The broader impact of this Small Business Innovation Research (SBIR) Phase I project is to enable a more efficient, profitable, and sustainable plastic recycling process. In the United States less than 10% of plastics are currently recycled, and the remainder are incinerated (15%) or placed in landfills (75%). Emissions from global plastics production and incineration could reach 56 billion tons of carbon between now and 2050, accounting for 15% of global greenhouse gas emissions. The economics of conventional plastic recycling are poor, because the high temperatures used in recycling cause quality degradation that greatly reduces the economic value. This project develops a low-temperature system for high quality, high-value plastic products in closed-loop recycling.The proposed project will apply synthetic biology and related biotechnologies to identify, engineer, and optimize new enzymes and enzyme cocktails to break down polyethylene (PE) and polyethylene terephthalate (PET) plastics. These enzymes will enable closed-loop plastic recycling in an economically viable, low temperature, low CO2 emission process. The first objective is to sample plastic contaminated environments for naturally occurring enzymes that have evolved to depolymerize PE and PET synthetic polymers. Candidate PE and PET enzymes will be engineered to accelerate their ability to efficiently target and cut complex PE and PET polymers under scalable process conditions. Millions of enzyme variants will be constructed, tested, and analyzed using synthetic biology, high-throughput screening, and machine learning technologies. A primary goal of this effort is to demonstrate a 10-fold increase in PE and PET depolymerization rates compared to naturally occurring plastic degradation proteins.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.
