Optimization of vegetable waste composting and the exploration of microbial mechanisms related to fungal communities during composting

The application of additives to regulate the microbial functional composition during composting has attracted much research attention. However, little is known about the succession and role of the fungal community in the laboratory-scale composting of vegetable waste supplemented with pig manure and microbial agents. The purpose of this study was to identify effective additives for improving vegetable waste composting performance and product quality, and to analyze the microbial community succession during composting. The results showed that the combined addition of pig manure and microbial agents (T2 treatment) accelerated the pile temperature increase, enhanced total organic carbon degradation (23.36%), and promoted the maturation of the compost. Furthermore, the T2 treatment increased the activities of most enzymes, reshaped the microbial community, and reduced the relative abundance of potential animal (1.60%) and plant (0.095%) pathogens. The relative abundance of Firmicutes (71.23%) increased with the combined addition of pig manure and microbial agents in the thermophilic stage. In the middle and late stages, Saccharomonospora, Aspergillus, and Thermomyces, which were related to C/N and total phosphorus, were enriched in the T2 treatment. Network analysis demonstrated that the complexity and stability of the fungal network were more evidently increased in the T2 treatment, and Saccharomonospora, Aspergillus, and Microascus were identified as keystone taxa. The keystone taxa associated with extracellular enzymes contributed significantly to compost maturation. These results provide a reference for the application of additives to improve compost safety in pilot-scale composting.