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United States Department of Agriculture

Agricultural Research Service

Title: Examination of Cell Morphological Changes of Escherichia Coli Treated with Acidic Electrolyzed Water, Peroxyacetic Acid and Chlorine Using a Mfp-3dtm Atomic Force Microscope

Authors
item Wang, Hua - UIUC, IL
item Feng, Hao - UIUC, IL
item Maclaren, Scott - UIUC, IL
item Luo, Yaguang

Submitted to: Annual Meeting of the Institute of Food Technologists
Publication Type: Abstract Only
Publication Acceptance Date: March 10, 2006
Publication Date: June 23, 2006
Citation: Wang, H., Feng, H., Maclaren, S., Luo, Y. 2006. Examination of cell morphological changes of escherichia coli treated with acidic electrolyzed water, peroxyacetic acid and chlorine using a mfp-3dtm atomic force microscope [abstract]. Institute of Food Technologists. Paper No. 003a -16.

Technical Abstract: The MFP-3DTM atomic force microscopy (AFM) is a newly developed AFM with high precision, accuracy and flexibility in acquiring and analyzing images and conducting specific measurements. The aim of this study was to investigate the bactericidal mechanism of acidic electrolyzed water (AEW), peroxyacetic acid (POAA) and chlorine on Escherichia coli K12 cells by examining the changes in the cell morphology of the bacterium with a MFP-3DTM AFM. One ml E. coli K12 cell suspension was treated with 9 ml AEW, chlorine or POAA for 30, 60, or 120 s. At the end of each contacting time, 0.1 ml treated mixture was diluted with sterilized water, from which 5 ml was taken and concentrated on an isopore filter. The filter was fixed to the center of a glass slide for AFM imaging in a tapping mode with a silicon tip. The force was measured in a contact mode with a silicon nitride tip. Viable bacteria were enumerated by the culturing method using MacConkey agar media. Cell morphology changes were observed on E.coli after a 30 s treatment. Extending contacting time to 120 s did not cause any additional morphological changes. POAA treatment caused separation of cell membrane from cell cytoplasm while AEW and chlorine treatments damaged cell surfaces as evidenced by significant changes in surface topography and morphology. Adhesion force between AFM tip and cell surface was sharply decreased when morphological changes were observed. The differences in cell morphological changes of E.coli cells treated with three sanitizers indicate that different bactericidal mechanism among the sanitizers may have existed. The similarity in cell morphological changes of E.coli treated with AEW and chlorine suggests a similar inactivation mechanism. MFP-3DTM AFM can be a useful tool to elucidate the bactericidal mechanism of sanitizers by examining the cell morphological changes.

Last Modified: 8/29/2014
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