NOVELTY - Recombinant beta-xylosidase variant and/or biologically active recombinant beta-xylosidase variant fragment (I), comprising at least one amino acid sequence comprising specified sequence identity to SEQ ID NO: 2 (a 845 amino acid sequence fully defined in the specification) and at least one mutation at position 31, 108, 115, 174, 177, 203, 209, 211, 219, 235, 264, 280, 309, 320, 322, 345, 347, 375, 379, 389, 394, 398, 431, 438, 449, 475, 482, 484, 499, 525, 539, 560, 565, 571, 572, 589, 662, 727, 761, 763, 798 and/or 842 of SEQ ID NO: 2, is new.    USE - (I) is useful for producing at least one fermentable sugar (such as glucose and/or xylose) from a feedstock by saccharification reaction to produce a fermentation end product, where the feedstock is a cellulosic and/or lignocellulosic feedstock including wheat grass, wheat straw, barley straw, sorghum, rice grass, sugarcane, sugar beet, bagasse, switchgrass, corn stover, corn fiber and/or grains and the fermentation end product is alcohol including ethanol (preferred) and butanol, fatty acids, lactic acid, acetic acid, 3-hydroxypropionic acid, acrylic acid, succinic acid, citric acid, malic acid, fumaric acid, succinic acid, amino acids, 1,3-propanediol, ethylene, glycerol and beta -lactams (all claimed).    ADVANTAGE - (I) ensures simple, effective and economical production of the fermentable sugar from the feedstock with high yields, has increased protein expression, thermoactivity, thermostability, pH activity, chemical stability, specificity, resistance to substrate or end-product inhibition and resistance to inhibitors (e.g. acetic acid, lectins, tannic acids, and phenolic compounds) and altered pH/temperature profile.    DETAILED DESCRIPTION - Recombinant beta-xylosidase variant and/or biologically active recombinant beta-xylosidase variant fragment, comprising at least one amino acid sequence comprising at least 70%, at least 75%, at least 80%, at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98% or at least 99% sequence identity to SEQ ID NO: 2 (a 845 amino acid sequence fully defined in the specification) and at least one mutation at position 31, 108, 115, 174, 177, 203, 209, 211, 219, 235, 264, 280, 309, 320, 322, 345, 347, 375, 379, 389, 394, 398, 431, 438, 449, 475, 482, 484, 499, 525, 539, 560, 565, 571, 572, 589, 662, 727, 761, 763, 798 and/or 842 positions of SEQ ID NO: 2, is new. INDEPENDENT CLAIMS are included for:    (1) an enzyme composition comprising (I), and optionally further comprising at least one additional enzyme, one or more enzymes including cellulases, hemicellulases, xylanases, amylases, glucoamylases, proteases, esterases and lipases, and/or one or more enzyme(s) including endoglucanases (EG), beta -glucosidases (BGL), type 1 cellobiohydrolases (CBH1), type 2 cellobiohydrolases (CBH2), glycoside hydrolase 61 (GH61) enzymes and xylanases;    (2) a recombinant organism comprising (I);    (3) a recombinant fungal organism comprising at least one polynucleotide comprising at least one nucleic acid sequence encoding (I), and/or at least one polynucleotide that hybridizes under stringent hybridization conditions to the polynucleotide and/or a complement of a polynucleotide that encodes a polypeptide comprising the amino acid sequence, where the polynucleotide comprises a sequence that has least 70%, at least 75%, at least 80%, at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98% or at least 99% identity to SEQ ID NOs: 1 (a 2532 base pair sequence fully defined in the specification), 4 (a 2665 base pair sequence fully defined in the specification), 6 (a 2668 base pair sequence fully defined in the specification), 8 (a 2483 base pair sequence fully defined in the specification), 10 (a 2492 base pair sequence fully defined in the specification), 12 (a 2786 base pair sequence fully defined in the specification), 14 (a 2756 base pair sequence fully defined in the specification), 16 (a 2294 base pair sequence fully defined in the specification), 18 (a 2700 base pair sequence fully defined in the specification), 20 (a 2756 base pair sequence fully defined in the specification), 22 (a 2756 base pair sequence fully defined in the specification), 24 (a 2581 base pair sequence fully defined in the specification), 26 (a 2581 base pair sequence fully defined in the specification), 28 (a 2581 base pair sequence fully defined in the specification), 30 (a 2581 base pair sequence fully defined in the specification), 32 (a 2581 base pair sequence fully defined in the specification), 34 (a 2581 base pair sequence fully defined in the specification), 36 (a 2526 base pair sequence fully defined in the specification), 38 (a 2581 base pair sequence fully defined in the specification), 40 (a 2581 base pair sequence fully defined in the specification), 42 (a 2581 base pair sequence fully defined in the specification), 44 (a 2671 base pair sequence fully defined in the specification), 46 (2581 base pair sequence fully defined in the specification), 48 (a 2581 base pair sequence fully defined in the specification), 50 (a 2581 base pair sequence fully defined in the specification), 52 (a 2581 base pair sequence fully defined in the specification), 54 (a 2582 base pair sequence fully defined in the specification), and/or 58 (a 2581 base pair sequence fully defined in the specification);    (4) a recombinant nucleic acid construct comprising at least one polynucleotide sequence;    (5) a recombinant host cell that expresses at least one polynucleotide sequence encoding (I);    (6) a method-1 for producing at least one fermentable sugar from a feedstock, comprising contacting the feedstock with (I), the recombinant host cell and/or the enzyme composition under culture conditions to produce fermentable sugars;    (7) a method-2 of producing an end product from a feedstock, comprising contacting the feedstock with (I), the recombinant host cell and/or the enzyme composition under conditions to produce at least one fermentable sugar from the substrate, and contacting the fermentable sugar with a microorganism under conditions such that the microorganism uses the fermentable sugar to produce an end-product; and    (8) a method-3 of producing a fermentation end product from a feedstock, comprising obtaining at least one fermentable sugar by the method, contacting the fermentable sugar with a microorganism in a fermentation to produce at least one fermentation end product, and recovering the fermentation end product, where the microorganism is a yeast.