Factorial design to optimize biosurfactant production by Yarrowia lipolytica.

In order to improve biosurfactant production by Yarrowia lipolytica IMUFRJ 50682, a factorial design was carried out. A 2(4) full factorial design was used to investigate the effects of nitrogen sources (urea, ammonium sulfate, yeast extract, and peptone) on maximum variation of surface tension (Delta ST) and emulsification index (EI). The best results (67.7% of EI and 20.9 mN m(-1) of Delta ST) were obtained in a medium composed of 10 g 1(-1) of ammonium sulfate and 0.5 g 1(-1) of yeast extract. Then, the effects of carbon sources (glycerol, hexadecane, olive oil, and glucose) were evaluated. The most favorable medium for biosurfactant production was composed of both glucose (4% w/v) and glycerol (2% w/v), which provided an EI of 81.3% and a Delta ST of 19.5 mN m(-1). The experimental design optimization enhanced Delta EI by 110.7% and Delta ST by 108.1% in relation to the standard process.