Summary.
In vitro experiments were conducted to examine the degradation of d- and l-isomers of tryptophan (Trp) and 10 related indolic compounds by mixed rumen bacteria (B), protozoa (P) and a combination of the two (BP). The analyses were carried out by HPLC. d-Trp (1.0 mM) was not degraded by rumen microorganisms during the 24-h incubation period. The net degradation of 1 mM l-Trp was 46.5%, 8.7% and 80.0% by B, P and BP suspensions, respectively. Trp was degraded into indoleacetic acid, indolelactic acid and indole by rumen bacteria and protozoa, and into skatole, p-cresol and indolepropionic acid by rumen bacteria only. Of them, indoleacetic acid was the major product of Trp found in B (15.4%) and P (3.1%), and skatole in BP (43.2%). This is the first report of the production of indolelactic acid and p-cresol from Trp by rumen microbes. Starch, d-glucose, salinomycin and monensin inhibited the production of skatole and indole from Trp, and skatole from indoleacetic acid by rumen bacteria.
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Received August 2, 2001 Accepted June 21, 2002 Published online November 14, 2002
Acknowledgements The authors are extremely grateful to Dr. H. Ogawa, Professor, the University of Tokyo and Dr. T. Hasegawa, Associate Professor, Miyazaki University, for inserting a permanent fistula in goats. The present study was financially supported by research grants from Kyowa Hakko Kogyo Co. Ltd. and Daiichi Seiyaku Co., Japan. Nazimuddin Mohammed thanks the Ministry of Education, Science, Sports and Culture of Japan (Monbusho) for the award of a research studentship from 1996.
Authors' address: Dr. Nazimuddin Mohammed, Laboratory of Agricultural Production Technology, Faculty of Agriculture, Field Science Center, Tokyo University of Agriculture and Technology, Saiwai-cho 3-5-8, Fuchu-shi, Tokyo 183-8509, Japan
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Mohammed, N., Onodera, R. & Or-Rashid, M. Degradation of tryptophan and related indolic compounds by ruminal bacteria, protozoa and their mixture in vitro. Amino Acids 24, 73–80 (2003). https://doi.org/10.1007/s00726-002-0330-8
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DOI: https://doi.org/10.1007/s00726-002-0330-8