Mesophilic Anaerobic Digestion of JUNCAO for Biogas Production: Structure and Functional Analysis of Microbial Communities Based on High-Throughput Sequencing

JUNCAO, as energy grass, was used in mesophilic anaerobic digestion (MAD) to produce methane, which has a huge market potential in biomass energy. This study was to investigate the characteristics of MAD of Arundo donax cv. Lvzhou No.1 (Lvzhou No.1) and Pennisetum giganteum z.x.lin ( P. giganteum ) (the growth cycle of 5 months), explore the relationship between microbial community structure and its function during MAD process. The results showed that the cumulative biogas production of Lvzhou No.1 and P. giganteum reached up to 370.37 mL/g VS and 313.04 mL/g VS, respectively. And the maximum methane concentration of both reached 75%. The volatile fatty acid (VFA) showed a trend of increasing at first then decreasing. Microbiota analysis based on high-throughput sequencing technology showed that the same microflora could differentiate into different microflora due to different fermentation materials. Firmicutes, Bacteroidetes and Proteobacteria were the dominant bacterial phyla with two predominant genera of Unidentified_Clostridiales and Romboutsia . In addition, Euryarchaeota and Methanosaeta were the dominant archaeal phyla and genus, respectively. Spearman correlation analysis showed that the production of acidic substances in this system was mainly the reaction effect of bacteria, and the methanogenic function was mainly associated with the dominant flora of archaea. In conclusion, this study would provide new evidence for MAD of JUNCAO as new energy resources, which would pave the way for large-scale MAD of energy plants in the future.