Cell Wall-Treated Lactococcus lactis Increases the Plasmid Transfer Efficiency of Internal Ribosome Entry Site-Incorporated Lactococcal Bicistronic Vector into DF1 Cells

Abstract

This study demonstrates that cell wall treatment of <i>Lactococcus lactis</i> harbouring the internal ribosome entry site-incorporated lactococcal bicistronic vector pNZ:VIG mediated the delivery of genes into an eukaryotic cell line, DF1 cells, through bactofection. Bactofection analysis showed that the pNZ:VIG plasmid in <i>L. lactis</i> can be transferred into DF1 cells and that both the <i>VP2</i> and <i>gfp</i> genes cloned in the plasmid can be transcribed and translated. The protein band relative to the M_r of VP2 protein (49 kDa) was successfully detected via Western blot analysis, while green fluorescence was successfully detected using a fluorescence microscope. The intensity of the bands detected increased for samples treated with both 1.5% (w/v) glycine and 10 μg/mL of lysozyme when compared to <i>L. lactis</i> treated with glycine alone and without treatment. Cell wall treatment of <i>L. lactis</i> with a combination of both glycine and lysozyme was not only shown to mediate plasmid transfer to DF1 cells, but also to increase the plasmid transfer efficiency.