Plastic pollution is out of control. Every year, more than 8 million tons of synthetic polymers enter the ocean, and while some sinks into the groundgo back to the shoreor pick up at the in the middle of nowhereAn important part it’s not so easy to explain.
All that missing plastic is a mystery, but some researchers suspect hungry microbes are partly responsible.
Experiments in the laboratory have now shown that a species of marine bacteria, known as Rhodococcus rubercan slowly break down and digest plastic made from polyethylene (PE).
Mainly used in packaging, PE is the most produced plastic in the world and, although it is not clear if R.ruber chews this waste in the wild, new research confirms that it is at least capable of doing so.
Previous studies They have found strains of R.ruber floating in dense cell films on marine plastic. Additionally, initial research in 2006 He suggested the plastic underneath R.ruber it was decomposing at a faster rate than normal.
The new study confirms that is the case.
“This is the first time we have shown in this way that bacteria actually digest plastic into CO2 and other molecules.” He says microbial ecologist Maaike Goudriaan from the Royal Netherlands Institute for Marine Research (NIOZ).
To emulate the natural ways plastic disintegrates on the ocean surface, Goudriaan and his colleagues exposed their plastic samples to ultraviolet light and placed them in artificial seawater.
“The ultraviolet light treatment was necessary because we already know that sunlight partially breaks down plastic into bite-sized pieces for bacteria.” Explain Goudrian.
The team then introduced a variety of R.ruber to the scene
By measuring levels of an isotope of carbon released by disintegrating plastic called carbon-13, the authors estimated that the polymers in their experiments break down at a rate of about 1.2 percent a year.
The team can’t be sure how much the UV lamp decayed the plastic compared to the activity of the microbes, but bacteria were clearly playing a role. The bacterial samples after the experiment showed carbon-13 enriched fatty acid membranes.
The rate of plastic decomposition identified in the current study It’s too slow to fully solve the problem of plastic pollution in our oceans, but it does indicate where some of the missing plastic on our planet might have gone.
“Our data shows that sunlight could have degraded a substantial amount of all the floating plastic that has been deposited in the oceans since the 1950s.” He says microbiologist Annalisa Delre.
Microbes could have entered and digested some of the Sun’s remnants.
Since 2013, researchers have warned that microbes likely thrive in patches of plastic in the ocean, forming a synthetic ecosystem known as a ‘plastisphere’.
There is even evidence to suggest that some of these microbial communities they are adapting to eat different types of plastic.
Previous studies have identified specific bacteria and fungi, on land Y at sea, which seems to eat plastic. But while that knowledge might help us better Recycle our waste before it ends up in the wild, its other uses are controversial.
Some scientists have proposed that we release chewy equivalents of plastic at pollution hotspots, such as the Great Pacific Garbage Patch.
Others are I’m not so sure it’s a good idea. designed enzymes Y bacteria Breaking down plastic may sound like a great way to make our waste disappear, but some experts are concerned about unwanted side effects on natural ecosystems and food webs.
After all, breaking down plastic isn’t necessarily a good thing. Microplastics are much more difficult to clean than larger pieces, and these tiny bits could find their way into food webs. Filter filters, for example, could mistakenly catch small pieces of plastic before microbes.
in a Study In 2020, all fish samples tested at a market in Australia contained microplastics.
What that is doing to human or animal health is completely unknown.
“Much better than cleaning is prevention”, argues Goudriaan.
“And only we humans can do that.”
The study was published in Marine Pollution Bulletin.
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