The cellobiase gene from Aspergillus niger was cloned and connected with the strong promoter Pcbh1 from Trichoderma reesei to construct a recombinant plasmid pHB9 with the hygromycin B resistance marker. The plasmid was transformed into conidia of T. reesei using the modified PEG-CaCl(2) method. Main factors effecting the transformation were discussed and about 99-113 transformants/mu g DNA could be obtained under optimal conditions. It was found that the molecular mass of the recombinant cellobiase was about 120 kDa by SDS-PAGE analysis. The activity of cellobiase could reach 5.3 IU/ml after 48 h fermentation, which was as high as 106 times compared with that of the host strain. Meanwhile, the filter paper activity of recombinant T. reesei was 1.44-fold of the host strain. Saccharification of corncob residue with the crude enzyme showed that the hydrolysis yield (84.2%) of recombinant T. reesei was 21% higher than that (69.5%) of the host strain. (C) 2011 Elsevier Ltd. All rights reserved.