A beta-glucosidase from Clostridium cellulovorans (CcBG) was fused with one of three different types of cellulases from Clostridium thermocellum, including a cellulosomal endoglucanase CelD (CtCD), a cellulosomal exoglucanase CBHA (CtCA) and a non-cellulosomal endoglucanase Cel9I (CtC9I). Six bifunctional enzymes were constructed with either beta-glucosidase or cellulase in the upstream. CtCD CcBG showed the favorable specific activities on phosphoric acid swollen cellulose (PASC), an amorphous cellulose, with more glucose production (2 folds) and less cellobiose accumulation (3 folds) when compared with mixture of the single enzymes. Moreover, CtCD CcBG had significantly improved thermal stability with a melting temperature (T(m)) of 10.9 degrees C higher than that of CcBG (54.5 degrees C) based on the CD unfolding experiments. This bifunctional enzyme is thus useful in industrial application to convert cellulose to glucose. (C) 2010 Elsevier Ltd. All rights reserved.