책임운영기관 농촌진흥청 국립축산과학원 (로고)

changes and dysfunction of their immature organs. The colonization of S. Typhimurium could disrupt the gut microbiota and increase susceptibility to the bacterium. This study aimed to investigate the alterations of gut microbiota in S. Typhimurium-infected weaned piglets. Ten 49-day-old pigs were divided into two groups: S. Typhimurium-inoculated (ST, n = 6) and negative control (NC, n = 4) groups. The body weight and S. Typhimurium fecal shedding were monitored for 14 days after S. Typhimurium inoculation (dpi). The intestinal tissues were collected at 14 dpi; histopathological lesions and cytokine gene expression were evaluated. The gut microbiome composition and short-chain fatty acid concentrations were analyzed in fecal samples collected at 14 dpi. The average daily gain and gut microbiota alpha diversity in ST group tended to be lower than NC group at 14 dpi. Linear discriminant analysis effect size results showed a significant increase in the abundance of two genera and five species, while a significant decrease was observed in the five genera and nine species within the gut microbiota of ST group. Among the significantly less abundant bacteria in the ST group, Lachnospira eligens and Anaerobium acetethylicum produce acetate and butyrate, and may be considered as key S. Typhimurium infection-preventing bacteria. The overall results provide invaluable information about changes in the gut microbiota of S. Typhimurium-infected weaned piglets, which can be used to develop alternative measures to antibiotics and prevent ST bacterial infection.