Induction of resistance of Salmonella typhimurium to environmental stresses by exposure to short-chain fatty acids

Short-chain fatty acids (SCFA), which are widely used as food preservatives and are also present in the gastrointestinal (GI) tract of animals at high concentrations, may play a role in the persistence of Salmonella typhimuri um in the environment. To test the hypothesis, S. typhimurium was adapted t o SCFA for 1 h and the % survivors against various stress conditions was de termined. For adaptation, the SCFA mixtures at the concentrations found in small (SI) and large intestine (LD were used. The % survivors against extre me acid (pH 3.0),high osmolarity (2.5 M NaCl), and reactive oxygen (20 mM H 2O2) was greatly increased by exposure to SCFA LI, but to a much less exten t by SCFA SI. The results suggest that encountering SCFA by S. typhimurium in the large intestine of the host food animal or food materials treated wi th them may increase the persistence of S. typhimurium in food animal pre- and postharvest production by enhancing overall stress resistance.