FIG. 2.

Dose-dependent repressive effect of glucose (Glu) on C. perfringens gliding proficiency. (A) Glucose gradient effect on the gliding motility of the enterotoxigenic cpe⁺ food poisoning C. perfringens strain SM101. One-third of a TYA plate was cut out and replaced with 7 ml of melted TGYA medium, which contained 2% glucose (see Materials and Methods and elsewhere in text for details). After solidification of the added TGYA, a natural glucose gradient was generated (shown from left to right) due to the diffusion of glucose molecules from the TGYA section (which contained 2% added glucose) to the TYA portion (which contained 0% added glucose) of the plate. (B) Evaluation of the minimum glucose concentration required to inhibit gliding proficiency of the food poisoning and gas gangrene producer strains NCTC8239 and 13. For panels A and B, strains were grown on TYA plates as indicated in Fig. 1 and supplemented with glucose as shown in the figure. Top-bottom photographs were taken after 72 h of anaerobic incubation at 37°C.