RUI: Synergistic biodegradation of polyethylene terepthalate (PET) plastic by microbial consortia

With nearly 400 million metric tons of new plastics produced every year and with recycling rates at only 9%, the majority of plastics eventually enter the environment. Single-use items, such as water bottles and food containers, and textiles made from polyethylene terephthalate (PET) comprise a significant proportion of this waste. With the idea of creating a more circular PET economy, a community of soil bacteria with the ability to degrade PET plastic waste was identified. The overall goal of this project is to determine how this bacterial community achieves this environmentally and potentially commercially important feat. Undergraduates and high school students will participate in the research. Previous research identified a snapshot of bacterial genes induced during the late exponential phase of growth on PET plastic. This information, combined with metagenome analysis indicated that synergistic cross-feeding among a consortium of soil bacteria was partly responsible for the ability to degrade PET plastic. In this project, threshold requirements for PET degradation will be explored by RNA sequencing to analyze the gene products necessary for colonization by the bacteria and for polymer cleavage during the initial stages of growth. Informed by these analyses, individual genes within the metagenome will be targeted for creating deletion mutations. Genes targeted for deletion will include those encoding biosurfactants, uptake systems, enzymes known to degrade and metabolize PET, and regulators that perceive environmental signals. The mutants will be analyzed by HPLC and NMR to monitor breakdown products, thus allowing inference of which genes contribute to PET degradation within the consortium. Such a systems approach offers an avenue to understand the observed synergistic growth of microbes on PET and has the potential to revolutionize understanding of how plastics are recycled in natural environments. In turn, this knowledge could be applied to create a more circular plastics economy using bio-recycling techniques. 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.