Fig. 3

The descent of Z-mating products (illustrative example). Illustrative results of the subclonal analysis of clones issuing from Z-mating between MG407 (P1) and IL1 (P2) and selected for biparental nutritional features (growth on LCA) or for transient double resistance to kanamycin and gentamicin. All isolates labelled P1 and P2 resembled parents Gm^R and Km^R, respectively. R Recombinant types, R1 (P1Km ^R Gm ^S) recombinant phenotype characterized by kanamycin resistance (a marker of P2) plus all the nutritional (including fermentation) markers of P1; R2 (P2Km ^S Gm ^R) recombinant phenotype characterized by gentamicin resistance (a marker of P1) plus all the nutritional markers of P2; R3 (P2Km ^R Gm ^R) and R5 (P1Km ^R Gm ^R) recombinant phenotypes characterized by all the nutritional markers of the indicated parent plus resistance to both kanamycin and gentamicin; R4 (P2Km ^S Gm ^S) recombinant phenotype characterized by all the nutritional markers of P2 plus sensitivity to both kanamycin and gentamicin. P1/2/Km ^R /Gm ^R mixed subclone. L.St./NA Long stay on NA slopes (for several months at room temperature). ^aMating mixture exposed to gentamicin and kanamycin for 3 h and kept on ice for 48 h. The colonies examined were isolated on NA and gave rise to positive replicas on NA + KG (see text). ^bColonies on LcA replica-plated on NA + KG; re-isolation on NA of resistant bacteria