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An evaluation of a genotoxicity assay with liver s9 for activation and luminescent bacteria for detection
Author(s) -
Thomas Johnson B.
Publication year - 1992
Publication title -
environmental toxicology and chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.1
H-Index - 171
eISSN - 1552-8618
pISSN - 0730-7268
DOI - 10.1002/etc.5620110404
Subject(s) - genotoxicity , ames test , carcinogen , photobacterium phosphoreum , bioassay , chemistry , pyrene , toxicology , bacteria , mutagen , biology , biochemistry , microbiology and biotechnology , chromatography , environmental chemistry , salmonella , toxicity , genetics , organic chemistry
A new short‐term in vitro genotoxicity assay with marine bioluminescent bacteria was evaluated for sensitivity and cost. Known under the trade name of Mutatox™, this assay is a simple and rapid screening tool that detects DNA‐damaging substances (genotoxins) by measuring light output from an isolated dark mutant strain of the luminescent bacterium Photobacterium phosphoreum. A positive response indicates the ability of the test chemical to restore the luminescent state in the dark mutant strain; the degree of light increase indicates the relative genotoxicity of the sample. In this study, the Mutatox assay with rat hepatic fractions (S9) as an exogenous metabolic activation system detected genotoxic activity with known progenotoxins: 2‐acetamidofluorene, aflatoxin B 1 , 2‐aminoanthracene, 2‐aminofluorene, 2‐aminonaphthalene, benzo[ a ]pyrene, 3‐methyl‐cholanthrene, and pyrene. Each chemical clearly demonstrated a dose response between 5.0 and 0.6 μg per tube. Known nongenotoxic controls carbofuran, di‐2‐ethylhexyl phthalate, malathion, simazine, and permethrin showed no genotoxic responses. The optimum assay conditions were determined to be rat S9 concentration of 0.4 mg/ml, preincubation at 37°C for 30 min, and 18 h incubation at 23°C. Genotoxicity data were obtained in <24 h. The Mutatox assay compared favorably in sensitivity with the Ames test; it was easier and more rapid to perform and, as a result, cost less. The sensitivity, specificity, and predictive value suggested that the Mutatox assay could be a valuable screening tool to monitor complex environmental samples for genotoxins.

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