The present invention provides methods and compositions for the conversion of plant biomass to fermentable sugars that can be converted to useful products. The methods include methods for degrading lignocellulosic material using enzyme mixtures to liberate sugars. The compositions of the invention include enzyme combinations that break down lignocellulose. The invention includes methods to identify the optimum ratios and compositions of enzymes with which to degrade each lignocellulosic material. These methods entail tests to identify the optimum enzyme composition and ratios for efficient conversion of any lignocellulosic substrate to its constituent sugars. While the multi-enzyme product may contain many types of enzymes, mixtures comprising enzymes that increase or enhance sugar release from biomass are preferred, including hemicellulases. The enzymes of the multi-enzyme product can be provided by a variety of sources. In one embodiment, the enzymes can be produced by a growing microorganism, especially a fungus, which produce the enzymes naturally or by virtue of being genetically modified to express the enzyme or enzymes.