BACKGROUNDThe aim of this study was to investigate how the synergistic protocols between nutrient and light affect the cell growth, lipid content and fatty acid profile of Cylindrotheca closterium. Furthermore, the flow hydrodynamics of a laboratory scale internal loop air-lift photobioreactor were investigated for the cultivation of C. closterium. RESULTSMaximum lipid productivity of 7.364 mg L-1 d(-1), which corresponded to the maximum biomass production of 0.356 g L-1, was obtained in F/2 medium under light intensity of 56 E m(-2) s(-1), highlighting the importance of high biomass accumulation for efficient lipid production. The most abundant saturated and monounsaturated fatty acids were pentadecanoic acid (C15:0) and palmitoleic acid (C16:1) which constituted 16-45% and 17-35% of total fatty acids for all growth conditions, respectively. CONCLUSIONPalmitoleic acid was the dominant monounsaturated fatty acid, followed by oleic acid, whereas the most abundant saturated fatty acids were pentadecanoic acid and palmitic acid for C. closterium. Another notable outcome was that the fatty acid content increased in N-free medium under low light intensity, while nitrogen starvation did not affect the fatty acid content under high light intensity. (c) 2015 Society of Chemical Industry