Atomic force microscopy study of the antibacterial effects of chitosans on Escherichia coli and Staphylococcus aureus

• Type: Article in International Scientific Journal
• Date: 2008

Authors

Peter Eaton (Author) Other; Joao C Fernandes (Author) Other; Eulalia Pereira (Author) FCUP; Manuela E Pintado (Author) Other; Xavier X Malcata (Author) Other

Journal

Title: Ultramicroscopy

Vol. 108

Pages: 1128-1134

ISSN: 0304-3991

Publisher: Elsevier

Indexing

ISI Web of Knowledge - 266 Citations

Scopus - 286 Citations

Scientific classification

FOS: Natural sciences > Biological sciences

Other information

Authenticus ID: P-003-WWE

DOI: 10.1016/j.ultramic.2008.04.015

Abstract (EN): Chitosan has been reported to be a non-toxic, biodegradable antibacterial agent. The aim of this work was to elucidate the relationship between the molecular weight of chitosan and its antimicrobial activity upon two model microorganisms, one Gram-positive (Staphylococcus aureus) and one Gram-negative (Escherichia coli). Atomic force microscopy (AFM) imaging was used to obtain high-resolution images of the effect of chitosans on the bacterial morphology. The AFM measurements were correlated with viable cell numbers, which show that the two species reacted differently to the high- and low-molecular-weight chitosan derivatives. The images obtained revealed not only the antibacterial effects, but also the response strategies used by the bacteria; cell wall collapse and morphological change, reflected cell death, whereas clustering of bacteria appeared to be associated with cell survival. m addition, nanoindentation experiments with the AFM revealed mechanical changes in the bacterial cell wall induced by the treatment. The nanoindentation results suggested that despite little modification observed in the Gram-positive bacteria in morphological studies, cell wall damage had indeed Occurred, since cell wall stiffness was reduced after chitooligosaccharide treatment.

Language: English

Type (Professor's evaluation): Scientific

No. of pages: 7