Fundulus spp. Gut Microbiomes as a Novel Source of PET-Degrading Bacteria

Date of Submission

6-2026

Document Type

Thesis

Degree Name

Master of Science in Cellular and Molecular Biology

Department

Biology and Environmental Sciences

Advisor

Nikolas M. Stasulli, Ph.D.

Committee Member

Christian Conroy, PhD.

Committee Member

Anna Kloc, Ph.D.

Abstract

Since the 1970s, an increasing reliance on plastics has led to pervasive, ubiquitous pollution. As traditional disposal methods are insufficient to address increasing levels of plastic waste, there is a growing need to investigate remediation strategies, including the biodegradation of plastic waste. While previous studies have isolated plastic-degrading bacteria from a variety of contaminated environments, few have explored the microbiomes of organisms occupying plastic-polluted areas as sources of plastic-degrading bacteria. This study investigated Fundulus spp. gut microbiomes as a novel source of polyethylene terephthalate (PET)-degrading bacteria.

Bacteria were isolated from Fundulus spp. specimens collected from the Quinnipiac River, Connecticut. Isolates were cultured with PET as the sole carbon source to identify potential degraders. Degradation capabilities were assessed through PET weight loss and biofilm percent coverage, and a Rhodamine B/olive oil assay was used to assess lipolytic activity of the isolates. Top-performing isolates were identified by 16S rRNA sequencing, and functional analyses were conducted to identify potential PET-degrading enzymes in the proteomes of identified isolates.

This study obtained 103 bacterial isolates, with 88 undergoing PET degradation assays. Ten isolates were selected for additional analysis based on biofilm coverage. An isolate tentatively identified as Pseudomonas aeruginosa produced a statistically significant reduction in PET mass over a four-week incubation period. Furthermore, Phyllobacterium myrsinacearum and Enterobacter chuandaensis were identified as novel potential PET-degraders. Functional analysis revealed 17 enzymes of interest between these three species, including two with catalytic triads characteristic of PET-degraders, and one esterase containing a predicted PETase motif. These findings indicate that the Fundulus spp. gut is a viable source of plastic-degrading bacteria and contribute to the current body of research on the biodegradation of plastic waste.

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