Free fatty acids and a high initial amount of biomass in the medium increase the synthesis of mannosylerythritol lipids by Pseudozyma antarctica

It was shown that the addition of lipase to a YPG cultivation medium containing 5% (v/v) of rapeseed oil increased the yield of mannosylerythritol lipids synthesized by P. antarctica from 12.69 to 26.97g·L-1 compared to the control culture. As a renewable resource of free fatty acids for P. antarctica cultivation, post-refining fatty acids (Post-FFA) were used and after 192h a 85.43g·L-1 of biosurfactant was obtained. The experiments indicated that the biosurfactant synthesis could depend on carbon source availability and biomass concentration in the cultivation medium. The supplementation of the medium after 8 days of cultivation (fed-batch culture), with glucose to 2% (w/v) and Post-FFA to 20% (v/v), did not increase the concentration of the biosurfactant in the medium but did increase the total amount of the product from about 170 to 232g. By increasing the initial concentration of the biomass to 500g·L-1, the concentration of biosurfactant was increased to 120.50g·L-1 after 168h.