A bioreactor system to study survival of Salmonella Typhimurium in pig gutcontent

The batch Culture system included six bioreactors. Three bioreactors contai ning stomach slurry were maintained at pH 4,5 and 6 respectively. Bioreacto rs containing small intestine slurry were maintained at pH 5,6 and 7 respec tively. The bioreactors were inoculated with 10 ml of viable Salmonella. Th e bioreactors were maintained for 6 hours. Samples of 10 ml were taken at 0 time and at 1, 2, 4 and 6 hours. The samples were analysed for the presenc e of Salmonella and SCFA. In the stomach samples Salmonella numbers increas ed at pH 6 but fell at pH 4. In the small intestine sample Salmonella numbe rs increased at pH 6 and 7. In terms of SCFA production, in the stomach, wi th samples at pH 6 there was little change in the amounts of lactate, succi nate and formate to that detected at 0 time, however levels of acetate did increase slightly, In the small intestine samples levels of succinate and f ormate increased slightly up to 4 hours, levels of acetate increased signif icantly from 0 to 6 hours. In terms of the specific growth rates of the ind ividual strains, both strains grew at pH 6 in the stomach content and to a greater extent in the small intestinal content. A bactericidal effect was o bserved at pH 4 in the stomach content while neither killing nor growth occ urred at pH 5 either in the stomach or the small intestine content. Both st rains grew well in the small intestine content at pH 7, showing generation times of up to 24 min.