Woodside, E. E. (U.S. Army Medical Research Laboratory, Fort Knox, Ky.), and W. Kocholaty. Carbohydrate and lipid content of radiation-resistant and -sensitive strains of Escherichia coli. J. Bacteriol. 87:1140-1146. 1964.-Total lipid contents of acetate minimal medium cultures of Escherichia coli, strains B, B/r, and B(s), were not significantly different when identical pretreatment and extraction procedures were compared. Wide variations in intracellular hexose and pentose derivatives of E. coli B, B/r, and B(s) were induced by changes in carbon and nitrogen sources and by changes in the growth phases. The three strains produced more intracellular carbohydrate when grown in nutrient broth-glucose medium than when grown in unsupplemented nutrient broth. Acetate minimal medium cultures of the radiation-sensitive mutant, E. coli B(s), contained the least, and the radiation-resistant mutant, E. coli B/r the largest, amounts of intracellular hexoses. Environmental conditions which increased the radiation resistance of E. coli B/r were similar to the environmental conditions which favored increased intracellular hexose accumulation. After X ray of E. coli B/r, considerable amounts of hexoses and pentoses were released into the growth medium. Alterations in hexose distribution patterns of X-rayed E. coli B/r preceded alterations in pentose distribution patterns. Prolonged postirradiation incubation resulted in a net synthesis of extracellular hexose, with concomitant loss of intracellular hexose accumulation.