| Summary: | 碩士 === 大同大學 === 生物工程學系(所) === 97 === Gluconic acid is derived by fermentation. Gluconic acid and its salts can be applied in food, pharmaceutical, steel and cement industries. In the present work, the fermentative production of gluconic acid in a 5-liter fermenter was investigated. Glucose served as substrate and calcium hydroxide was used as neutralizing agent. The seed culture was carried out in a 500-mL shake flask containing 150 mL of culture medium composed of the following ingredients in gram per liter: glucose 50, (NH4)2HPO4 1, KH2PO4 0.5 and Mg SO4•7H2O 0.15 (pH 7.0). After inoculated with spores at a dose of 106/mL, the culture was incubated in a 30°C shaker at 200 rpm for 12 hours Two flasks of seed culture were inoculated in a 5-liter fermenter containing 3 liters of fermentation medium composed of similar ingredients to the seed culture except glucose, which was in concentrations of 120 and 150 g/L. The fermentation was carried out at 30°C, 1 vvm and 600 rpm. During the fermentation, the pH of the culture broth decreased due to the production of gluconic acid. The pH of the culture broth was controlled at pH 5.5 ± 0.2 by adding a 20% Ca(OH)2 suspension using a peristaltic pump, which was pulsed automatically through a pH controller. When 120 g/L of glucose was used, the fermentation completed in 24 hours with a final concentration of gluconic acid at 124 g/L and a yield of 103%（yield =100% × mass of gluconic acid / mass of glucose）. When 150 g/L of glucose was used, the fermentation completed in 32 hours with a final concentration of gluconic acid at 153 g/L and a yield of 102%.
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