Peptide-based recovery of gallium

High-tech metals are almost ubiquitous in our everyday lives. Due to their great importance for the electronics industry, the demand is continuously growing. The supply of these important raw materials is currently mainly covered by primary raw material sources. However, with increasing technological progress, the supply situation on the global market becomes tense. The recovery of high-tech metals from secondary raw material sources could help to ease the situation. This task is a major challenge due to a strongly mixed matrix and sometimes low concentrations of valuable metals from such sources. However, highly innovative strategies are required to meet this challenge. Modern biotechnology offers promising concepts for the efficient, economical and sustainable recycling of high-tech metals [1].
Recently we’ve established a phage display technology platform for the highly specific recognition of mineral particles as well as of metal ions in polluted water streams. This is escorted by a newly developed system for the heterologous expression of identified peptides [2-4].
Here we report in detail about the development of high-affinity peptide ligands for the recovery of gallium from industrial wastewater. Various gallium binding peptide sequences were identified by applying a commercial dodecamer peptide library (Ph.D.-12, NEB, US). Biopanning conditions were optimized for the enrichment of metal ion binding phage clones, which allows a more precise selection process. By single clone binding studies and competitive binding experiments, 3 sequences were characterized to show high binding affinity and selectivity for gallium above other metals, especially arsenic.
Gallium binding peptides are now produced for further spectroscopic characterization and evaluation of binding properties. In addition immobilization strategies to create peptide-based materials for the recovery of gallium binding peptides will be discussed.

[1] K. Pollmann, S. Kutschke, S. Matys, J. Raff, G. Hlawacek, F.L. Lederer, Bio-recycling of metals: Recycling of technical products using biological applications, Biotechnology Advances, (2018)
[2] R. Braun, S. Matys, N. Schönberger, F.L. Lederer, K. Pollmann, Simplified Expression and Production of Small Metal Binding Peptides, Solid State Phenomena, (2017)
[3] S. Matys, F.L. Lederer, N. Schönberger, R. Braun, F. Lehmann, K. Flemming, S. Bachmann, S. Curtis, R.T.A. MacGillivray, K. Pollmann, Phage Display - A Promising Tool for the Recovery of Valuable Metals from Primary and Secondary Resources, Solid State Phenomena, (2017)
[4] F.L. Lederer, S.B. Curtis, S. Bachmann, W.S. Dunbar, R.T. MacGillivray, Identification of lanthanum-specific peptides for future recycling of rare earth elements from compact fluorescent lamps, Biotechnol Bioeng, (2017)