30 March 2020
Polyurethane is everywhere, for good and bad.
DmyTo / GETTY IMAGES
Preliminary study reveals
Scientists continue in the quest to conscript microbes in the battle
against burgeoning plastic waste.
We reported previously on research focusing on the
well-known polyethylene terephthalate (PET) plastics used in drink
Now a German team says it has identified and characterized a strain
of bacteria capable of degrading some of the chemical building
blocks of the equally prolific and problematic polyurethane.
Writing in the journal Frontiers in Microbiology, the
researchers describe a strain of an extremophile group of bacteria
that is capable of ingesting toxic organic compounds as its sole
source of carbon, nitrogen and energy.
They stress, however, that the work is preliminary, with more
knowledge needed before commercial developments are possible.
Led by the Helmholtz Centre for Environmental Research in
Leipzig, the project is part of the European Union program
(From Plastic waste to Plastic value using Pseudomonas putida
Synthetic Biology), which is attempting to find useful
microorganisms that can bioconvert oil-based plastics into fully
In this case, the researchers isolated a bacterium, Pseudomonas sp.
TDA1, from a site rich in brittle plastic waste that shows promise
in attacking some of the chemical bonds that make up polyurethane
They performed a genomic analysis to identify the degradation
pathways at work, making preliminary discoveries about the factors
that help the microbe metabolize certain chemical compounds in
plastic for energy.
They also conducted other analyses and experiments to understand the
Co-author Christian Eberlein says this strain is part of a
group of bacteria well known for their tolerance of toxic organic
compounds and other forms of stress.
"That trait is also
named solvent-tolerance and is one form of extremophilic
microorganisms," he says.
corresponding author Hermann J Heipieper says the next step
in any future research would be to identify the genes that code for
the extracellular enzymes that are capable of breaking down certain
chemical compounds in polyester-based polyurethanes.
Extracellular enzymes, also called exoenzymes, are proteins secreted
outside of a cell that cause a biochemical reaction.
The potential is to engineer these or other enzymes using synthetic
biology techniques for bioplastic production. That could involve,
for instance, genetically converting the bacteria into
mini-factories capable of transforming oil-based chemical compounds
into biodegradable ones for planet-friendly plastics.
Polyurethane, which accounted for 3.5 million tonnes of the plastic
produced in Europe in 2015, is difficult and energy-intensive to
recycle or destroy because is usually does not melt when heated.