Studies on the Mechanism of Radiation Inactivation of Microorganisms: VIII. Inactivation of Intracellular Multiply Marked Haemophilus Influenzae Deoxyribonucleic Acid by High-Voltage Electrons

Abstract

Living bacteria carrying 3 linked antibiotic-resistance markers, were exposed to high-voltage electrons. Inactivation of these markers, singly and in all combinations, proceeded semilogarithmically with the dose. Intracellular DNA was much more resistant to radiation injury under anaerobic conditions or in the presence of 3% cysteamine. It was concluded from the relative inactivation rates that there were 2 types of DNA damage, i.e. single-strand breakage which prevented the assimilation of adjacent DNA regions and degradation of the base rings, damage which is readily incorporated in the transformation process and replicated by the recipient cells.