Biosorption of heavy metals by Saccharomyces cerevisiae: A review

Abstract

Heavy metal pollution has become one of the most serious environmental problems today. Biosorption, using biomaterials such as bacteria, fungi, yeast and algae, is regarded as acosteffective biotechnology for the treatment of high volume and low concentration complex wastewaters containing heavy metal(s) in the order of 1 to 100 mg/L. Among the promising biosorbents for heavy metal removal which have been researched during the past decades, Saccharomyces cerevisiae has received increasing attention due to the unique nature in spite of its mediocre capacity for metal uptake compared with other fungi. S. cerevisiae is widely used in food and beverage production, is easily cultivated using cheap media, is also a by-product in large quantity as a waste of the fermentation industry, and is easily manipulated at molecular level.

The state of the art in the field of biosorption of heavy metals by S. cerevisiae not only in China, but also worldwide, is reviewed in this paper, based on a substantial number of relevant references published recently on the background of biosorption achievements and development. Characteristics of S. cerevisiae in heavy metal biosorption are extensively discussed. The yeast can be studied in various forms for different purposes. Metal-binding capacity for various heavy metals by S. cerevisiae under different conditions is compared. Lead and uranium, for instances, could be removed from dilute solutions more effectively in comparison with other metals. The yeast biosorption largely depends on parameters such as pH, the ratio of the initial metal ion and initial biomass concentration, culture conditions, presence of various ligands and competitive metal ions in solution and to a limited extent on temperature. An assessment of the isotherm equilibrium model, as well as kinetics was performed. The mechanisms of biosorption are understood only to a limited extent. Elucidation of the mechanism of metal uptake is a real challenge in the field of biosorption. Various mechanism assumptions of metal uptake by S. cerevisiae are summarized.

Article Outline

1. Introduction

2. Advantages of S. cerevisiae as biosorbents in metal biosorption

3. Forms of S. cerevisiae in biosorption research

4. Biosorption capacity of S. cerevisiae

4.1. Metal ion uptake

4.2. Biosorption capacity

4.3. Selectivity and competitive biosorption by S. cerevisiae

4.4. Comparison with other biomaterials

5. Influential factors

5.1. Properties of metal ions in solution

5.2. Environmental conditions

5.2.1. pH

5.2.2. Temperature

5.2.3. Contact time

5.2.4. Competing ions/co-ions

5.2.5. Initial concentration of metal ions and biomass

5.2.6. Composition of cultural medium

5.2.6.1. Glucose

5.2.6.2. Other compositions of cultural medium

5.2.7. Cell age

6. Pretreatment

7. Biosorption equilibrium isotherm models and kinetics models

7.1. Equilibrium isotherm models

7.2. Kinetics of biosorption

7.3. Process of metal uptake

7.4. Kinetic models for S. cerevisiae

8. Biosorption mechanism by the cell of S. cerevisiae

8.1. Extracellular accumulation/precipitation

8.2. Cell surface sorption/precipitation

8.3. Intracellular accumulation/ precipitation

9. Instrumental tools and techniques used in metal biosorption studies

10. Discussions and future directions

10.1. Mechanism research

10.2. Application of biosorption technology

10.3. Screening of biomaterials

10.4. Hybrid technology

Acknowledgements

References