【摘要】 为克服甾醇生物转化中存在的底物溶解度偏低的问题,拟选取多种有机溶剂、环糊精及其衍生物作为增溶剂,以探讨不同底物甾醇对其偏好性,并对增溶剂添加时间、添加量、底物的投料浓度等进行了详细研究。结果表明,植物甾醇(混合甾醇)最适于作为侧链降解转化底物,且底物甾醇对不同的增溶剂无明显偏好性。有机溶剂作为增溶剂时,乙醇和丙酮在提高产率方面均优于其它有机溶剂;而环糊精作为增溶剂时,甲基-β-环糊精效果最好,在投料浓度为15 g/L时(环糊精与底物物质的量比2:1),产率仍不低于60%。更多还原

【Abstract】 In order to solve the shortage of dioscin used in the synthesis of steroid drugs, the production of androst-4-ene-3,17-dione(AD) and other intermediates using phytosterols as the substrate has drawn great attention in recent years. The main problem of sterols conversion in side-chain cleavage of sterols by microbial fermentation is its strong hydrophobic character, which leads to poor contact between substrate and enzymes and thus results in low conversion rate and the fermentation time was delayed. In this study, 6 kinds of organic solvents and 8 kinds of cyclodextrin and their derivatives were used to enhance the dissolution of sterols in side-chain cleavage of sterols by Mycobacterium sp. MB 3863, and the preferences of different substrates on solubilizer were investigated. The results showed that phytosterols(mixture sterols) was one of the most suitable substrates in producing AD, and different substrates showed no preferences for given solubilizer to some extent. When organic solvents were used as solubilizer, ethanol and acetone were found to be the most ideal. As for cyclodextrin and its derivatives, the methyl-β-cyclodextrin was the best candidate; when the concentration of phytosterols was increased to 15 g/L, the molar yield of AD could still be over 60% at optimized feeding time and molar ratio of methyl-β-cyclodextrin to phytosterols(2:1).更多还原