DEVELOPMENT OF NOVEL ANTIMICROBIAL RANDOM PEPTIDE MIXTURES TO COMBAT SPORULATING BACTERIA

The overuse of antibiotic agents in medicine and agriculture contributes to the rise of antibiotic-resistant infections that are difficult to treat. There is an urgent need to design novel antimicrobial agents. Antimicrobial peptides present novel mean to combat harmful microorganisms. The broad molecular diversity among natural antimicrobial peptides suggests that their activity is not tightly coupled to specific features of amino acid sequence or peptide conformation. This has inspired us to develop a novel approach to generate random cationic peptide mixture (RPMs). We have previously shown¹ that RPMs of hydrophobic and cationic amino acids, such as tryptophan and lysine (WK) display strong antimicrobial activity. In the current research, we explored the effect of our RPMs on B. subtilis as a Gram positive spore forming bacterium vastly involved in food spoilage. This study aimed to develop new RPMs which are active toward spores. We tested the RPMs in vitro toward 10⁶ CFU/mL spores in PBS medium. Our results show 3 to 5 log reduction using different modifications such as change of Chirality and various cationic amino acid. Furthermore, we used the RPMs to inhibit the bacterial growth in biofilm which considered as a protective mode of growth. In order to check the cytotoxicity of the RPMs, we performed a MTT test on HEK 293T cell culture and found that it is not toxic even at high concentrations. We conclude that the RPMs have considerable potential to combat the biofilm and spore forming bacteria.

Reference: 1. Hayouka, Zvi, et al. "Interplay among Subunit Identity, Subunit Proportion, Chain Length, and Stereochemistry in the Activity Profile of Sequence-Random Peptide Mixtures." Journal of the American Chemical Society 135.32 (2013): 11748-11751.‏