The Cel-BL11 gene from Paenibacillus cam pinasensis BL11 was cloned and expressed in Escherichia coli as a His-tag fusion protein. Zymographic analysis of the recombinant protein revealed cellulase activity corresponding to a protein with a 38-kDa molecular weight. The optimum temperature and pH for purified cellulase were 60 degrees C and pH 7.0, respectively. The enzyme retained more than 80% activity after 8 h at 60 degrees C at pH 6 and 7. The cellulase has a K(m) of 11.25 mg/ml and a V(max) of 1250 mu mol/min/mg with carboxylmethyl cellulose (CMC). Then enzyme was active on Avicel, swollen Avicel, CMC, barley beta-glucan, laminarin in the presence of 100 mM acetate buffer. It was inhibited by Hg(2+), Cu(2+) and Zn(2+). Significant kraft pulp refining energy saving, 10%, was exhibited by the pretreatment of this cellulase applied at 2 IU per gram of oven-dried pulp. Broad pH and temperature stability render this cellulase a convenient applicability toward current mainstream biomass conversion and other industrial processes. (c) 2010 Elsevier Ltd. All rights reserved.