A modified method for plasmid extraction from Lactobacillus plantarum contained lysozyme removal step

Plasmids of Lactobacillus plantarum PC518 cannot be effectively extracted by existing methods. It was studied that the effect of lysozyme treatment and removal on plasmid extraction by 7 protocols. The modified method was compared with a commercial kit using L. plantarum PC518, 410, 9L15, and JS193 and Weissella cibaria M2 as the tested strains. The results suggested that the step of lysozyme removal is the key to improve the efficiency of plasmid extraction. The concentrations of plasmid DNA isolated from the 5 tested strains were increased by 10.6, 9.5, 6, 5.6 and 1.5 times respectively compared with the commercial kit. •We added a washing step to remove lysozyme.•The step of lysozyme removal allowed the concentration of lysozyme was greatly increased during lysozyme treatment.•The modified method increased the efficiency of plasmid extraction.