# Enrichment of native plastic‐associated biofilm communities to enhance polyester degrading activity

## TL;DR

Researchers enriched plastic-associated bacteria to boost their ability to break down plastic, identifying a key species and new enzymes involved in the process.

## Contribution

The study introduces a novel enrichment method to enhance plastic-degrading activity in biofilms and identifies new enzymes and a key bacterial species.

## Key findings

- Seven enriched bacterial communities showed increased plastic degrading activity compared to original communities.
- Pseudomonas stutzeri was identified as a strong polyester degrader in six of the seven enriched communities.
- Sequencing revealed two putative polyesterases and one putative MHETase in P. stutzeri.

## Abstract

Plastic pollution is an increasing worldwide problem urgently requiring a solution. While recycling rates are increasing globally, only 9% of all plastic waste has been recycled, and with the cost and limited downstream uses of recycled plastic, an alternative is needed. Here, we found that expanded polystyrene (EPS) promoted high levels of bacterial biofilm formation and sought out environmental EPS waste to characterize these native communities. We demonstrated that the EPS attached communities had limited plastic degrading activity. We then performed a long‐term enrichment experiment where we placed a robust selection pressure on these communities by limiting carbon availability such that the waste plastic was the only carbon source. Seven of the resulting enriched bacterial communities had increased plastic degrading activity compared to the starting bacterial communities. Pseudomonas stutzeri was predominantly identified in six of the seven enriched communities as the strongest polyester degrader. Sequencing of one isolate of P. stutzeri revealed two putative polyesterases and one putative MHETase. This indicates that waste plastic‐associated biofilms are a source for bacteria that have plastic‐degrading potential, and that this potential can be unlocked through selective pressure and further in vitro enrichment experiments, resulting in biodegradative communities that are better than nature.

In this work, we demonstrate an approach to unlock the plastic‐degrading potential of marine plastic‐associated biofilms. We also identify Pseudomonas stutzeri as a plastic degrading species and discover three new enzymes potentially linked to polyester degradation.