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Characterization and pulp refining activity of a Paenibacillus campinasensis cellulase expressed in Escherichia coli

Ko, Chun-Han, Tsai, Chung-Hung, Lin, Po-Heng, Chang, Ko-Cheng, Tu, Jenn, Wang, Ya-Nang, Yang, Chien-Ying
Bioresource technology 2010 v.101 no.20 pp. 7882-7888
Escherichia coli, Paenibacillus, acetates, barley, biomass, buffers, cellulose, endo-1,4-beta-glucanase, energy, genes, kraft pulp, molecular weight, pH, recombinant proteins, refining, temperature
The Cel-BL11 gene from Paenibacillus campinasensis 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°C and pH 7.0, respectively. The enzyme retained more than 80% activity after 8h at 60°C at pH 6 and 7. The cellulase has a Km of 11.25mg/ml and a Vmax of 1250μmol/min/mg with carboxylmethyl cellulose (CMC). Then enzyme was active on Avicel, swollen Avicel, CMC, barley β-glucan, laminarin in the presence of 100mM acetate buffer. It was inhibited by Hg²⁺, Cu²⁺ and Zn²⁺. Significant kraft pulp refining energy saving, 10%, was exhibited by the pretreatment of this cellulase applied at 2IU 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.