Abstract: | The sensitivity of Escherichia coli to the lethal effect of colicin E(2) was reduced by elevation of osmotic pressure of the incubation medium. Optimal protection of the cells from the lethal effect of colicin E(2) was achieved with 0.6 to 0.8 m NaCl or with 0.8 m sucrose containing 0.01 m MgSO(4). Under such conditions, the degradation of deoxyribonucleic acid caused by colicin E(2) was also suppressed markedly. It was concluded that a high concentration of sucrose with Mg(++) might prevent the action of the adsorbed colicin E(2). A similar protection was observed against the lethal effect of colicin K. |