Material conversion, microbial community composition and metabolic functional succession during green soybean hull composting

In this study, green soybean hulls and maize straw were used for composting to explore the dynamics of material conversion, bacterial and fungal communities and metabolic functions. The results showed that bacterial and fungal communities had different temporal successions during composting. The bacterium Streptosporangiaceae was a biomarker in the thermophilic stage of composting, and the fungus Chaetomiaceae was a biomarker in the thermophilic stage and cooling stage. In the bacterial network, the germination index (GI) had a time-delayed association with Truepera, Pseudomonas and Methylococcaceae, which represented the key physicochemical characteristics that affect the community. In the fungal community, the GI, pH, fulvic acid (FA) and temperature etc. had a joint effect. Carbohydrate metabolism and amino acid metabolism were the main metabolic pathways, and saprotrophs represented the dominant fungal trophic mode in the composting process. These results provide a reference from screening specific and efficient agents to accelerate natural vegetable composting.