From crude glycerol and volatile fatty acids to biodiesel and other bioproducts using Yarrowia lipolytica NCYC 2904 as a cell factory

Abstract

Biodiesel production using microbial lipids derived from low-cost feedstocks could provide a sustainable alternative for the replacement of conventional fossil fuels. This work studied fed-batch and two-stage batch cultures for microbial lipids production by oleaginous yeast Yarrowia lipolytica NCYC 2904 from crude glycerol (a by-product of the biodiesel industry) and volatile fatty acids (obtained during the anaerobic fermentation of organic wastes). Fed-batch at a constant feeding rate of the medium with 100 g L⁻¹ of glycerol and an initial dilution rate of 0.004 h⁻¹, followed by the pulse addition of an 18 g L⁻¹ VFAs mixture at the end of the fed-batch phase was the best strategy to obtain the highest intracellular lipids accumulation per dry cell mass of 38% (w/w). Microbial lipids produced by Y. lipolytica NCYC 2904 (90% of unsaturated fatty acids) were successfully converted into biodiesel, whose main properties are within the international biodiesel standards EN 14214 and are similar to those of biodiesel produced from vegetable oils. Furthermore, a high amount of citric acid (28 g L⁻¹) and total polyols (mannitol and arabitol) of 3 g L⁻¹ was produced during this bioprocess, which makes it even more interesting within an integrated biorefinery framework.