Prospect of agro-industrial residues as feedstock of biodiesel

Oleaginous yeasts can use different kinds of residues as nutrients. Their biomass contains a significant fraction (>20%) of lipids, that can be used as feedstock for biodiesel production. Lipomyces starkeyi were able to survive and proliferate in the presence of olive mill wastewater (OMWW), without external organic supplement, in spite of the antimicrobial activity of their phenolic components. Some cellulosic agricultural residues were evaluated as feedstock for oleaginous yeasts. The tomato residuals were preliminarily subjected to a hydrolysis treatment, to obtain simple sugars molecules from cellulosic material. In this case, the extraction of fermentable sugars required a more complex pretreatment. A combined optimisation of the operating conditions has been carried out to achieve higher level of the (lipid/dry biomass) ratio, obtaining at the same time a satisfactory degradation of the organic matter in the feedstock. The lipids extracted from biomass have been evaluated as regards their fatty acids composition, as well as their potential for the synthesis of biodiesel.