Differences in Survival of Heat Stress Adapted Cells of Listeria Monocytogenes Egd (Bug600) in Disinfectants and Essential Oils

The objective of this study was to investigate the differences in survival of L. monocytogenes EGD (Bug600) (serotype 1/2a) in various disinfectants and essential oils after sublethal heat stress at 48°C for 60 min. The survival of heat stressed L. monocytogenes cells was decreased in lethal acid (HCl or H3PO4 pH 2.5), lethal oxidative stress (H2O2 1000 ppm) and lethal quaternary ammonium compounds (QAC 2.5-3.5 ppm) compared to non-stressed control cells. By contrast, the survival of heat stressed L. monocytogenes cells was higher in lethal alkali (NaOH or KOH pH 12) than the control cells. Also, the survival of heat stressed L. monocytogenes cells was higher in lethal carvacrol (428 ppm) and bay oil (1100 ppm) but was decreased in lethal red thyme oil (300 pm) compared to control. These findings indicate that the heat stressed cells of L. monocytogenes are not easily killed by alkali-based disinfectants and essential oils containing carvacrol and bay oil. Therefore, disinfectants and essential treatments should be carefully considered when heat stressed cells of L. monocytogenes may be present