Isolation and culture of a marine bacterium degrading the sulfated fucans from marine brown algae

Fucoidans are matrix polysaccharides from marine brown algae, consisting of an alpha-L-fucose backbone substituted by sulfate- ester groups and masked with ramifications containing other monosaccharide residues. In spite of their interest as biologically active compounds in a number of homologous and heterologous systems, no convenient sources with fucanase activity are available yet for the degradation of the fucalean algae. We here report on the isolation, characterization, and culture conditions of a bacterial strain capable of degrading various brown algal fucoidans. This bacterium, a member of the family Flavobacteriaceae, was shown to secrete fucoidan endo-hydrolase activity. An extracellular enzyme preparation was used to degrade the fucoidan from the brown alga Pelvetia canaliculata. End products included a tetrasaccharide and a hexasaccharide made of the repetition of disaccharidic units consisting of alpha- 1 --> 3- L-fucopyranose-2-sulfate-alpha-1-->4- L-fucopyranose- 2,3- disulfate, with the 3- linked residues at the nonreducing end.