Test systems to study transcriptional regulation and promoter activity in Bacillus megaterium

Plasmid-located (multi-copy) and chromosomally located (single-copy) promoter test systems were developed for Bacillus megaterium by making use of the homologous β-galactosidase-encoding bgaM gene. The multi-copy system facilitates rapid promoter analyses and promoter trapping, whereas the single-copy system, integrated into the chromosome, allows investigation of tightly regulated promoters. As a prerequisite for both the multi- and the single-copy systems, a β-galactosidase-deficient B. megaterium strain was generated by deletion mutagenesis. Both test systems were verified using the promoter of the xylose operon (P xylA ) from B. megaterium along with its repressor (XylR). As expected, expression levels in the two systems differed significantly, although expression of the bgaM reporter gene was induced by xylose in both cases, thereby proving the functionality of both the multi- and the single-copy system.