Homologous cloning, purification and characterization of highly active cellobiohydrolase I (Cel7A) from Penicillium canescens.

ABSTRACT

Penicillium canescens is a filamentous fungus that normally does not secrete notable levels of cellulase activity. Cellobiohydrolase I of P. canescens (PcCel7A) was homologously cloned into a host strain RN3-11-7 (niaD-) and then expressed under the control of a strong xylA promoter. Using three steps of chromatography, PcCel7A was purified. The enzyme displayed maximum activity at pH 4.0-4.5. PcCel7A was stable at 50°C and pH 4.5 at least for 3h, while at 60°C it lost 45% of activity after 30min of incubation. When equalized by protein concentration, PcCel7A demonstrated a higher performance in prolonged hydrolysis of Avicel and milled aspen wood than CBH I (Cel7A) from Trichoderma reesei, the most industrially utilized cellulase at this moment. The high catalytic efficiency of the PcCel7A makes it a potential candidate for industrial applications.