Improvement in electroporation efficiency for Lactobacillus plantarum by the inclusion of high concentrations of glycine in the growth medium

Abstract

The electroporation efficiency of Lactobacillus plantarum NCFB1193 using plasmids pLP3537 or pLP825 was improved by the inclusion of glycine in the growth medium. Optimum transformation efficiency was achieved following growth for 4.5 h in the presence of 6–8% (w/v) glycine prior to electroporation. An additional improvement was obtained when the medium also contained 0.3 M sucrose and the results became more reproducible. Consistent frequencies of >10 4 transformants per μg plasmid DNA could be obtained using an electroporation voltage of 7.5 kV cm −1. The use of multiple pulses, increasing cell densities and increasing the concentration of magnesium ions in the electroporation buffer did not affect the transformation efficiency significantly. A number of previously non-transformable strains of Lb. plantarum were rendered electrocompetent by the modifications to the growth medium described.