A Thermostable Multifunctional GH5 Endoglucanase From Bacillus sp. for Lignocellulosic Biomass Saccharification

Area of Science:

• Biotechnology
• Enzymology
• Biomass Conversion

Background:

• Enzymatic conversion of lignocellulosic biomass to glucose is crucial for cost-effective biofuel production.
• Current enzyme complexity and cost present significant challenges.
• Developing efficient and robust enzymes is essential for advancing biofuel technologies.

Purpose of the Study:

• To characterize BsEG2, a novel multifunctional endoglucanase from Bacillus sp. strain BS.
• To evaluate BsEG2's potential for efficient glucose production from lignocellulosic feedstocks.
• To assess BsEG2's stability, substrate specificity, and tolerance to inhibitors and environmental conditions.

Main Methods:

• Cloning and heterologous expression of BsEG2 from Bacillus sp. strain BS.
• Enzyme activity assays across various pH and temperature conditions.
• Kinetic analysis using carboxymethyl cellulose (CMC) and cellobiose.
• Stability and tolerance testing under high salt, ionic liquids, and seawater conditions.

Main Results:

• BsEG2 exhibits optimal activity at pH 6.0 and 55°C, efficiently hydrolyzing amorphous and crystalline cellulose.
• The enzyme demonstrates high substrate affinity, catalytic efficiency, and broad specificity, degrading cellulose chains and oligosaccharides.
• BsEG2 possesses β-glucosidase-like activity, yielding glucose from cellobiose.
• It shows remarkable thermostability, salt tolerance, ionic liquid tolerance, and resistance to cellobiose inhibition (up to 200 mM).
• BsEG2 remains active in seawater, indicating reduced freshwater requirements.

Conclusions:

• BsEG2 is a multifunctional enzyme with combined endoglucanase and β-glucosidase-like activities.
• Its high stability, inhibitor tolerance, and halotolerance make it a promising candidate for industrial applications.
• BsEG2 can contribute to simplified and cost-effective enzyme formulations for lignocellulosic biomass conversion to glucose.