Efficient biosynthesis of levan from sucrose by a novel levansucrase from Brenneria goodwinii

•A novel levansucrase was characterized from B. goodwinii.•The polysaccharide biosynthesized from sucrose was determined to be levan.•The enzyme displayed maximal transfructosylation activity at pH 6.0 and 35°C.•The enzyme produced 185g/L levan from 50% (w/v) sucrose.•The molecular weight of the produced levan reached 1.3×108Da. Levan, a unique homopolysaccharide consisting of fructose residues linked by β-(2, 6) bonds, possess promising physiochemical and physiological properties with numerous potential applications. In this study, a novel levan-producing levansucrase was characterized from Brenneria goodwinii. The polysaccharide produced by the recombinant enzyme from sucrose was structurally determined to be levan-type fructan connected by β-(2, 6) linkages. The optimum pH was measured to be pH 6.0 for both sucrose hydrolysis and transfructosylation. The optimum temperature was 35, 45, and 40°C for transfructosylation, sucrose hydrolysis, and total activity, respectively. Higher sucrose concentration greatly favored to levan biosynthesis. The purified recombinant enzyme produced 185g/L levan from 50% (w/v) sucrose at pH 6.0 and 35°C for 12h. The molecular weight of the produced levan polysaccharide reached 1.3×108Da, which was much higher than the ones produced by many reported levansucrases.