Molecular cloning, over-expression and enzymatic characterization of an endo-acting beta-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-beta-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 50a"integral and pH 8. The enzyme was stable at 50a"integral 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 beta-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 beta-1,3-glucanase (EC 3.2.1.39) and thus is a potential candidate for use in agriculture, drug, chemical and bioethanol industries.