FIG. 9.

Lack of induction of a yqfS-lacZ fusion by paraquat, H₂O₂, or mitomycin. B. subtilis PERM317 was grown to an OD₆₀₀ of 0.5 in either minimal Spizizen medium (A) or LB medium (B). The culture made in minimal Spizizen medium was divided into three subcultures; one (labeled “0”) was left untreated, and the other two were treated with either paraquat (PQ; 10 μM) or H₂O₂ (200 μM). The LB culture was treated in the same manner except that mitomycin C (MC; 0.5 μg/ml) was added to the culture. (C) B. subtilis YB3000 was grown in LB medium to an OD₆₀₀ of 0.5; at this point, the culture was equally divided, and mitomycin C (0.5 μg/ml) was added to one of the subcultures. In all cases, the β-galactosidase activity was determined with cell samples collected 2 h after the addition of the inducers.