The Effect of Amino Acid on the Uptake and Utilization of Tryptophan and other Precursors of Nicotinic Acid by Neurospora crassa

Abstract
The influence of casein hydrolysate and certain amino acids on the uptake and utilization of tryptophan and other precursors of nicotinic-acid biosynthesis by mutant of Neurospora crassa which can grow on tryptophan or nicotinic acid was investigated. Whereas casein hydrolysate and certain amino acids inhibited the growth of the organism when tryptophan, kynurenine, or 3-hydroxykynurenine was present in the medium, they had no effect in the presence of other precursors, i. e. 3-hydroxyanthranilic acid or nicotinic acid. Studies have been made with wild strain and the mutant on the amount of tryptophan taken up from the medium at different periods of growth of the organism.