INFLUENCE OF OXIDATION-REDUCTION REDUCTANTS ON SALMONELLA TYPHIMURIUM GROWTH RATES AFTER INITIAL pH ADJUSTMENT AND ZINC COMPOUND ADDITION

The objective of this study was to examine the separate influence of acidic pH, reductants (cysteine and sulfide) and zinc compounds (Zn acetate and Zn sulfate) during anaerobic growth of a S. typhimurium poultry isolate in rich or minimal media. The anaerobic growth of a S. typhimurium poultry isolate in TSB medium was significantly inhibited by either acidic initial pH or higher concentrations of Zn acetate. S. typhimurium anaerobic growth in M9 minimal medium was significantly inhibited by either acidic pH or higher concentrations of Zn acetate or Zn sulfate. Most anaerobic growth rates of the S. typhimurium poultry isolate in acidic media and with higher concentrations of Zn acetate or Zn sulfate were less than 0.10 h-1. The overall anaerobic growth rates of S. typhimurium were inhibited more in the presence (0.089 h-1) of reductants than in the absence (0.102 h-1) of reductants in M9 medium. Results in this study suggest that either increasing Zn concentration or decreasing initial pH can reduce growth rate of foodborne Salmonella under anaerobic growth conditions.