Figure 5. Effects of glycerol and GlpR on IS5 insertions at other IS5 insertional hot spots.

(A) Effect of glycerol and sorbitol on IS5 insertion upstream of the flhDC promoter. Swarming mutation assay was conducted on soft-agar plates of minimal M9 + sorbitol or glycerol and soft-agar plates of nutrient broth ± sorbitol or glycerol. The swarming mutations were normalized as outgrowing subpopulations (mutations) per 9-cm cell streak. ‘sorb’: sorbitol; and ‘gly’: glycerol. (B) Effects of the loss of GlpR on IS5 hopping into its insertion sites in the flhDC master switch operon controlling motility, the bglGFB β-glucoside utilization operon, and the fucAO fucose/propanediol operon. The swarming mutation assay was conducted on nutrient broth soft agar plates, and the mutations were normalized as outgrowing subpopulations (mutations) per streak. Bgl⁺ or propanediol⁺ mutation assays were conducted on minimal M9 arbutin plates or M9 minimal propanediol plates, and colonies (mutants) were counted daily and were normalized as mutations (colonies) per 10⁸ cells.