Authors: Kumar, M.¹; Hora, R.¹; Kostrzynska, M.²; Warriner, K.¹

Source: Journal of Applied Microbiology, Volume 102, Number 5, May 2007 , pp. 1427-1436(10)

Publisher: Wiley-Blackwell

Abstract:

Aim: 

To determine the mechanisms by which a stabilized oxychloro (SOC)-based sanitizer, applied to decontaminate seeds destined for sprout production, inactivates Escherichia coli O157:H7 ph1 and Salmonella serotype Meleagridis. Materials and Results: 

The action of SOC on the metabolism, membrane and DNA integrity of Salmonella and E. coli O157:H7 was studied. In both pathogens, there was an oxidative burst and depletion of intracellular glutathione (GSH) upon initial exposure to 200 ppm SOC. Metabolic activity, measured via bioluminescence, decreased over a 4-h period in E. coli O157:H7 ph1 cells exposed to SOC. Membrane integrity, assessed through viability staining, decreased progressively over 23 h when exposed to SOC. The appearance of auxotrophic mutants suggested that DNA damage had also occurred. Enzymes rich in disulfide bonds (alkaline phosphatase and protease) were sensitive to the chlorite-based sanitizer. Through challenging other microbial types, it was found that Gram positive had higher tolerance to SOC than Gram negatives with the exception of Salmonella. MS2 bacteriophage was highly sensitive; however, Bacillus endospores were not inactivated by SOC. Conclusions: 

SOC inactivates E. coli O157:H7 and Salmonella through GSH oxidation and disruption of disulfide bonds. Ultimately, membrane damage resulting from prolonged exposure to SOC leads to the loss of cell viability. Significance and Impact of the Study: 

The results provide a basis for understanding why extended treatment times are required to inactivate bacteria using SOC.

Keywords: bacterial inactivation; chlorite; decontamination; Escherichia coli O157:H7; Salmonella; sprouted seed

Document Type: Research article

DOI: http://dx.doi.org/10.1111/j.1365-2672.2006.03175.x

Affiliations: 1:  Department of Food Science, University of Guelph, Guelph, ON, Canada 2:  Agriculture and Agri-Food Canada, Guelph, ON, Canada

Publication date: 2007-05-01

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