Cloning and Expression of Two New Recombinant Antimicrobial Dermaseptin B1 Peptides in Tobacco to Control the Growth of Human Bacterial Pathogens

Background and purpose: Rapid emergence of traditional antibiotic-resistant pathogens is one of the most important global challenges in medical sciences. To this end, substitution of current antibiotics with strong antimicrobial peptides could be of great benefit. Materials and methods: In this study, the DNA sequence encoding dermaseptin B1 (DrsB1) antimicrobial peptide derived from Phyllomedusa bicolor frog species was fused to either N or C terminal end of the sequence encoding the chitin-binding domain of the Avr4 gene from Cladosporium fulvum. The recombinant expression vectors containing two separate structures were transferred to Agrobacterium rhizogenes bacterium and then used to produce Hairy Roots (HRs) in tobacco plants. Recombinant dermaseptin B1 peptides were extracted from HRs and their antimicrobial activity was evaluated against some important human pathogens. Results: Transgene integration and expression of recombinant DrsB1 in hairy roots were confirmed by PCR and semi-quantitative RT-PCR analysis, respectively. Antimicrobial activity of the protein extracts from transgenic HRs showed that both recombinant proteins had significant inhibitory effects on the bacterial pathogens growth (P>0.01). CBD-DrsB1 recombinant protein had the highest inhibitory activity against Enterococcus faecalis and Bacillus subtilis, whereas DrsB1-CBD recombinant protein showed the least antimicrobial activity against Escherichia coli, Staphylococcus aureus, and Pseudomonas aeruginosa. Conclusion: To the best of our knowledge, this study for the first time showed that the new recombinant peptides possess a high antibacterial activity. Acquiring resistance to antimicrobial peptides in bacteria is not readily feasible, therefore, present findings may find application as suitable alternative for current antibiotic drugs.