Suitable carbon sources selection and ranking for biodiesel production by oleaginous Mucor circinelloides using multi-criteria analysis approach

Crude oil is the most important raw material used in chemical industry and for energy supply. Microbial lipids are ideal for various industrial applications as an alternative to conventional fuel. However, the main factor controlling the total production costs is the choice of the growth substrates. For this reason, economically feasible substrate such as agro-industrial residues has been explored. In addition, the most suitable substrates for biodiesel production were selected by PROMETHEE-GAIA analysis on the basis of the fatty acid profile of the produced oils. Six strains were selected as the best lipid producer among twenty-three fungal strains screened by colorimetric methods. The strains identified belong to the genera Fusarium and Mucor. Mucor circinelloides was chosen for comparative evaluation of the accumulation performance with different carbon sources. The use of soap stock of refined soybean oil, waste cooking oils and soap stock of refined olive-pomace successfully resulted in improved lipid yield (4.07, 2.69 and 2.44 g/L) (rho = 0.001; rho > 0.05) and the lipid content at 46%, 51% and 44% (rho = 0.049; rho < 0.05) respectively. The ability to use low-cost agro industrial raw materials for the production of microbial lipids has been proven. The fatty acid profile of M. circinelloides grown on used cooking oils improved the level of linoleic acid (56.26%) that can be valorized as additive in health and dietary supplements. Glucose, refined olive-pomace oil soap stock, and refined soybean oil have influenced the resulting fatty acid profile and meet the characteristics required for successful biodiesel production.