Core fungal species strengthen microbial cooperation in a food-waste composting process.

In ecosystem engineering research, the contribution of microbial cooperation to ecosystem function has been emphasized. Fungi are one of the predominant decomposers in composting, but thus far, less attention has been given to fungal than to bacterial cooperation. Therefore, network and cohesion analyses were combined to reveal the correlation between fungal cooperation and organic matter (OM) degradation in ten composting piles. Positive cohesion, reflecting the cooperation degree, was positively linked to the degradation rate of OM. From the community perspective, core species (i.e., Candida tropicalis, Issatchenkia orientails, Kazachstania exigua, and Dipodascus australiensis) with high occurrence frequency and abundance were the key in regulating positive cohesion. These species were highly relevant to functional genera associated with OM degradation in both fungal and bacterial domains. Therefore, focusing on these core fungal species might be an appropriate strategy for targeted regulation of functional microbes and promotion of degradation rates.

Interval aeration improves degradation and humification by enhancing microbial interactions in the composting process.

Five full-scale food waste composts were conducted under different aeration frequencies (no aeration, aeration at different intervals, and continuous aeration) to reveal the optimal strategy and its microbial mechanisms. The highest degradation rate (77.2%) and humus content (29.3%) were observed in Treatment D with interval aeration (aeration 20 min, pause 10 min). Aeration influenced the degradation and humification rate by regulating microbial interactions. The microbial interactions peaked in Treatment D, with a 1.30-fold increase. In terms of the microbial community, Thermobifida was a key genus for improving positive cohesion, fulfilling three criteria (high abundance, high occurrence frequency, and significant differences between treatments). The aeration strategy employed in Treatment D not only increased relative abundance of Thermobifida (1.2 times higher) but also strengthened interaction between it and functional genera (34 nodes). Overall, interval aeration, featured by 20 min aeration and 10 min pause, could increase microbial interactions and improve composting efficiency.