Analysis On Microbial Community Of Plant-scale Biogas Digestor With Straw As Substrate

China is one of the countries which have abundant straw resource in the world. It is a clean and efficientstraw energy utilization pathway for using straw to biogas production. However, the gas productioninstability problems existed in straw biogas fermentation process. In order to provide a theoretical basisfor improve the rate of biogas production, optimize the anaerobic fermentation process, and ensurestable operation of the anaerobic reactor, the microbial community in the methane fermentation withcrop stalks as raw material was cleared.In this paper, modern molecular biology was chosen as analytical methods. Combined PCR-basedT-RFLP with clone library construction for analysis of bacteria, methanogenic archaea and anaerobiccellulose degrading bacteria’s community structure in the straw biogas projects. The results showedthat:(1) There were seven phylums of bacteria in straw biogas fermentation system, such as Firmicutes,Bacteroidetes, Proteobacteria, Chloroflexi, Tenericutes, Actinobacteria and Synergistetes. Which therespectively of storage capacity of Proteobacteria, Firmicutes and Bacteroidetes were40.48%,30.1%and21.45%. There are five types of bacteria. Combined with the Genebank data, the clones weresimilar to Thermopolyspora flexuosa, Clostridium jejuense, Solirubrobacter soli, Pseudomonaspseudoalcaligenes and Clostridium innocuum.(2) The most abundance phylums of archaea in straw biogas fermentation system was Euryarchaeota.Itcontains seven families: Methanobacterium, Methanosphaerula, Methanocorpusculum, Methanosarcina,Methanosaeta, Methanolinea and Methanospirillum. According to the results of T-RFLP, the dominantarchaea in straw biogas plants was Methanosaeta concilii with the relative abundance69.2%-71.9%,and the dominant archaea in straw biogas plants added manure was Methanosarcina with the relativeabundance73.1%；(3) Cellulose-degrading bacteria were belonging to the phyla Firmicutes, the degrees of similarity tocharacterised bacteria were often low and some clones were more closely related to uncultured bacteria.Firmicutes contained two families, such as Clostridia and Bacilli.According to the results of T-RFLP,the dominant cellulose-degrading bacteria in straw biogas plants were Clostridium cellulovorans,Bacillus licheniformis and Clostridium stercorarium with the relative abundance14.41%-70.06%,10.88%-14.23%and10.11%-19.87%.