Variations in Microbiota Communities with the Ranks of Coals from Three Permian Mining Areas

Abstract

Microorganisms play vital roles in the biogeochemical processes, such as biomethane production, which is an important source of coal bed methane (CBM), that occur in coal beds. However, little information is available regarding the microbial communities in in situ coal beds of different ranks from Permian mining areas. In this study, anaerobic Biolog ECO microplates were used to determine the microbial metabolic activity, and high-throughput sequencing was used to investigate the bacteria and archaea communities in three typical mining areas. Anaerobic Biolog ECO microplates showed that the peak value of average well color development (AWCD) in low-rank coal seams from Anhui Province (A-L) was 0.46 higher than that of medium-rank coal from Shanxi Province (S-M). Phylogenetic analysis indicated that the bacterial phyla Proteobacteria, Firmicutes, and Actinobacteria were the predominant lineages in all samples, in particular, the family Oxalobacteraceae accounted for the overwhelming majority of the bacterial sequences (from 47.20 to 92.67%). Most of the identified genera, Herbaspirillum, Pseudomonas, and Acinetobacter, were fermentative bacteria that can convert coal macromolecules into methanol, acetic acid, and CO2. In addition, the archaea in A-L were dominated by the phyla Euryarchaeota, Thaumarchaeota, and Woesearchaeota. Additionally, Euryarchaeota was the dominant archaeal lineage in S-M, and Thaumarchaeota was predominant in the Guizhou Province group of high-rank coals (G-H). Canonical correspondence analysis (CCA) showed that there were significant correlations between the microbial community and porosity, hydrogen content, and oxygen content (p < 0.05). The KEGG pathway analysis indicated that biomethane production mainly depended on archaea and that the methane metabolism capacity of A-L coals was the highest. Overall, the results suggest that the diversities of the microbial communities were related to the porosity and chemical elements of the different ranks of coal.

Subsurface Microbial Invasion Affects the Microbial Community of Coal Seams

“…Our previous study 5 found that soluble carbon sources had stimulative effects on microbial diversity in different coal samples. Bucha et al 34 also found that various nutrients stimulated microbial activity and further increased coal methanogenic capacity.…”

“…After hundreds of millions of years of biochemical and geological processes, nutrients in coal seams are depleted, and low nutrient availability limits microbial activity and function; however, the infiltration of soil extraction can provide a large amount of nutrients and inorganic salts to microorganisms in a relatively short time. Our previous study found that soluble carbon sources had stimulative effects on microbial diversity in different coal samples. Bucha et al also found that various nutrients stimulated microbial activity and further increased coal methanogenic capacity.…”

“…In contrast, the soil extractions at two different depths had a weak effect on the archaeal diversity, and unique archaeal OTUs treated by soil_1 exhibited a decreasing trend. Thus, the archaeal diversity in the coal samples needed specific influencing conditions, such as metabolic substrates, 25 temperature, 5 and minerals. 35 In addition, by comparing the coal seam microbiome (CSMB) data, it was also found that the two soil extractions did not change the relative abundance of archaeal OTUs assigned to the CSMB data 24 but decreased the relative abundance of the bacterial OTUs assigned to the CSMB data (Table S1).…”

“…Coal formation is closely associated with many important factors, including geological events, 3 geologic settings, 4 and microorganisms. 5 Among these factors, the microorganisms in coal seams have the capacity to produce methane through a series of biogeochemical processes. 1 Due to the effects of sulfur, metals, and dust from the utilization of coal resources on the environment, the exploration and development of unconventional natural gas, including coalbed methane (CBM), have intensified.…”

“…Coal is the main energy source of the world and represents more than 70% of all fossil fuels on earth, , a value that is far above that of other important sources of energy, including petroleum and natural gas. Coal formation is closely associated with many important factors, including geological events, geologic settings, and microorganisms . Among these factors, the microorganisms in coal seams have the capacity to produce methane through a series of biogeochemical processes .…”