Effects of Adding Compound Microbial Inoculum on Microbial Community Diversity and Enzymatic Activity During Co-Composting

Composting is an effective method for disposing of plant and animal manure, including apple tree branches. In this study, effects of temperature, enzyme activity, and microbial community diversity were investigated in high-temperature aerobic composting using pig manure and apple tree branches as the experimental materials. This study showed that a compound microbial inoculum (Ralstoinia sp., Penicillium sp., Penicillium aurantiogriseum, and Acremonium alternatum) could improve the temperature and extend the period of high-temperature decomposition by 4 days. Compared with control treatment, inoculation with compound microbial inoculum improved cellulase, urease, and polyphenol oxidase activities by 15.0-19.8%, 2.3-71.4%, and 0.3-28.4%, respectively. Denaturing gradient gel electrophoresis analysis showed that the dominant bacteria were Firmicutes species, Bacillus sp. PML14, Acinetobacter sp., Pseudomonas sp., Phormidium sp., and bacteria that cannot be cultured using traditional methods. Addition of compound microbial inoculum improved bacterial community diversity during composting, thereby promoting the succession of the bacterial community structure as well as enhancing quality and efficiency of composting.