In this study, the oleaginous yeasts cultured in tomato waste hydrolysates (TWH) to produce microbial lipids that offer a suitable alternative to vegetable oils as feedstock for the biodiesel synthesis. The TWH were prepared by acid hydrolysis (2.5% H2SO4). To obtain higher growth rates, as well as higher lipid contents, Lipomyces starkeyi were cultured under original nitrogen content (TWHON), lower nitrogen content (TWHLN), attained by alkaline precipitation of TWHON followed by centrifugation and filtration, and higher nitrogen content (TWHHN), prepared by addition of (NH4)2SO4.
To reduce the effect of the inhibitors of the microbial growth (acetic acid, furfural etc.) generated during the acid hydrolysis of tomato waste, the hydrolysates were preliminary diluted. However, the highest values of microbial growth and biomass yield were observed when using undiluted medium with lower nitrogen content. The addition of a N source to the medium had no significant effect on the growth rate of the yeasts, as well as on lipid accumulation. The distribution of fatty acids in microbial lipids was almost similar to that of plant oils. Consequently, these lipids can be used to synthesize a biodiesel offering excellent performances as automotive fuel.