Process for the preparation of L-amino acids using a gene encoding 6-phosphogluconate dehydrogenase

A process for the preparation of an L-amino acid, comprising:

• a) fermenting an L-amino acid producing coryneform bacteria in a culture medium, the bacteria having at least an overexpressed gnd gene encoding 6-phosphogluconate dehydrogenase;
• b) concentrating L-amino acid produced by said fermenting in the culture medium or in the cells of the bacteria;
• and
• d) isolating the L-amino acid produced;
• wherein intracellular activity of pyruvate oxidase encoded by a pyruvate oxidase gene is decreased or switched off in the bacteria;
• and
• wherein the L-amino acid is selected from the group consisting of L-threonine, L-isoleucine and L-tryptophan.