CADMIUM SEQUESTRATION IN THE MARINE MACROALGA KAPPAPHYCUS-ALVAREZII

We identified phytochelatins (PCs) as the major intracellular cadmium (Cd) chelators in the marine macroalga Kappaphycus alvarezii. Phytoche latin isolated from this alga showed a less complex thiol profile than that of yeast and higher plants. In the general structure of (Glu-Cys )(n)-Gly for PC, the n value was less than 3 for this alga. Algal PC-C d complexes existed in the high molecular weight and low molecular wei ght forms. The high molecular weight form is rich in acid-labile sulfi de. The PC content in algal fronds was directly correlated with the am bient Cd concentration as well as exposure time. After the Cd-treated algal fronds were transferred to Cd-free seawater, the algal PC conten t showed no significant change, while the total Cd content decreased.