Link to bioRxiv paper: http://biorxiv.org/cgi/content/short/2020.09.23.309799v1?rss=1 Authors: Stellacci, F., Maerkl, S. J., Mezzenga, R., Giaveri, S., Murello, A., Roset Julia, L., Ortiz, D., Menin, L., Patiny, L., Schmitt, A. M., Bolisetty, S. Abstract: In 2070, 1012 Kg of polymer-based materials (i.e. plastics) might be produced yearly, posing one of the greatest challenges that humanity has to face. Even though natural polymers, such as proteins and nucleic acids, are more abundant than synthetic ones, they are sustainable. The key property of such natural polymers is that they are sequence-defined. This allows for recycling to start with depolymerization into monomers, and end in the re-assembly of new polymers of arbitrarily different sequence. This process breaks a common recycling paradigm that a material is recycled only into itself. An organism digests proteins into amino acids. These are re-assembled into new proteins whose identity depends on the cell's needs at the time of protein synthesis. Here we show that the process described above is achievable extra-cellularly. Specifically, we depolymerized a mixture of different peptides and/or proteins into their amino acid constituents and used these amino acids to synthesize fluorescent proteins using an amino acid-free cell-free transcription-translation system. We were successful in recycling proteins with high relevance in materials engineering ({beta}-lactoglobulin films, used for water filtration, or silk fibroin solutions) into a biotechnologically relevant protein (green fluorescent protein). The potential long-term impact of this approach to recycling lies in its compatibility with circular-economy models where raw materials remain in use as long as possible, thus reducing the burden on the planet. Copy rights belong to original authors. Visit the link for more info