Study of the antibacterial effects of chitosans on Bacillus cereus (and its spores) by atomic force microscopy imaging and nanoindentation

• Type: Article in International Scientific Journal
• Date: 2009

Authors

Fernandes, JC (Author) Other; Eaton, P (Author) Other; Gomes, AM (Author) Other; Pintado, ME (Author) Other; F. Xavier Malcata (Author) Other

Journal

Title: Ultramicroscopy

Vol. 109

Pages: 854-860

ISSN: 0304-3991

Publisher: Elsevier

Indexing

ISI Web of Knowledge - 60 Citations

Scopus - 66 Citations

Other information

Authenticus ID: P-003-J3P

DOI: 10.1016/j.ultramic.2009.03.015

Abstract (EN): Bacillus cereus is a Gram-positive, spore-forming bacterium that is widely distributed in nature. Its intrinsic thermal resistance coupled with the extraordinary resistance against common food preservation techniques makes it one of the most frequent food-poisoning microorganisms causing both intoxications and infections. In order to control B. cereus growth/sporulation, and hence minimize the aforementioned hazards, several antimicrobial compounds have been tested. The aim of this work was to assess by atomic force microscopy (AFM) the relationship between the molecular weight (MW) of chitosan and its antimicrobial activity upon both vegetative and resistance forms of B. cereus. The use of AFM imaging studies helped us to understand how chitosans with different MW act differently upon B. cereus. Higher MW chitosans (628 and 100 kDa) surrounded both forms of B. cereus cells by forming a polymer layer-which eventually led to the death of the vegetative form by preventing the uptake of nutrients yet did not affect the spores since these can survive for extended periods without nutrients. Chitooligosaccharides (COS) (< 3 kDa), on the other hand, provoked more visible damages in the B. cereus vegetative form-most probably due to the penetration of the cells by the COS. The use of COS by itself on B. cereus spores was not enough for the destruction of a large number of cells, but it may well weaken the spore structure and its ability to contaminate, by inducing exosporium loss. (c) 2009 Elsevier B.V. AM rights reserved.

Language: English

Type (Professor's evaluation): Scientific

No. of pages: 7