Fig. 1

Conversion of an IPTG-inducible into an inducer-free expression vector for B. subtilis. a Schematic representation of the location of two lacO operators, e.g., in pHT01-bgaB and repression of the target gene by the presence of LacI (circles) encoded by lacI gene. b Removal of the lacI gene resulted in the inducer-free expression plasmid, such as pHT1655. c Map of the pHT1655 vector