Screening, production, optimization and characterization of β-glucosidase using microbes from shellfish waste

Area of Science:

• Microbiology
• Enzymology
• Biotechnology

Background:

• Extracellular enzymes play crucial roles in microbial metabolism and have industrial applications.
• Proteus mirabilis is a bacterium known for its diverse metabolic capabilities.
• Beta-glucosidases are enzymes that hydrolyze beta-linked glucose, important in various biological processes.

Purpose of the Study:

• To isolate and characterize an extracellular beta-glucosidase from Proteus mirabilis VIT117.
• To optimize the production conditions for enhanced enzyme yield.
• To determine the biochemical and kinetic properties of the purified enzyme.

Main Methods:

• Isolation and cultivation of Proteus mirabilis VIT117 on prawn shells.
• Optimization of culture parameters (pH, carbon/nitrogen sources, temperature, time) using statistical methods (Plackett-Burman, Response Surface Methodology).
• Partial purification using ammonium sulfate precipitation, dialysis, gel filtration, and SDS-PAGE; enzyme characterization and kinetics.

Main Results:

• Optimized enzyme production at pH 9, 37°C, with sorbitol and yeast extract, yielding 14.58 U/ml.
• Significant parameters for production: inoculum size, pH, yeast extract, incubation time, and sorbitol.
• Purified beta-glucosidase has a molecular weight of ~50 kDa, optimal activity at pH 9 and 37°C.
• Enzyme kinetics revealed Vmax of 5.613 U/ml and Km of 0.082 mM.

Conclusions:

• Proteus mirabilis VIT117 produces a robust extracellular beta-glucosidase with potential biotechnological applications.
• Optimized fermentation conditions significantly enhance enzyme yield.
• The characterized enzyme exhibits specific activity and kinetic properties suitable for industrial use.