ABSTRACT
In order to gain the strain which has high growth vigor and whose biomass concentration satisfy further fermentation to produce arachidonic acid, we took the yield of microbes olein and arachidonic acid as evaluative index, adopted twice ultraviolet mutation, determined the time of ultraviolet irradiation by single factor expriment, and then the content of the arachidonic acid was measured by GC. The results of this experiment showed that the power of viltalight lamp was 20 W, exposure distance was 30 cm and exposure time was 80 s, lethality of spores of Mortierella isabellina was 76.4%. After twice ultraviolet mutation and repeatedly screen, a mutation of Mortierella isabellina Z80s2-109 whose arachidonic acid concentration in biomass were 3.77 times of the control strains was obtained and genetic stability.