Challenges addressed

Bioplastics have a great potential to replace petroleum-based plastics, moreover some of them show a higher biodegradability, forming a closed cycle whereby material used to produce them can be redirected back into soil biomass via microbial degradation. Achieving this vision relies on developing robust biodegradation approaches. Current certified bioplastic degradation protocols have several drawbacks: ecotoxicological impacts of the polymer and the microparticle release are difficult to assess, and microbial species and communities associated with biodegradation and bioplastic-derived carbon recycling into microbial biomass are treated as a black box, leading to high variability in their efficacy. These ambiguities regarding the true biodegradability and sustainability of bioplastics that are generally more expensive than petrol-based plastics prevents their broader acceptance by industry and customers.

The project aims to reduce the environmental persistence of undegraded bioplastics by directing the bioplastic-derived carbon stock for longer-term storage in form of soil microbial biomass. The preliminary and literature data reveal the existence of bacterial species that can enzymatically break-up chemical bonds in specific biopolymers and incorporate monomeric units of the polymer into their biomass.

Objectives

To help develop standardized degradation protocols and new biodegradability labels. In the longer term, to analyze the mechanisms behind the break-up of specific chemical bonds in biopolymers to identify novel plastic-degrading enzymes that may be optimized by recombinant DNA techniques.

To reduce consumers’ concerns regarding the true biodegradability and eco- and climate-friendly benefits of these materials.

What are the expected outputs of this project?

To use bacterial species to design whole communities capable of bioplastic degradation with the help of advanced analytical tools. An in-depth molecular analysis of the microbial-driven degradation of bioplastics will also help define more appropriate test criteria for evaluating the biodegradation potential of these materials.

Milestones

  • October 2022 to March 2023

    Conditions for PBX degradation by bacterial monocultures and communities

  • October 2022 to March 2023

    Collection of bacterial strains involved in PBX degradation

  • April and May 2023

    Liquid chromatography coupled with high-resolution mass spectrometry (LC-MS) method adaptation to study polybutylene-xylose (PBX) degradation and metabolites

  • June 2023 to November 2023

    LC-MS time-resolved monitoring of the PBX degradation

  • April to November 2023

    Breeding bacterial communities for PBX degradation

  • Synthesis of bioplastics (Prof. Luterbacher)

Funding

This project is financed by CLIMACT.

Principal investigators

Dr.
Dr. Horst Pick

SB & ENAC, EPFL

Prof.
Prof. Sara Mitri

FBM, UNIL

Prof.
Prof. Jeremy Luterbacher

SB, EPFL

Prof.
Prof. Christian Ludwig

ENAC, EPFL

Sustainable Development Goals

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