Engineered Enzymes for Polyurethane Recycling

C53-31a-271169Significant technical innovations are needed to improve the economics of plastic recycling. Plastic recycling rates in the United States have been stagnant for more than a decade: less than 10% of plastics are currently recycled, and only 5.5% of polyurethane plastics are recycled. Plastics have become a major contributor to global warming, as emissions from global plastics production and incineration are expected to account for 15% of global greenhouse gas emissions by 2050. The economics of conventional plastic recycling are poor, as high temperatures are frequently used to recycle plastics, resulting in degradation of plastic quality that greatly reduces the economic value of recycled plastics. This proposal uses synthetic biology to design, engineer, and optimize new enzymes to break down polyurethane plastic waste for recycling and upcycling into new, high value plastic products. In Phase I of this research, naturally occurring polyurethanase enzymes were identified and engineered to improve their ability to break down polyurethane polymers under scalable recycling conditions. Importantly, these engineered enzymes re-generate the building block chemicals that are used to manufacture polyurethane plastics today, enabling manufacture of 100% recycled polyurethane plastics using chemicals recovered from enzyme-mediated polyurethane decomposition. This Phase II proposal is focused on further improving the economics of enzyme-mediated polyurethane recycling through continued improvement of high-performance polyurethanase enzymes. In addition, this proposal seeks to demonstrate high yield recycling of polyurethanes under scalable, industrial conditions as a demonstration of the robustness and favorable technoeconomics of enzyme-mediated recycling of polyurethane plastics. The 2020 market for plastic recycling was $1.7 billion in the United States and $26.5 billion globally. High- performance engineered enzymes and bioprocess technology will accelerate growth of this industry and mitigate the unsustainable manufacture of virgin polyurethanes from oil and gas, including the downstream landfilling of polyurethanes with their associated environmental contamination and carbon emissions. Improved economics of plastic recycling will motivate materials recovery facilities to invest in polyurethane recycling infrastructure, as enzyme-mediated polyurethane recycling could save millions of dollars in shipping and dumping fees. Societal and environmental benefits resulting from reductions in oil consumption and carbon emissions will accelerate as these technologies are implemented. Importantly, market growth will be spurred by governmental policies designed to encourage efficient, circular plastic recycling, such as national taxation of carbon emissions, state requirements for minimum recycled plastic content in packaging and other materials, and producer responsibilities for the fate of plastic products.