Fig 2. Recombination activity of IntI1 integrase in the mouse gut.

On day 0, two groups of germ-free mice were inoculated with 10⁸ CFU of MG/intI1 (carrying p6851 and pZE1intI1 allowing the expression of intI1 SOS-regulated, n = 4) (A) or MG/intI1* (carrying p6851 and pZE1intI1* allowing the constitutive expression of intI1, n = 3) (B). Recombination activity of IntI1, reflected by the frequency of recombinants (FR), was estimated by determining the frequency of emergence of tobramycin-resistant recombinants, as a result of specific recombination between attC sites located on a synthetic array of two cassettes (attC_aadA7-cat(T4)-attC_VCR2-aac(6’)-Ib*) carried on plasmid p6851. Each symbol represents the FR in the gut calculated from a single mouse exhibiting recombinants. For each sampling day, the average FR is shown as a black horizontal line.