Document Detail

Inhibition of Bacillus cereus spore outgrowth and multiplication by chitosan.
MedLine Citation:
PMID:  21798612     Owner:  NLM     Status:  Publisher    
Bacillus cereus is an endospore-forming bacterium able to cause food-associated illness. Different treatment processes are used in the food industry to reduce the number of spores and thereby the potential of foodborne disease. Chitosan is a polysaccharide with well-documented antibacterial activity towards vegetative cells. The activity against bacterial spores, spore germination and subsequent outgrowth and growth (the latter two events hereafter denoted (out)growth), however, is poorly documented. By using six different chitosans with defined macromolecular properties, we evaluated the effect of chitosan on Bacillus cereus spore germination and (out)growth using optical density assays and a dipicolinic acid release assay. (Out)growth was inhibited by chitosan, but germination was not. The action of chitosan was found to be concentration-dependent and also closely related to weight average molecular weight (M(w)) and fraction of acetylation (F(A)) of the biopolymer. Chitosans of low acetylation (F(A)=0.01 or 0.16) inhibited (out)growth more effectively than higher acetylated chitosans (F(A)=0.48). For the F(A)=0.16 chitosans with medium (56.8kDa) and higher M(w) (98.3kDa), a better (out)growth inhibition was observed compared to low M(w) (10.6kDa) chitosan. The same trend was not evident with chitosans of 0.48 acetylation, where the difference in activity between the low (19.6kDa) and high M(w) (163.0kDa) chitosans was only minor. In a spore test concentration corresponding to 10(2)-10(3)CFU/ml (spore numbers relevant to food), less chitosan was needed to suppress (out)growth compared to higher spore numbers (equivalent to 10(8)CFU/ml), as expected. No major differences in chitosan susceptibility between three different strains of B. cereus were detected. Our results contribute to a better understanding of chitosan activity towards bacterial spore germination and (out)growth.
Hilde Mellegård; Cecilie From; Bjørn E Christensen; Per E Granum
Publication Detail:
Type:  JOURNAL ARTICLE     Date:  2011-7-5
Journal Detail:
Title:  International journal of food microbiology     Volume:  -     ISSN:  1879-3460     ISO Abbreviation:  -     Publication Date:  2011 Jul 
Date Detail:
Created Date:  2011-7-29     Completed Date:  -     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  8412849     Medline TA:  Int J Food Microbiol     Country:  -    
Other Details:
Languages:  ENG     Pagination:  -     Citation Subset:  -    
Copyright Information:
Copyright © 2011 Elsevier B.V. All rights reserved.
Dept. of Food Safety and Infection Biology, Norwegian School of Veterinary Science, P.O. Box 8146 Dep, NO-0033 Oslo, Norway.
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