Recently two attempts have been made to permit Y. lipolytica to grow on xylose. Firstly, Stephanopoulos and Tai (2013) overexpressed XR and XDH of S. stipitis in Y. lipolytica strain Po1g. Although the modified strain was unable to use xylose, the authors performed an adaptation that resulted in moderate growth on xylose (doubling time of around 25 h). The engineered strain was cultured with helper substrates such as glucose or glycerol, and the ability to produce lipids was tested. A biomass of 18 g/L (13 g/L generated by glycerol) and 7.64 g/L of lipids, as well as 9.13 g/L citrate, was achieved from 20 g/L glycerol and 80 g/L xylose.