Characterization of a new endo-type alginate lyase from Vibrio sp. W13

A gene, encoding a new alginate lyase Algb, was identified and cloned from marine bacterium Vibrio sp. W13. The recombinant alginate lyase was characterized followed by being purified on Ni-NTA Sepharose. It exhibited the highest activity (457U/mg) at pH 8.0 and 30°C. Interestingly, Algb possessed broader substrate specificity. It showed activities toward both polyM (poly β-d-mannuronate) and polyG (poly α-l-guluronate). Furthermore, K_m values of Algb toward alginate (0.67mg/ml) and polyMG (0.50mg/ml) are lower than those toward polyG (1.04mg/ml) and polyM (6.90mg/ml). The TLC and ESI-MS analysis suggested that Algb mainly released oligosaccharides with DP of 2-5 from the four kinds of substrates in an endolytic manner. Therefore, it may be a potent tool to produce alginate oligosaccharides with low DP.