Optimisation of Melon Vine Composting for Disposal and Exploration of Microbial Mechanisms Related with Fungal Communities

The functional composition of the microbial community, which can be regulated by different additives, plays critical roles in the composting process of vegetable waste straw. The purpose of this study was to find an effective additives for improving composting performance and product quality, as well as to analyse the microbial community succession in medium-scale composting of melon vine. The dynamics of extracellular enzymatic activity and the microbial community were monitored in composting piles with added pig manure and microbial agents. The combined addition of pig manure and microbial agents accelerated the pile temperature increase, prolonged the thermophilic stage (14 days), enhanced total organic carbon degradation, and resulted in a higher germination index in advance. Furthermore, compared with other treatments, the combined treatment promoted the activities of most enzymes, reshaped the microbial community, and reduced the relative abundance of potential animal and plant pathogens. The relative abundance of Firmicutes increased with the combined addition of pig manure and microbial agents in the thermophilic stage. In the middle and late stage, Saccharomonospora , Aspergillus , and Thermomyces, which were related to C/N and total phosphorus, were enriched in the combined treatment. Network analysis demonstrated that the complexity and stability of the fungal network were more evidently increased in the combined treatment, and the members of Saccharomonospora , Aspergillus , and Microascus were identified as keystone taxa. The keystone taxa associated with extracellular enzymes contributed significantly to the development of compost maturity. These findings provide a theoretical basis to aid in screening specific functional microorganisms and optimize the management of vegetable waste composting processes.