The increased sensitivity of recA and recBC mutant strains to BLM indicates a role for homologous recombination in cell survival. This result is consistent with a requirement for recombinational repair as a consequence of DSBs in DNA. Surprisingly, recN and recG mutant strains, in an otherwise wildtype background, were also found to be sensitive to BLM exposure, a feature not shared with other common DNA damaging agents. The role of RecN in recombination/repair is unknown while RecG is a helicase that translocates Holliday junction intermediates in recombination and repair. We have confirmed and extended the above observations to additional mutant strains and show that at the low concentrations of BLM used here, homologous recombination is the principal pathway of repair in cells growing in broth. We also show that there is differential sensitivity of E. coli in glucose minimal medium versus rich medium after exposure to BLM. The survival experiments described above utilized wildtype and mutant cells grown in L broth. However, when wildtype cells were grown and exposed to BLM in glucose or glycerol minimal medium there was greater survival compared to the same doses used with wildtype cells in L broth. The increased survival in glucose minimal versus L medium, was seen with all the mutant strains involved in recombination that were Pyriproxyfen tested above and the xthA nfo AP-endonucleasedeficient strain. At high BLM concentrations, there was increased killing of the wildtype cells ; however, even at these high concentrations the survival of the recA mutant strain paralleled that of the wildtype. This result suggests that homologous recombination and SOS induction are not required to resist the toxic effects of BLM at these high concentrations. Only the temperature sensitive DNA ligase-deficient strains showed sensitivity to BLM when MI-538 cultivated in glucose minimal medium. In L broth, reduced survival of the lig-7 strain was apparent even at the permissive temperature and was decreased further at the non-permissive temperature. In glucose minimal medium, survival at both temperatures was higher compared to L broth. The survival at the permissive temperature was identical to a wildtype strain but there was a sharp decrease in survival at the non-permissive temperature. The lig-4 strain was also tested and gave qualitatively the same result as the lig-7 strain. BLM requires ferrous ions to generate radicals but supplementing the glucose minimal medium with 1 mg/ml Fe2SO4 did not alter survival of wildtype or recA bacteria. L broth addition to glucose minimal medium in a 1:1 ratio only partially reduced survival of wildtype cells. Supplementing the glucose minimal medium with casamino acids did not change the survival compared to glucose minimal medium. Supplementing L broth with individual components of glucose minimal medium did not produce an increase in survival. Replacement of glucose with glycerol in the minimal medium did not alter survival.