Enhancing kitchen waste composting by cellulolytic microorganisms: New insights from quorum sensing and carbohydrates metabolic functions

Quorum sensing (QS) is a critical microbial communication mechanism. This study specifically investigated how brown-rot fungi (BRF), cellulolytic nitrogen-fixing bacteria (CNFB), and their composite microbial inoculants (CMI) regulate QS processes and carbohydrate metabolism through different QS signaling pathways. The results indicated that cellulolytic microorganisms accelerated lignocellulose degradation, enhanced lignocellulose-degrading enzyme activities, and increased both the abundance of signaling molecules and QS-related genes. Specifically, BRF primarily regulated QS via AHLs, whereas CNFB relied on AI-2. The CMI synergistically enhanced the production of both AHLs and AI-2, further promoting QS. Molecular reaction network analysis revealed that all three inoculants stimulated amide and Maillard reactions, generating key precursors for humification. Additionally, cellulolytic microorganisms increased the abundance of carbohydrate-active enzymes (CAZymes), including CBMs and GTs, thereby accelerating carbohydrate degradation during composting. Overall, BRF had a stronger impact on carbohydrate metabolism and QS regulation than CNFB, while CMI further reinforced these processes through synergistic interactions. This study provides new insights into the regulatory effects of cellulolytic microorganisms on QS and carbohydrate metabolism, and presents new strategies for optimizing the resource utilization of organic solid waste.