Development of utilization of lipid containing polyunsaturated fatty acids produced by microbes.

分离得到的葱孢Mortierella alliacea n -15在烧瓶中能产生3.9 g/L花生四烯酸，在罐式发酵罐中能产生5.0 g/L花生四烯酸。该菌株能代谢可溶性淀粉和葡萄糖。我们分离到了另一种花生四烯酸产菌Achlya sp.ma-2801，该菌在细胞中也含有大量的二十碳五烯酸。从海洋中分离出8株产生二十二碳六烯酸的微生物，其中一株在罐式发酵罐中培养，似乎含有大量由二十二碳六烯酸组成的磷脂。从一株Schizochytrium sp.SR21中分离到一株能产生高水平二十二碳六烯酸的突变株MS14-13。突变体总脂肪酸中二十二碳六烯酸的含量高于野生型菌株。从蓝藻中克隆了一个编码δ -6去饱和酶的基因，并在酵母中进行了功能表达，成功地将外源亚油酸转化为γ -亚麻酸。我们在分析过敏患者的血清脂肪酸组成时发现，个体患者的RAST值与其血脂中亚油酸的含量呈正相关，提示过敏患者的δ -6去饱和酶活性降低。认为脂肪酸脱饱和和链延伸多酶系统的操作是培养产生多不饱和脂肪酸的微生物所必需的。分离脱饱和酶缺陷突变体和/或克隆这些酶的编码基因是必不可少的。

An isolated fungus Mortierella alliacea YN-15 had a capable of producing 3.9 g/L of arachidonic acid in a flask and 5.0 g/L in a jar fermentor. This strain could metabolize soluble starch as well as glucose. We isolated another arachidonic acid producing microbe Achlya sp.ma-2801 which also contained a significant amout of eicosapentaenoic acid in the cell. Eight stains of microbes producing docosahexaenoic acid were isolated from the sea and one of them, by cultivation in a jar fermentor, appeared to contain high amount of phospholipids consisted of docosahexaenoic acid. A mutant strain MS14-13 that produced higher level of docosahexaenoic acid was isolated from a strain Schizochytrium sp.SR21. The mutant showed higher content of docosahexaenoic acid in total fatty acid than of wild type strain. A gene encoding delta-6 desaturase has been cloned from blue algae and expressed functionally in yeast resulting a successful conversion of exogenious linoleic acid into gamma-linolenic acid.We found, in analyzes of serum fatty acid compositions of allergic patients, RAST value of indivisual patients had a positive correlation with linoleic acid content in their plasma lipid, suggesting the depressed activity of delta-6 desaturase in allergic patients.It is considered that the manipulation of multi-enzyme system of fatty acid desaturation and chain elongation is neccessary for breeding of microbes producing polyunsaturated fatty acids. Isolation of mutants defective in desaturase enzymes and/or cloning of genes coding for such enzymes would be indispensable.