More microbes that can degrade plastics in places with heavy plastic
pollution

Date:
December 14, 2021
Source:
Chalmers University of Technology
Summary:
The number of microbial enzymes with the ability to degrade
plastic is growing, in correlation with local levels of plastic
pollution. That is the finding of a new study that measured samples
of environmental DNA from around the globe. The results illustrate
the impact plastic pollution is having on the environment, and
hint at potential new solutions for managing the problem.



FULL STORY ==========================================================================
The number of microbial enzymes with the ability to degrade plastic is
growing, in correlation with local levels of plastic pollution. That is
the finding of a new study from Chalmers University of Technology, Sweden,
that measured samples of environmental DNA from around the globe. The
results illustrate the impact plastic pollution is having on the
environment, and hint at potential new solutions for managing the problem.


==========================================================================
The problems of global plastic pollution are all too widespread, as
mass- production of plastic has exploded in the last 70 years or so --
from around 2 million tonnes per year to around 380 million. This has
given sufficient evolutionary time for various microbes present in the environment to respond to these compounds, and many different enzymes
have been discovered in previous studies with the ability to degrade
different plastics.

The new study, recently published in the scientific journal mBIO,
analysed samples of environmental DNA from hundreds of locations around
the world. The researchers used computer modelling to search for microbial enzymes with plastic-degrading potential, which was then cross-referenced
with the official numbers for plastic waste pollution across countries
and oceans.

"Using our models, we found multiple lines of evidence supporting the
fact that the global microbiome's plastic-degrading potential correlates strongly with measurements of environmental plastic pollution --
a significant demonstration of how the environment is responding to
the pressures we are placing on it," says Aleksej Zelezniak, Associate Professor in Systems Biology at Chalmers University of Technology.

More enzymes in the most polluted areas In other words, the quantity and diversity of plastic-degrading enzymes is increasing, in direct response
to local levels of plastic pollution. In total, over 30,000 enzyme
'homologues' were found with the potential to degrade 10 different types
of commonly used plastic. Homologues are members of protein sequences
sharing similar properties. Some of the locations that contained the
highest amounts were notoriously highly polluted areas, for example
samples from the Mediterranean Sea and South Pacific Ocean.

"Currently, very little is known about these plastic-degrading enzymes,
and we did not expect to find such a large number of them across so many different microbes and environmental habitats. This is a surprising
discovery that really illustrates the scale of the issue," explains
Jan Zrimec, first author of the study and former post-doc in Aleksej Zelezniak's group, now a researcher at the National Institute of Biology
in Slovenia.

Potential value for fighting the global plastic crisis Every year around
8 million tonnes of plastic escapes into the world's oceans.

The natural progresses for plastic degradation are very slow --
the lifetime of a PET-bottle, for example, can be up to hundreds of
years. The growth and accumulation of plastic waste in the oceans and
on land is a truly global problem and there is an increasing need for
solutions to manage this waste. The researchers believe that their
results could potentially be used to discover and adapt enzymes for
novel recycling processes.

"The next step would be to test the most promising enzyme candidates in
the lab to closely investigate their properties and the rate of plastic degradation they can achieve. From there you could engineer microbial communities with targeted degrading functions for specific polymer types," explains Aleksej Zelezniak.

========================================================================== Story Source: Materials provided by
Chalmers_University_of_Technology. Original written by Susanne Nilsson
Lindh and Joshua Worth. Note: Content may be edited for style and length.


========================================================================== Journal Reference:
1. Jan Zrimec, Mariia Kokina, Sara Jonasson, Francisco Zorrilla,
Aleksej
Zelezniak. Plastic-Degrading Potential across the Global Microbiome
Correlates with Recent Pollution Trends. mBio, 2021; 12 (5) DOI:
10.1128/ mBio.02155-21 ==========================================================================

Link to news story: https://www.sciencedaily.com/releases/2021/12/211214084551.htm

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