Response to bleomycin of Escherichia coli mutants deficient in DNA repair.

Abstract

The effect of bleomycin on the colony forming ability of E. coli K12 strains in exponential growth at 37.degree. C was not affected by introducing recA13, lexA1, polA1 and uvrA6 mutations. For cells starved for amino acids, wild type strains became 10-fold more resistant to bleomycin, but again introducing lexA1, polA1 and uvrA6 strains did not change the effect on colony forming ability; starved recA13 cells were now 4-fold more sensitive. Strains with recA13, lexA1 and polA1 mutations were always more sensitive than wild type to .gamma. rays under the same conditions as used for the bleomycin treatment. Bleomycin-induced lesions may be concentrated in that part of the bacterial genomes at the cell wall, near the replication forks.