Molecular Cloning, Over-expression and Enzymatic Characterization of an Endo-acting β-1,3-glucanase from Marine Bacterium Mesoflavibacter zeaxanthinifaciens S86 in Escherichia coli

Abstract

Glucanases are involved in degradation of glucans. Here, we report a new endo-β-1,3-glucanase Mzl86 identified in Mesoflavibacter zeaxanthinifaciens S86. The deduced amino-acid sequence of Mzl86 showed highest similarity (45.1%) with Leeuwenhoekiella blandensi and thus placed in glycosyl hydrolase family 16. Purified recombinant protein (rMz186) showed an optimum enzyme activity against laminarin at 50°C and pH 8. The enzyme was stable at 50°C for 1 hour (maintaining 80% of its maximum activity) and was strongly activated (187%) in the presence of 2.5 mM manganese. Substrate-specific activities of rMzl86 against laminarin, barley β-glucan and lichenan were 261, 128 and 115 unit/mg, respectively. rMzl86 degraded laminarioligosaccharides (lager than biose) and laminarin while producing mainly biose and glucose. Molecular and biochemical properties reveal that rMzl86 shares typical features of β-1,3-glucanase (EC 3.2.1.39) and thus is a potential candidate for use in agriculture, drug, chemical and bioethanol industries