Abstract: Provided are microorganisms, e.g., the Saccharomyces yeast, that have been made able to co-ferment xylose sugar-obtained from hydrolyzing plant cellulosic biomass form trees, grasses, straws, etc., with glucose that can be obtained from hydrolyzing either edible feedstocks such as starch, cane sugar, etc. or from hydrolyzing cellulose from various types of non-edible cellulosic biomass. The microorganisms are also capable of expressing an amylase, e.g., glucoamylase, having nonnegligible enzymatic activity, capable of producing glucose from oligo- or polysaccharides obtained by treating soluble starch with ?-amylase. In some embodiments, nucleotidic material is provided comprising genes actively expressing xylose reductase, xylitol dehydrogenase and xylulokinase as well as an active gene expressing glucoamylase. Vectors and other compositions of matter are provided as.