Mortierella isabellina cultivated in nitrogen-limited media presented remarkable cell growth (up to 35.9 g/l) and high glucose uptake even with high initial sugar concentrations (e.g. 100 g/l) in media. After nitrogen depletion, significant fat quantities were accumulated inside the fungal mycelia (50-55%, wt/wt oil in dry biomass), resulting in a notable single cell oil production of 18.1 g/l of culture medium. Total dry biomass and lipid yields presented greatly increased values (0.34 and 0.17 g respectively per gram of glucose consumed). The microbial lipid produced contained gamma-linolenic acid (GLA) at a concentration of 3.5 +/- 1.0%, wt/wt, which corresponded to 16-19 mg GLA per gram of dry microbial mass and a maximum concentration of 0.801 g GLA per liter of culture medium. (C) 2004 Elsevier Ltd. All rights reserved.