Effect of pH on Pb2+ accumulation in Saccharomyces cerevisiae and Aureobasidium pullulans

The optimum pH conditions of Pb2+ accumulation in Saccharomyces cerevisiae and Aureobasidium pullulans were 4 similar to 5 and 6 similar to 7, respect ively. The initial Pb2+ accumulation rates according to the increase of ini tial Pb2+ concentration and pH were increased both in S. cerevisie and A. p ullulans. And the initial Pb2+ accumulation rate of A. pullulans was much h igher than that of S. cerevisiae because of the difference of Pb2+ accumula tion mechanism. The Pb2+ accumulation isotherm of S. cerevisae obeyed a ful ly competitive inhibition, whereas that of A. pullulans showed a mixed inhi bition of competition and non-competition associated with the proton (H+) a s an accumulation inhibitor.