Process for production of organic acids

Disclosed is a process for producing L-tartaric acid or a salt thereof and/or glycolic acid or a salt thereof from glucose, which comprises the following steps (A) to (C): (A) culturing a microorganism capable of producing 5-keto-D-gluconic acid from glucose in a glucose-containing culture medium in the presence of an alkali capable of producing a water-soluble salt of 5-keto-D-gluconic acid, thereby producing a culture containing a water-soluble salt of 5-keto-D-gluconic acid; (B) adjusting the pH value of the culture containing the water-soluble salt of 5-keto-D-gluconic acid, which has been produced in step (A), to 7 to 12 and retaining the culture at that pH value, thereby producing a reaction solution in which the water-soluble salt of 5-keto-D-gluconic acid is converted into L-tartaric acid or a salt thereof and/or glycolic acid or a salt thereof; and (C) collecting L-tartaric acid or the salt thereof and/or glycolic acid or the salt thereof from the reaction solution which has been produced in step (B).