裂殖壶藻发酵过程中脂肪酸合成代谢规律及其影响因素探讨

Anabolism regulation of fatty acids and its influencing factors during Schizochytrium fermentation process

探究裂殖壶藻(Schizochytrium sp.)A3-9在不同发酵条件下生物量和脂肪酸含量的变化规律。结果显示,初始葡萄糖含量90 g/L,碳氮比8时最有利于裂殖壶藻生物量积累,此时生物量可达38.12 g/L,较对照组提高了104.59%;装液量220 m L/500 m L,柠檬酸添加量1.6 g/L,碳氮比23时总脂肪酸的积累可达47.16 g/100 g藻粉,较对照组提高了40.25%。不同发酵条件下裂殖壶藻胞内脂肪酸的代谢流量分布分析显示,初始葡萄糖含量90 g/L,碳氮比8,装液量60 m L/500 m L,柠檬酸和苹果酸添加量1.6 g/L时最有利于乙酰辅酶A(CoA)流入聚酮合酶(PKS)途径合成不饱和脂肪酸,此时不饱和脂肪酸与饱和脂肪酸含量之比可达1.15,相比对照组提高了21.28%;而当碳氮比14.75,装液量220 m L/500 m L时二十二碳六烯酸(DHA)与二十二碳五烯酸(DPA)含量之比可达6.82,较对照组提高了3.02%。

The change regulations of biomass and fatty acid contents of Schizochytrium sp.A3-9 were studied under different fermentation conditions.The results showed that the optimal fermentation conditions for biomass accumulation of Schizochytrium sp.were as follows:initial glucose content 90 g/L and carbon-nitrogen ratio 8.Under the optimal condition,the biomass could reach 38.12 g/L,which was 104.59%higher than that of the control group.The optimal fermentation conditions for total fatty acid accumulation were as follows:liquid loading volume 220 ml/500 ml,citric acid addition 1.6 g/L,and carbon-nitrogen ratio 23.Under the optimal condition,the content of total fatty acids could reach 47.16 g/100 g algal powder,which was 40.25%higher than that of the control group.The fatty acid metabolic flux distribution in the cell of Schizochytrium sp.under different fermentation conditions showed that when the initial glucose content was 90 g/L,liquid loading volume was 60 ml/500 ml,carbon-nitrogen ratio was 8,the addition of citric acid and malic acid were 1.6 g/L,it was most beneficial to the synthesis of unsaturated fatty acid by acetyl-CoA(CoA)influx into the polyketide synthase(PKS)pathway.Under the condition,the ratio of unsaturated fatty acid to saturated fatty acid contents could reach 1.15,which was 21.28%higher than that of the control group.When carbon-nitrogen ratio was 14.75 and liquid loading volume was 220 ml/500 ml,the content ratio of docosahexaenoic acid(DHA)to docosapentaenoic acid(DPA)could reach 6.82,which was 3.02%higher than that of the control group.