METABOLISM OF D-TRYPTOPHAN BY A SPECIES OF FLAVOBACTERIUM

Abstract

D-Tryptophan can be utilized by a species of Flavobacterium but growth of this bacterium was very slow when D-trytophan was used as the sole carbon and energy source. The addition of other exogenous carbon sources facilitated the utilization of D-tryptophan. The growth yield was less per unit of D-tryptophan than with an equimolar concentration of DL- or L-tryptophan. D-Tryptophan was catabolized via indolepyruvic acid, L-tryptophan, N-formyl-L-kynurenine, L-kynurenine, and anthranilic acid. The organism did not possess a tryptophan racemase. D-Tryptophan was oxidatively deaminated to indolepyruvic acid which was transaminated to form L-tryptophan with L-glutamic acid, L-aspartic acid, or L-glutamine serving as the amino donor. The oxidation as well as the accumulation of anthranilic acid in the medium from D-tryptophan was slower than when L-tryptophan was the substrate. Both the production and utilization of the anthranilic acid formed during the dissimilation of D- or L-tryptophan were suppressed by N-rnethylanthranilic acid.