Production Of Wuxistatin By Immobilized And Its Optimization Of Fermentation Conditions

Amycolatopsis sp. ST2710 could transform lovastatin to wuxistatin. But in the process of microbial transformation there are problems that the virtual concentration of mycelium is too low and the period of fermentation is too long. When lovastatin concentration was 0.5mg/mL, the bioconversion rate was 48% after 120h of fermentation. In this paper, immobilized the mycelium of strain ST2710 with sodium alginate, and the conditions of immobilization and fermentation were optimized.The immobilization conditions of Amycolatopsis sp.ST2710 were optimized. The results showed that the better immobilization conditions were as follows: sodium alginate 2g/100ml, calcium chloride 1g/100ml,suspended microbial cells 2.5ml/50 ml gel. Compared with free cells, the fermentation period of immobilized cells was shorted greatly, which was from 120 hours to 48 hours. And the ratio of transformation was improved. The fermentation conditions of immobilized strain ST2710 was studied primarily. The better transformation conditions were as follows: temperature 28℃, pH 7.0, cell concentration 7.5ml sodium alginate/20ml medium,rotate speed 100r/min.The effect of substrate concentration and biotransformation time were also studied. The store stability and repeated fermentation were also presented.Glass wool was selected as the adsorptive carrier and the best dosage was o.5g/20ml medium. Compared with free cells, the dry weight of cells was increased from 0.043g to 0.089g. The fermentations of adsorption cells were also studied. The results were as follows: swing-bed-adsorption, 100r/min, proliferates time 48h. By glass wools adsorption, when the lovastatin concentration was up to 3 mg/ml, the biotransformation yield was more than 50% after 96h of fermentation.The transformation rate under different inoculums was discussed, and 5% was the best. The optimization of fermentation conditions was presented. The addition of tween-80 would accelerate the bioconversion rate obviously. At the best addition point, the transformation rate was increased from 36.5% to 55% when the lovastatin concentration was 2mg/ml after 48h of fermentation.When the substrate was 5mg/mL the transformation rate could reach the peak of more than 50% through batch feed, which showed that the approach of batch feeding is available.The fermentation medium was optimized. The best fermentation medium was as follows: soluble starch 50,Hycase SF 2,corn steep liquor 3.