Survival of acid stress adapted cells of Listeria monocytogenes serotypes 1/2a and 4b in commonly used disinfectants in broth and water models

Abstract The purpose of this study was to determine the survival of acid stress adapted Listeria monocytogenes Bug600 and ScottA cells in various lethal concentrations of disinfectants in broth and water models. Acid stress adapted cells had significantly greater survival than the non-adapted cells in lethal concentrations of hydrochloric acid, lactic acid, and acetic acid in tryptic soy broth containing yeast extract (TSBYE). Also, acid stress adaptation protected L. monocytogenes cells against lethal sodium hydroxide (NaOH), potassium hydroxide (KOH) and ammonium hydroxide (NH 4 OH). Increased tolerance to lethal concentrations of ethanol and isopropanol was also observed after acid stress adaptation. Acid stress adapted cells also exhibited higher survival in two quaternary ammonium compounds (QAC-1 and QAC-2). Acid stress adapted cells were more susceptible to hydrogen peroxide (H 2 O 2 ) inactivation. Similar survival patterns were observed for the acid stress adapted and non-adapted cells in both water and broth models, suggesting that the impact of acid adaptation on L. monocytogenes survival in disinfectants was not altered due to the presence of nutrients. Overall, these findings indicate that oxidative based agents are the best choice to decontaminate the food contact surface where acid stress adapted L. monocytogenes cells may be present.