Genetic manipulation of lactic acid bacteria is often difficult due to the inability to transform them with high efficiency. Multi-pulse electroporation offers a simple approach to increase transformation efficiencies. Using cells grown with 1% glycine and pretreated with lithium acetate and dithiothreitol, multi-pulse electroporation (five pulses of 12.5 kV cm-1) of Lactococcus lactis JB704 cells resulted in a transformation efficiency of up to 1.2 × 106 colony forming units (CFU) μg-1 pGK13, an 8-fold increase in the transformation efficiency compared to single pulse electroporation. Other cell growth and pretreatment conditions with JB704 resulted in lower transformation efficiencies but had 4-fold to 27-fold higher transformation efficiencies with the five pulse electroporations. With similarly grown and pretreated Lactobacillus casei 32G cells, multi-pulse electroporation (five pulses of 7.5 kV cm-1) resulted in a mean transformation efficiency of 7.3 × 103 CFU μg-1 pTRKH2, a 4-fold increase in the transformation efficiency compared to single pulse electroporation.
Keywords: Electroporation; Lactic acid bacterium; Multi-pulse; Transformation.
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