Patent ID: 8323931

Claim:
A fed-batch or continuous fermentation process for the production of a cellulase mixture, said process comprising: a) providing a modified host filamentous fungus that overexpresses a Xyr1 transcription factor, said Xyr1 transcription factor being a protein (i) having an amino acid sequence exhibiting from about 90% to about 100% identity to SEQ ID NO: 27 (ii) containing a class III zinc binuclear cluster with a conserved amino acid motif (CX 2 CX 6 CX 5-12 CX 2 CX 6-8 C) at the N-terminal part of the protein, and (iii) exhibiting DNA binding activity specific to a consensus sequence GGC(T/A) 3 -like motif within cellulase and/or hemicellulase promoter sequences; and b) culturing the modified host filamentous fungus of step a) in a medium comprising a carbon source, wherein the carbon source contains from about 60 wt % to about 100 wt % of a hemicellulose-derived carbohydrate selected from the group consisting of xylo-oligosaccharides, arabinoxylo-oligosaccharides, D-xylose, xylobiose, L-arabinose, and combinations thereof, and about 0 wt % of a cellulase-inducing carbohydrate selected from the group consisting of cellulose, lactose, cellobiose, sophorose, gentiobiose and a combination thereof, to produce a cellulase mixture; wherein the fermentation process produces at least 10 g/L of the cellulase mixture, cellulase components represent at least 40 wt % of the total protein in the cellulase mixture, and the cellulase mixture exhibits at least 1.7-fold higher cellulase activity than a cellulase mixture produced by a parental filamentous fungus that does not overexpress the Xyr1 transcription factor when cultured in the same medium.