Escherichia coli xth mutants are hypersensitive to hydrogen peroxide

Escherichia coli mutants lacking exonuclease III (xthA) are exceptionally sensitive to hydrogen peroxide. They are killed by H2O2 at 20 times the rate of wild-type bacteria and at 3 to 4 times the rate of recA cells. This is the first clear phenotypic sensitivity reported for xth- E. coli and should aid in clarifying peroxide-induced lethality and the in vivo role of exonuclease III.