Isolation and characterization of spontaneous srl-recA deletion mutants in Escherichia coli K-12.

A method was developed for the isolation of spontaneous mutants of Escherichia coli K-12 with deletions extending from the srl operon to the adjacent recA gene. The srl-recA deletion mutants were extremely sensitive to dNA-damaging agents; unable to support growth of the feckless red gam mutant lambda bio11; and recombination-deficient in transduction and in conjugation. They therefore resembled recA point mutants such as recA13. The existence of these recA deletion mutants shows that the recA gene is not essential for viability.