Improving compost nutrient composition and microbial community structure through Bacillus licheniformis

Spent Mushroom Substrate (SMS) from mushroom cultivation is an agricultural waste with potential for resource utilization. Fermentation of waste mushroom sachets by Bacillus licheniformis has not been adequately studied for its effect on nutrient content and microbial composition. In this study, a strain of Bacillus licheniformis TRM58488 was isolated from Pamir Plateau soil. The strain is safe, and its effects on co-composting spent mushroom substrate (SMS) with chicken manure were further evaluated. After inoculation with the strain in the experimental group, the effective potassium content of the compost was significantly elevated, the organic matter and humic acid content was reduced, and the microbial community structure was significantly changed, with the abundance of degrading functional phyla, such as Actinomycetota and Pseudomonadota, increased. The study showed that this strain can optimize the nutrient composition and microbial composition of compost, but its safety and long-term fertilizer efficiency need to be further verified by extending the fermentation time, adding high-carbon auxiliaries and field trials. The study provides new options of microbial agents for resource utilization of agricultural wastes, while emphasizing the importance of ecological risk assessment of compost.