In a micro-algae culture method, at least one strain of microalgae is grown in one bioreactor, predominantly with the accumulation of carotenoids in its cell biomass and at least one other strain of microalga predominantly with the accumulation of polyunsaturated fatty acids in its cell biomass. Preferably, they are cultivated as a strain predominantly with the accumulation of carotenoids in their cell biomass of green algae of the order Sphaeropleales, in particular the green alga Scenedesmus sp., And as a strain predominantly with the accumulation of polyunsaturated fatty acids in their cellular biomass of the eustigmatophytic algae of the order Eustigmatales, especially the eustigmatic alga Trachydiscus sp , or eustigmatic alga Trachydiscus minutus. The strains of micro-algae cultured by the method of the invention are used as a nutritional supplement for both animal and human nutrition and for the extraction of a mixture of polyunsaturated fatty acids and carotenoids.