Plastics Recycling Using Microbes


The international collaborative project MIX-UP receives funding from the EU's Horizon 2020 program.

  Persons in the lab Copyright: © Peter Winandy Preparation for an experiment in the bioreactor at the RWTH Institute of Applied Microbiology.

In 2019 alone, around 360 million tons of plastic were produced worldwide, often ending up either in landfill sites or even in the countryside or the sea. An international, multidisciplinary consortium – funded by the EU HORIZON 2020 program – is therefore researching new and environmentally sustainable recycling methods. The aim is to find viable complementary alternatives to mechanical and chemical processes.

RWTH Professor Lars Blank, Chair of Applied Microbiology, is coordinator of the MIX-UP project, short for Mixed Plastics Biodegradation and Upcycling Using Microbial Communities. The Chair of Biotechnology, the Institute of Technical and Macromolecular Chemistry, the chemical engineering institutes of the AVT, as well as various international partners are contributing to the project. The overall aim is to develop processes for the microbial transformation of plastic waste into valuable molecules.

Biotechnological Plastics Recycling

“MIX-UP uses plastic mixtures from the five most important fossil-based plastics as well as future bio-based plastics for biochemical recycling and upcycling,” explains Lars Blank. The enzymatic degradation of plastic waste is coupled with the subsequent transformation into value-added chemicals and plastics, achieved with the help of dedicated microbial communities.”

To this end, known polymer-degrading enzymes will be optimized with respect to high specific binding capacities, stability, and catalytic efficiency for a broad spectrum of plastic polymers under high salt concentrations and temperatures. Furthermore, new enzymes with activities on recalcitrant polymers are to be isolated.

The project also seeks to optimize the production of these enzymes and develop enzyme cocktails tailored to specific plastic mixtures. “The released plastic monomers will be selectively used by stable microbiome mixtures as substrates to produce, among other products, value-added chemicals or microbial polyesters,” explains Blank. Any remaining material recalcitrant to enzymatic activity will be recirculated into the process after a physico-chemical treatment.

Towards a Bio-Based and Resource-Saving Economy

The technologies developed in MIX-UP are set to increase recycling rates and add value to poorly recycled streams of unsorted plastic waste. The Science Year 2020/21 project, which was initiated by the Federal Ministry of Education and Research and has a focus on the bioeconomy, featured the project as an important contribution towards establishing a bio-based and resource-saving economy and lifestyle.

In its recent issue, the science journal Nature Catalysis published a report on the MIX-UP project, titled Possibilities and limitations of biotechnological plastic degradation and recycling. The article highlights the current state of research on the biotechnological value creation from plastic waste streams.

For further information on the project, please refer to the MIX-UP website.