Muhammad Yasir

PhD Candidate

PhD Candidate

Research Title: Mechanism of Action of Surface Bound Antimicrobial Peptides 

Supervisors: Professor Mark Willcox, Dr Debarun Dutta 






Microbial colonisation of surfaces leads to the production of biofilms, high-density populations encapsulated within a self-produced polymeric matrix that are resistant to biocides including antibiotics. Prevention of bacterial adhesion and subsequent biofilm formation on biomaterials is important from both an economic and health perspective. Antimicrobial peptides (AMPs) are important alternatives to conventional antibiotics. AMPs have been recognized as promising candidates for development of antimicrobial surfaces owing to the minimal possibility of bacterial resistance development and broad-spectrum activity at low concentrations. My research is focused on whether bacteria can develop resistance against the AMPs melimine and Mel4. Moreover, I am also investigating how these peptides interact and kill bacteria and prevent biofilm formation once surface immobilized. Understanding the mechanism of action of surface bound AMPs will help with the design of new effective antimicrobial coatings for contact lenses and other biomaterials.

In my current studies, we have found that both Pseudomonas aeruginosa and Staphylococcus aureus did not develop resistance against melimine and Mel4 but could easily develop resistance against ciprofloxacin when grown at low concentrations. Both immobilized peptides interacted and neutralized bacterial lipid toxins. Moreover, immobilized peptides damaged the cell membrane of both the bacteria, and this resulted in the release of the bacterial cytoplasmic contents. When I compared the mechanism of action of surface bound AMPs to their soluble counterparts, they generally had the same mechanism of action, but the immobilised forms tended to work more slowly.



Muhammad Yasir is a Microbiologist and received his M. Phil degree in Microbiology from Quaid-e-Azam University, Islamabad, which is one of top ranked Universities in Pakistan. After completing his M. Phil degree, he joined the University and served as a Lecturer for three years. He joined Professor Willcox’s research group as a PhD research scholar in 2016. In his PhD project, he has investigated the mechanism of action of soluble and surface bound antimicrobial peptides melimine and mel4 against Gram-negative and Gram-positive bacteria. He has also examined how bacteria may become resistant to antibiotics and antimicrobial peptides. 



2013    M.Phil Microbiology  



Journal Articles 

  1. Yasir, M., D. Dutta, and M.D.P. Willcox. Comparative Mode of Action of the Antimicrobial Peptide Melimine and its Derivative Mel4 against Pseudomonas aeruginosa. Scientific Reports, 2019. 9(1): p. 7063. 
  2. Yasir, M., M. Willcox, and D. Dutta, Action of Antimicrobial Peptides against Bacterial Biofilms. Materials, 2018. 11(12): p. 2468 
  3. Kuppusamy, R, Yasir, M, Yee, E, Willcox, M. Black, D StC, Kumar, N (2018). Guanidine Functionalized Anthranilamides as Effective Antibacterial with Biofilm Disruption Activity. Organic & Biomolecular Chemistry 16 (32) 5871-5888. 
  4. Kuppusamy, R, Yasir, M, Berry, T, Cranfield, C G, Nizalapur, S, Yee, E, Kimyon, O, Taunk, A. Ho, Kitty K, Cornell, B.  Design and synthesis of short amphiphilic Cationic Peptidomimetics Based on Biphenyl Backbone as Antibacterial Agents. European journal of Medicinal Chemistry. 143 1702-1722. 
  5. Ahmad, Z, Babar, S, Abbas F, Awan A M, Attique A, Khan M A, R Nadeem, Amin S, Wadood A, Shafee, Asadullah M, Jan S and Yasir, M (2013). Evaluation of a Saponin Adjuvanted Inactivated Mycoplasma bovis (A Field Isolate from Cattle Lungs in Balochistan, Pakistan) Vaccine. International Journal of Agriculture & Biology. 12–1280/2013/15–6–1169–1174.   



Travel Award, International Cornea and Contact lenses Society Singapore, 2019

Post-doctoral and Student Travel award San Francisco, USA, American Society for Microbiology, 2019

Travel Award, World Life Science Conference Beijing, China, 2018

Research Award, Cornea and Contact lens Society of Australia (CCLSA), 2018-2019

Travel Award, Molecular Microbiology Meeting (3MMM) Sydney, Australia, 2018



Yasir M; Debarun Dutta; Mark Willcox (2019). Killing mechanism of surface bound antimicrobial peptides melimine and mel4 against Staphylococcus aureus. In American Society for Microbiology (ASM, microbes) at Sana Francisco, CA, from 20th June - 24th  June 2019. 

Yasir M; Debarun Dutta; Mark Willcox (2019). Mechanism of action of antimicrobial peptides melimine and its shorter derivative mel4 against S. aureus. Gordon Research Conference in “Mechanisms and Application: Realizing the Potential of Antimicrobial Host Defense Peptides for Human and Veterinary Medicine Renaissance” Tuscany Il Ciocco Via Giovanni Pascoli Lucca (Barga), Italy from 24 February - 1 March 2019. 

Yasir M; Debarun Dutta; Mark Willcox (2018). Mechanism of action of surface bound antimicrobial peptides melimine and mel4 against P. aeruginosa. World Life Science Conference from 27th -29th October, Beijing, China. 

Yasir M; Debarun Dutta; Mark Willcox (2018). The role of antimicrobial peptides in reducing bacterial biofilms alone or in combination with ciprofloxacin. Molecular Microbiology Meeting at 11th and 12th April in Sydney, Australia.  

Yasir M; Debarun Dutta; Mark Willcox (2017). Depolarizing effect of cationic antimicrobial peptides melimine and mel4 on bacterial cell membranes, presented at Australian Society of Microbiology, 2nd–5th July in Hobart, Australia. 

Kuppusamya R, Muhammad Yasir, Thomas Berry, Charles G. Cranfield, Mark Willcox, David StC Black, Naresh Kumar (2017) “Design and Synthesis of Short Amphiphilic Cationic Peptidomimetics Based on Biphenyl Backbone as Antibacterial Agents” was presented at the RACI Centenary Congress at 23rd-28th July in Melbourne Australia. 



American Society for Microbiology  

Cornea and Contact Lenses Society of Australia