Issue 06/2020

Bioplastics from Waste streams
By:
Uwe Bornscheuer and Ren Wei
Institute of Biochemistry
Greifswald University
Greifswald Germany
After around 100 years production of plastics, plastic
particles are almost everywhere: in ground water,
the oceans, the air and the food chain. Worldwide
considerable efforts are undertaken to solve this plastic
crisis by using biotechnological methods. However, most
progress is restricted to a specific type of plastic, namely
polyesters such as PET. In a comment in the journal Nature
Catalysis [1] the state of the current research is critically
discussed and strategies for a biobased circular economy
for plastics are suggested.
Sophisticated solutions are required to achieve a
circular economy for plastics. Currently, only a fraction of
the plastic materials are recycled using energy and costintensive
processes. One possibility to degrade certain
plastics into their building blocks is the use of enzymes
or biotechnological processes using microorganisms (cf
e.g. [2]). The thus accessible building blocks, also called
monomers, can be used to make new plastics. In case
the building blocks cannot be directly re-used, the plastic
should at least be sufficiently degraded to relieve the
environment and to access the raw materials. For both, the
end-of-use recycling of plastics as well as for the aim of a
carbon dioxide neutral balance, modern biotechnology can
make a substantial contribution.
In the publication “Possibilities and limitations of
biotechnological plastic degradation and recycling“ [1]
jointly written by scientists from the Universität Greifswald,
the RWTH Aachen, the Fraunhofer Institut UMSICHT and the
University College Dublin, the state of the current research
is discussed and strategies for future developments are
highlighted. The authors study within the joint project
MIX-UP – funded by the European Union in the framework
of Horizon 2020 – together with scientists from China the
creation of value from plastic waste, originating from oceans
as well as households, through biotechnology methods.
In these processes, microorganisms use the degradation
Circular
economy
for plastics
Biotechnological solutions for
degradation and recycling of
plastics
products from plastics in a so-called Up-cycling as carbon
source to make value-added products.
“While for the widely used plastic polyethylene
terephthalate (PET) already highly efficient enzymes have
been discovered and improved, which enable an economical
recycling, there is no significant progress yet for most
other plastics“ explains Uwe Bornscheuer from Greifswald
University. Ren Wei, who leads a junior research group at
the Institute of Biochemistry adds that: “Unfortunately
there are several publications, which raise wrong hopes.
For instance, in some reports about plastic-eating larvae
of certain insects (cf. p. 13) scientifically solid proofs are
missing.“
Lars Blank from the RWTH Aachen emphasises: “We
need to distinguish two aspects: Plastics, which we
deliberately expose to the environment such as mulching
foils for agriculture need to be decomposed rapidly – within
weeks or months. For durable plastics we need a mediumterm
solution. A degradation should be ensured to take
place within a few years – instead of so far centenaries.“
The authors suggest a scenario based on the following
six principles: rethink – refuse – reduce – reuse – recycle
– replace. They aim for a lively discussion how a circular
economy for plastics can be achieved within the near future.
Plastics in the sea © Jan_Meßerschmidt
References:
[1] Wei, R. et al. (2020): “Possibilities and limitations of biotechnological
plastic degradation and recycling,“ in: Nature Catalysis. https://doi.
org/10.1038/s41929-020-00521-w
[2] Thielen, M.: Waste to plastics by enzymes and bacteria, bioplastics
MAGAZINE, Vol. 15, 02/2020, p22
[3] Bornscheuer, U. et al.: Possibilities and limitations of biotechnological
plastic degradation and recycling (Behind the paper), https://
chemistrycommunity.nature.com/posts/possibilities-and-limitations-ofbiotechnological-plastic-degradation-and-recycling
https://www.uni-greifswald.de/en
bioplastics MAGAZINE [06/20] Vol. 15 23