L-缬氨酸对Streptomyces natalensis HW-2合成纳他霉素的影响

Effect of L-Valine on Biosynthesis of Natamycin by Streptomyces natalensis HW-2

以Streptomyces natalensis HW-2为研究对象,考察了添加L-缬氨酸对纳他霉素生物合成途径的影响。结果表明:在纳他霉素发酵至36 h时添加0.5 g/L L-缬氨酸,纳他霉素产量达到1.83 g/L,比对照组提高了84.85%。添加L-缬氨酸后引起菌体生物量降低和pH升高,而葡萄糖利用速率加快;胞内丙酮酸激酶(PK)、磷酸烯醇式丙酮酸羧化酶(PEPC)和丙酮酸羧化酶(PC)活性增强,柠檬酸合酶(CS)活力降低了26.57%;发酵液中丙酮酸(色谱法)、草酰乙酸(色谱法)和乙酰辅酶A(分光光度法)的含量分别提高了80.50%、53.28%和47.19%,乙酸(色谱法)、丙酸(色谱法)和α-酮戊二酸(色谱法)的含量分别提高了16.98%、10.65%和15.40%,而柠檬酸(色谱法)的含量降低了27.01%。

The effect of L-valine(L-Val) on biosynthesis pathway of natamycin by Streptomyces natalensis HW-2 was investigated. The experimental results showed that the maximal yield of natamycin reached 1.83 g/L when the adding amount of L-Val was 0.5 g/L during the fermentation of Streptomyces natalensis HW-2 for 36 h, which was 84.85% higher than that of the control. The addition of L-Val resulted in a decrease of biomass and an increase of pH, and an improvement of glucose utilization. The activities of pyruvate kinase(PK), phosphoenolpyruvate carboxylase(PEPC) and pyruvate carboxylase(PC) in intracellular enhanced,while that of citroyl synthetase(CS) decreased by 26.57%. Comparing with the control, the contents of pyruvic acid, oxaloacetic acid, acetyl-Co A in the broth increased by 80.50%, 53.28% and 47.19%,respectively. And, the contents of acetic acid, propionic acid and α-ketoglutaric acid increased by 16.98%,10.65% and 15.40%, respectively. But, the content of citric acid decreased by 27.01%.