Aurantiochytrium sp. was mutated by the combination of nitrosoguanidine and UV radiation. The intracellular lipid content and DHA proportion in total fatty acid of three hundred mutants were detected by means of a rapid in situ NMR method, and 10 mutants were selected considering these two indicators. Finally, one high DHA yield mutant was characterized through further characterization of its other properties. Compared with the wild strain, the mutant has equivalent
biomass but 1.17 and 1.14 times of lipid contents and DHA proportion, which reached 68% of dry cell weight and 57% of total fatty acids respectively. This mutant was designated as Aurantiochytrium sp. KYX-01, which is very suitable for the industrial production of DHA oil because of its excellent properties.