Feedback of co-inoculation of lignocellulose degrading microorganisms on dissolved organic matter during rice straw composting: neutral balance of bacterial community.

This study explores the impact of co-inoculating various Bacillus species with Aspergillus fumigatus on the characteristics of dissolved organic matter (DOM) derived from composting. Four treatments were established: Control (CK), (2) Bacillus velezensis + Aspergillus fumigatus (AF), (3) Bacillus subtilis + Aspergillus fumigatus (BF), and (4) Bacillus tequilensis + Aspergillus fumigatus (DF). Among the treatments, BF exhibited the highest lignin degradation rate (58.27 %), representing a 12.78 % increase compared to CK. The DF treatment achieved the most significant reductions in cellulose (91.06 %) and hemicellulose (89.29 %), exceeding CK by 10.46 % and 7.13 %, respectively. During the DOM humification process, the humic acid-like component C3 showed the greatest variation in BF (19.46 %). Additionally, the R values of microbial community assembly models were higher in AF (0.385), BF (0.398), and DF (0.396) than in CK (0.295), suggesting a shift toward neutral theory-driven community structure and improved microbial dissemination due to co-inoculation. The similar humification patterns in AF and DF were likely driven by increased microbial diversity linked to carbon metabolism genes. In contrast, the BF treatment exhibited a stronger correlation between microbial composition and diversity with carbon metabolism-related functional genes. This study reveals new insights into the microbial processes behind DOM humification during lignocellulose degradation.