Characterization of a novel alginate lyase Alg0392 with organic solvent-tolerance from Alteromonas sp. A1-6.

Enzymatic depolymerization of seaweed polysaccharides aroused great interest in the production of functional oligosaccharides and fermentable sugars. Alginate lyase Alg0392, a potential novel member of the polysaccharide lyase PL17 family, was cloned from Alteromonas sp. A1-6. The enzymatic properties, kinetic parameters, and hydrolytic products of Alg0392 were systematically characterized. Especially, the recombinant enzyme Alg0392 showed excellent tolerance to organic reagents. When treated with 5 mmol/L of TritonX-100 or 20%(v/v) of methanol, its relative enzyme activity could be maintained at more than 70%. The recombinant enzyme has a substrate preference for poly (β-D-mannuronic acid). The products of alginate hydrolysis catalyzed by Alg0392 are mainly monosaccharides, disaccharides, and trisaccharides. The products generated by the degradation of polymannuronic acid (polyM) are mainly monosaccharides. So Alg0392 is a polymannuronate cleaving enzyme. It has excellent organic solvent-tolerance and possesses both endo- and exo-glycosidase activities towards alginate. These unique properties make the recombinant enzyme Alg0392 more advantageous for the future industrial production of biofuels and the preparation of alginate oligosaccharides. KEY POINTS: • Alg0392 is a bifunctional alginate lyase with exolytic and endolytic cleavage activity. • Alg0392 exhibits excellent organic solvent tolerance. • The enzymatic hydrolysates of Alg0392 exhibit antioxidant activity.