Effect of thermo-tolerant actinomycetes inoculation on cellulose degradation and the formation of humic substances during composting

Abstract The inoculum containing four cellulolytic thermophilic actinomycetes was screened from compost samples, and was inoculated into co-composting during different inoculation phases. The effect of different inoculation phases on cellulose degradation, humic substances formation and the relationship between inoculation and physical–chemical parameters was determined. The results revealed that inoculation at different phases of composting improved cellulase activities, accelerated the degradation of cellulose, increased the content of humic substances and influenced the structure of actinomycetic community, but there were significant differences between different inoculation phases. Redundancy analysis showed that the different inoculation phases had different impacts on the relationship between exogenous actinobacteria and physical–chemical parameters. Therefore, based on the promoting effort of inoculation in thermophilic phase of composting for the formation of humic substances, we suggested an optimized inoculation strategy to increase the content of humic substances, alleviate CO 2 emission during composting.