Variation of fatty acids composition in the hydrocarbon producer Botryococcus braunii BOT 22

Highlights: • High fatty acids productivities were obtained with B. braunii continuous cultures. • The main fatty acids were oleic acid, palmitic acid, α-linoleic acid, erucic acid and stearic acid. • In cell density lower than 6 g L⁻¹, C16 and C18 fatty acids constituted main composition of microalgae oil content. • According to make biofuels production feasible, the biodiesel and hydrocarbon production considered simultaneously. Botryococcus braunii Bot-22, a hydrocarbon rich microalga known as a potential source of jet fuel, was photoautotrophically grown in a beveled shape flat-panel photobioreactor in continuous cultures. Two photon flux densities (PFD) 50 and 500 μmol photons m⁻² s⁻¹, two dilution rates, 0.178 and 0.357 d⁻¹ and two different inlet oxygen concentrations were applied to find suitable conditions for biodiesel production by B. braunii. The main fatty acids detected by GC-FID, were oleic acid, palmitic acid, α-linolenic acid, erucic acid and stearic acid. By doubling the dilution rate from 0.178 to 0.357 d⁻¹ at 500 μmol photons m⁻² s⁻¹ light intensity, the PUFAs decreased from 17.65% to 9.98%. In lower dilution rate, the sum of suitable fatty acids percentage for biodiesel known as oleic, palmitic, stearic, and linoleic acids was higher than all other conditions. In cell density lower than 6 g L⁻¹, C16 and C18 fatty acids constituted main composition of microalgae oil content. The maximum productivity of suitable fatty acids for biodiesel mentioned above, all together, was achieved at higher dilution rate, 21% of inlet oxygen concentration and higher light intensity while the highest hydrocarbon productivity achieved at higher dilution rate, higher light intensity and 4% of inlet oxygen concentration.