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United States Department of Agriculture

Agricultural Research Service

Research Project: ANAEROBIC MICROBIOLOGICAL PROCESSES IN ANIMAL MANURE MANAGEMENT Title: Determination of Breakdown Pathway of Tryptophan and Indole Acetic Acid to Skatole by Clostridium Drakei and Swine Manure Slurry


Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: June 24, 2006
Publication Date: June 24, 2006
Citation: Whitehead, T.R., Price, N.P., Cotta, M.A. 2006. Determination of breakdown pathway of tryptophan and indole acetic acid to skatole by Clostridium drakei and swine manure slurry [abstract]. Reproduction Nutrition Development. 46(S60):113.

Technical Abstract: Production of the odorant chemical skatole (3-methyl-indole) is a problem both within swine (boar taint) and during storage of swine manure, where skatole can contribute to odor production from large-scale swine facilities. Previous research has suggested that skatole is produced from the bacterial breakdown of tryptophan, but definitive proof has not been published. Clostridium drakei (formerly C. scatologenes) is one of the few isolated bacterial strains reported to produce skatole. Skatole production was initially determined from medium containing increased levels of tryptophan or indole acetic acid (IAA) using gas chromatography-mass spectrometry (GC-MS) following growth of C. drakei. In order to conclusively determine that skatole was being produced from these substrates, deuterium-labeled tryptophan or IAA was added to the medium and deuterated products were identified by GC-MS. Deuterated skatole was found to be synthesized from both tryptophan and IAA, and deuterated IAA was also formed from tryptophan. When the same deuterium-labeled substrates were incubated with fresh swine manure slurry, deuterated IAA and skatole were again identified, as well as a number of oxidation products. These results demonstrate conclusively that skatole can be derived from tryptophan and/or IAA by C. drakei, and bacteria are present in stored swine manure that can produce skatole and other products from these substrates.

Last Modified: 4/22/2015
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