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United States Department of Agriculture

Agricultural Research Service

Title: Steady-State and Time-Resolved Spectroscopy of F420 Extracted from Methanogen Cells and Its Utility As a Marker for Fecal Contamination

item Casey, Thomas
item Rasmussen, Mark

Submitted to: Journal of Agricultural and Food Chemistry
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: December 7, 2000
Publication Date: N/A

Interpretive Summary: In people, foodborne diseases cause about 76 million illnesses, 325,000 hospitalizations and 5,000 deaths each year in the United States. Most of these illnesses are caused by ingesting food or water contaminated with feces containing disease-causing bacteria. Current methods for detecting feces on meat are insensitive, time consuming, and labor intensive. We investigated an alternative way to identify feces and characterized a fluorescent compound from bacteria that are commonly present in feces. We found that the properties of this fluorescent compound may be used to instantaneously detect very small amounts of feces. This information, and methods based on detecting fluorescent compounds, can be used by industry to develop commercial devices to detect feces on the carcasses of slaughtered animals. Such devices can be used by regulatory agencies and the meat packing industry as a tool to identify and prevent fecal contamination. Consumers will ultimately benefit because of increased wholesomeness of meat and reduced incidence of foodborne illnesses.

Technical Abstract: Methanogenic bacteria which are common inhabitants of the animal digestive tract, contain the fluorescent compound F420 (coenzyme 420), a 7-8-didemethyl-8-hydroxy-5-deazariboflavin chromophore. We characterized F420 as an initial step in determining if this compound would be useful as a fluorescent marker for the detection of fecal and ingesta contamination. Using a single anion exchange chromatographic process, F420 was separated from other cell components of a Methanobrevibacter sp. cell culture. The extent of separation was determined spectroscopically. To aid in the development of possible techniques for the detection of fecal contamination using F420 as a marker, further spectroscopic investigation of F420 was conducted using steady-state and time-resolved fluorescence methods. The fluorescence lifetime of F420 in an elution buffer of pH 7.5 was found to be 4.2 ns. At higher pH values, the fluorescence decay, F(t), was best described by a sum of two exponentials: at pH 13, F(t) = 0.31 exp (-t / 4.20 ns) + 0.69 exp (-t / 1.79 ns). Further investigation using front-faced fluorescence techniques has shown that emission from F420 can be collected efficiently from samples of methanogen cell cultures as well as from fecal material.

Last Modified: 4/21/2015
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