Biochemical characteristics of Myceliophthora thermophila recombinant β-glucosidase (MtBgl3c) applicable in cellulose bioconversion

Abstract

The GH3 β-glucosidase gene of Myceliophthora thermophila (MtBgl3c) has been cloned and heterologously expressed in E. coli for the first time. This study highlights the important characteristics of recombinant MtBgl3c (rMtBgl3c) which make it a promising candidate in industrial applications. Optimization of the production of rMtBgl3c led to 28,000 U L⁻¹. On purification, it has a molecular mass of ∼100 kDa. It is a broad substrate specific thermostable enzyme that exhibits pH and temperature optima at 5.0 and 55 °C, respectively. The amino acid residues Asp287 and Glu514 act as nucleophile and catalytic acid/base, respectively in the enzyme catalysis. Its low K_m value (1.28 mM) indicates a high substrate affinity as compared to those previously reported. The rMtBgl3c displays a synergistic action with the commercial enzyme cocktail in the saccharification of sugarcane bagasse suggesting its utility in the cellulose bioconversion. Tolerance to solvents, detergents as well as glucose make this enzyme applicable in wine, detergent, paper and textile industries too.

Keywords:

• Cellulase
• cellulose saccharification
• β-glucosidase
• thermostable
• glucose and ethanol tolerance

Acknowledgements

AD is grateful to Netaji Subhas Institute of Technology (Delhi, India) for granting research fellowship while carrying out this investigation.

Authors’ contribution

TS conceived and supervised the study. AD designed and performed the experiments, analyzed the data and wrote the initial draft of the manuscript. SS and TS critically revised the manuscript. All authors reviewed and approved the final manuscript.

Disclosure statement

No potential conflict of interest was reported by the author(s).

Data availability statement

The data associated with this study are included in this article.

Additional information

Funding

This research has been partially funded by Indo-US Science and Technology Forum (IUSSTF) and Department of Biotechnology (DBT), New Delhi and University Grants Commission (UGC), Govt. of India, New Delhi.