高产DHA海洋真菌Thraustochytrium sp.N4-103脂肪酸组成及其18SrRNA基因的克隆与序列分析

Profile of Fatty Acid and Cloning and Sequencing Its 18S rRNA Gene in Thraustochytrium sp.N4-103 High Producing DHA

采用松花粉垂钓法分离到一株docosahexaenoicacid(DHA)高产菌Thraustochytriumsp.N4-103.该菌株细胞油脂的脂肪酸组型为47.3%DHA,11.6%C22∶5(n-6),9.4%C20∶5(n-3),9.1%C20∶4(n-6)和22.6%C16∶0;单细胞油脂由42.6%极性脂肪,45.3.%中性脂肪和12.1%糖脂组成.细胞生长与DHA合成的最佳条件:碳源为葡萄糖,氮源为酵母膏,温度为25℃.利用PCR技术分离得到N4-103菌株18SrRNA基因并进行了克隆测序,序列含有Thraustochytrids的特征插入片段.依据18SrRNA基因序列所构建的遗传进化树表明该菌是一株与Thraustochytriumsp.KK17-3具有紧密亲源关系的未报道的破囊壶菌.

Thraustochytrium sp.N4-103 producing much docosahexaenoic acid(DHA) was isolated by using pine pollen as bait.The profile of its fatty acids in cell oil was composed of 47.3% DHA,11.6% docosapentaenoic acid (DPA), 9.4% eicosapentaenoic acid(EPA),9.1% arachidonic acid(AA) and 22.6% C16∶0.The total lipid in cell was fractionated into 42.6% polar lipid,45.3% neutral lipid and 12.1% glycolipids. The optimum condition for cell growth and DHA production was glucose as carbon source,yeast extracted as nitrogen source at 25℃.Its 18S rRNA gene was successfully isolated by PCR and sequenced.There was the specific insertion sequence shared by Thraustochytrium 18S rRNA gene.The phylogenetic tree based on Thraustochytrium 18S rRNA gene showed that Thraustochytrium sp.N4-103 was a newly isolate which was the closest to Thraustochytrium sp.KK17-3.