Appl. Environ. Microbiol. doi:10.1128/AEM.02458-07
Copyright (c) 2008, American Society for Microbiology and/or the Listed Authors/Institutions. All Rights Reserved.
Catabolic Pathway for the Production of Skatole and Indole Acetic Acid by the Acetogen Clostridium drakei, Clostridium scatologenes, and Swine Manure
Terence R. Whitehead*,
Neil P. Price,
Harold L. Drake,
and
Michael A. Cotta
Fermentation Biotechnology Research Unit and Bioproducts and Biocatalysis Research Unit, National Center for Agricultural Utilization Research, USDA, Agricultural Research Service, 1815 N. University Street, Peoria, IL 61604, U.S.A., and Department of Ecological Microbiology, University of Bayreuth, 95440 Bayreuth, Germany
* To whom correspondence should be addressed. Email:
terry.whitehead{at}ars.usda.gov.
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Abstract |
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Skatole (3-methyl-indole) is a malodorous chemical in stored swine manure and is implicated as a component of foul tasting pork. Definitive evidence for the skatole pathway is lacking. Deuterium-labeled substrates were employed to resolve this pathway in the acetogenic bacterium Clostridium drakei and Clostridium scatologenes, and to determine if a similar pathway is used by microorganisms present in stored swine manure. Indole acetic acid (IAA) was synthesized from tryptophan by both bacteria, and skatole was synthesized from both IAA and tryptophan. Microorganisms in swine manure produced skatole and other oxidation products from tryptophan, but IAA yielded only skatole. A catabolic mechanism for the synthesis of skatole is proposed.