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3-Methylindole production is regulated in Clostridium scatologenes ATCC 25775

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3-Methylindole (3-MI) is a degradation product of l-tryptophan and is both an animal waste malodorant and threat to ruminant health. Culture conditions influencing 3-MI production in Clostridium scatologenes ATCC 25775 were investigated. Extracellular 3-MI levels in cells cultured in brain heart infusion (BHI) medium (pH 7·0) at 33°C and 37°C for 72 h were 907 ± 38 and 834 ± 121 μmol l⁻¹, respectively. Cells cultured in tryptone-yeast (TY) extract medium at 37°C for 48 h produced 104 ± 86 μmol l⁻¹ 3-MI; however, addition of 1 mmol l⁻¹ l-tryptophan failed to increase extracellular levels (113 ± 50 μmol l⁻¹ 3-MI). Specific activity of indole acetic acid decarboxylase measured in BHI, TY and TY plus 1 mmol l⁻¹ tryptophan-grown cells displayed 35-, 33- and 76-fold higher levels than in semi-defined medium-grown cells. When cultured in rich medium, at 33°C or 37°C and pH 7·0, Cl. scatologenes ATCC 25775 optimally produced 3-MI. Addition of l-tryptophan to medium did not lead to significant increases in extracellular 3-MI levels. Whole cell assays indicate growth in rich medium significantly up-regulated 3-MI production. Information presented here may prove useful in understanding what factors influence 3-MI production in malodorous animal wastes.
Doerner, K.C. , Cook, K.L. , Mason, B.P.
Includes references
Letters in applied microbiology 2009 Jan., v. 48, no. 1
Blackwell Publishing Ltd
Journal Articles, USDA Authors, Peer-Reviewed
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