Transformation of Bacillus amyloliquefaciens by electroporation

A method for transformation of whole Bacillus amyloliquefaciens cells by electroporation was developed. The procedure is as efficient as the protoplast transformation method, resulting in up to 105 transformants/µg plasmid DNA, but requires less effort and time. Cells for electroporation were grown to late exponential phase in a rich medium supplemented with 0.25 M sucrose, washed with and resuspended in 0.25 M sucrose, 1 mM HEPES, 1 mM MgCl2, 10% (v/v) glycerol, pH 7.0, at 3–5 × 1010 cells/ml for storage at -80%°C. The highest transformation frequency was obtained at 7.5 kV/cm with a 25 µF capacitor. The transformation efficiency increased linearly with DNA concentration at least over the range 10 ng-12.5 µg/ml. Transformations with ligated DNA and of industrial strains were also successful. In addition, B. subtilis cells treated as above could be transformed by electroporation, resulting in 104 transformants/µg DNA at 12.5 kV/cm.