Biochemical characterization of a novel hyperthermophilic chitinase from a deep-sea Thermotogae bacterium

Abstract

Chitin represents the most abundant source of renewable biomass in marine ecosystems, and its degradation by chitinase holds potential for numerous industrial applications. In this study, a novel hyperthermophilic chitinase, TbChi52, derived from a deep-sea bacterium of the Thermotogae phylum was introduced. TbChi52 exhibits optimal enzymatic activity at 90 ℃ and pH 5.5. Furthermore, it shows exceptional thermal stability characterized by a prolonged thermal denaturation half-life and a significant melting temperature. Functionally, TbChi52 displays dual activities, acting as both an exo-chitinase and a β-N-acetylaminoglucosidase (NAGase). It yields N-acetyl-D-glucosamine (GlcNAc) as the primary product during the hydrolysis of colloidal chitin. Leveraging the robust thermo-stability of TbChi52, a streamlined, one-step purification protocol was developed. A mere 10-minute thermal treatment at 75 ℃ suffices to yield a highly pure TbChi52 preparation with minimal enzyme activity loss in chitin hydrolysis, achieving an 87.4 % hydrolysis rate of colloidal chitin and a 92.7 % purity of GlcNAc. Collectively, the outstanding thermal properties and the simple preparation of TbChi52 highlight its potential for industrial applications. It provides a sustainable and eco-friendly approach to harnessing the world's most abundant marine biomass, along with serving as a potential enzyme-engineered template tailored for specific applications.