The Chalmers University of Technology recently published a study showing an increase in the number of microbial enzymes capable of degrading plastic in correlation to local plastic pollution levels.
mBio Journal published the study. Global plastic pollution is all too prevalent, as mass-production of plastic has surged from 2 million tonnes per year to 380 million in the last 70 years or so. In previous studies, many different enzymes have been discovered that degrade different plastics, and this has provided the environment with enough evolutionary time to adapt to the compounds.
Environmental DNA samples were collected from hundreds of locations around the world for the new study. Using computer modeling, the researchers looked for bacteria that could degrade plastic, which were 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,” said Aleksej Zelezniak, Associate Professor in Systems Biology at the Chalmers University of Technology.
The number and diversity of plastic-degrading enzymes are increasing, as a consequence of local plastic pollution levels. Homologues are members of protein sequences that share similar characteristics and are capable of degrading ten types of commonly used plastics. Samples from the Mediterranean Sea and South Pacific Ocean, for example, contained some of the highest amounts.
“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,” said Jan Zrimec, first author of the study and former post-doctoral researcher in Aleksej Zelezniak’s group, now at the National Institute of Biology in Slovenia.
The world’s oceans receive around 8 million tonnes of plastic every year. In nature, plastic degradation is very slow — a PET bottle, for instance, can last hundreds of years. There is an increasing need for solutions to managing plastic waste in the oceans and on land due to the growth and accumulation of plastic waste. Research results could potentially be used to discover and adapt enzymes for new recycling processes, according to the researchers.
“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,” explained Aleksej Zelezniak.
(With inputs from ANI)