Effects of antibacterial compound of Saccharomyces cerevisiae from koumiss on immune function and caecal microflora of mice challenged with pathogenic Escherichia coli O8

Abstract

The yeastSaccharomyces cerevisiaefrom koumiss has been shown to have antibacterial effects onEscherichia coli, possibly by producing antibacterial compound in metabolism; however, there is limited knowledge about its application in animal production. We therefore investigated the effects of an antibacterial compound ofS. cerevisiaefrom koumiss on the immune function and caecal microflora of mice challenged with pathogenicEscherichia coliO8. Three groups were formed: negative control (NC), positive control (PC), and the antibacterial compound ofS. cerevisiaeat pH 2.0 (S2). Mice in the NC and PC groups were orally administered phosphate buffer solution (PBS) for 7 d. At 4 d,E. coliO8 was administered intraperitoneally in group PC. Mice in group S2 were first administered orally as mice in group NC, and subsequently intraperitoneally administeredE. coliO8 as mice in group PC. Compared with the NC group, mice in the PC group displayed clinical symptoms and pathological changes in the small intestine. Small intestine villi in the S2 group also developed some histologically pathological changes but not as severe as in the PC group. Moreover, there was less mortality in the S2 group than in the PC group. In PC group, thymus indexes, immunoglobulin A (IgA) in serum andBifidobacteriumin caecum were decreased andE. coliin the caecum was increased. In the S2 group, CD8+ of T lymphocyte subsets in blood andBifidobacteriumin caecum were decreased, while spleen indexes, IgG, IgM in serum, and CD3+ of T lymphocyte subsets in blood were increased. This suggests that S2 can relieve clinical symptoms of mice challenged with pathogenicE. coliO8, enhance their immune function, and influence their caecal microflora. The study will provide a theoretical foundation for utilizing antibacterial compound ofS. cerevisiaefrom koumiss for curative purposes.