Construction of a modular plasmid family for chromosomal integration in Bacillus subtilis.

The investigation of molecular processes involves the generation of knockout strains, the determination of promoter strength and protein overexpression. Here, we report the construction of the multifunctional pMG expression vector family for integration into the Bacillus subtilis chromosome that allows gene expression under single copy conditions. The pMG family enables a rapid exchange of all features for integration, selection and gene expression with or without N-terminal strep-tags. This modular architecture increases the applicabilities for these plasmids tremendously, permitting the construction of pMG derivatives for chromosomal integration at versatile loci and in different Bacillus species under control of natural or heterologous constitutive or inducible promoters. Additionally, the possible replacement of the antibiotic resistance cassettes helps circumvent problems that arise when the use of more than three antibiotics is required. Furthermore, the high copy number and structural stability of the pUC19-based pMG vectors in Escherichia coli facilitates template production for target host transformation.