Submitted to: Poultry Science Meeting
Publication Type: Abstract Only
Publication Acceptance Date: October 21, 2005
Publication Date: July 16, 2006
Citation: Hinton Jr, A., Murry, A.C. 2006. Comparison of in vitro inhibition of growth of salmonella typhimurium and escherichia coli on chicken fee media by two sources of bacillus subtilis [abstract]. Poultry Science Meeting. 85(Suppl.1):192.
In this study, a Bacillus subtilis isolate obtained from the fecal contents of adult male broilers was compared with B. subtilis ATCC #10774 to evaluate their ability to produce antimicrobial metabolites that inhibit the growth of Salmonella Typhimurium and Escherichia coli in vitro. B. subtilis fecal isolates were recovered from broiler fecal droppings and identified using the MIDI Sherlock Microbial Identification System. For the inhibition assay, an agar media composed of 7.5 % broiler starter feed or grower feed and 1.2 % agar was inoculated with 18-24 h cultures of Salmonella Typhimurium or E. coli. Sterile filter paper disks were dipped into cultures of the B. subtilis isolates that had been were grown in Tryptic Soy Broth (TSB) for 24 hours at 30oC. The disks were then placed in the center of plates of feed agar inoculated Salmonella Typhimurium or E. coli, and the plates were incubated for 24 hours at 37oC. Disks dipped in sterile TSB were used as controls. After incubation, zones of inhibition of S. Typhimurium and E. coli growth around the filter paper disks were measured. Results from the in vitro inhibition assay indicated that the zones of inhibition of S. Typhimurium (P < 0.03) and E. coli (P < 0.001) produced by both Bacillus isolates were larger than zones for the controls on the starter and grower feed agar media. In addition, the fecal B. subtilis isolate produced zones of inhibition of Salmonella Typhimurium and E. coli that were larger (P < 0.001) than zones produced by the ATCC isolate. These findings indicate that although B. subtilis isolates from different environments can inhibit the growth of Salmonella Typhimurium and E. coli in vitro, isolates recovered from the fecal content of broiler chickens may produce significantly greater inhibition of the growth of enteric bacteria associated with poultry.