Conditional lethality of deletions which include uvrB in strains of Escherichia coli lacking deoxyribonucleic acid polymerase I.

Deletions of the uvrB gene were not obtained in polA1 strains of Escherichia coli either by selecting for spontaneous deletions or by transduction from strains carrying such deletions. A strain forming a temperature-sensitive deoxyribonucleic acid polymerase I and carrying a deletion of the uvrB gene is inviable at the nonpermissive temperature.