Comparative evaluation of hydrolytic efficiency toward microcrystalline cellulose of Penicillium and Trichoderma cellulases

Composition, stability at different pH and temperatures and hydrolytic efficiency toward microcrystalline cellulose (MCC) of Penicillium cellulase were evaluated. The pH optimum (4•5-5•0) of filter paper activity (FPA) and temperature optimum (50–55°C) were determined. Maximum stability of FPA was observed at pH 4•0–5•0 and temperature 40–50°C. A minor contribution of stirring (3–4%) in inactivation of Penicillium preparation was shown. Kinetic parameters of MCC hydrolysis by Penicillium cellulase were determined at optimal conditions (pH 4•5, 50°C): Km = 50 g/l, Vmax = 330 μM/min per gram of protein. More effective saccharification of MCC by Penicillium preparations compared to Trichoderma reesei cellulases with the same level of total cellulolytic activity (FPA=1•0 U/ml) was demonstrated. Glucose concentration in 24 h hydrolysate was 41 g/l for Penicillium cellulase, 15 g/l for T. reesei (Privolzhski Fermentation Plant) and 26 g/l for T. reesei (Genencor). Hydrolysates of Penicillum cellulase contained only 9% of cellobiose compared to 24–40% of cellobiose for T. reesei cellulases. Factors contributing to superior properties of Penicillium cellulase — higher level of cellobiase activity and higher operational stability — are discussed