A comprehensive set of 74 fungal genes encoding enzyme types active towards all known carbohydrate linkages within plant cell wall polysaccharides were recently cloned from the saprophytic filamentous fungus Aspergillus nidulans and made publically available (Bauer et al., PNAS 103:11417–11422, 2006). Recombinant production of these enzymes provide monocomponent activity preparations (i.e., having no major competing or distinguishable side activities) and eliminate expensive labor-intensive purification from heterogeneous enzyme mixtures.  Monocomponent enzymes can be used as a high resolution analytical tool to decipher polysaccharide fine structure and as a specific biochemical tool to modify and tune functional properties of polysaccharides with commercial value.  Such enzyme preparations can also be used to evaluate and optimize complementary enzyme blends for efficient hydrolysis of plant cell walls through synergistic action.  Hemicelluloses, such as glucuronoarabinoxylans, and pectins are complex structural polysaccharides present in cell walls due to their extensive side-branching and accessory functional groups.  Selective modification or saccharification therefore requires a broad set of complementary enzymes.  We are filling our enzyme toolbox with hemicellulases and pectinases, and we will present our progress on the in vitro production and biochemical characterization of these enzymes.  Hemicellulases under investigation include endo-β-xylanases, β-xylosidases, α-arabinofuranosidases acetylxylan esterases, α-glucuronidase, and ferulic acid esterase.  Pectinases include endo- and exo-polygalacturonases, pectin methylesterase, rhamnogalacturonase, and rhamnogalacturonan acetylesterase.  Determination of substrate specificity of the xylanases will be highlighted.  These enzymes may find use in generating renewable polysaccharide-based bioproducts or for more efficient biomass conversion to liquid biofuels.