New method for electroporation of Lactobacillus species grown in high salt

Abstract We here describe a new method for electroporation of Lactobacillus species, obligately homofermentative and facultatively heterofermentative, based on the cell-wall weakening resulting from growth in high-salt media. For L. casei , optimum transformation efficiency of up to 10 5 transformants per microgram of plasmid DNA was achieved following growth in the presence of 0.9 M NaCl. Plasmids of different sizes and replication origins were also similarly transformed. These competent cells could be used either directly or stored frozen, up to 1 month, for future use, with similar efficiency. This protocol was assayed with different Lactobacillus species: L. delbrueckii subsp. lactis , L. paracasei , L. plantarum and L. acidophilus , and it was found that they were transformed with similar efficiency.