Increasing humification and reducing CH4emission during rice straw fermentation: the role of Streptomyces rocheiZY-2

This research aims to explore the effects of ZY-2 inoculant under different aeration intensities on humification process and greenhouse gas emissions during rice straw fermentation by physicochemical and high-throughput pyrosequencing technology. The results showed that the degree of humification was increased by 18.31% and the emission of CH4was reduced by 30.21% in the ZY-2 inoculation with 0.3 L min−1kg−1organic matter (OM) aeration intensity treatment. Meanwhile, the structure of humus in the inoculation treatments was more complicated due to more polyphenols were participated in the formation of humus. The degradation of cellulose, hemicellulose, and lignin was increased by 35.41%, 23.92%, and 14.67% in the inoculation with 0.3 L min−1kg−1organic matter aeration intensity treatment, respectively. Therefore, more amino acids (27%), reducing sugars (26%), and polyphenols (14%) were produced for participating in the formation of humus. The inoculation of ZY-2 with an appropriate aeration intensity reduced the abundance of Tepidimicrobium and Caldicoprobacterthat contributed to the emission of CH4while enriched Bacillus, Oceanobacillus and Thermobificafor OM biodegradation and humification. Therefore, we concluded that the Streptomyces rocheiZY-2 inoculant combined with 0.3 L min−1kg−1OM aeration intensity was an effective strategy to improve the fermentation quality and reduce CH4emission during rice straw fermentation.