Bioconversion of coal to methane by microbial communities from soil and from an opencast mine in the Xilingol grassland of northeast China

Abstract

Background The Xilingol grassland ecosystem has abundant superficial coal reserves. Opencast coal mining and burning of coal for electricity have caused a series of environmental challenges. Biogenic generation of methane from coal possesses the potential to improve economic and environmental outcomes of clean coal utilization. However, whether the microbes inhabiting the grassland soil have the functional potential to convert coal into biomethane is still unclear. Results Microbial communities in an opencast coal mine and in grassland soil covering and surrounding this mine and their biomethane production potential were investigated by Hiseq sequencing and anaerobic cultivation. The microbial communities in covering soil showed high similarity to those in the surrounding soil, according to the pairwise weighted UniFrac distances matrix. The majority of bacterial communities in coal and soil samples belonged to the phyla Firmicutes, Bacteroidetes, Actinobacteria and Proteobacteria. The dominant bacterial genera in grassland soil included Gaiella, Solirubrobacter, Sphingomonas and Streptomyces; whereas, the most abundant genus in coal was Pseudarthrobacter. In soil, hydrogenotrophic Methanobacterium was the dominant methanogen, and this methanogen, along with acetoclastic Methanosarcina and methylotrophic Methanomassiliicoccus, was detected in coal. Network-like Venn diagram showed that an average of 28.7% of microbial communities in the samples belonged to shared genera, indicating that there is considerable microbial overlap between coal and soil samples. Potential degraders and methanogens in the soil efficiently stimulated methane formation from coal samples by the culturing-based approach. The maximum biogenic methane yields from coal degradation by the microbial community cultured from grassland soil reached 22.4 μmol after 28 day. Conclusion The potential microbial coal degraders and methanogenic archaea in grassland soil were highly diverse. Significant amounts of biomethane were generated from coal by the addition of grassland soil microbial communities. The unique species present in grassland soil may contribute to efficient methanogenic coal bioconversion. This discovery not only contributes to a better understanding of global microbial biodiversity in coal mine environments, but also makes a contribution to our knowledge of the synthetic microbiology with regard to effective methanogenic microbial consortia for coal degradation.

Energy Availability Determines Strategy of Microbial Amino Acid Synthesis in Volatile Fatty Acid–Fed Anaerobic Methanogenic Chemostats

“…Furthermore, we observed a strong AA synthesis complementarity between MAGs belonging to Methanosarcina and those belonging to Methanomassiliicoccus ( Figure 8A ). Methanosarcina and Methanomassiliicoccus are frequently observed to co-occur in anaerobic methanogenesis systems ( Wang et al, 2019 ; Wang F. et al, 2020 ), including our AMCs ( Zheng et al, 2019 ; Chen et al, 2020a , b ). Previous studies suggest that this co-occurrence is possibly due to the potential methyl supply of Methanosarcina to Methanomassiliicoccus ( Dong et al, 2017 ).…”

Aesthetic Alteration of Marble Surfaces Caused by Biofilm Formation: Effects of Chemical Cleaning

“…Pseudarthrobacter was among the main genera with a strong ability to immobilize heavy metal and to remove Cd and Pb from soil [54]. Opencast coal mining and burning of coal for electricity is an environmental concern in the Xilingol grassland ecosystem [55]. In the coal environment, the most abundant genus was Pseudarthrobacter.…”

Deciphering the initial products of coal during methanogenic bioconversion: Based on an untargeted metabolomics approach

“…The cell pellet was washed thrice with phosphate buffer saline solution; inoculum size was adjusted to 0.02 (optical density of 600 nm) with phosphate buffer saline solution and was then incubated in a basic anaerobic medium with lignite or bituminous (particles<250 μm; 30 g/L) as a sole carbon source for 7 days at 35°C, 100 rpm in an incubator shaker. The lignite sample used for degradation in this study was obtained from previous research (Wang, Wang, et al, 2019). After cultivation, aliquots of culture were collected, respectively.…”