China.

Coalbed hydrogen sulfide (H₂S) is a toxic and corrosive gas, it's very important for researching the origin of H₂S in coalbed and related metabolic characteristics of microbes in the bioconversion of coal. The purpose of this study is to clarify the contribution and influencing factors of bacterial and sulfate-reducing bacterial (SRB) communities in the Taiyuan Formation (Nos. 5 and 11 coal seams) of the Hancheng mining area, by using gas composition testing, water quality measurements, 16S rRNA amplicon sequencing, and fluorescence real-time quantitative (qPCR) analysis. The results indicate that the coal seam gas is mainly composed of methane with a trace amount of H₂S ranging from 4 to 56 ppm. The H₂S content exhibits a positive correlation with the SRB gene copy number within the range of ∼30 to 200 copies/mL, indicating a strong association between the production of H₂S and the contribution of SRB in the study area. The presence of Desulfobulbus, Desulfovibrio, Desulfomicrobium, Desulfotomaculum, Desulfobacca, Thermosinus, Desulfococcus, Desulfarculus, and Syntrophobacter genus from the coalbed-produced water further proves that H₂S is reduced in dissimilatory sulfate reduction (DSR) pathway. Bacteria and SRB play a critical role in the conversion of coal organic matter through biodegradation. SRB community composition is more related to total organic carbon, total dissolved solids, SO 4 2- and trace elements. This study gives an in-depth explanation of the formation of H₂S in coalbed and provides novel views in toxic gas removal in future gas exploitation. The community composition of in-situ bacteria and sulfate-reducing bacteria in the coal seam is characterized. The genesis and control factors of hydrogen sulfide in coal seams are discussed. The possible pathways during hydrogen sulfide formation are analyzed. [ABSTRACT FROM AUTHOR]