Abstract
Filamentous fungus, genus Mortierella has a high productivity of fatty acids, such as γ-linolenic acid.Mortierella alpina produces extraordinarily high percentages of arachidonic acid (AA), terminal metabolite of n-6 fatty acids, in intracellular lipids. The essential nutrients were organic nitrogen, minerals, and sugar. The highest AA contents and yields were 71.2% and 11.1g/L for liquid cultivation and 80.2% and 13.1g/kg-medium for solid cultivation, respectively. These results are attributed to neither high growth amounts nor high lipid contents of the fungus but to high activities in enzymes involved in chain elongation and (Δ9, Δ12, Δ6, Δ5) desaturases. Fungal form changed from pulp to pellets under starvation and high agitation with AA content increase until dying. In addition the fungus excreted prostaglandins (PGE1, PGE2, PGF2α) over days in a liquid medium and also converted AA added in the medium to those prostaglandins. Thus, M. alpina shows the specificity of remarkable AA/PG productivities and is an interesting model for n-6 fatty acid metabolism.
