Presents a study which examined the use of mutations in the genes encoding single-strand deoxyribonucleic exonucleases (ssExos) of Escherichia coli in determining the effects on mutation avoidance, ultraviolet (UV) repair, and conjugational recombination. Degradation of single-strand DNA by three exonucleases in the bacterium Escherichia coli; Implication of the three exonucleases; Reduction of ability to inherit genetic markers.