Imaging Bacterial Cell Death Induced by Antimicrobial Peptides in Real Time using high speed AFM

Dr.Georg Fantner
Massachusetts Institute of Technology
Department of materials Science and Engineering

Wednesday, 17th February 2010
3:00PM Samsung Auditorium

Georg E. Fantner*, Roberto J. Barbero#, David S. Gray*, Angela M. Belcher*#. *Biomolecular Materials Group, Department of Materials Science and Engineering, Massachusetts Institute of Technology, Cambridge MA, 02139 USA #Biomolecular Materials Group, Department of Biological Engineering, Massachusetts Institute of Technology, Cambridge MA, 02139 USA *fantner@mit.edu Antimicrobial peptides (AMP) are a promising class of antimicrobial agents in the battle against bacteria that have built up resistance to conventional antibiotics. The mechanism by which these peptides kill bacteria is still poorly understood. We have used custom-built AFM components based on small cantilevers to image for the first time the bactericidal action of antimicrobial peptides in real time. With this system, we investigated the activity of the chimeric AMP CM15 with nanometer spatial- and seconds temporal-resolution on live E.coli cells. We observed rapid changes in surface morphology of the cells after injection of the AMP, with a response time that differs between individual monoclonal bacteria in the same image . Using combined AFM and fluorescence microscopy, we correlated the change in cell morphology to cell wall permeability and cell death. We believe that this technique will enable a whole new method of characterizing and studying the effectiveness of synthetic antimicrobial peptides.