Plastic Degradation Is Not a Solution: The Life-Threatening Effects of PET Monomers on Marine Rotifers (Branchionus)

Overview

The Great Pacific Garbage Patch is a massive accumulation of microplastics located between the coasts of Hawaii and California. In 2016, the enzyme PETase showed its ability to depolymerize PET into monomers: BHET, MHET, and TPA. Marine rotifers (Branchionus) are resilient filter feeders that mechanically fragment ingested materials and are essential for regulating the algae populations. Our hypothesis was that the combination of transgenic Z1-PETase E.coli and rotifers would result in a more efficient PET depolymerization. However, in our study, we found that rotifers cannot form symbiotic relationships with PETase E. Coli. When we placed varying concentrations of PETase and 1 micron PET in the rotifers’ living environment, we found a positive correlation between the PETase and PET concentrations and the death of the rotifers. Additionally, mortality occurred only in rotifers exposed to PET and PETase, while rotifers exposed to PET and unedited E. coli showed no decrease in survival. Further examination showed that rotifers did not survive in environments with MHET and TPA, respectively, for over 24 hours. This study shows how, despite being able to reduce the amount of PET in our environment, PETase, or plastic degradation in general, may be life-threatening to marine microorganisms. The unintended and consequential side effects of plastic degradation suggest that decreased plastic consumption is a friendlier solution to the growing plastic pollution.

Competition history

• CSEF 2026 Earth & Environmental Sciences(Senior Division) · Entry S-08-15

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