Optimization of Nature-Inspired Antibacterial Peptide

Abstract

Antimicrobial resistance (AMR) is considered a global health challenge, which has made it imperative to urgently develop new antimicrobial agents. This thesis is focused on the optimization of MD016, a 15-mer antimicrobial peptide originating from a natural peptide (lactomodulin) in the human gut microbiome1 . Naturally occurring AMPs have shown potential as antibacterial agents; however, their clinical use is limited by their toxicity, instability, and high production costs. Modified MD016 peptide libraries were synthesized using an automated solid-phase peptide synthesizer (SPPS). Peptides were purified using High-Performance Liquid Chromatography (HPLC), and a complete molecular weight and sequence verification was done using Liquid Chromatography-High Resolution Mass Spectrometry (LC-HRMS) and Tandem Mass Spectrometry (MS/MS). The antibacterial activity of the new variants was evaluated using agar disk-diffusion test and minimal inhibitory concentration (MICs) assay against Gram-positive Staphylococcus aureus and Gram-negative Escherichia coli bacterial strains. 10K and 12K lysine-substituted peptides showed a similar and slightly improved antibacterial activity compared with the parent MD016 peptide against E. coli, with an MIC value of 0.39 µM, even better than most currently in-use antibiotics. The study also considered issues concerning peptide quantification and solvent compatibility in biological assays. Further testing of the other synthesized derivatives along with the potent earlier mentioned ones is required to verify the results and identify the best of the series and inform further modifications.

Date of Award	2025
Original language	American English
Supervisor	Emilia Oueis (Supervisor)