“Millions of years ago, evolution turned tiny microbes into multicellular plants, animals, and humans. Now, evolution is turning them into something equally remarkable: environmentalists.
So finds a new study from researchers at Sweden’s Chalmers University of Technology.1 Published this month in the scientific journal mBIO, it found plastic waste is giving rise to a growing number of microbes that produce pollution-fighting enzymes. The enzymes, which can degrade various types of plastic, appear to be evolving in direct response to the accumulation of plastic pollution, the quantity of which has increased from approximately 2 million tons per year 70 years ago to approximately 380 million tons per year today.1
“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,” Aleksej Zelezniak, associate professor of systems biology at the Chalmers University of Technology, said in a news release.
To arrive at their conclusion, Zelezniak and his colleagues compiled a dataset of 95 microbial enzymes already known to degrade plastic, which are typically produced by bacteria in garbage dumps and other plastic dumping grounds. They then collected samples of environmental DNA from hundreds of locations across the globe, both on land and at sea, and used computer modeling to search for similar “plastic-eating” enzymes. Because no plastic-degrading enzymes have been discovered in humans, despite concerns about the ingestion of microplastics, they used samples of the internal human microbiome as a control for false positives. In total, they identified approximately 30,000 enzymes with the ability to degrade 10 major commercial plastics.1
Nearly 60% of the identified enzymes were new to researchers, and environmental samples with the largest concentrations of enzymes were from highly polluted areas like the Mediterranean Sea and the South Pacific Ocean. Plus, more of the enzymes found on land were able to degrade plastic additives commonly found in soil, such as phthalates, which often leak during plastic production, disposal, and recycling. Among the ocean samples, meanwhile, enzymes were most prevalent at lower ocean depths, where microplastics accumulate in large quantities…..”
View the whole story here: https://www.treehugger.com/study-microbes-evolving-eat-plastic-pollution-5213822