Expression and characterization of a κ-carrageenase from marine bacterium Wenyingzhuangia aestuarii OF219: A biotechnological tool for the depolymerization of κ-carrageenan

kappa-Carrageenases are desirable tools for tailoring the molecular weight, physicochemical properties and functionalities of kappa-carrageenan, a macromolecule widely utilized in various industries. In this study, a novel GH16 family kappa-carrageenase, designated as Cgk16A, was cloned from the genome of marine bacterium Wenyingzhuangia aestuarii OF219 and expressed in Escherichia coil. Its biochemical properties, kinetic parameters and hydrolytic pattern were characterized. The enzyme demonstrated a low optimal reaction temperature (25 degrees C) and a cold adapted feature. As an endo-acting glycoside hydrolase, Cgk16A degraded kappa-carrageenan in a random manner, and it was competent to prepare the degradation products with varying degrees of polymerization. The mass spectrometry analysis revealed that the end products of Cgk16A were majorly composed of kappa-carrageenan tetrasaccharide with a minor portion of disaccharide. The enzyme showed higher enzyme-substrate affinity over all hitherto characterized GH16 kappa-carrageenases, indicated by its low K-m value (0.17 mu M). Cgk16A could be employed as a potential biotechnological tool for depolymerizing kappa-carrageenan, which would facilitate the future application of kappa-carrageenan and its degradation products. (C) 2018 Elsevier B.V. All rights reserved.