Cloning and in planta expression of an omiganan antimicrobial peptide in tobacco and potato plants to control the growth of human bacterial pathogens

Antimicrobial peptides are one of the vital components of innate immunity in plants and animals. The identification and introduction of novel and effective peptide molecules to plants is a cost-effective way both to improve the resistance of crop plant species to pathogens, and to produce peptides for pharmaceutical applications by using recombinant DNA technology. An expression construct containing the omiganan (MBI-226) antimicrobial gene sequence was cloned and used for tobacco and potato Agrobacterium tumefaciens-mediated transformation. Following tissue culture, Polymerase chain reaction analysis (PCR) confirmed that some kanamycin resistant plants are transgenic. A number of transgenic plants, along with a non-transgenic control, were selected. Total protein was extracted from the transgenic plants, and the non-transgenic control, and was used for antimicrobial activity assay against some human pathogens, including; Escherchia coli, Staphylococcus epidermis, Pseudomonas aeruginosa, Salmonella typh, Staphylococcus aureus, Bacillus cereus, Candida albicans using the disc diffusion method. Total protein extract from transgenic plants was significantly (P<0.05) able to inhibit the majority of bacteria growth, whereas non-transgenic total protein extract did not inhibit human pathogens growth. There was a significant difference (P<0.05) between transgenic lines with respect to omiganan peptide activity. In contrary to gram-negative bacteria, omiganan peptide did not have a significant effect (P>0.05) on human gram-positive pathogenic bacteria. The total protein from the omiganan-expressing peptide had a strong antibacterial activity against some human bacterial pathogens. By expression and purification of the omiganan peptide, the peptide could be used as an antibiotic to destroy pathogenic bacteria. This approach could open an opportunity to produce antibacterial peptides in plants for pharmaceutical applications.