A broad pH range and processive chitinase from a metagenome library

Area of Science:

• Biochemistry
• Enzymology
• Environmental Microbiology

Background:

• Chitinases are enzymes crucial for degrading chitin, a major component of arthropod exoskeletons and fungal cell walls.
• Identifying novel chitinases with robust activity is essential for various industrial applications, including waste valorization and biocontrol.

Purpose of the Study:

• To isolate and characterize a novel chitinase from a wastewater-contaminated soil metagenomic library.
• To evaluate the enzymatic properties and potential industrial applicability of the identified chitinase.

Main Methods:

• Functional screening of a metagenome fosmid library for chitinase activity.
• Gene cloning, overexpression in Escherichia coli, and protein purification via affinity chromatography.
• Enzymatic characterization including pH and temperature optima, salt tolerance, substrate specificity, and kinetic analysis.

Main Results:

• Isolation and identification of the metachi18A gene encoding a 92-kDa chitinase (MetaChi18A).
• Optimal activity at pH 5 and 50°C, with significant stability across pH 4-9 and up to 600 mM NaCl.
• Chitobiose identified as the primary product; kinetic analysis suggests a conformational change mechanism.

Conclusions:

• MetaChi18A is a novel, highly stable chitinase with broad operational conditions.
• Its characteristics suggest significant potential for industrial applications in chitin processing and biomass conversion.