Metagenomic insights into the lignocellulose degradation mechanism during short-term composting of peach sawdust: Core microbial community and carbohydrate-active enzyme profile analysis

Short-term composting, utilizing agricultural and forestry waste as raw materials, is a method for converting biomass waste into substrates for the production of high-value products. The microbial-driven degradation mechanism of lignocellulose in this process warrants further investigation. In the present study, an 11-day composting process was conducted using peach sawdust as the main raw material. To elucidate the degradation mechanism of lignocellulose, metagenomics analysis was performed on three samples selected according to the change of physicochemical properties. By the end of composting, cellulose, hemicellulose and lignin were degraded by 39.67 %, 38.67 % and 23.33 %, respectively. Microbial abundance analysis revealed that Pseudxanthomonas and Pseudomonas from Proteobacteria, along with Streptomyces and Saccharopolyspora from Actinobacteria dominated the composting process and were highly correlated with lignocellulosic degradation. Carbohydrate metabolism and amino acid metabolism were the most enriched pathways and genes belonging to CE1, CE4, AA3, AA7, CE3, AA4, GH3, GH1, GH2, AA1, etc. were the major carbohydrate- active enzymes (CAZymes) involved in lignocellulosic degradation. Streptomyces, Pseudoxanthomonas, Pseudomonas, Saccharopolyspora and Microbispora were identified as the main contributors to these pathways and CAZymes, suggesting their crucial roles in lignocellulose degradation. The identification of key CAZymes and microorganisms enhances our understanding of the mechanism of lignocellulosic degradation in short-term composting, which could be beneficial for improving efficiency.