A Novel Thermostable GH3 β-Glucosidase from Talaromyce leycettanus with Broad Substrate Specificity and Significant Soybean Isoflavone Glycosides-Hydrolyzing Capability

Biomed Res Int. 2018 Oct 23:2018:4794690. doi: 10.1155/2018/4794690. eCollection 2018.

Abstract

A novel β-glucosidase gene (Bgl3B) of glycoside hydrolase (GH) family 3 was cloned from the thermophilic fungus Talaromyce leycettanus JM12802 and successfully expressed in Pichia pastoris. The deduced Bgl3B contains 860 amino acid residues with a calculated molecular mass of 91.2 kDa. The purified recombinant Bgl3B exhibited maximum activities at pH 4.5 and 65°C and remained stable at temperatures up to 60°C and pH 3.0-9.0, respectively. The enzyme exhibited broad substrate specificities, showing β-glucosidase, glucanase, cellobiase, xylanase, and isoflavone glycoside hydrolase activities, and its activities were stimulated by short-chain alcohols. The catalytic efficiencies of Bgl3B were 693 and 104/mM/s towards pNPG and cellobiose, respectively. Moreover, Bgl3B was highly effective in converting isoflavone glycosides to aglycones at 37°C within 10 min, with the hydrolysis rates of 95.1%, 76.0%, and 75.3% for daidzin, genistin, and glycitin, respectively. These superior properties make Bgl3B potential for applications in the food, animal feed, and biofuel industries.

MeSH terms

  • Amino Acids / chemistry
  • Cellobiose / chemistry
  • Enzyme Stability
  • Glycine max / chemistry*
  • Glycosides / chemistry*
  • Hydrolysis
  • Isoflavones / chemical synthesis
  • Isoflavones / chemistry*
  • Pichia / chemistry
  • Substrate Specificity
  • Talaromyces / chemistry*
  • beta-Glucosidase / chemistry*

Substances

  • Amino Acids
  • Glycosides
  • Isoflavones
  • Cellobiose
  • genistin
  • daidzin
  • beta-Glucosidase
  • glycitin