NOVELTY - A CelZ variant where: the variant has at least 90% sequence identity to fully defined 384 amino acids (SEQ ID NO: Z), given in the specification; the variant comprises a substitution at Asp90, Gln234, Asp304, Asp324, Val330 or Asn383 using the amino acid sequence of SEQ ID NO: Z for determining position numbering; and where the variant exhibits improved cellulase activity as compared to SEQ ID NO: Z, is new.    USE - The CelZ variant, isolated polypeptide, isolated or recombinant polynucleotide, and methods are useful for processing biomass; and for preparing ethanol (all claimed).    ADVANTAGE - The CelZ variant has improved properties and capability, and can be efficiently used in the processing of plant biomass material in a cost effective manner.    DETAILED DESCRIPTION - INDEPENDENT CLAIMS are:    (1) an isolated polypeptide comprising approximately fully defined 400 amino acids (SEQ ID NO: BA, CA, DA, EA, A, and/or AA), given in the specification;    (2) an isolated or recombinant polynucleotide comprising a sequence selected from: (a) any one of approximately fully defined 1,100 bp (SEQ ID NO: F, SEQ ID NO: G, SEQ ID NO: H and SEQ ID NO: I), given in the specification; (b) a nucleic acid sequence that is a degenerate variant of any one of SEQ ID NO: F, SEQ ID NO: G, SEQ ID NO: H and SEQ ID NO: I; (c) a nucleic acid sequence at least 80-99.9% identical to any one of SEQ ID NO: F, SEQ ID NO: G, SEQ ID NO: H and SEQ ID NO: I; (d) a nucleic acid sequence that encodes a polypeptide having any one of the amino acid sequences SEQ ID NO: A, SEQ ID NO: AA, SEQ ID NO: B, SEQ ID NO: BA, SEQ ID NO: C, SEQ ID NO: CA, SEQ ID NO: D, SEQ ID NO: DA, SEQ ID NO: E and SEQ ID NO: EA; (e) a nucleic acid sequence that encodes a polypeptide at least 99-99.9% identical to any one of the sequences SEQ ID NO: A, SEQ ID NO: AA, SEQ ID NO: B, SEQ ID NO: BA, SEQ ID NO: C, SEQ ID NO: CA, SEQ ID NO: D, SEQ ID NO: DA, SEQ ID NO: E and SEQ ID NO: EA; and (f) a nucleic acid sequence that hybridizes under stringent conditions to any one of the sequences SEQ ID NO: F, SEQ ID NO: G, SEQ ID NO: H and SEQ ID NO: I;    (3) a vector comprising the polynucleotide;    (4) a host cell comprising the polynucleotide;    (5) a cellulolytic mixture comprising one of the CelZ variants or polypeptide;    (6) a method for processing biomass comprising contacting biomass with any one of the CelZ variants or polypeptide; and    (7) a method for preparing ethanol, comprising contacting biomass with any one of the CelZ variants or polypeptide; a beta-glucosidase and a yeast.