NOVELTY - Degrading arabinoxylan-containing material in xylan-containing material by mixing xylan-containing material and xylanase comprising polypeptide sequence e.g. one of 7 (305-328) amino acid sequences (SEQ ID NOs: 1-3,9,10, 11 and 15) all fully defined in the specification, variant, homologue, fragment or their derivatives having at least 75% sequence homology to the above-mentioned sequences, and xylanase obtained from Fusarium verticilloides.    USE - The method (M1) is useful for degrading arabinoxylan-containing material in xylan-containing material for preparing fermented beverage e.g. beer, producing biofuel e.g. bioethanol and biochemical e.g. bio-based isoprene and separating wheat gluten-starch. The method (M2) is useful for preparing feed stuff (all claimed).    ADVANTAGE - The method enables to degrade arabinoxylan without increasing viscosity in reaction medium and formation of high molecular weight compounds, and solubilize pentosans.    DETAILED DESCRIPTION - Method (M1) for degrading arabinoxylan-containing material in xylan-containing material involves mixing the xylan-containing material and xylanase comprising polypeptide sequence chosen from (a) one of 7 (305-328) amino acid sequences (SEQ ID NOs: 1-3,9,10, 11 and 15) all fully defined in the specification, (b) variant, homologue, fragment or their derivatives having at least 75% sequence homology to the above-mentioned sequences, (c) the above-mentioned sequences with conservative substitution of at least one of the amino acids, (d) xylanase encoded by one of 9 (942-1039) base pair sequences (SEQ ID NOs: 4,5,6,12,13,14,16,17 and 18) all fully defined in the specification, (e) sequence which hybridizes the above-mentioned sequences under high stringency conditions, (f) base pair sequence having at least 75% sequence homology to the above-mentioned base pair sequences, (g) base pair sequences which differs from the above-mentioned base pair sequences due to degeneracy of genetic code, and (h) xylanase obtained from Fusarium verticilloides. INDEPENDENT CLAIMS are included for the following:    (1) polypeptide having xylanase activity comprising sequence chosen from (a) SEQ ID NOs: 1-3, (b) variant, homologue, fragment or their derivatives having at least 99% sequence homology to the above-cited sequences, (c) polypeptide encoding nucleotide sequences of SEQ ID NOs: 4-6, and (d) nucleotide sequence having at least 97.7%, preferably 98% sequence homology to the above-cited nucleotide sequences;    (2) isolated or recombinant nucleic acid molecule and vector e.g. plasmid comprising polynucleotide sequence which encodes the above-cited polypeptide sequence;    (3) host cell comprising above-cited nucleic acid and vector;    (4) feed additive composition or premix comprising xylanase, polypeptide and optionally at least one mineral or vitamin; and    (5) method (M2) for preparing feed stuff involves mixing feed component with xylanase, polypeptide and feed additive composition.