As of 2015, nearly 80% of the world’s virgin plastic ended up in a landfill or the natural environment, a majority accredited to the packaging industry. Due to the composition of the durable plastic, polyethylene terephthalate (PET), the primary polymer found in single-use packaging, is not naturally biodegradable and thus accumulates. Recently, several microbes were discovered that could degrade the plastic compounds within their gut with no signs of toxicity. Ideonella sakaiensis is a novel bacterium capable of depolymerizing PET using a hydrolase termed PETase. An additional enzyme, MHETase, aids in converting dimers for the complete recovery of monomers within I. sakaiensis. Ultimately, efficiency in degrading PET of varying crystallinity occurs with a preference of low crystallinity PET, in opposition to other species currently known. During degradation, I. sakaiensis forms a thin biofilm over the plastic. It is known that the cells contain special appendages to adhere to the plastic surface, however, little research has been conducted on how the biofilm formation affects the degradation process. Multi-species biofilms have been shown to create complex communities for enhanced PET degradation in marine plastic debris using other bacterial strains.
This research aims to study the biofilm formation as well as its effects on its degradation properties of I. sakaiensis as an isolate, as well as a dual species biofilm with known biofilm forming bacteria: Stenotrophomonas maltophilia, Staphylococcus aureus, and Pseudomonas aeruginosa. The first half of the project characterized the effects of introducing biofilm forming bacteria on I. sakaiensis’ biofilm growth. The second half of the project analyzes the biofilm growth along with a degradation assay to determine the effects of these bacterial strains on the degradation process of I. sakaiensis. These effects were then evaluated to determine the role of biofilm formation in the degradation process. This study provides a foundation that can be used by the biotech, environmental, and molecular communities to lead to a commercialization of plastic degradation products, ultimately creating a circular and stable economy within the consumer world.
