Submitted to: Avian Diseases
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: August 5, 1994
Publication Date: N/A
Interpretive Summary: Young animals are more susceptible to infection by intestinal disease- causing bacteria than adult animals. The inhibition of Salmonella growth by the presence of a normal gut bacterium, Veillonella, was examined. The Veillonella bacteria was grown in culture in the laboratory on two different media. When Salmonella was then added to the cultures its growth was inhibited by the Veillonella bacteria already present in the cultures. In further studies we were able to identify three factors that correlated with the inhibition of Salmonella growth: 1) The production of propionate, an organic acid, by Veillonella; 2) a specific media component; and 3) high acidity (low pH) of the medium. These results indicate that the treatment of young chicks with a Veillonella bacterium may help to prevent Salmonella colonization.
The inhibition of salmonellae growth by a Veillonella bacterium isolated from the cecal contents of adult chickens was examined. The Veillonella isolate was grown on an agar medium supplemented with 175 umol of lactate or succinate/ml. Either 0, 100, 125, 150, or 175 umol of succinate/ml was added to the lactate medium; either 0, 100, 125, 150, or 175 umol of lactate/ml was added to the succinate medium; and the pH of all media was adjusted to 6.0. Agar overlays of Veillonella cultures grown on the media were inoculated with Salmonella typhimurium or S. enteritidis. The largest zones of inhibition of salmonellae growth were produced by Veillonella cultures grown on medium supplemented with 175 umol/ml of both lactate and succinate. The widths of the zones of inhibition decreased as the concentration of lactate was reduced in the succinate medium and as the concentration of succinate was reduced in the lactate medium. Analyses of lactate broth and succinate broth inoculated with Veillonella indicated that inhibition of salmonellae growth on the agar media was related to the production of volatile fatty acids by Veillonella, the presence of residual succinate in the media, and the final pH of the media.