Abstract:

Introduction. Some bacteria in the cecal microflora of broilers can inhibit colonization of chicks bySalmonella. Beneficial cecal bacteria may reduce Salmonellacolonization by competing for nutrients and attachment sites or by producing metabolites that inhibit Salmonellagrowth. The purpose of this study was to determine if cecal bacteria cultured in media supplemented with lactate and succinate produced metabolites that inhibit Salmonellagrowth in vitro. Materials and Methods. Cecal cultures were prepared by inoculating broth media with cecal contents of processed broilers and anaerobic incubation at 37oC for 48 h. Media supplemented with 0, 50, 100, or 150 mM of sodium lactate and sodium succinate were inoculated with the cecal culture, only; SalmonellaTyphimurium, only; or the cecal culture and SalmonellaTyphimurium. Inoculated media was incubated anaerobically at 37oC, and samples were removed after 7, 14, and 21 days for microbial and chemical analysis. Cecal bacteria and SalmonellaTyphimurium were enumerated, and concentrations of formic, acetic, propionic, butyric, lactic, and succinic acids were measured. Cecal bacteria were selected from agar and identified using the Biolog Microbial Identification System. Three trials of the experiment were conducted, and statistical analysis was performed using GraphPad InStat. Results. After 21 days of incubation, significantly (p Andamp;lt; 0.05) fewer Salmonellawere recovered from mixed cultures of cecal bacteria and Salmonellaincubated in media supplemented with 50, 100, or 150 mM lactate and succinate than from non-supplemented media. Significantly higher concentrations of propionate were produced in media supplemented with lactate and succinate and inoculated with cecal bacteria only or cecal bacteria and Salmonella, but not in media inoculated with Salmonellaonly. Cecal isolates were included Abiotrophia, Arcanobacterium, Atopobium, Bacteroides, Clostridium, Enterococcus, Eubacterium, Gemella, Lactobacillus, Lactococcus, Peptostreptococcus, Proteus, Propionibacterium, and Weissella. Conclusion. Propionate produced by the metabolism of lactate and succinate may play a role in the inhibition of the Salmonellaby cecal bacteria. Understanding the anti-Salmonella activity of these bacteria may assist in defining the inhibitory mechanisms of competitive inhibition and identifying bacteria that should be included in effective probiotics.