Functional characterization of the CS-CbnK-CbnR system-controlled promoter P BM1 in Lactococcus lactis. Dose-response curve showing GusA activity as a function of CS concentration (A) and time course showing the GusA activity of cultures treated with 20 μg/ml of CS (white columns) or 0.05% trifluoroacetic acid (black columns) (B). In the time course experiment, the cultures were harvested for GusA activity determination at the indicated times. GusA activity was determined as described in Methods. Means ± standard error of triplicate assays are shown.