FIG. 2.

Action of the groE promoter-gluconate operator in B. subtilis. (A) Action of the promoter. WB1200 harboring the engineered groE promoter-gluconate operator (•) and WB1201 (negative control) (▴) were cultured in superrich medium containing 0.2% sodium gluconate. (B) Action of the operator. WB1200 was cultured in superrich medium with 0.2% (•) or without (▴) sodium gluconate. At different hours of culture at 37°C, the cells were harvested and disrupted by French press. β-Galactosidase activity in the cell lysates was determined using ONPG as substrate. One Miller unit = (A₄₂₀ × 1,000)/(reaction time [minutes] × A₅₉₅) (23).