Patent ID: 8530201

Claim:
A method of converting a biomass substrate to a fermentable sugar, the method comprising contacting the biomass substrate with a recombinant β-glucosidase polypeptide variant having beta-glucosidase activity, under conditions suitable for the production of the fermentable sugar from said biomass substrate, wherein the recombinant β-glucosidase polypeptide variant comprises: (a) an amino acid sequence that has at least 85% amino acid sequence identity to the amino acid sequence of SEQ ID NO: 4, wherein SEQ ID NO: 4 is the amino acid sequence of wild type Azospirillum irakense β-glucosidase and wherein said amino acid sequence comprises substitution or deletion of the amino acid residue F211, wherein amino acid position is numbered with reference to the amino acid sequence of SEQ ID NO:4; or (b) an amino acid sequence encoded by a nucleic acid that hybridizes under highly stringent conditions with the complementary strand of a polynucleotide encoding the amino acid sequence of SEQ ID NO: 4, wherein the highly stringent conditions comprise prehybridization and hybridization at 42° C. in 5×SSPE, 0.3% SDS, 200 μg/mL sheared and denatured salmon sperm DNA and 50% formamide and washing three times each for 15 minutes using 2×SSC, 0.2% SDS at 65° C., wherein the encoded amino acid sequence has a substitution or deletion of the amino acid residue F211, wherein amino acid position is numbered with reference to the amino acid sequence of SEQ ID NO: 4, and wherein the nucleic acid encodes a polypeptide having beta-glucosidase activity.