Assessing Microbial Stability and Physicochemical Properties Variations Following Bacterial Inoculation in Rapid Spent Mushroom Substrate Composting

ABSTRACT This study investigated how the newly established microbial consortium interacts with spent mushroom substrate (SMS) as a model lignocellulosic substrate, with a focus on the contribution of microorganisms to compost maturity. The effect of sequential‐batch enrichments on compositional stability and enzyme activities was evaluated. The activities of cellulase also led to a remarkable increase at the conclusion of the serial passage. An increase in available phosphorus (P) and potassium (K) by 130.30% and 77.63%, as well as a favorable carbon:nitrogen (C/N) ratio of 19.02, indicating that the microbial consortium accelerated SMS decomposition within 45 days. Compared to other treatments, the composted SMS product demonstrated a dynamic shift in bacterial and fungal diversity, characterized by an obvious increase in beneficial Actinobacteria and Ascomycota phyla. Remarkably, dominant microbial groups related to lignocellulose degradation were observed in both final composts. Predictive functional analysis revealed that microbial consortium inoculation significantly promoted the metabolic pathways of starch and sucrose metabolism, pyruvate metabolism, and butanoate metabolism associated with carbohydrate metabolism (93%, 90%, and 84%, respectively). This study demonstrates the valuable guidance of using a domesticated compost‐based microbial consortium for the SMS biovalorization into high‐quality soil enrichment, providing a promising solution for accelerating the composting process.