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United States Department of Agriculture

Agricultural Research Service

Title: Detection of Bacteria from a Cecal Anaerobic Competitive Exclusion Culture with An Immunoassay Electrochemiluminescene Sensor

Authors
item BEIER, ROSS
item Young, Colin
item STANKER, LARRY

Submitted to: Society of Photo-Optical Instrumentation Engineers
Publication Type: Proceedings
Publication Acceptance Date: October 5, 1998
Publication Date: N/A

Interpretive Summary: Our laboratory has developed a bacterial culture that contains 29 different types of bacteria. The bacterial culture can be used to reduce Salmonella typhimurium colonization in chickens. It would be advantageous to detect individual bacteria in this culture. We demonstrated the use of the commercial instrument, called the ORIGEN Analyzer, to detect S. typhimurium and Eubacteria a levels low enough to be useful for protecting the food supply. Using this instrument and methods described herein, both S. typhimurium and Eubacteria were detected at a level useful for protecting the food supply.

Technical Abstract: A competitive exclusion (CE) culture of chicken cecal anaerobes has been developed and used in this laboratory for control of Salmonella typhimurium in chickens. The CE culture consists of 29 different species of microorganisms, and is known as CF3. Detection of one of the CF3 bacteria, Eubacteria, and S. typhimurium were demonstrated using a commercial immunomagnetic (IM) electrochemiluminescence (ECL) sensor, the ORIGEN Analyzer. Analysis was achieved using a sandwich immunoassay. Bacteria were captured on antibody-conjugated 280 micron sized magnetic beads followed by binding of reporter antibodies labeled with ruthenium (II) tris(dipyridyl) chelate (Ru(bpy)3**2+). The magnetic beads were then trapped on an electrode in the reaction cell of the ORIGEN Analyzer by a magnet, and the ECL was evoked from Ru(bpy)3**2+ on the tagged reporter antibodies by an electrical potential at the electrode. Preliminary IM- ECL assays with Eubacteria yielded a detection limit of 10**5 cfu/mL. Preliminary IM-ECL assays with S. typhimurium yielded a similar detection limit of 10**5 cfu/mL.

Last Modified: 9/10/2014
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