Yeasts for bioconversion of crude glycerol to high-value chemicals

Abstract

Biodiesel production is a fast-growing industry. Biodiesel is obtained through transesterification of different kinds of oils with methanol. This process results in a formation of substantial amounts (up to 10% of a total product mass) of the by-product fraction that mainly contains glycerol but also some toxic contaminations (spent catalyst, salts after neutralization, residual methanol, methyl esters, and free fatty acids), and that is therefore called crude glycerol. Efficient utilization of this fraction is imperative to the sustainability of the biodiesel industry. This review describes different methods of valorization of the crude glycerol fraction with the focus on biotechnological processes conducted by yeasts. In particular, production of organic acids, polyols, ethanol, microbial oil, carotenoids, γ-decalactone, sophorolipids, heterologous proteins, and biomass is discussed.