NOVELTY - A polypeptide comprising the amino acid sequence of a variant beta -glucosidase, where the variant beta -glucosidase comprises at least one substitution as compared to a reference beta -glucosidase polypeptide is new.    USE - In the preparation of composition; in fermentation broth, which is a filamentous fungal fermentation broth or cell-free fermentation broth; for saccharifying biomass; for producing a fermentation product, where the fermentation product is ethanol; in recombinant cell, where the cell is a eukaryotic cell or is a filamentous fungal cell and the filamentous fungal cell is of the genus Aspergillus, Penicillium, Rhizopus, Chrysosporium, Myceliophthora, Trichoderma, Humicola, Acremonium or Fusarium and the filamentous fungal cell is of the species Aspergillus niger, Aspergillus oryzae, Trichoderma reesei, Penicillium chrysogenum, Myceliophthora thermophila, or Rhizopus oryzae; or the recombinant cell is a yeast cell of the genus Saccharomyces, Kluyveromyces, Candida, Pichia, Schizosaccharomyces, Hansenula, Klockera, Schwanniomyces or Yarrowia; or is of the species S. cerevisiae, S. bulderi, S. barnetti, S. exiguus, S. uvarum, S. diastaticus, K. lactis, K. marxianus or K. fragilis; in a host cell, which is a prokaryotic cell or bacterial cell or eukaryotic cell (claimed); in compositions e.g. cellulase compositions; in variety of agricultural and industrial applications; in detergent compositions; as a softening agent and/or improve the feel of cotton fabrics (e.g. stone washing or biopolishing), or in cellulase compositions for degrading wood pulp into sugars (e.g. for biofuel production); in the treatment of mechanical pulp; as a feed additive; and in grain wet milling.    ADVANTAGE - The polypeptide retains at least 1%, at least 10%, at least 50%, at least 60%, or at least 80% of its specific activity at 25 degrees C following a 30-minute thermal challenge at 66 degrees C or at 70 degrees C or at 80 degrees C. The polypeptide retains greater than 0.1 U/mg, greater than 0.5 U/mg, greater than 10 U/mg, or greater than 50 U/mg specific activity at 25 degrees C following a 30-minute thermal challenge at 66 degrees C or at 70 degrees C or at 80 degrees C. The polypeptide has at least 0.7-fold, at least 5-fold, or at least 10-fold the specific activity of a reference beta -glucosidase without the substitution(s), following a 30-minute thermal challenge at 66 degrees C; or at 70 degrees C or at 80 degrees C. The polypeptides have enhanced thermostability. The at least one substitution in the polypeptide increases thermotolerance as compared to the reference beta -glucosidase polypeptide. The compound exhibits enhanced cleaning ability.    DETAILED DESCRIPTION - A polypeptide comprising the amino acid sequence of a variant beta -glucosidase, where the variant beta -glucosidase comprises at least one substitution as compared to a reference beta -glucosidase polypeptide, where the at least one substitution is selected from: a substitution at the amino acid position corresponding to 163 of SEQ ID No. 379 containing 453 amino acids (163 substitution); a substitution at the amino acid position corresponding to Ala68 of SEQ ID No. 379 (Ala68 substitution); a substitution at the amino acid position corresponding to Ala73 of SEQ ID No. 379 (Ala73 substitution); a substitution at the amino acid position corresponding to Tyr74 of SEQ ID No. 379 (Tyr74 substitution); a substitution at the amino acid position corresponding to Val167 of SEQ ID No. 379 (Val167 substitution); a substitution at the amino acid position corresponding to Val203 of SEQ ID No. 379 (Val203 substitution); a substitution at the amino acid position corresponding to Ile216 of SEQ ID No. 379 (Ile216 substitution); a substitution at the amino acid position corresponding to Thr219 of SEQ ID No. 379 (Thr219 substitution); a substitution at the amino acid position corresponding to Lys231 of SEQ ID No. 379 (Lys231 substitution); a substitution at the amino acid position corresponding to Met246 of SEQ ID No. 379 (Met246 substitution); a substitution at the amino acid position corresponding to Phe292 of SEQ ID No. 379 (Phe292 substitution); a substitution at the amino acid position corresponding to Ser296 of SEQ ID No. 379 (Ser296 substitution); a substitution at the amino acid position corresponding to Met325 of SEQ ID No. 379 (Met325 substitution); a substitution at the amino acid position corresponding to Asn326 of SEQ ID No. 379 (Asn326 substitution); a substitution at the amino acid position corresponding to Glu365 of SEQ ID No. 379 (Glu365 substitution); a substitution at the amino acid position corresponding to Gln366 of SEQ ID No. 379 (Gln366 substitution); a substitution at the amino acid position corresponding to Tyr399 SEQ ID No. 379 (Tyr399 substitution); a substitution at the amino acid position corresponding to Val400 SEQ ID No. 379 (Val400 substitution); a substitution at the amino acid position corresponding to Trp401 SEQ ID No. 379 (Trp401 substitution); a substitution at the amino acid position corresponding to Arg410 SEQ ID No. 379 (Arg410 substitution); a substitution at the amino acid position corresponding to Asp414 SEQ ID No. 379 (Asp414 substitution); a substitution at the amino acid position corresponding to Leu427 SEQ ID No. 379 (Leu427 substitution); a substitution at the amino acid position corresponding to Thr441 SEQ ID No. 379 (Thr441 substitution); a substitution at the amino acid position corresponding to Glu450 SEQ ID No. 379 (Glu450 substitution); and where the at least one substitution increases thermotolerance as compared to the reference beta -glucosidase polypeptide, is new. INDEPENDENT CLAIMS are included for the following:    (1) a composition comprising the polypeptide;    (2) a method (M1) for saccharifying biomass, involving: treating biomass with the composition or with fermentation broth comprising the polypeptide;    (3) a method (M2) for producing a fermentation product, involving treating biomass with the composition or with fermentation broth comprising the polypeptide, thereby producing fermentable sugars; and culturing a fermenting microorganism in the presence of the fermentable sugars produced in above step under fermentation conditions, thereby producing a fermentation product;    (4) new nucleic acid comprising a nucleotide sequence encoding the polypeptide;    (5) new vector comprising the nucleic acid;    (6) a recombinant cell engineered to express the nucleic acid;    (7) a host cell transformed with the vector; and    (8) a method of producing the polypeptide.