Purpose: The ability of cecal bacterial cultures to inhibit Salmonella growth when incubated aerobically in media supplemented with lactate and succinate was examined, and bacteria in the cultures were identified.
Methods: Cecal cultures were prepared by inoculating broth media with cecal contents of broilers and incubating media anaerobically at 35°C for 48 h. Media supplemented with 0, 50, 100, or 150 mM of lactate and succinate were inoculated with 0.1 ml of the cecal culture, 104 CFU/ml of Salmonella Typhimurium, or the cecal culture and Salmonella. Inoculated media were incubated aerobically at 35°C for 14 days, and aliquots of media were removed on Days 0, 7, and 14 to enumerate CFU/ml (n = 3).
Results: After 14 days of incubation of media inoculated with Salmonella only, there were significant (P < 0.05) increases in the number of Salmonella recovered from media supplemented with 0, 50, 100, or 150 mm of lactate and succinate. However, after incubation of media inoculated with Salmonella and cecal cultures, there was no significant increase in the number of Salmonella recovered from media that was not supplemented with lactate and succinate, while there were significant decreases in the number of Salmonella recovered from media supplemented with 50, 100, or 150 mm of lactate and succinate. Enterococcus, Bacillus, and Proteus were recovered from the media.
Significance: Findings indicate that cecal cultures incubated aerobically can metabolize lactate and succinate to produce substances that inhibit the growth of Salmonella. Identifying the bacteria that produce these substances will aid the formulation of defined probiotics that can reduce the colonization of broilers by Salmonella.