Abstract
Over the last few decades, many scientists considered microalgae as promising actors for future biofuels because of the high lipid productivity inside their cells. Moreover, much attention has been paid to algal lipids as they can be used in biodiesel production. In this study, we optimized the different suitable conditions such as incubation time, incubation temperature, Dimethylesulfoxide and Nile red concentrations of the lipophilic fluorescence dye Nile red as an excellent and fast vital stain to detect and quantify intracellular lipids. This was achieved using the green alga Nannochloropsis salina. In addition, investigating the accumulation of lipid vesicles inside different isolated microalgal species as a response to temperature stress. Furthermore, the confocal laser scanning microscopy (LS510) for imaging and measuring the size and volume of the accumulated lipid vesicles was used.