Degradation of tryptophan and related indolic compounds by ruminal bacteria, protozoa and their mixture in vitro.
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.
Mohammed
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Laboratory of Animal Nutrition and Biochemistry, Faculty of Agriculture, Miyazaki University, Miyazaki, Japan.
Onodera
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R
Or-Rashid
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MM
D000818:Animals; D001419:Bacteria / Q000378:metabolism*; D056890:Eukaryota / Q000378:metabolism*; D006041:Goats; D006868:Hydrolysis; D007211:Indoles / Q000378:metabolism*; D012417:Rumen / Q000382:microbiology* / Q000469:parasitology*; D014364:Tryptophan / Q000378:metabolism*
D007211:Indoles; D014364:Tryptophan