Preparation of trisaccharides from alginate by a novel alginate lyase Alg7A from marine bacterium Vibrio sp. W13

Enzymatic digestion of sodium alginate to produce specific oligosaccharides has attracted great attention. However, commercial enzymes that efficiently produce specific oligosaccharides are still unavailable. In the present study, a novel gene encoding an alginate lyase (designated alg7A) was cloned from the marine bacterium Vibrio sp. W13 and expressed in E. coli. The recombinant Alg7A shows high activities toward alginate, poly-α-L-guluronate (polyG), poly-β-D-mannuronate (polyM) and polyMG, and more preferred to polyMG. Moreover, the enzyme contains a highly conserved domain of the Polysaccharide Lyase (PL) 7 family (R*E*R, Q*H and Y*KAG*Y*Q), which indicates that it belongs to PL7. Furthermore, the thin layer chromatography and ESI-MS analysis showed that Alg7A mainly releases trisaccharides from alginate. These results demonstrated that Alg7A has a great potential to be used to produce oligosaccharides from alginate.