生黑葡萄糖酸杆菌转化高浓度山梨醇的条件优化

目前,国内维生素C主要采用二步发酵法生产,其中第一步为生黑葡萄酸杆菌(Gluconobacter melano-genus)将D-山梨醇转化为L-山梨糖。考察了该菌株在提高培养基中山梨醇浓度时的发酵特性和发酵条件。实验室摇瓶实验结果显示,通风量、发酵前期及后期pH值控制、接种种液类型都影响高浓度山梨醇摇瓶发酵的转化率。以35%山梨醇浓度发酵液做种子液明显优于生产上采用的三级种子液(12%~17%山梨醇浓度),培养基前期pH值5.0~6.0,后期pH值4.2~3.9,装液量180 mL,发酵周期在30 h之内,山梨醇转化率在98%以上。培养基山梨醇浓度由23%提高到35%,发酵周期延长8 h。上述实验结果对指导生产工艺优化具有重要意义。

Conditions Optimization of Gluconobacter melanogenus to Convert High-Concentration of Sorbitol

The vitamin C production in recent China mainly adopts bi-step fermentation.One of them is to convert D-sorbitol into L-sorbose by Gluconobacter melanogenus.The fermentation characters and conditions of the strain during the increment of the sorbitol concentration in the medium were observed and studied.The results of the shaker flask experiment in the laboratory indicated that,aeration volume,the control of pH in early and later stages,and the type of inoculation liquid affected the conversion rate of high concentration of sorbitol in shaker flask.With 35% sorbitol fermentation liquid as seed liquid was obviously superior to three steps of seed liquid(12%~17% of sorbitol concentration) adopted in the production,pH of medium in early stage at 5.0~6.0,and in later stage at 4.2~3.9,filling volume at 180 mL,within 30 h of fermentation period,the conversion rate of sorbitol was over 98%.And sorbitol concentration increased from 23% to 35%,fermentation period prolonged by 8 h.The above-mentioned experimental results have very important significance to guide the optimization of the production technology.