Research On Screening Of Microbial Communities For Bioenhancement Of Coal Seam Methane And Biohydrogen Production And Microbial Community Structure

With the global depletion of fossil energy and increasing environmental pollution fromennery consuming, clean energy became the strategic selection for the aim of high efficiency and eco-friendly. In this work, in aim of producing mehthane and hydrogen, coal-degrading and xylan degrading microbial communities was screened from environmental sample.16S rRNA analysis were employed to reveal microbial community diversity and structure variation. Furthermore, metagenomics analysis was used to investgate relationship between differen genomes and genes and enzymes involved in hemicellulose degradation process.Firstly, experiments of methane stimulation from peat, brown coal and coking coal by microbial communities collected from the gut of woodlice and termite, oil sample and mangrove sediment were conducted. To our knowledge, it is the first time we found that microbial community enriched from gut of woodlice Porcellio scaber sp. was able to use peat as the only carbon source and produced22μmol/g methane in150d.16S rRNA analysis revealed that the dominant methanogens was hydrogenotrophic Methanobrevibacter sp. Oil enrichment sample LSP was able to produce2.1μmol/g and3.5μmol/g from peat and coking coal, respectively, OTU number of hydrogenotrophic Methanobacterium sp. was increased after biodegradation. Mangrove sediment LM1produced89μmol/g and108μmol/g from brown coal and coking coal, hydrogenotrophic Methanobacterium sp. and mixotrophic Methanosarcina were dominant methanogens.Utilizing brown coal as the only carbon source, adding LM1microbial community to coal formation water MP02not only enhanced the total methane production for36μmol/g, but also shortened lag phase to20d earlier compare to MP02alone. In mixed inocula sample, dominant bacterial Desulfuromonas sp. and Wolinella sp. may use humics as electron shuttle to accelerate acetate oxidation to CO2, together with abundant fermenting bacteria Clostridium sp. which may proved H2as produced, may provide available substrats for methanogens to produce methane.Termite gut (Nasutitermes exitiosus) microbial community was able to utilize xylan as the only carbon source and produced260μmol/g hydrogen in30days incubation at33℃. Metagenomic analysis revealed that the TNE culture was comprised, almost exclusively, of three clostridial taxa which were named Nel, which is mostly clost to Clostridium beijerinckii, Ne2, which is mostly clost to Clostridium magnum and Ne3, which is mostly clost to a Ruminiclostridium species. Ne3is the primary degrader of xylan in the consortium. Its genome encodes an array of catabolic genes including glycoside hydrolases from families implicated in activities against hemicellulose including various xylanases and xyloglucanases, debranching enzymesand enzymes with activities against hemicelluloses-derived oligosaccharides. Ne2possesses xylanases, one probable xyloglucanase and various enzymes which target hemicellulose-derived oligosaccharides and sidebranches. Genome of Nel does not appear to encode many enzymes involved in the degradation of xylan. Nel appears to have genes mostly involved in cleaving side branches from the xylan molecule and for oligosaccharide catabolism, it appears to lack specific xylanases.