STUDY OF SOLUTE INFLUENCES ON THE BINDING OF METALS TO STICHOCOCCUS-BACILLARIS WITH CD-113 NMR

The interaction between a unialgal species (Stichococcus bacillaris) a nd cadmium in the presence of several different solutes was investigat ed by Cd-113 NMR. The interaction between the algae and cadmium was ve ry strong, and the Cd/algae complex has an average formation constant of 2.8 x 10(5). Upon addition of different solutes into the algae susp ension, two results were obtained: in some cases the cadmium in the Cd /algae biomass was removed, and in other situations water molecules ar ound the bound cadmium were replaced by the added ligands. When the Cd /algae biomass was suspended in acetic acid or sodium acetate buffer s olutions, some of the bound cadmium was released, but only one resonan ce was observed for both the Cd/algae complex and the free cadmium in the solution. This chemical shift similarity indicates that the predom inant functional group on the cell wall of S. bacillaris is carboxylat e. Gold(III) was also found to strongly interact with S. bacillaris.