Identification of Peptides as alternative recycling tools via Phage Surface Display – How biology supports Geosciences

The application of biological tools in Geosciences such as bacteria or microbial products that mobilize metallic components raises increasing interest in classical mining industries. Today, 10% of the total copper production in Chile originated from bioleaching operations (Gentina and Acevedo, 2016). However, the application of biological tools is limited due to poor specificity, complex material composition and heterogenous particle size. New studies focus on smaller biological components such as peptides with higher material specificity to mobilize and recycle materials of interest.
End-of-life electronic products like smart phones or compact fluorescent lamps (CFL) contain a wide variety of precious elements in very low concentrations. Currently, no cost-efficient and environmentally friendly technology exists for the separation and recycling of the majority of high-tech industry supporting elements such as the rare earth element (REE) Lanthanum phosphate (LAP) from electronic scrap. The focus of this project was the identification of peptides with high specificity for the rare earth mineral LAP, a component of CFL, for future material recycling. By using a biological method called phage surface display and the random PVIII phage peptide library f88.4/Cys6, the phage-bound peptide TSTQCPSHIRACLKKR was identified and characterized as not only an efficient LAP binder, which is furthermore able to discriminate between LAP and other components of fluorescent lamps. The application of phage particles displaying the recombinant PVIII fused peptide TSTQCPSHIRACLKKR in recycling processes is not possible due to limited scale-up, critical public perception, low biological efficiency and fast mutation rates in phage particles. Future applications will be based on peptides that are stable under a variety of challenging conditions such as heat, varying pH or in the presence of toxic scrap components. The development of peptide-based separation tools represents a new way of recycling of electronic scrap.