Transformation of Bacillus thuringiensis plasmid DNA by a new polyethylenimine polymeric nanoparticles method

Although electroporation technique has been mostly used to transform Bacillus thuringiensis (Bt), this method is not readily applicable to strains other than the one for which it was optimized. Polyethylenimine (PEI) is a golden standard non-viral vector that interacts with plasmids to form compact polymeric nanoparticles (PNPs) via electrostatic interactions. This PNPs system is very attractive because they are easily prepared, able to carry large nucleic acid constructs, and show low toxicity. In this study, PEI/pBTdsSBV-VP1 PNPs were successfully prepared at various N/P ratios which is positively-chargeable polymer amine (N = nitrogen) groups to negatively-charged nucleic acid phosphate (P) groups, and the internalization of the complexes into Bt 4Q7 was confirmed by confocal laser scanning microscopy. The PEI-mediated transformation showed similar efficiency comparable to that of electroporation method, suggesting that the method of PNPs will be an effective alternative for transformation of Bt strains.