Efficiency of New Fungal Cellulase Systems in Boosting Enzymatic Degradation of Barley Straw Lignocellulose

• Published in: Biotechnology progress 2006-03, Vol.22 (2), p.493-498
• Main Authors: Rosgaard, L, Pedersen, S, Cherry, J.R, Harris, P, Meyer, A.S
• Format: Article
• Language: English
• Subjects: Ascomycota - enzymology; Aspergillus niger; barley straw; Biological and medical sciences; Biotechnology; Cellobiose - metabolism; Cellulase - metabolism; cellulases; cellulolytic microorganisms; Cellulose - metabolism; Chaetomium; Chromatography, High Pressure Liquid; Chromatography, Ion Exchange; Culture Media; enzymatic hydrolysis; enzymatic treatment; Fermentation; Fundamental and applied biological sciences. Psychology; fungi; glucose; Glucose - metabolism; Hordeum - enzymology; Hordeum vulgare; Hydrogen-Ion Concentration; Hydrolysis; Hypocrea jecorina; Lignin - metabolism; lignocellulose; Multienzyme Complexes - metabolism; Myceliophthora thermophila; Plant Stems - enzymology; pretreatment; steaming; Substrate Specificity; Temperature; Thermoascus aurantiacus; thermophilic fungi
• ISSN: 8756-7938; 1520-6033
• DOI: 10.1021/bp050361o

This study examined the cellulytic effects on steam‐pretreated barley straw of cellulose‐degrading enzyme systems from the five thermophilic fungi Chaetomium thermophilum, Thielavia terrestris, Thermoascus aurantiacus, Corynascus thermophilus, and Myceliophthora thermophila and from the mesophile Penicillum funiculosum. The catalytic glucose release was compared after treatments with each of the crude enzyme systems when added to a benchmark blend of a commercial cellulase product, Celluclast, derived from Trichoderma reesei and a β‐glucosidase, Novozym 188, from Aspergillus niger. The enzymatic treatments were evaluated in an experimental design template comprising a span of pH (3.5–6.5) and temperature (35–65 °C) reaction combinations. The addition to Celluclast + Novozym 188 of low dosages of the crude enzyme systems, corresponding to 10 wt % of the total enzyme protein load, increased the catalytic glucose yields significantly as compared to those obtained with the benchmark Celluclast + Novozyme 188 blend. A comparison of glucose yields obtained on steam‐pretreated barley straw and microcrystalline cellulose, Avicel, indicated that the yield improvements were mainly due to the presence of highly active endoglucanase activity/activities in the experimental enzyme preparations. The data demonstrated the feasibility of boosting the widely studied T. reeseicellulase enzyme system with additional enzymatic activity to achieve faster lignocellulose degradation. We conclude that this supplementation strategy appears feasible as a first step in identifying truly promising fungal enzyme sources for fast development of improved, commercially viable, enzyme preparations for lignocellulose degradation.