Promoter-driven β-galactosidase activity. B. subtilis GRSW2-B1, harboring each constructed expression vectors, was grown in LB medium to the same OD600 of approximately 0.8, and induced with the optimal induction condition of each promoter (if necessary) (as described in text). pHZT and pHZTK is pHY300PLK, carrying trpA, MCS, lacZ, with Tcr and Kmr, respectively. P43, PK, P2N, P2L, PT, PS, PX are P43, Pkan, P2N, P2L, PTetL, PSapc, and PxylA promoters (as described in details in Table 2). BtOH is butanol, which was added at 1% v/v. Inset is the enlarged y-axis scale to elaborate differences of the first eight data values. Data are means of the results from at least three individual experiments.