The role of extracellular carbonic anhydrase activity in inorganic carbon utilization of Phaeocystis globosa (Prymnesiophyceae): A comparison with other marine algae using The isotopic disequilibrium technique

摘要

The utilization of inorganic carbon species by the marine microalga Phaeocystis globosa (Prymnesiophyceae) and several other algal species from different taxa, was investigated by determining the time course of 14~C incor- poration in isotopic disequilibrium experiments. From these kinetic data, conclusions can be drawn about the carbon species, CO_2 or HCO_3, that is being utilized. By comparing the uptake kinetics in the absence and presence of acetazolamide (AZ) or dextran-bound sulfonamide, inhibitors of external carbonic anhydrase (CA), it was deter- mined that P. Globosa, Dunaliella tertiolecta, and some strains of Emiliania huxleyi do use HCO_3- by extracellular, CA-catalyzed conversion to CO_2, which then diffuses across the membrane.