Fig. 4

Growth inhibition assays. Cells of a rifampicin-resistant derivative of BB-1 were mixed 1:1 with cells of mutant strains ΔmafA _MGI-3 , lacking mafA of MGI-3, ΔmafB2IB-CTs _MGI-2 , lacking mafB2 and all downstream genes of MGI-2, ΔmafBIB-CTs _MGI-1 , lacking mafB and all downstream genes of MGI-1, or ΔMGI-3,lacking the entire MGI-3 island, all carrying a kanamycin-resistance cassette. The suspensions were spotted on GC plates without antibiotics and incubated for 48 h. The ratios of the mutants over wild-type bacteria in the spots were determined by plating on GC media containing kanamycin or rifampicin and counting colony-forming units after overnight incubation. Results are means and s.d. of three independent experiments. Statistically significant differences between time 0 and 48 h are marked with an asterisk (unpaired t-test of P < 0.001). All strains tested here did not show differences in viability when grown separately