Trichoderma-driven shifts in microbial communities improve spent mushroom substrate composting and...

This study evaluated the role of an isolated strain, Trichoderma sp. BZ01A, in enhancing the composting of Flammulina filiformis spent mushroom substrate (SMS) for producing bio-organic fertilizer. The objective was to determine how inoculation influences microbial community dynamics, compost properties, and the resulting biocontrol efficacy against cucumber-wilt disease. Amendment with Trichoderma sp. BZ01A significantly altered the compost environment, reshaped microbial communities by reducing the relative abundance of fungal pathogens such as Fusarium (from 15% to <1%) and Aspergillus, while increasing the inoculated Trichoderma to over 95% dominance. Community assembly analysis indicated a shift towards stochastic processes, and co-occurrence network analysis revealed a simplified fungal community with higher modularity and reduced connectivity for Fusarium. These microbial changes were associated with significant improvements in the final compost product. The germination index increased significantly (P < 0.05), and pot trials demonstrated that application of the Trichoderma-amended compost significantly reduced the incidence of cucumber-wilt disease by over 50% compared to the control, whereas the uninoculated compost exacerbated disease. Statistical analyses (PLS-PM) indicated that the fungal community composition was the primary factor influencing disease suppression. The results demonstrate that inoculating Trichoderma sp. BZ01A during SMS composting effectively steers the microbial community toward a suppressive state, leading to a high-quality compost with significant biocontrol potential against a major soil-borne disease.