FIG. 4.

Effects of cefoxitin and cefotaxime on septation. Cultures of S. griseus were grown vegetatively (C) or induced to sporulate by phosphate starvation (A, B, and D to F) for 10 or 12 h in the presence or absence of the indicated β-lactam antibiotic. (A) Untreated culture at 10 h of starvation. (B) Untreated culture at 12 h of starvation. (C) Culture treated with 50 μg of cefoxitin per ml in vegetative growth. (D) Culture treated with 50 μg of cefoxitin per ml after phosphate starvation for 12 h. (E) Culture treated with 6 μg of cefoxitin per ml for 12 h. (F) Culture treated with 20 μg of cefotaxime per ml for 12 h. Arrowheads indicate sporulation septa. VS, vegetative septum. Bar, 0.5 μm.