研究了在250 mL摇瓶发酵过程中添加豆油和丙氨酸对利福霉素SV生物合成的影响。72 h分别向培养基中添加3 mL/L豆油和0.8 g/L丙氨酸,发酵液中利福霉素SV的效价分别比对照提高5.3%和6.9%。通过响应面分析法优化考察了豆油和丙氨酸对利福霉素SV合成的交互作用,确定在72 h添加0.89 g/L的丙氨酸和2.57 mL/L豆油时,摇瓶发酵单位是5 179 U/mL,比对照提高12.3%。有机酸分析结果显示,发酵培养72～120h,添加组的α-酮戊二酸和柠檬酸的利用速率分别是0.86 mg/(L.h)和0.77 mg/(L.h),分别比对照提高了115.7%和23.3%;同时,琥珀酸浓度上升到1.01 g/L,添加组比对照提高了16.1%。说明添加豆油和丙氨酸后,TCA循环由柠檬酸、α-酮戊二酸到琥珀酸转化效率提高,从而促进了琥珀酰CoA和甲基丙二酰CoA的合成,有利于利福霉素SV的合成。

Effects of soybean oil and alanine on rifamycin SV biosynthesis in 250 mL flask were studied in this paper.When 3 mL/L soybean oil and 0.8 g/L alanine was added into the medium at 72 h,rifamycin SV production was increased by 5.3% and 6.9% over the control,respectively.Response surface methodology was used to study the interaction between soybean oil and alanine.Result showed that their optimal amount was 2.57 mL/L and 0.89 g/L,respectively.Under the optimal conditions,rifamycin SV production reached 5179 U/mL that was 12.3% higher than control.The results of organic acids analysis demonstrated that utilization rate of a-ketoglutarate and citriate was 0.86 mg/(L·h) and 0.77 mg/(L·h),respectively,which was 115.7% and 23.3% higher than that of control in the fermentation process from 72 h to120 h.Meanwhile,succinate concentration reached 1.01 g/L that was 16.1% higher than the control.The result indicated that the conversion efficiency of a-ketoglutarate and citrate to succinate in the TCA cycle was greatly improved with the addition of oil and alanine,which led to enhanced synthesis of succinyl-CoA and methylmalony-CoA and the facilitation of rifamycin SV biosynthesis.