Effect of Sodium Chloride on Subsequent Survival of Staphylococcus aureus in Various Preservatives

Chemical preservatives in foods are nowadays added at lower concentrations. However, this may allow survival of bacterial cells and induce increased resistance to various preservatives. In this study, the effects of growth in NaCl (10% or 15%) on survival of Staphylococcus aureus strains in various chemical and physical preservatives were investigated. Growth of the strains for 20 h at 37 ̊C in nutrient broth containing 10% NaCl enhanced survival in chemical preservatives (e.g. nutrient broth containing 20% NaCl, or 0.3% thyme extract, or 0.1% ascorbic acid). Growth at 37 ̊C for 20 h in nutrient broth containing 15% NaCl or for 5 d in nutrient broth containing 10% NaCl greatly enhanced survival of the strains in the tested preservatives. For survival at low temperature (5 ̊C) (physical preservative), cells grown at 37 ̊C for 20 h in nutrient broth containing 10% NaCl were not more tolerant to low temperature. Growth of the strains at 37 ̊C for 20 h in nutrient broth containing 15% NaCl or for 5 d in nutrient broth containing 10% NaCl only slightly increased the survival of cells at low temperature.