Applied Microbiology and Biotechnology

, Volume 53, Issue 4, pp 461–468

Simultaneous production of high activities of thermostable endoglucanase and β-glucosidase by the wild thermophilic fungus Thermoascus aurantiacus

  • I. Gomes
  • J. Gomes
  • D. J. Gomes
  • W. Steiner
ORIGINAL PAPER

DOI: 10.1007/s002530051642

Cite this article as:
Gomes, I., Gomes, J., Gomes, D. et al. Appl Microbiol Biotechnol (2000) 53: 461. doi:10.1007/s002530051642

Abstract

The culture-medium composition was optimised, on a shake-flask scale, for simultaneous production of high activities of endoglucanase and β-glucosidase by Thermoascus aurantiacus using statistical factorial designs. The optimised medium containing 40.2 g l−1 Solka Floc as the carbon source and 9 g l−1 soymeal as the organic nitrogen source yielded 1130 nkat ml−1 endoglucanase and 116 nkat ml−1β-glucosidase activities after 264 h as shake cultures. In addition, good levels of β-xylanase (3479 nkat ml−1) and low levels of filter-paper cellulase, β-xylosidase, α-l-arabinofuranosidase, β-mannanase, β-mannosidase, α-galactosidase and β-galactosidase were detected. Batch fermentation in a 5-l laboratory fermentor using the optimised medium allowed the production of 940 nkat ml−1 endoglucanase and 102 nkat ml−1β-glucosidase in 192 h. Endoglucanase and β-glucosidase showed optimum activity at pH 4.5 and pH 5, respectively, and they displayed optimum activity at 75 °C. Endoglucanase and β-glucosidase showed good stability at pH values 4–8 and 4–7, respectively, after a prolonged incubation (48 h at 50 °C). Endoglucanase had half-lives of 98 h at 70 °C and 4.1 h at 75 °C, while β-glucosidase had half-lives of 23.5 h at 70 °C and 1.7 h at 75 °C. Alkali-treated bagasse, steam-treated wheat straw, Solka floc and Sigmacell 50 were 66, 48.5, 33.5 and 14.4% hydrolysed by a crude enzyme complex of T. aurantiacus in 50 h.

Copyright information

© Springer-Verlag Berlin Heidelberg 2000

Authors and Affiliations

  • I. Gomes
    • 2
  • J. Gomes
    • 1
  • D. J. Gomes
    • 3
  • W. Steiner
    • 1
  1. 1.Institute for Biotechnology, Technical University Graz, Petersgasse 12, A-8010 Graz, Austria e-mail: gomes@biote.tu-graz.ac.at Tel.: +43-316-8738406 Fax: +43-316-8738434AT
  2. 2.Bangladesh Jute Research Institute, Dhaka, BangladeshBD
  3. 3.Department of Microbiology, University of Dhaka, BangladeshBD