In order to get a Mortierella alpina which is more active and has a higher production of arachidonic acid(ARA),biomass,oil content and the production of ARA were considered as the evaluation index.The original strain M12 is managed by Co60γ-ray mutagenesis.After screening,we breed a M12-2-2 saltant.Its fermentation of biomass is 30.73 g/L.Oil length is 40.51%.ARA content is 4.75 g/L,production of which is 1.65 times higher than the orig...