Optimization of culture conditions of Rhodotorula graminis S1/2R to obtain saponifiable lipids for the production of second-generation biodiesel

The use of biodiesel has generated a diversification of the energy matrix, which has led to a lower dependence on fossil fuels and a concomitant reduction of the adverse effects on the environment generated by their use. Currently, biodiesel is mainly produced by transesterification with short-chain alcohols of oils from different sources, in particular from oil crops, such as soybean and canola. Since the use of crops for the generation of fuels competes with their use as food, it seems appropriate to explore new oil sources for the production of biodiesel, such as the intracellular triglycerides accumulated by oleaginous yeasts. In this case, to achieve a competitive process, yeast production should be carried out using low-cost fermentable substrates such as industrial wastes or by-products. In this work we optimized the production of intracellular lipids by a previously selected oleaginous yeast strain in a fed-batch culture in presence of crude glycerol as a source of carbon and energy. In the optimized conditions an important improvement of lipid concentration was achieved, obtaining 12.2 g L−1 of fatty acid methyl esters (FAMEs) and 26.6 g L−1 of dry biomass in 360 h of culture.