Inactivation and Injury of a Hemolytic Radiation‐Resistant Micrococcus Isolated From Chicken Meat

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Abstract
The effects of environmental factors on a highly radiation‐resistant hemolytic micrococcus isolated from chicken meat were studied. NaCl tolerance and gamma radiation resistance of the cells were growth phase related. The cells were resistant to injury from drying or freezing/thawing. Under certain conditions, cells in the frozen state required approximately 5 Mrad to inactivate 90% of the population; 0.2 Mrad injured an equivalent proportion. Survival curve of the cells heated at 60°C showed a unique pattern which was in three distinct phases. Heat‐stressed cells were much more sensitive to radiation inactivation than unheated cells. When suspended in fresh m‐Plate Count Broth (PCB), the injured cells repaired without multiplication during incubation at 32°C. The repair process in this bacterium, however, was slower compared to thermally injured organisms studied by other workers.