novel strains of microalgae which belong to the botryococcus genus and which can grow in a mixotrophic mode and a cultivation method which includes providing light in the form of flashes for the production of lipids and hydrocarbons in particular in the form of botryococcenes which are useful in the production of biofuel application_number US 201113878468 A description the present invention thus concerns a method making it possible to screen or select strains of unicellular algae microalgae in particular of the botryococcus genus capable of ensuring a high yield in the production of lipids and hydrocarbons the selected algae are capable of growing both in mixotrophic mode therefore using one or more carbon containing substrates as an energy source and taking advantage by photosynthesis of a variable or discontinuous supply of light algae having these properties are considered as having a higher lipid and hydrocarbon production potential than others the invention also concerns a method for the culture of microalgae of the botryococcus genus using a variable or discontinuous light supply under conditions similar to those used for the selection of the microalgae this method is characterized in that the light flux supplied to the cultured algae is variable or discontinuous over time in contrast to conventional wisdom it was found that variable or discontinuous illumination.