摘要Background Our previous study demonstrated that dietary supplementation of Bacillus subtilis enhanced growth performance and intestinal integrity in weaned pigs challenged with enterotoxigenic Escherichia coli(ETEC).There-fore,this study aimed to explore the impact of Bacillus subtilis on gut health and its role in modulating host-microbe interactions in post-weaning pigs.Results ETEC infection disrupted key metabolic pathways in distal colon,including glutathione,beta-alanine,and pyrimidine metabolism,indicating increased oxidative stress,impaired nucleotide balance,and amino acid cata-bolic stress.Bacillus subtilis supplementation induced distinct metabolomic and microbiome profiles in colon digesta of weaned pigs challenged with ETEC.Bacillus subtilis-treated pigs under ETEC challenge exhibited significant enrich-ment in amino acid-and energy-related pathways such as arginine biosynthesis,phenylalanine metabolism,panto-thenate and CoA biosynthesis.ETEC infection induced microbial dysbiosis in the distal colon,resulting in decrease(P＜0.05)in abundance of Streptococcaceae and Enterobacteriaceae compared to healthy controls.Bacillus subtilis supplementation mitigated the ETEC-induced disruptions by increasing the relative abundance of beneficial bacterial families,including Lachnospiraceae and Bacteroidaceae.Conclusion Supplementation of Bacillus subtilis improves intestinal health and resilience against ETEC challenge by mitigating infection-induced metabolic disruptions and gut dysbiosis in weaned pigs.