Mechanisms of Bacillus amyloliquefaciens on alleviating lipopolysaccharide-induced oxidative stress in broilers.

This study aimed to investigate the mechanism by which Bacillus amyloliquefaciens JF (JF) mitigates lipopolysaccharide (LPS)-induced oxidative stress in broilers. Whole genome sequencing was employed to predict the potential resistance of JF to oxidative stress. A total of 240 one-d-old Arbor Acres broilers (41.2 ± 0.5 g) were divided into four treatment groups based on a 2 × 2 factorial arrangement, which included LPS (with or without) and JF (with or without) as the two factors. Each treatment consisted of 6 replicates, with ten broiler chicks per replicate. The experiment lasted for 21 d. The results showed that the JF genome was predicted to contain 138 carbohydrate-active enzymes, 8 secondary metabolites, and genes linked to various stress responses. In broiler experiment, the addition of JF significantly improved the average daily gain and average daily feed intake (P < 0.001). Lipopolysaccharide and JF exhibited interactive effects on serum total antioxidant capacity (T-AOC) (P = 0.030), catalase (CAT) (P = 0.003), malondialdehyde (MDA) (P < 0.001), and glutathione-peroxidase (GSH-Px) (P = 0.007), with a trend of interaction observed in interleukin-6 (IL-6) (P = 0.065) and interleukin-8 (IL-8) (P = 0.092). There were interactive effects on the villus height (VH) (P = 0.028) of the duodenum of broilers, as well as on the villus height to crypt depth (VH/CD) ratio in the jejunum (P = 0.036) and ileum (P < 0.001), with an interactive trend noted for jejunal VH (P = 0.093). In comparison to the control (CON) group, JF group significantly increased the abundance of Subdoligranulum in the intestine (P = 0.037). Furthermore, correlation analysis demonstrated a significant positive relationship between Subdoligranulum and growth performance, antioxidant indicators, and intestinal morphology (P < 0.05). In summary, JF strain exhibited significant antioxidant and protective effects, which can be attributed to its rich array of oxidative stress resistance genes (catalase, superoxide dismutase, glutathione peroxidase, etc.) and diverse bioactive compounds (bacilysin, surfactin, lichenysin D, etc.). Furthermore, JF enhanced the antioxidant capacity of broilers by increasing the intestinal abundance of Subdoligranulum.