Cd²⁺ Impact on Metabolic Cells of Saccharomyces cerevisiae over an Extended Period and Implications for Bioremediation

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.

Keywords:

• S. cerevisiae
• Cd
• bioaccumulation
• biosorption
• toxicity

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).