Production of β-glucosidase on solid-state fermentation by Lichtheimia ramosa in agroindustrial residues: Characterization and catalytic properties of the enzymatic extract

Fabiano Avelino Gonçalves,Marcelo Fossa Da Paz,Rodrigo Simões Ribeiro Leite,Nayara Fernanda Lisboa Garcia,Gustavo Graciano Fonseca,Flávia Regina Da Silva Santos

doi:10.1016/j.ejbt.2015.05.007

Fabiano Avelino Gonçalves, Marcelo Fossa Da Paz + Show 4 more

Open Access

https://doi.org/10.1016/j.ejbt.2015.05.007

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Abstract

Background: β-glucosidases catalyze the hydrolysis of cellobiose and cellodextrins, releasing glucose as the main product. This enzyme is used in the food, pharmaceutical, and biofuel industries. The aim of this work is to improve the β-glucosidase production by the fungus Lichtheimia ramosa by solid-state fermentation (SSF) using various agroindustrial residues and to evaluate the catalytic properties of this enzyme. Results: A high production of β-glucosidase, about 274 U/g of dry substrate (or 27.4 U/mL), was obtained by cultivating the fungus on wheat bran with 65% of initial substrate moisture, at 96 h of incubation at 35oC. The enzymatic extract also exhibited carboxymethylcellulase (CMCase), xylanase, and β-xylosidase activities. The optimal activity of β-glucosidase was observed at pH 5.5 and 65oC and was stable over a pH range of 3.5 - 10.5. The enzyme maintained its activity (about 98% residual activity) after 1 h at 55oC. The enzyme was subject to reversible competitive inhibition with glucose and showed high catalytic activity in solutions containing up to 10% of ethanol. Conclusions: β-glucosidase characteristics associated with its ability to hydrolyze cellobiose, underscore the utility of this enzyme in diverse industrial processes. Normal 0 21 false false false ES X-NONE X-NONE /* Style Definitions */ table.MsoNormalTable {mso-style-name:Tabla normal; mso-tstyle-rowband-size:0; mso-tstyle-colband-size:0; mso-style-noshow:yes; mso-style-priority:99; mso-style-parent:; mso-padding-alt:0cm 5.4pt 0cm 5.4pt; mso-para-margin:0cm; mso-para-margin-bottom:.0001pt; mso-pagination:widow-orphan; font-size:10.0pt; font-family:Calibri,sans-serif;}

Highlights

The pronounced scarcity of fossil fuels related to environmental problems resulting from their processing and consumption has prompted the search for alternative sources of biofuels and renewable energy
The enzymatic reaction was stopped with 2 mL of sodium carbonate (2 M), and the liberated product was spectrophotometrically quantified at 410 nm
L. ramosa has proven to be a remarkable fungus for use in β-glucosidase production when cultivated by solid-state fermentation using wheat bran as the substrate

Summary

Introduction

The pronounced scarcity of fossil fuels related to environmental problems resulting from their processing and consumption has prompted the search for alternative sources of biofuels and renewable energy. This in turn, has generated significant interest in the use of cellulases and other enzymes to convert vegetal biomass into fermentable sugars [1]. The ability of β-glucosidase to utilize different glycosidic substrates renders it suitable for several industrial processes, including the enzymatic hydrolysis of cellulose in order to obtain fermentable sugars and the production of functional foods derived from soy. The method results in higher levels of productivity and low catabolite repression, and favors increased stability of the secreted enzymes [7]

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