A strain of <i>Paenibacillus polysaccharolyticus</i> XY5 promotes fiber component degradation in a co-fermentation system of mulberry leaves and distillers’ grains

With the increasing emphasis on environment and the concept of sustainable development, the wasted distillers' grains (DG) and mulberry leaves (ML), via mixed fermentation, are further developed into new feed resources. However, addressing the high cellulose content in the products of fermentation presents a substantial challenge for effectively harnessing their vast potential. This study identified a cellulose-degrading bacterium named Paenibacillus polysaccharolyticus XY5 through 16S rDNA sequencing technology. The bacterium was used to ferment a mixture of DG and ML under anaerobic solid-state fermentation conditions, and the microbial community structure within the mixture was analyzed using high-throughput sequencing technology. The results indicate that the degradation rate increased by 21.97% compared to the natural fermentation control group. Analysis of the microbial community structure revealed that the relative abundance of Firmicutes increased from 22.53% to 39.68%, while that of Bacteroidetes changed from 66.44% to 51.89%. Additionally, the relative abundances of the genera Weizmannia and Paenibacillus increased. Redundancy analysis results revealed that Paenibacillus was the most correlated with neutral detergent fiber degradation. In summary, after inoculating with P. polysaccharolyticus, the mixed fermentation approach effectively reduced NDF content, altered microbial community structure, and enhanced potential feed value.