Effects of a novel thermophilic cellulose-degrading agent on the quality of compost and change in microbial community of garden waste

Knowledge about the microbial communities in composting has advanced, but definitive knowledge concerning the application of actinomycetal communities in garden waste composting is still lacking. In this study, we compared the effects of amending compost with mixed agent M1 (five high-degradability strains) and other agents on the physicochemical indices and microbial community succession. The results showed that Pile A (only applying M1), exhibited a pH closer to neutral, the complete degradation of organic matter, and the highest remaining levels of nitrogen, phosphorus, and potassium. The seed germination rate, root length, and seed germination index values were significantly higher in piles amended with M1 and/or commercially available agents than in piles without exogenous microbial agents. Analyzing the microbial communities, these treatments were dominated by Proteobacteria, Firmicutes, Actinobacteria, and Bacteroidetes during composting. The amount of Streptomyces was negatively correlated with the carbon/nitrogen ratio and positively correlated with total phosphorus and total potassium. Adding M1 increased microbial diversity, and the dominant microbial communities at the end of composting were similar to those found in the commercial microbial inoculum. Overall, agent M1 can shorten the composting process and increase the extent of degradation. This research provides additional insights into the potential function of Actinomycetes in compost ecology.