二十碳五烯酸高产菌株的诱变选育及柠檬酸对其油脂合成的影响

Mutation Breeding of High Yielding Strain of Eicosapentaenoic Acid and Effect of Citric Acid on the Lipid Synthesis

利用UV-LiCl复合诱变腐霉出发菌株,通过低温培养和苏丹Ⅱ染色镜检初筛、摇瓶发酵复筛,获得1株二十碳五烯酸(Eicosapentaenoic acid,EPA)高产菌株腐霉H6,经20℃-15℃二阶段培养168 h,所得生物量、油脂含量和EPA含量分别为23.50 g/L、17.54%和15.36%,EPA产量为633.17 mg/L,较出发菌株(263.80 mg/L)提高了140.02%,且产量、性状稳定。添加不同浓度柠檬酸对腐霉H6油脂合成调控的研究表明,发酵中期添加1.5 g/L柠檬酸可显著增加葡萄糖的利用率,提高油脂含量和EPA含量,EPA产量达890.49 mg/L,与对照相比提高40.64%。发酵实验表明腐霉H6极有潜力开发成为工业化生产菌种。

The original strain Pythium was mutated by UV combined with LiC1. After preliminary screening by low -temperature culturing and microscope observation after Sudan I1 staining, and re-screenlng by shake flask fermentation, a high -yielding eicosapentaenoic acid- producing strain Pythium H6 was obtained. Its biomass, oil and EPA content was 23.5 g/L, 17.54 % and 15.36 % respectively after two stages of 15 -20℃ culture for 168h. In addition, the EPA production of H6 was 633. 17 mg/L, which was 140.01% higher than the original strain, and the product character was stable. The study of the lipid synthesis of Pythium H6 exposed to different concentrations of ex- ogenous citric acid indicated that adding 1.5 g/L citric acid to fermentation medium can significant increase its glucose utilization, lipid and EPA content with EPA yield up to 890.49 mg/L, 40.64 % higher compared to the control. Fermentation experiments suggested that Pythium H6 has the potential to be developed into a highly industrial production strain.