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Saccharification of cellolulose by the cellulolytic enzyme system of Thermonospora sp. I. Stability of cellulolytic activities with respect to time, temperature, and pH
Author(s) -
Hägerdal Bärbel,
Ferchak John D.,
Pye E. Kendall
Publication year - 1980
Publication title -
biotechnology and bioengineering
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.136
H-Index - 189
eISSN - 1097-0290
pISSN - 0006-3592
DOI - 10.1002/bit.260220802
Subject(s) - cellulase , hydrolysis , chemistry , sonication , food science , enzyme , enzyme assay , extracellular , chromatography , biochemistry
The stabilities and optima with respect to temperature and pH of the β‐glucosidase, Avicelase, and carboxymethylcellulase (CMCase) activity of Thermomonospora sp., in the culture filtrate, culture whole broth, and filtrate after sonication of culture solids, are reported. The β‐glucosidase is cell associated and has an optimal activity at about pH 6.5 and 55°C. In the whole culture broth, it has a half‐life of about 8 hr at 55°C and less than 1 hr at 60°C, while the half‐life of the activity in the sonicated, cell‐free filtrate is less than 1 hr at 55°C. The Avicelase and CMCase activities occur in the extracellular culture fluid and have optima at about pH 7.0 and 5.9, and 65 and 70°C, respectively. The CMCase activity is stable over 24 hr at 60°C, but declines by 50% in the same period at 65°C. The Avicelase activity declines by 15% over 24 hr at 55°C, and by 50% at 60°C. The highest pH studied (pH 7.3) was the most destabilizing for all three activities. The thermostable characteristics of the cellulases from Themomonospora appear to make them suitable for commercial saccharification processes operating at elevated temperatures.