Abstract
Sulfaguanidine-resistant mutant S-225, derived from a tryptophan-producing 5-fluorotryptophan-resistant mutant of Brevibacterium flavum, accumulated 19 g/liter of L-tryptophan at maximumwhencultured for 72hr in a mediumcontaining 13%glucose as carbon source, 1.8-fold higher than did the parent. Strain S-225 accumulated 17 g/liter of L-tryptophan in a medium containing 10% sucrose as carbon source (17% yield based on the sugar). It also accumulated 450mg/liter of chorismate, an intermediate commonto the biosyntheses of tryptophan and p-aminobenzoate. The accumulation was 1.7-fold higher than that by the parent, suggesting that the intracellular concentration of chorismate was increased through acquisition of the sulfaguanidine resistance. Sulfaguanidine-resistant mutants were also derived from a tryptophanproducing mutant of Corynebacterium glutamicum. The mutants showed 2.2-fold higher maximumtryptophan production than did the parent.
