NOVELTY - An isolated glycoside hydrolases 61 (GH61) polypeptide having cellulolytic enhancing activity, chosen from (a) a GH61 polypeptide exhibiting at least 95% sequence identity to amino acids 20-334 of SEQ ID NO: 4, (b) a GH61 polypeptide encoded by a polynucleotide that hybridizes under very high stringency conditions, (c) a GH61 polypeptide encoded by a polynucleotide having at least 99% sequence identity to nucleotides 58-1250 of SEQ ID NO: 3 or its cDNA sequence, and (d) an isolated fragment of a GH61 polypeptide of (a), (b), or (c) that has cellulolytic enhancing activity, is new.    USE - The isolated GH61 polypeptide having cellulolytic enhancing activity is useful in detergent composition for producing transgenic plant, plant part or plant cell, producing a protein, and degrading or fermenting a cellulosic material for producing a fermentation product (all claimed).    DETAILED DESCRIPTION - An isolated GH61 polypeptide having cellulolytic enhancing activity, chosen from (a) a GH61 polypeptide exhibiting at least 95% sequence identity to amino acids 20-334 of SEQ ID NO: 4, (b) a GH61 polypeptide encoded by a polynucleotide that hybridizes under very high stringency conditions with (i) nucleotides 58-1250 of SEQ ID NO: 3, (ii) the cDNA sequence contained in the mature polypeptide coding sequence of SEQ ID NO: 1, or (iii) the full-length complement of (i) or (ii), where very high stringency conditions are prehybridization and hybridization at 42 degrees C in 5Xsaline sodium phosphate-EDTA (SSPE), 0.3% sodium dodecyl sulfate (SDS), 200 mu g/ml sheared and denatured salmon sperm DNA, and 50% formamide and washing three times each for 15 minutes using 2Xsaline sodium citrate (SSC), 0.2% SDS at 70 degrees C, (c) a GH61 polypeptide encoded by a polynucleotide having at least 99% sequence identity to nucleotides 58-1250 of SEQ ID NO: 3 or its cDNA sequence, and (d) an isolated fragment of a GH61 polypeptide of (a), (b), or (c) that has cellulolytic enhancing activity, is new. INDEPENDENT CLAIMS are included for the following: (1) DNA construct comprising the isolated polynucleotide comprising a nucleotide sequence that encodes the above-mentioned polypeptide operably linked to one or more heterologous control sequences that direct the production of the polypeptide in an expression host, or nucleic acid encoding the signal peptide comprising or consisting of amino acids 1-19 of SEQ ID NO: 4 operably linked to a heterologous nucleic acid encoding a protein; (2) recombinant expression vector comprising the isolated polynucleotide comprising a nucleotide sequence that encodes the polypeptide; (3) recombinant host cell comprising the isolated polynucleotide comprising a nucleotide sequence that encodes the polypeptide; (4) method of producing the polypeptide, involves (a) cultivating an isolated Thielavia terrestris cell under conditions conducive for production of the polypeptide, and (b) recovering the polypeptide; (5) method of producing a GH61 polypeptide having cellulolytic enhancing activity; (6) transgenic plant, plant part or plant cell transformed with the polynucleotide encoding the polypeptide, where the polypeptide comprises a signal peptide directing the polypeptide into the secretory pathway; (7) method of producing a protein, involves cultivating a recombinant host cell comprising the construct under conditions conducive for production of the protein, and recovering the protein; (8) method (M1) for degrading a cellulosic material, involves treating the cellulosic material with an enzyme composition in the presence of the GH61 polypeptide having cellulolytic enhancing activity; (9) method (M2) for producing a fermentation product, involves (a) saccharifying a cellulosic material with an enzyme composition in the presence of the GH61 polypeptide having cellulolytic enhancing activity, (b) fermenting the saccharified cellulosic material with one or more fermenting microorganisms to produce the fermentation product, and (c) recovering the fermentation product from the fermentation; (10) method (M3) for fermenting a cellulosic material, involves fermenting the cellulosic material with one or more fermenting microorganisms, where the cellulosic material is saccharified with an enzyme composition in the presence of the polypeptide having cellulolytic enhancing activity; and (11) detergent composition comprising the polypeptide and a surfactant.