[Effects of microbial agents on bacterial community composition during swine manure composting]

The process of swine manure and wheat straw aerobic composting was examined, with exogenous microbial agents being added in treatment group. The physicochemical properties were measured by conventional methods, and bacterial community characteristics were investigated by high throughput sequencing analysis. Exogenous microbial agents increased high-temperature duration, reduced pH value at the end of fermentation stage, augmented total nitrogen content, reduced C/N ratio. Results from principal component analysis showed that microbial agents affected the stability of bacterial community during composting. At the phylum level, the relative abundance of Firmicutes, Proteobacteria, and Chloroflexi was higher in the treatment group. At the class level, the relative abundance of Clostridia, Alphaproteobacteria, and Gammaproteobacteria in the treatment group were higher at the mesophilic and thermophilic phases. At the family level, Peptostreptococcaceae, Clostridiaceae_1, and Halanaerobiaceae of the Clostridia and Micromonosporaceae in the treatment group were higher at the mesophilic and thermophilic phases. Halocella was significantly positively correlated with exogenous microbial agents, while Ammoniibacillus was significantly negatively correlated with it. It suggested that microbial agents significantly changed the physicochemical properties and bacterial community structure during swine composting.