The Sulfur Conversion Functional Microbial Communities in Biogas Liquid Can Participate in Coal Degradation

The addition of biogas liquid is a practical way to improve the yield of biological coalbed methane. The microbial composition in biogas liquid is complex, and whether it could participate in the sulfur conversion of coal remains unknown. In this study, sulfur conversion-related microbial communities were enriched from biogas liquid, which was dominated by genera <i>Anaerosolibacter</i>, <i>Bacillus</i>, <i>Hydrogenispora</i>, and <i>Oxobacter</i>. The co-culture of these groups with coal significantly changed the coal microbial community composition but did not increase the content of CH₄ and H₂S. The changed microbial communities mainly belonged to phyla Firmicutes, Proteobacteria, and Actinobacteriota, and increased the relative abundance of genera <i>Bacillus</i>, <i>Thermicanus</i>, <i>Hydrogenispora</i>, <i>Oxobacter</i>, <i>Lutispora</i>, <i>Anaerovorax</i>, <i>Desulfurispora</i>, <i>Ruminiclostridium</i>, and <i>Fonticella</i>. From the microscopic structure of coal, an increase in the number of holes and roughness on the surface of the coal was found but the change of surface functional groups was weak. In addition, the addition of S-related microbial communities increased the contents of phoxim, methylthiobenzoylglycine and glibornuride M5 in aromatic compounds, as well as the content of lauryl hydrogen sulfate in alkyl compounds. Furthermore, the dibenzothiophene degradation-related microbial communities included <i>Bacillus</i>, <i>Brevibacillus</i>, <i>Brevundimonas</i>, <i>Burkholderia-Caballeronia-Paraburkholderia</i>, and <i>Thermicanus</i>, which can break C-S bonds or disrupt benzene rings to degrade dibenzothiophene. In conclusion, the S-related microbial communities in biogas liquid could rebuild the coal microbial community and be involved in the conversion process of organic sulfur in coal.