In nine of eleven species of brown algae tested, much of the 14C-glucose taken up from aqueous media was readily leached out again during subsequent washing in ice-cold seawater. Whilst none of the unleachable fraction was converted to 14C-mannitol, a considerable proportion was incorporated into insoluble glucose polymers and some was lost in respiration.
Two species—Ascophyllum nodosum and Pelvetia canaliculata—were very different in that very little accumulated 14C-glucose could be leached out. Most of the 14C-glucose in the tissues of these two algae was rapidly converted to 14C-mannitol, the remainder being either incorporated into insoluble compounds or respired.
These two species were also able to convert exogenously supplied 14C-mannose to mannitol, and Pelvetia incorporated much 14C from exogenous mannitol into a disaccharide compound. Fucus, as a representative of the other species investigated, was unable to metabolize either exogenous mannose or mannitol.
None of the eleven species converted either galactose or fructose, supplied exogenously, to mannitol.