Molecular biologist holding a yeast genome microarray (gene chip). Microarrays help researchers determine which genes, and networks of genes, will help improve next-generation biorefinery yeasts. Engineering strains that can tolerate stressful conditions and efficiently ferment sugars from straw or other biomass, will aid increased yields of biofuels. This research is being carried out by the Agricultural Research Service (ARS) of the US Department of Agriculture.