NOVELTY - An isolated polypeptide having cellulase activity selected from (i) a polypeptide comprising the sequence of SEQ ID NO. 1, (ii) a polypeptide comprising a sequence having greater than or equal to 80% identity to SEQ ID NO. 1, and (iii) a polypeptide which is encoded by a polynucleotide which hybridizes to SEQ ID NO. 6 under low, medium, medium-high, high or very high stringency conditions, is new.    USE - The polypeptide, fragment or variant, or composition is useful for producing fermentable sugar and a byproduct from biomass; and for degrading biomass to produce byproducts. The byproduct is selected from alcohols such as ethanol, methanol, butanol, hexanol, octanol, decanol, dodecanol, 1,3-butanediol (1,3-diol), or 1-alcohol; organic acids such as citric acid, acetic acid, itaconic acid, lactic acid, glutamic acid, succinic acid, beta-keto acid, beta-ketoalcohol, or beta hydroxy acid; ketones such as acetone; gases such as hydrogen or carbon dioxide; hydrocarbons such as alkanes, alkenes or alkynes; nitrogenous substances such as amine, amide, nitro or nitrile; halides; amino acids such as glutamic acid; antibiotics such as penicillin or tetracycline; vitamin such as riboflavin, vitamin B12 and beta-carotene; fatty acids such as dodecanoic acid, trans-A2 fatty acids or palmitic acid; and other products such as ethylene, glycerol, 1,3-propanediol, cephalosporins, furan or trans fatty acids (all claimed).    ADVANTAGE - The polypeptide, fragment or variant, or composition is used for more competitive, economical and environmental-friendly fermentable sugar and byproduct production.    DETAILED DESCRIPTION - INDEPENDENT CLAIMS are:    (1) a functional fragment or variant of a polypeptide defined above;    (2) a polynucleotide sequence encoding a polypeptide or a fragment or variant defined above;    (3) a gene construct comprising an operably linked to control sequences that modulate polypeptide expression;    (4) an expression vector comprising a gene construct o (3);    (5) a host cell comprising a gene construct of (3) or a vector of (4) and expressing the polypeptide or a fragment or variant defined above;    (6) a method for producing a polypeptide having cellulolytic activity;    (7) a cellulolytic composition comprising a polypeptide and/or fragment or variant defined above, and optionally a component which facilitates the degradation of biomass;    (8) a method for producing fermentable sugar by incubating biomass with the polypeptide, fragment or variant, or composition defined above; and    (9) a process for producing a byproduct from biomass by (a) producing fermentable sugars according to the method of (8), (b) conducting a chemical transformation of sugars obtained in step (a) to produce a byproduct, and (c) recovering a byproduct obtained in step (b).