Genome-Wide and 16S rRNA Sequencing-Based Analysis on the Health Effects of XLK401 on Chicks.

, serves as a growth promoter used in the poultry industry, contributeing to broiler development. However, practical studies are needed to determine the probiotic potential and growth-promoting effects of specific strains. This study aims to determine whether XLK401 influences broiler chicken growth and the mechanisms involved. Notably, we identified several bile salt and acid tolerance-related genes (, , , , and ) in XLK401. This bacterium demonstrates robust probiotic properties under acidic conditions (pH 2.0) and 0.3% bile salt conditions. It also contains a variety of antioxidant-related genes (, , and ), carbohydrate-related genes, gene-encoding glycosidases (e.g., and ), and three clusters of genes associated with antimicrobial compounds. Supplementation with XLK401 significantly increased the body weight of the chicks. In addition, it significantly increased hepatic antioxidant enzyme activities (GSH-Px, SOD, and T-AOC) while significantly decreasing the levels of oxidative damage factors and inflammatory factors (MDA and IL-6), resulting in improved chick health. Improvements in body weight and health status were associated with significant increases in α-amylase activity and the remodeling of the host gut microbiota by XLK401. Among them, actinobacteria abundance in chicken intestines after feeding them XLK401 was significantly decreased, abundance was also significantly decreased, and sp. abundance was significantly increased. This suggests that XLK401 can regulate the abundance of certain bacteria without changing the overall microbial structure. In addition, in the correlation analysis, sp. were positively correlated with SOD and negatively correlated with IL-1β and MDA. Overall, our study demonstrates that XLK401 effectively promotes healthy chick growth. This is made possible by the modulation of gut microbe abundance and the underlying probiotic effect of XLK401. Based on these findings, we postulate XLK401 as a potential efficient growth promoter in broiler farming.