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 typhimurium in the environment. To test the hypothesis, S. typhimurium was adapted to SCFA for 1 h and the % survivors against various stress conditions was determined. For adaptation, the SCFA mixtures at the concentrations found in small (SI) and large intestine (LD were used. The % survivors against extreme acid (pH 3.0),high osmolarity (2.5 M NaCl), and reactive oxygen (20 mM H2O2) was greatly increased by exposure to SCFA LI, but to a much less extent 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 with them may increase the persistence of S. typhimurium in food animal pre- and postharvest production by enhancing overall stress resistance.