title: Production of 2-Keto-l-Gulonic Acid from d-Glucose by Two-Stage Fermentation.
abstract: A practical method for the production of calcium 2-keto-l-gulonate (an intermediate in the Reichstein synthesis of l-ascorbic acid) from d-glucose has been established by using a two-stage fermentation system. d-Glucose was first converted to calcium 2,5-diketo-d-gluconate by a mutant strain of Erwinia sp. in a medium containing d-glucose, corn steep liquor, (NH(4))(2)HPO(4), and CaCO(3). After a 26-h cultivation, 328.6 mg of calcium 2,5-diketo-d-gluconate per ml was obtained, with a 94.5% yield from d-glucose. This broth was used directly for the next conversion without removal of cells by treatment with sodium dodecyl sulfate. The stereospecific reduction of calcium 2,5-diketo-d-gluconate to calcium 2-keto-l-gulonate was performed with a mutant strain of Corynebacterium sp. When the cell growth reached a maximum (about 16 h) in a medium containing d-glucose, corn steep liquor, NaNO(3), KH(2)PO(4), and trace elements, NaNO(3) was added to the culture, and then the calcium 2,5-diketo-d-gluconate broth was fed over a period of about 50 h. Since the mutant strain requires a hydrogen donor for reduction, the calcium 2,5-diketo-d-gluconate broth was mixed with d-glucose before being fed. The results of four two-stage fermentations in 10-m conventional fermentors showed that an average of 106.3 mg of calcium 2-keto-l-gulonate per ml was obtained, with a 84.6% yield from d-glucose, the starting material of calcium 2,5-diketo-d-gluconate production. Calcium 2-keto-l-gulonate was stable in the broth. Neither 2-keto-d-gluconic acid nor 5-keto-d-gluconic acid was detected in the final broth.
authors.affiliation: Department of Production, Shionogi and Company, Ltd., 192, Imafuku, Amagasaki, Hyogo 660, Japan.
authors.forename: T
authors.initials: T
authors.lastname: Sonoyama
authors.forename: H
authors.initials: H
authors.lastname: Tani
authors.forename: K
authors.initials: K
authors.lastname: Matsuda
authors.forename: B
authors.initials: B
authors.lastname: Kageyama
authors.forename: M
authors.initials: M
authors.lastname: Tanimoto
authors.forename: K
authors.initials: K
authors.lastname: Kobayashi
authors.forename: S
authors.initials: S
authors.lastname: Yagi
authors.forename: H
authors.initials: H
authors.lastname: Kyotani
authors.forename: K
authors.initials: K
authors.lastname: Mitsushima