METHOD OF 2-KETO-L-GULONIC ACID OR ITS SALT PREPARING Russian patent published in 1998 - IPC

FIELD: biotechnology. SUBSTANCE: 2-keto-L-gulonic acid or its salt is prepared by enzymatic conversion of D-sorbitol. Method involves culturing microorganism of genus Gluconobacter and Acetobacter showing capability to produce L-sorbose from D-sorbitol and microorganism showing capability to produce 2-keto-L-gulonic acid from L-sorbitol (strain Gluconobacter oxidants DSM N 4025). Culturing is carried out on medium containing D-sorbitol and the indicated two microorganisms in medium for complete culturing period. The following microorganisms were used: Gluconobacter suboxydants, Gluconobacter gluconicus, Gluconobacter albidus, Gluconobacter cerinus, Acetobacter acetixylinum. Process is carried out at pH = 5-8, at 18-33 C, at sorbitol concentration 20-120/l in nutrient medium. 2-Keto-L-gulonic acid can be isolated and purified by the known methods and obtained as a corresponding salt (for example, sodium, potassium, calcium, ammonium salt) which can be used then for conversion to L-ascorbic acid directly. EFFECT: improved method of preparing. 5 cl, 3 tbl