The degradation of lignocellulosic materials needs the combined and synergistic action of a complex array of enzymes. Our focus has been to discover, express, and engineer xylanolytic enzymes for the deconstruction of the hemicellulose fraction. Complete enzymatic hydrolysis of arabinoxylans requires (1) endo-xylanase and β-xylosidase which act on the xylan main chain, and (2) auxiliary enzymes, which remove the side chains and break crosslinks between xylan and other cell wall polymers.  Metagenomic screening of microbial sources is used to isolate novel genes, which are cloned into E. coli or yeast systems for expression.  The gene products are purified and characterized for biochemical optimization.  The xylanolytic enzymes in development include: endo-β-1,4-xylanases, β-xylosidases, α-L-arabinofuranosidases, acetylxylan esterases, and feruloyl esterases.  Bifunctional and chimeric genes are constructed, expressed, and characterized.