Transformation of Bacillus subtilis.

Bacillus subtilis has tremendous applications in both academic research and industrial production. However, molecular cloning and transformation of B. subtilis are not as easy as those of Escherichia coli. Here we developed a simple protocol based on super-competent cells prepared from the recombinant B. subtilis strain SCK6 and multimeric plasmids generated by prolonged overlap extension-PCR. Super-competent B. subtilis SCK6 cells were prepared by overexpression of the competence master regulator ComK that was induced by adding xylose. This new protocol is simple (e.g., restriction enzyme, phosphatase, and ligase free), fast, and highly efficient (i.e., ~10(7) or ~10(4) transformants per μg of multimeric plasmid or ligated plasmid DNA, respectively). Shuttle vectors for E. coli-B. subtilis are not required.