Identifying and characterizing the most significant beta-glucosidase of the novel species Aspergillus saccharolyticus

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The newly discovered fungal species Aspergillus saccharolyticus was found to produce a culture broth rich in beta-glucosidase activity. In this present work, the main beta-glucosidase of A. saccharolyticus responsible for the efficient hydrolytic activity was identified, isolated, and characterized. Ion exchange chromatography was used to fractionate the culture broth, yielding fractions with high beta-glucosidase activity and only 1 visible band on an SDS-PAGE gel. Mass spectrometry analysis of this band gave peptide matches to beta-glucosidases from aspergilli. Through a polymerase chain reaction approach using degenerate primers and genome walking, a 2919 bp sequence encoding the 860 amino acid BGL1 polypeptide was determined. BGL1 of A. saccharolyticus has 91% and 82% identity with BGL1 from Aspergillus aculeatus and BGL1 from Aspergillus niger, respectively, both belonging to Glycoside Hydrolase family 3. Homology modeling studies suggested beta-glucosidase activity with preserved retaining mechanism and a wider catalytic pocket compared with other beta-glucosidases. The bgl1 gene was heterologously expressed in Trichoderma reesei QM6a, purified, and characterized by enzyme kinetics studies. The enzyme can hydrolyze cellobiose, p-nitrophenyl-beta-D-glucoside, and cellodextrins. The enzyme showed good thermostability, was stable at 50 degrees C, and at 60 degrees C it had a half-life of approximately 6 h.


  • Annette Sorensen
  • Birgitte K. Ahring
  • Mette Luebeck
  • Wimal Ubhayasekera
  • Kenneth S. Bruno
  • David E. Culley
  • Peter S. Luebeck
Research areas and keywords

Subject classification (UKÄ) – MANDATORY

  • Physical Sciences
  • Natural Sciences


  • beta-glucosidase, Aspergillus saccharolyticus, enzyme characterization, thermostability, biomass hydrolysis
Original languageEnglish
Pages (from-to)1035-1046
JournalCanadian Journal of Microbiology
Issue number9
StatePublished - 2012
Publication categoryResearch