Purification and enzymatic characterization of a novel β-1,6-glucosidase from Aspergillus oryzae

Akira Watanabe, Moe Suzuki, Seiryu Ujiie, Katsuya Gomi

Research output: Contribution to journalArticle

17 Citations (Scopus)

Abstract

In this study, among the 10 genes that encode putative β-glucosidases in the glycoside hydrolase family 3 (GH3) with a signal peptide in the Aspergillus oryzae genome, we found a novel gene (AO090038000425) encoding β-1,6-glucosidase with a substrate specificity for gentiobiose. The transformant harboring AO090038000425, which we named bglH, was overexpressed under the control of the improved glaA gene promoter to form a small clear zone around the colony in a plate assay using 4-methylumbelliferyl β-d-glucopyranoside as the fluorogenic substrate for β-glucosidase. We purified BglH to homogeneity and enzymatically characterize this enzyme. The thermal and pH stabilities of BglH were higher than those of other previously studied A. oryzae β-glucosidases, and BglH was stable over a wide temperature range (4°C-60°C). BglH was inhibited by Hg2+, Zn2+, glucono-δ-lactone, glucose, dimethyl sulfoxide, and ethanol, but not by ethylenediaminetetraacetic acid. Interestingly, BglH preferentially hydrolyzed gentiobiose rather than other oligosaccharides and aryl β-glucosides, thereby demonstrating that this enzyme is a β-1,6-glucosidase. To the best of our knowledge, this is the first report of the purification and characterization of β-1,6-glucosidase from Aspergillus fungi or from other eukaryotes. This study suggests that it may be possible to find a more suitable β-glucosidase such as BglH for reducing the bitter taste of gentiobiose, and thus for controlling the sweetness of starch hydrolysates in the food industry via genome mining.

Original languageEnglish
Pages (from-to)259-264
Number of pages6
JournalJournal of Bioscience and Bioengineering
Volume121
Issue number3
DOIs
Publication statusPublished - 2016 Mar 1

Keywords

  • Aspergillus oryzae
  • Gentiobiose
  • Glycoside hydrolase family 3
  • β-1,6-Glucosidase
  • β-Glucosidase

ASJC Scopus subject areas

  • Biotechnology
  • Bioengineering
  • Applied Microbiology and Biotechnology

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