Effects of synthetic community and additives on microbial community structure and carbon and nitrogen transformation...

In this study, we examined the effects of synthetic community and ferrous sulfate-calcium superphosphate composite additives on the microbial community structure and carbon/nitrogen transformations during chicken manure-straw composting. The results revealed that addition of a synthetic bacterial community significantly increased the abundance and diversity of the bacterial community, particularly the relative abundance of dominant phyla, including Firmicutes and Actinobacteria. Neutral community modeling revealed that exogenous bacteria interact synergistically with chemical additives to shift microbial community assembly from a stochastic to a deterministic process. Co-occurrence network analysis further indicated that these additives enhanced the efficiency of compost maturation by increasing the complexity and stability of the microbial interaction networks. Furthermore, environmental factor analyses identified temperature, pH, and moisture as key drivers of microbial community succession, with pH playing a prominent role in regulating bacterial and fungal diversity, whereas random forest and variance partitioning analysis indicated the key role of microbial-environmental interactions in the carbon and nitrogen cycling of compost. Additionally, functional predictions indicated that the additive package reduced greenhouse gas emissions and enhanced nitrogen retention efficiency by promoting the expression of genes associated with microbial carbon metabolism and nitrogen cycling. Linear discriminant analysis Effect Size revealed that the complex additives significantly altered the microbial community structure and ecological functions. Our findings provide a theoretical basis for optimizing composting and facilitated elucidation of mechanisms underlying the synergism between microbial agents and chemical additives, which are essential for promoting the low-carbon resource utilization of agricultural waste and achieving carbon neutrality goals.