Within any population of microorganisms surviving exposure to preservation treatments or environmental stresses there exist individual cells that are regarded as sublethally injured. Stress treatments that cause injury include heating, refrigeration, freezing, irradiation, high acid or alkali, high salt levels, preservatives, desiccation, exposure to disinfectants and starvation or nutrient limitation. Individually, cells subjected to these stresses will suffer differing degrees of injury. Some will remain fully intact, exhibiting no signs of damage, some will suffer sufficient damage to lead to a loss of viability and the remainder will be sublethally injured, the latter suffering damage that will lead to a temporary change in physiology. From a methodological point of view, injury manifests itself in three important ways: (i) sensitivity to the selective agents used traditionally in microbiological culture media; (ii) sensitivity to low levels of reactive oxygen species that can exist in microbiological culture media; and (iii) extended lag times during which repair of damage takes place. Sublethal injury and its repair have been reviewed in numerous articles and book volumes (Busta, 1976; Hurst, 1977; Mossel and Corry, 1977; Beuchat, 1978; Andrew and Russell, 1984; Mackey, 2000).