ABSTRACT

The abundance of microorganisms found in nature, including both bacteria and fungi, is extremely diverse. Many of these microorganisms can degrade a variety of polymeric materials such as biomass and plastic waste. However, the few known microorganisms that can degrade plastics do so slowly. More efficient plastic-degrading microorganisms could be leveraged as industrial biotechnology to recycle waste plastic materials and create value-added products. In particular, the ability to biochemically recycle high-volume, difficult-to-recycle plastics like polystyrene and polyethylene would be an important step toward overcoming a mounting global environmental and health concern. The project team has recently isolated several promising bacterial and fungal strains that appear to degrade polystyrene and polyethylene. The multidisciplinary team will work together to decipher how these microorganisms degrade plastic waste and use this information to engineer bacterial cells to improve degradation efficiency. They will also utilize a mixture of different bacteria and fungi as a consortium to improve the plastic degradation efficiency, mimicking how microbes work together in nature to decompose complex materials. Finally, the plastic degradation products will be converted into high-value chemicals using novel engineered microorganisms. The proposed work will directly accelerate the research and development of microbe-driven plastic degradation and re-utilization and will address a critical national need for green technology through microbial bioproduction and biomanufacturing. The project will contribute to the training of next-generation researchers through exposure to multidisciplinary science and engineering at the high school and undergraduate levels. The team will also create online learning modules, presentations, and social network materials that will build partnerships between academia and the public to communicate and enhance the scientific awareness about the future of plastic waste and the potential for bioremediation.

The project vision is to degrade mixed waste plastic and upcycle the degradation products into high-value chemical precursors using bacterial/fungal consortia and engineered bacterial consortia. The first aim is to identify the key plastic-degrading enzymes from individual microorganisms isolated from the enriched polyethylene- and polystyrene-degrading environmental bacterial/fungal consortia. The second aim is to create tailored synthetic fungal-bacterial consortia that can bio-augment mixed polyethylene/polystyrene degradation. The third aim is to develop engineered strains that produce a useful chemical precursor, 3-hydroxypropionic acid, and use these to create a synthetic consortium of plastic-degrading engineered microbes. Innovative high-throughput microfluidic technologies will be used to accelerate the discovery and testing processes. The project will yield new insights into the biochemistry of plastic degradation and conversion of plastic degradation products to high-value products, as well as significantly accelerate the development of next-generation bioremediation and green bioproduction technologies. In addition, the synthetic biology strategy, stable microbial consortia construction strategy, and high-throughput microfluidic platforms are expected to have broad appeal in the fields of synthetic biology, biomanufacturing, and biotechnology. The anticipated outcomes, focused here on polystyrene and polyethylene mixtures, are expected to pave the way for biochemical degradation and re-utilization of other complex plastic mixtures encountered in the real world.

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.

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