Exploration of bacterial communities in products after composting rural wastes with different components: Core microbiome and potential pathogenicity

The co-treatment of solid waste has become a new trend of rural waste disposal in China in the future. However, the quality of compost products after co-treatment remains still ill-defined, especially the characteristics of microbiome related to the environmental safety of organic fertilizer. Here we investigated the composition and structure of bacteria in the composted products with different components based on 16S high-throughput sequencing. The results indicated that the bacterial communities of the products were not explained by the physicochemical proprieties of raw materials and the bacterial community changes in compost products were mainly driven by microorganisms in swine manure, while kitchen waste and rice straw, as composite additive materials, have little effect on the microbial composition of the composted products. A total of 38 OTUs affiliated with 4 phyla (Proteobacteria, Bacteroidetes, Firmicutes and Actinobacteria) were observed in more than 60% compost products, which were considered as core microbiomes. PICRUSt's prediction of microbial function found that average 8.1% of bacteria in the compost products were associated with human diseases, and 13.27% potential pathogenic bacteria were detected, such as Pseudomonas, Flavobacterium, Clostridium_sensu_stricto_1, Actinomadura, Corynebacterium_1 and Bacillus, suggesting that existing compost products still posed a risk of disease. The study provides basic data for the profile of core microorganisms and pathogenicity in composting products with different components of rural wastes.