The frequency of accumulation of Phe⁺ mutants in <i>P. putida</i> strains carrying the phe-lacI test system at different chromosomal locations^a.

aAverage number of Phe+ mutants per day and total number of mutants calculated per 1×107 cells with 95% confidence intervals are shown. The results with at least 7 (7–28) independent populations of each strain are presented. bStrains carrying the mutational target gene opposite to the direction of the movement of replisome in the chromosome are indicated in bold. Note that location of the test system in the chromosome of the strains phe-lacI_1, 8 and 12 has remained unknown. cHomogeneity group.