Enhanced Mesophilic Degradation of Rice Straw by Microbial Consortium SXJG15 Through Coordinated Enzymatic Activity...

The sustainable utilization of rice straw is challenged by its recalcitrant lignocellulosic structure, especially under low-to-moderate field temperatures. In this study, a novel microbial consortium (SXJG15) mainly containing Sphingobacterium, Azospirillum, and Pseudomonas was enriched from overwintering rice stubble in Zhejiang, China, and evaluated for its rice straw degradation efficiency at 25 °C. Over an 18-day cultivation period, SXJG15 achieved a 52.5% degradation of total rice straw, including 60.2% cellulose, 76.3% hemicellulose, and 40.7% lignin. High extracellular enzymatic activities, including cellulases (up to 80.3 U/mL) and xylanases (up to 324.8 U/mL), were observed during the biodegradation process. 16S rRNA gene sequencing and metagenomics analyses revealed a succession of dominant taxa, including Sphingobacterium, Azospirillum, and Cellulomonas. Further, CAZy annotation indicated that the SXJG15 enzyme system was rich in glycoside hydrolases (42.7%) and glycosyltransferases (34.2%), demonstrating its high potential for lignocellulose degradation. This study uniquely demonstrates the mesophilic (moderate temperature 25 °C) efficiency of SXJG15 in lignocellulose breakdown, provides new insights into the microbial mechanisms of straw decomposition, and lays a foundation for bioenergy and soil fertility applications for developing a sustainable agriculture system.