Biomolecular mechanism in the uptake of Pt(IV) by Saccharomyces cerevisiae EBY100 cells expressing platinum binding peptides

Platinum group metals (PGMs) are currently under increased demand due to limited availability and their unique properties; therefore, their limited availability presents an economically attractive opportunity to recover these metals from waste. The recovery of PGMs from effluents using conventional techniques such floatation, precipitation and ion exchange results in large volumes of hazardous waste as well as high operating costs and low efficiencies. Biosorption using biomass such as microorganisms as adsorbents can offer a cheap, efficient and environmentally friendly alternative for the recovery of PGMs. Despite previous research on the use of biosorption techniques for the recovery of PGMs; there is still room for improvement in the way that microorganisms absorb metals. Such advancements can be achieved through the use of genetically engineered peptides for inorganics (GEPI) for cell surface display purposes. In this work, Saccharomyces cerevisiae EBY100 cells were genetically engineered for cell surface display of platinum binding peptides to enable Pt(IV) adsorption from an aqueous solution. The transformed Saccharomyces cerevisiae EBY100 cells attained the maximum adsorption of 40 % for Pt(IV) after 3 h at the optimal pH = 3. As the initial metal concentration rose from 10 ppm to 50 ppm, the biosorption Pt(IV) increased as well, reaching a biosorption capacity of 85 mg/g. The findings also showed that the Freundlich model best explained the Pt(IV) biosorption isotherm onto P3.1, while the pseudo-secondorder model best explained the Pt(IV) adsorption kinetics onto P3.1.