氮源和溶氧限制对裂殖壶菌Schizochytrium limacinum SR21合成二十二碳六烯酸的影响

Effects of nitrogen starvation and oxygen limitation on docosahexenoic acid production by Schizochytrium limacinum SR21

本文研究了氮源限制和溶氧限制对二十二碳六烯酸(DHA)合成的影响。摇瓶实验表明0.4 g/L氮源(以氮元素计)最适合油脂和DHA积累,最佳C:N为80:1。在7 L发酵罐中研究了氮源限制条件下不同溶氧水平对DHA合成的影响,在1%、5%、10%溶氧水平下,DHA占总脂肪酸的百分比分别为50.95%、44.41%、38.99%,DHA产量分别为7.07、11.5、7.45 g/L。结果表明在氮源限制条件下低溶氧更利于DHA合成,DHA最高产量达11.5 g/L,与摇瓶发酵和单一的氮源限制发酵相比,分别提高了300%和50%,因此氮源限制时控制溶氧水平为5%的条件下最利于DHA发酵。

Effects of nitrogen and oxygen limitations on docosahexenoic acid （DHA） production by Schizochytrium limaci- num SR21 were investigated. Shaking-flask fermentation showed that 0.4 g/L nitrogen concentration was preferred for lip- id accumulation and DHA biosynthesis. The optimum ratio of carbon to nitrogen （C/N） was 80 ： 1. Three batches of fer- mentation were performed in 7 L bioreactor in which Schizochytrium limacinum SR21 was exposed to 1% ,5% ,10% dis- solved oxygen limitation, so as to compare the influence of oxygen limitation on DHA biosynthesis during nitrogen depletion stage. The results indicated that the content of DHA in total fatty acids was 50.95%, 44.41% and 38.99%, respective- ly ; and DHA yield was achieved by 7.07, 11.5,7.45 g/L, respectively. It showed that lower dissolved oxygen level was favorable for DHA biosynthesis. Combine nitrogen starvation with dissolved oxygen limitation strategy, DHA yield reached 11.5 g/L and was increased by 300% and 50% respectively as compared with those of shaking-flask and sole nitrogen starvation fermentation. As a result, 5% dissolved oxygen limitation was most preferred for DHA fermentation during nitro- gen depletion stage.