Study of the oxygen effect during growth of a bacterial culture

In study of the oxygen effect in relation to the growth curve ofEscherichia coli B, its size was found to be correlated to the stage of growth at which the bacteria were irradiated. The lowest dose reduction factor value (DRF = 1.5) was found with bacteria irradiated at the outset of the logarithmic phase and the highest value (DRF = 2.7) with bacteria in the stationary phase. This phenomenon was observed both in a culture cultivated under aerobic conditions prior to irradiation and in a culture cultivated under anaerobic conditions. The cultivation conditions influenced only the radiosensitivity of the bacteria.