Breeding Strains Producing 2-KDG And Study On Fermentation Conditions

2-keto-D-gluconic acid (2-KDG) was the precursor of D-isoascorbic acid, so studying how to improved the productive efficiency of 2-KDG had important meaning for the production of D-isoascorbic acid. This research was mainly studied the mutation breeding of the strains which produced 2-keto-D-gluconic acid and the mutant strain’s best fermentation conditions.The 2-KDG producing mutant strain 064-10-101 was obtained by UV mutation, which was improved greatly compared with original strain 10-9. The conversion ratio of the strain 064-10-101 increased by 16.92%, up to 43.33%, the content of 2-keto-D-gluconic acid was up to 21.35mg/mL.The features of 064-10-101 were shown stable after 10 subcultivations.According to the microwave-Acridine Orange multi-mutation, the mutant strain F-20-42 was screened out. Compared with the original strain 064-10-101, the content of 2-keto-D-gluconic acid was up to 24.25mg/mL, increased by 13.44%, the conversion ratio was up to 49.23%. The features of F-20-42 were shown stable after 10 subcultivations.Through orthogonal design, The best fermentation medium were acquired:glucose 4%, corn steep 2%, yeast extract 6%, carbamide 0.9%, MgSO4 0.04%, KH2PO4 0.1%, pH7.5. In addition, seed age, temperature, fermentation period and inoculation amount were optimized. Thereby, the fermentation conditions of the mutant strain F-20-42 were primarily acquired.