The invention relates to engineering microbial cells for utilization of cellulosic materials as a carbon source, including xylose.

Presented herein are oleaginous strains of yeast such as Saccharomyces cerevisiae that have been modified to allow for xylose utilization. Such strains are also modified to allow for higher lipid accumulation utilizing a broad range of sugar monomers such as those released during pretreatment and enzymatic saccharification of lignocellulosic biomass. Methods of producing lipids and ethanol using these yeast strains are also disclosed.

The present invention relates to a method of preparing a strain of sugar fermenting Saccharomyces cerevisiae with capability to ferment xylose, wherein said method comprises different procedural steps. The method comprises mating a first sporulated Saccharomyces cerevisiae strain with a second Saccharomyces cerevisiae haploid strain. Thereafter, screening for mated cells is performed, growing such mated cells, and verifying that mated cells exhibit basic morphology by microscopic inspection. Thereafter, creation of a mixture of the mated cells is performed, subjecting the mixture to continuous chemostat lignocellulose cultivation and obtaining the sugar fermenting Saccharomyces cerevisiae cells with capability to ferment xylose is performed. The invention also comprises strains obtained by said method.

Recombinant yeasts comprising recombinant xylose reductase, xylitol dehydrogenase, and/or xylulokinase genes and methods of using same, such as for producing ethanol from xylose-containing feedstocks.

Methods and engineered hosts are disclosed that convert a lignocellulosic xylose-containing biomass source into xylonic acid and/or xylonate, which can be further processed into other useful derivatives. In particular, an exemplary engineered Bacidiomycetes, e.g., R. toruloides, host produces/expresses one or more fungal enzymes that convert xylose into xylonic acid/xylonate. Methods of using such hosts to consume pretreated lignocellulosic biomass in combination with certain native promoters and heterologous genes are also described herein.