A strain of Paenibacillus polysaccharolyticus XY5 promotes fiber component degradation in a co-fermentation system of mulberry leaves and distillers' grains.

This article focuses on the identification and application of a cellulose-degrading bacterium, *Paenibacillus polysaccharolyticus* XY5, to enhance the fermentation of a mixed substrate composed of distillers' grains (DG) and mulberry leaves (ML) for use as animal feed. The study demonstrates that inoculating this bacterium under anaerobic solid-state fermentation conditions significantly increased the degradation rate of neutral detergent fiber (NDF) by 21.97% compared to natural fermentation, while also altering the microbial community structure by increasing the relative abundance of beneficial Firmicutes, including *Weizmannia* and *Paenibacillus*. These changes contributed to improved fiber degradation and potential feed value, suggesting that *P. polysaccharolyticus* XY5 can effectively modulate microbial populations to reduce anti-nutritional fiber content in DG and ML mixtures. The research highlights the promise of this microbial approach for sustainable feed resource development, while noting the need for further studies on long-term fermentation dynamics, nutritional evaluation, and scalability.