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

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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.