Production of cellulase from Aspergillus terreus MS105 on crude and commercially purified substrates.
Aspergillus terreus MS105 was originally isolated from soil and screened for cellulase production in the presence of various carbon sources including carboxymethyl cellulose (CMC), avicel, sigmacell, filter-paper and salicin. CMC induced the production of endoglucanase (EG) and filter-paperase while the levels of β-glucosidase (BGL) were increased when salicin was present in the medium. Nature of production medium influenced the duration of lag- and log-phase of the growth, rate of fungal dry-mass and enzyme production. The volumetric and specific productivity of cellulase under submerged fermentation of grass were 1.7-20-folds higher than sugarcane-bagasse, corncob and commercially available purified substrates. Nonetheless, solid state fermentation (SSF) of crude substrates also yielded high volumetric productivity of EG and BGL. The studies on characterization of enzymes showed that EG was more thermostable than BGL with an optimum activity at 70 °C and a melting temperature of 76 °C. A 1.2-1.5-folds increase in EG activity was observed in the presence of K+, Ca2+and Mg2+, whereas, the EG and BGL activities remained unaffected in the presence of EDTA. Both the enzyme activities performed optimally under acidic range of pH.
Department of Microbiology, University of Karachi, Karachi, 75270, Pakistan.
Muhammad
M
Sohail
Department of Microbiology, University of Karachi, Karachi, 75270, Pakistan.
Aqeel
A
Ahmad
Department of Microbiology, University of Karachi, Karachi, 75270, Pakistan. shakeelkhan@uok.edu.pk.
Shakeel Ahmed
SA
Khan
Aspergillus terreus; Crude substrates; Endoglucanase; Solid-state fermentation; β-glucosidase