Intermediate Products in the Catabolism of Amino Acids by Rumen Microorganisms

Abstract

Intermediary products arising from the catabolism of individual amino acids by rumen microorganisms were chromatographically and spectrophotometrically examined. Cheese cloth-strained rumen liquor and washed suspensions of rumen bacteria were employed. Substrate concentrations were 10 μm/milliliter. l-arginine yielded ornithine, σ-aminovaleric acid, and putrescine. l-ornithine gave rise to σ-aminovaleric acid and putrescine. l-lysine yielded σ-aminovaleric acid and cadaverine. Tests for amine production from casein hydrolysate and five individual amino acids—arginine, lysine, histidine, tryptophan, and phenylalanine—at pH 4.5, 5.5, and 6.5 were negative, except for cadaverine and putrescine. Ammonia production was usually greatest at pH 6.5, less at 5.5, and negligible at 4.5, with these same five amino acids. Lysine decarboxylase activity appeared at a more acid pH than ornithine decarboxylase. Amine production varied among inocula from diffeffrent animals, but was repeatable in both mediums from the same inocula. dl-tryphophan yielded indole and skatole in rumen fluid, but skatole appeared in trace amounts in washed-cell suspensions only in the presence of maltose. Indole and skatole concentrations of 12.8 to 19.2 and 5.7 to 7.8 μg/ml, respectively, were obtained from 24-hr rumen fluid incubations, whereas indole concentrations were 0.8 to 1.0 and 1.6 to 1.8 μg/ml in 24-hr and 48-hr washed-cell incubations, respectively. Glutaric acid was not dissimilated in vitro by rumen microorganisms. However, σ-aminovaleric (10 μm/milliliter) depressed acetic acid production. © 1962, American Dairy Science Association. All rights reserved.