甘油对利福霉素SV生物合成的影响

利福霉素SV脂肪链桥部分的合成是以乙酸单位（由丙二酰CoA提供）和丙酸单位（由甲基丙二酰CoA提供）为延伸单元经过缩合、环化和后修饰而形成的，一些短链碳前体对二碳或三碳延伸单位的合成具有调节作用。研究发现添加一定量的甘油对利福霉素SV的生成具有明显的促进作用，其最适添加量为3％，添加时间以72h为宜，并且分批补加效果更好，最高提高效价21％以上。有机酸分析结果显示，甘油的加入导致乙酸和琥珀酸在胞外积累的增加，促进了EMP和TCA代谢途径，有利于利福霉素SV合成前体的积累。

Effect of Glycerol Addition on Rifamycin SV Biosynthesis

Biosynthesis of rifamycin involves the assembly of a polyketide through chain extension of an unusual starter unit,3-amino-5-hydroxybenzoic acid (AHBA) by two acetate and eight propionate units on a type I polyketide synthase (PKS). Some short chain precursors have positive effects on the production of rifmaycin. In this paper,it was found that the production of rifamycin SV could be improved by adding glycerol in the fermentation broth. The optimal concentration of glycerol was 3% and the suitable adding time was at the 72h during fermentation. Furthermore,it exhibited better effect if the glycerol was added by fed-batch and the maximum improvement of titer was 21% higher than that of control. The results of organic acids analysis demonstrated that adding glycerol led to the accumulation of acetic acid and succinate,thus malonyl-CoA and methylmalonyl-CoA biosynthesis was strengthened; consequently the production of rifamycin SV production was improved.