Microbial interaction promote the degradation rate of organic matter in thermophilic period.

Composting is an efficient, microbe-driven method for the biodegradation of solid organic substrates. In such a complex engineering ecosystem, microbial interaction is more important to function than relative abundance and alpha diversity. However, microbial interaction and its driving force in the composting process has been rarely reported. Thus, we combined network analysis and positive cohesion to analyze the relationship between cooperation among bacteria taxa and the degradation of organic matter in ten industrial-scale food waste composting piles. The results showed that although the complexity of network and microbial diversity were inhibited by high temperature, microbial cooperation was stimulated in the thermophilic period. The positive cohesion, which reflected the degree of microbial cooperation, tended to be positively correlated with the degradation rate of organic matter, functional genera, and genes associated with organic matter degradation. Thus, microbial cooperation was a key factor in the promotion of the degradation of organic matter. From the insight microbial community, Thermobifida was the genera with high abundance, high occurrence frequency, and high contributions to microbial structure. Additionally, it was not only highly associated with the degree of cooperation but was also highly linked with the functional genera in the composting, implying that it might play an important role in regulating cooperation to promote the functional genera. Our research provides a deep understanding of the interaction among bacteria taxa during the composting process. Focusing on the abundance of Thermobifida might be an efficient way to improve composting quality by enhancing the cooperation of microbes.