Bifunctional acetylxylan esterase/xylanase involved in the hydrolysis of xylan, a major structural heterogeneous polysaccharide found in plant biomass representing the second most abundant polysaccharide in the biosphere, after cellulose. Degrades xylan from acetylxylan, beechwood, birchwood, and oat spelt, and releases acetate from 4-methylumbelliferyl acetate and beta-D-xylose tetraacetate. No activity is observed against carboxy methyl cellulose, beta-glucan, p-nitrophenol acetate, p-nitrophenol laurate, p-nitrophenol myristate, p-nitrophenol, palmitate, or beta-naphthol acetate. Deacetylation of xylans and xylo-oligosaccharides. Endohydrolysis of (1->4)-beta-D-xylosidic linkages in xylans. Optimum pH is 5.8 for acetylxylan esterase activity, and 5.8 for endo-1,4-beta-xylanase activity. Optimum temperature is 58 degrees Celsius for acetylxylan esterase activity, and 49 degrees Celsius for endo-1,4-beta-xylanase activity. Glycan degradation; xylan degradation. In the N-terminal section; belongs to the axeA family. In the C-terminal section; belongs to the glycosyl hydrolase 11 (cellulase G) family.