Expression of Two Novel β-Glucosidases from Chaetomium atrobrunneum in Trichoderma reesei and Characterization of the Heterologous Protein Products

Ana C. Colabardini, Mari Valkonen, Anne Huuskonen, Matti Siika-aho, Anu Koivula, Gustavo H. Goldman, Markku Saloheimo

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Two novel GH3 family thermostable β-glucosidases from the filamentous fungus Chaetomium atrobrunneum (CEL3a and CEL3b) were expressed in Trichoderma reesei, purified by two-step ion exchange chromatography, and characterized. Both enzymes were active over a wide range of pH as compared to Neurospora crassa β-glucosidase GH3-3, which was also expressed in T. reesei and purified. The optimum temperature of both C. atrobrunneum enzymes was around 60 °C at pH 5, and both enzymes had better thermal and pH stability and higher resistance to metallic compounds and to glucose inhibition than GH3-3. They also showed higher activity against oligosaccharides composed of glucose units and linked with β-1,4-glycosidic bonds and moreover, had higher affinity for cellotriose over cellobiose. In hydrolysis tests against Avicel cellulose and steam-exploded sugarcane bagasse, performed at 45 °C, particularly the CEL3a enzyme performed similarly to N. crassa GH3-3 β-glucosidase. Taking into account the thermal stability of the C. atrobrunneum β-glucosidases, they both represent promising alternatives as enzyme mixture components for improved cellulose saccharification at elevated temperatures.

Original languageEnglish
Pages (from-to)821-831
Number of pages11
JournalMolecular Biotechnology
Issue number12
Publication statusPublished - 1 Dec 2016
MoE publication typeA1 Journal article-refereed



  • Bioethanol
  • Chaetomium atrobrunneum
  • Hydrolysis
  • Thermostability
  • β-glucosidase

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