A method for simultaneous saccharification and fermentation comprising culturing a complete fermentation medium, said complete fermentation medium comprising at least one fermenting microorganism, at least one xylan-containing biomass, at least one cellulase, at least one hemicellulase, and at least one inverting β-xylosidase, for a period and under conditions suitable for producing a fermentation product which is an alcohol, wherein at least one inverting β-xylosidase is a GH43 family enzyme which is an Fv43D, a Pf43A, an Fv43E, an Fv43B, an Af43A, an Fo43A, a Gz43A, or a XynB3 polypeptide, wherein: (i) the Fv43D polypeptide has at least 90% sequence identity to an amino acid sequence corresponding to SEQ ID NO:2, or to residues 21 to 350 of SEQ ID NO:2; or (ii) the Pf43A polypeptide has at least 90% sequence identity an amino acid sequence corresponding to SEQ ID NO:8, or to residues 21 to 445 of SEQ ID NO:8; or (iii) the Fv43E polypeptide has at least 90% sequence identity to an amino acid sequence corresponding to SEQ ID NO:10, or to residues 19 to 530 of SEQ ID NO:10; or (iv) the Fv43B polypeptide has at least 90% sequence identity to an amino acid sequence corresponding to SEQ ID NO:12, or to residues 17 to 574 of SEQ ID NO:12; or (v) the Af43A polypeptide has at least 90% sequence identity to an amino acid sequence corresponding to SEQ ID NO:14, or to residues 15-558 of SEQ ID NO:14; or (vi) the Fo43A polypeptide has at least 90% sequence identity to an amino acid sequence corresponding to SEQ ID NO:24, or to residues 21-348 of SEQ ID NO:24; or (vii) the Gz43A polypeptide has at least 90% sequence identity to an amino acid sequence corresponding to SEQ ID NO:22, or to residues 19-340 of SEQ ID NO:22; or (ix) the XynB3 polypeptide has at least 90% sequence identity to an amino acid sequence corresponding to SEQ ID NO:25; and the complete fermentation medium comprises a greater amount of inverting β-xylosidases than that of retaining β-xylosidases on a mole basis. (i) the Fv43D polypeptide has at least 90% sequence identity to an amino acid sequence corresponding to SEQ ID NO:2, or to residues 21 to 350 of SEQ ID NO:2; or (ii) the Pf43A polypeptide has at least 90% sequence identity an amino acid sequence corresponding to SEQ ID NO:8, or to residues 21 to 445 of SEQ ID NO:8; or (iii) the Fv43E polypeptide has at least 90% sequence identity to an amino acid sequence corresponding to SEQ ID NO:10, or to residues 19 to 530 of SEQ ID NO:10; or (iv) the Fv43B polypeptide has at least 90% sequence identity to an amino acid sequence corresponding to SEQ ID NO:12, or to residues 17 to 574 of SEQ ID NO:12; or (v) the Af43A polypeptide has at least 90% sequence identity to an amino acid sequence corresponding to SEQ ID NO:14, or to residues 15-558 of SEQ ID NO:14; or (vi) the Fo43A polypeptide has at least 90% sequence identity to an amino acid sequence corresponding to SEQ ID NO:24, or to residues 21-348 of SEQ ID NO:24; or (vii) the Gz43A polypeptide has at least 90% sequence identity to an amino acid sequence corresponding to SEQ ID NO:22, or to residues 19-340 of SEQ ID NO:22; or (ix) the XynB3 polypeptide has at least 90% sequence identity to an amino acid sequence corresponding to SEQ ID NO:25; and the complete fermentation medium comprises a greater amount of inverting β-xylosidases than that of retaining β-xylosidases on a mole basis.