Bacterial isolates from the chicken gizzard and ceca with in vitro inhibitory activity against Salmonella typhimurium

Abstract

Bacterial isolates (197) obtained from the gizzard and ceca of 20 broiler and 40 specific-pathogen-free chickens, 21 days to 8 months of age, were evaluated for inhibitory activity against Salmonella typhimurium. One-hundred forty strains were characterized as gram negative and oxidase negative, typical of the Enterobacteriaceae. Five of the gram-negative and oxidase-negative isolate demonstrated inhibitory activity against six strains of S. typhimurium after 10- and 20-fold concentration and ammonium sulfate precipitation of the cell-free supernatant fluid from a culture grown in M9 minimal medium. Three isolates were identified as lactobacilli, 40 other strains exhibited Gram stain, oxidase, and catalase reactions typical of the Lactobacillus spp., and three known lactobacilli were included in the evaluation. Limited inhibitory activity was exhibited by these 46 isolates when tested against six S. typhimurium strains. Fourteen other strains not characterized as presumptive enterobacteria or lactic acid bacteria demonstrated little or no inhibitory activity against the six test strains.