Genetic map of the lactose repressor gene (i) of Escherichia coli.

39 tonB i(-) deletions were used to map 57 independently isolated i gene mutants. Methods selective for i(+) recombinants from various types of i mutants are described. i(+) recombination frequencies of 6 x 10(-6) to 6 x 10(-7) can be detected in the different selective systems. Twenty i(s) mutations and 12 i(-d) mutations map in distinct but different regions of the gene. i(-) (sus) mutations are scattered over the gene.