Considering the demand from many industrial sectors, the production of microbial lipids constitutes an attractive topic for research. Oleaginous microorganisms can produce over 60% of their dry matter in single cell oils (SCOs), especially in the form of triglycerides (TAGS). Approximately forty microbial genera, especially yeasts and moulds, are known to be high lipid producers. Many abiotic factors, such as the culture conditions or nutriment availability, influence the production of microbial lipids that are of interest. Among the factors that can influence SCO production, the carbon source, limiting nutriments (especially nitrogen), pH and temperature are cited most often in the literature. Improvement in SCO production through the optimisation of abiotic factors encounters several limitations. Thus, research is currently increasingly oriented toward genetic modifications to optimise the synthesis of lipids by oleaginous microorganisms. (C) 2014 Elsevier Ltd. All rights reserved.