无锡他汀分离式分段发酵初步研究

Studies on Separative Subsection Fermention of Wuxistatin

无锡他汀是一种新型HMG-CoA还原酶抑制剂,由洛伐他汀经拟无枝酸菌(Amycolatopsis sp.ST2710)转化产生的产物之一。转化产物Ⅰ则作为洛伐他汀转化为无锡他汀的中间产物,是影响无锡他汀生成及其产量的关键因素。研究发现,发酵过程中2种产物形成时的pH值有所不同。为提高无锡他汀产率,研究以pH值为主要调节因素,对发酵过程pH值调节、菌体补加和pH值协同调节,以及分离式分段发酵工艺进行了较全面的考察。结果表明,分离式分段发酵模式最好,即将产物Ⅰ分离提纯后作为底物再次发酵生成无锡他汀,2个阶段的pH值分别为7.5和5.5。同时也考察了金属离子对发酵的影响,研究表明,Fe2+、Mg2+和Cu2+对2种产物的生成均有一定促进作用。经策略优化,无锡他汀转化率提高15%,缩短了发酵时间,并使最终产物更易纯化。这种利用同菌株分离式分段发酵模式广泛为生成过程中存在中间产物或发酵时间较长的发酵过程的研究提供参考。

Wuxistatin was a novel inhibitor of 3-hydroxy-3-methylglutary（HMG）-CoA reductase which was the rate-limiting enzyme in the process of cholesterol synthesis.Amycolatopsis sp.ST2710 could convert lovastatin into wuxistatin.ProductⅠ,as the intermediate,was the key factor of producing wuxistatin.It was found that two products had different optimum pH.To increase the yield,the study took pH as the main factor to investigate by three ways;adjusting pH during fermentation;adjusting pH cooperated with adding fresh bacteria solution;separative subsection fermentation.Finally we found that the separative subsection fermentation had the best result.So the method was introduced;firstly,productⅠwas formed from lovastatin,pH 7.5 and pured by macroporous resin;then the conditions of fermentation were changed to pH 5.5 for transferring pured productⅠto wuxistatin.At the same time,the effect of some metal ions on transformation was studied and the result showed that Fe2＋,Mg2＋ and Cu2＋ could improve fermentation level.By this way,the convertion would increase by 15%,the time was shorten by a big margin and the final product would be more easily to purify.The fermentation pattern that based on one strain could provide reference for the study of fermentation with intermediate product and long-time fermentation.