Novel Antimicrobial Peptides Identified from Screening of Random Peptide Library by Yeast Two Hybrid Assay

Antimicrobial peptides are widely found in the living organisms and are known to play a critical role in the innate immunity. Numerous antimicrobial peptides from diverse species appear to be effective against pathogenic microorganisms of bacteria, fungi, protozoa and viruses. Since antibiotic resistance is a global health issue in the fight against pathogenic microorganisms, there has been an urgent need for the development of new antibiotic substances. In the present study, we sought to find new peptide antibiotics from random peptide library by yeast two hybrid screening using Beclin1 bait. Two candidate peptides from the screening were expressed in a yeast secretory system of Pichia pastoris and tested for any antimicrobial activity against Staphylococcus aureus, MRSA, MRSA2242, MRSA2250, Lactobacillus casei, Lactobacillus acidophilus. Disc clear zone assay and spectrophotometric analysis revealed that the two peptides carry a decent activity against the pathogenic bacteria, in contrast to minimal effect on the commensal Lactobacillus strains. Taken together, this study presents novel peptides with antibacterial activity against the pathogenic forms of Staphylococcus aureus and suggests a possibility that these peptides, upon further characterization, may be developed as clinically useful antibiotics.