[Purification and characterization of a novel alginate lyase from marine Vibrio sp. QY102]

A marine bacterium Vibrio sp. QY102 with high alginate-degrading activity was isolated from surface of sargassum. The alginate lyase recovered from culture supernatant was purified to electrophoretic homogeneity by a procedure of 0.22 microm membrane filtration, DEAE-sepharose ion-exchange and Superdex75 gel filtration chromatography. The molecular mass of the enzyme determined by SDS-PAGE was 28.5kD. The optimum pH and temperature for enzyme activity were pH 7.1 and 40 degrees C, respectively. The enzyme was stable from pH 5 to 10 and at temperature below 40 degrees C. Ca2+ and Mg2+ enhanced the enzyme activity, whereas Ni2+, Al3+, Zn2+ and Ba2+ inhibited the activity, and the lyase activity was strongly inhibited by SDS and EDTA. The activity of the alginate lyase purified in this experiment was obviously higher than that of others reported so far, and this enzyme showed a preference for polymannuronic acid in substrate specificity.