Abstract
Interaction between Cd2+ of different concentrations (1, 2, and 3 mg/L) and metabolic active cells of Saccharomyces cerevisiae was studied in YPD batch cultures for a time period of 168 hours. Temporal variations of cell biomass, protein yields, and aqueous and intracellular Cd2+ concentrations were measured. S. cerevisiae cells were inhibited to grow by the presence of Cd2+ at low concentration, and appears to show distinctive responses to different levels of Cd2+ stress. Total intracellular Cd accumulation is found to progressively increase over the whole experimental course, and is positively related to the initial Cd concentration to some extent. The intracellular Cd2+ amount per biomass was, however, observed to increase in the early growth stage, but decrease progressively in late growth stage and finally reach to a stable level in the 3 mg/L Cd-amended system. An inverse pattern in the temporal variation of the intracellular Cd2+ amount per biomass is present in 1 mg/L system with the transitional pattern being found in 2 mg/L system. Both intracellular and surface biosorptive Cd might contribute to the total removal of Cd from the solution, with 20% contribution from the intracellular Cd of metabolic cells of S. cerevisiae. Our data shed light on the potential application of metabolic cells in bioremediation of Cd contamination.
Acknowledgments
This research is jointly supported by National Basic Research Program of China (973 Program, 2007CB815601), the Program for New Century Excellent Talents in University (NCET-08-0831), Special Fund for Basic Scientific Research of Central Colleges, China University of Geosciences (Wuhan) (CUG090103, CUGL100502) and the provincial program for outstanding youth of Hubei (2008CDB373).