Exploitation of Oleaginous Yeasts for the Production of Microbial Oils from Agricultural Biomass

Lignocellulosic wastes from Arundo donax (AR) and Sorghum bicolor (SB) were used as a source of fermentable sugars for culturing the oleaginous yeasts Lipomyces starkey. In order to minimize the generation of inhibitors of the microbial growth, that is a serious bottleneck still limiting the industrial production of microbial oils, the lignocellulosic materials were first steam-exploded and subsequently treated with commercial preparations of cellulases and ß-glucosidases. This treatment made possible the growth of yeasts in the presence of raw hydrolysates, thus improving the production of microbial oils from oleaginous yeasts, potentially allowing a sustainable production of II- generation biodiesel. The conditions of the hydrolysis of the AD and SB, as well as the conditions of the fermentation of the hydrolysates, were optimized in order to maximize both the microbial biomass yield and the lipid fraction of the biomass. The composition of the triglycerides obtained adopting such conditions were compatible with the production of a good-quality automotive biodiesel.