Isolation and characterization of alginate-derived oligosaccharides with root growth-promoting activities

Lytic digestion of poly(mannuronate), poly(guluronate), and alginate with an alginate lyase from Alteromonas macleodii was used to prepare mixtures of unsaturated oligosaccharides. Four oligosaccharides isolated from the alginate lyase-lysate by anion-exchange chromatography on Q-Sepharose were found to be the major components of the root growth-promoting lysate. The oligosaccharides were analyzed by NMR and SIMS and identified as di- and tri-saccharides having O-(4-deoxy-L-erythro-hex-4-enopyranosyluronic acid)-1--> at the nonreducing terminus. The trisaccharides from the lysate were found to have root growth-promoting activity in a barley bioassay.