Influence of Growth Temperature on Injury and Death of Listeria Monocytogenes Scott A During a Mild Heat Treatment

The growth temperature of Listeria monocytogenes has a pro-found effect on injury and death of washed cells that are suspended in phosphate buffer and exposed to 52°C for 1 h. The temperature of 52°C had low lethality for cells grown at 37 or 42°C, but there was a 10-10-fold increase in killing for cells grown at 28, 19, 10, or 5°C. There was little injury with exposure to 52°C of cells grown at 5, 10, or 19°C, but injury increased as the temperature of growth increased. When cells were grown anaerobically, lethality induced at 52°C increased as the growth temperature decreased, but there was more injury under anaerobic conditions than for aerobically grown cells. The results indicate that L. monocytogenes cells growing at low temperatures are more susceptible to heat induced death.