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Proceedings Paper

Environmental effects on the production of Shiga-like toxins by Escherichia coli O157:H7 as revealed by sandwiched immuno-chemiluminescence detection
Author(s): Shu-I Tu; Joseph Uknalis; Yiping He
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Paper Abstract

We have developed a sandwiched immuno assay to detect sensitively Shiga-like toxins (SLTs) produced by Escherichia coli O157:H7. The method involved the capture of toxins by specific immuno magnetic beads followed by tagging the toxins with peroxidase-labeled anti E. coli O157:H7 antibody. Upon addition of proper substrate, peroxidase induced luminescence was used to measure the presence of SLTs. We have previously demonstrated that co-incubation of shiga toxin (SLT) producing E. coli O157:H7 with certain other bacteria can inhibit toxin production but does not affect the growth of the E. coli. We show here that media in which the cells have grown been centrifuged from (conditioned media) have similar effects on cell growth and SLT production. Adjusting the pH and adding nutrients to the conditioned media did not have any effect on the reduction of SLT produced. Bacteria communicate with each other via secreted sensing molecules. Several types of the molecules have been identified. However, the mechanisms of control remain to be established. This pattern for bacteria growth and toxin production is also observed when quorum-sensing molecules of homoserine lactone and indole are added to the media prior to inoculation.

Paper Details

Date Published: 27 April 2009
PDF: 10 pages
Proc. SPIE 7315, Sensing for Agriculture and Food Quality and Safety, 731506 (27 April 2009); doi: 10.1117/12.819122
Show Author Affiliations
Shu-I Tu, USDA Agricultural Research Service (United States)
Joseph Uknalis, USDA Agricultural Research Service (United States)
Yiping He, USDA Agricultural Research Service (United States)

Published in SPIE Proceedings Vol. 7315:
Sensing for Agriculture and Food Quality and Safety
Moon S. Kim; Shu-I Tu; Kaunglin Chao, Editor(s)

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