Abstract
We isolated mutations in cys genes located in close vicinity of recA gene in Escherichia coli, by insertion of Tn1, Tn5 or Tn1O. We deviced a simple method constructing recA strains using these mutations. The cys mutations were transduced by P1kc into an appropriate recipient selecting for drug resistance of the mutations. The resultant Cys- transductants were crossed with an Hfr RecA- strain, KL16-99, and Cys+ recombinants were picked up. Among them, small colony formers were Rec- strains.
