February 6, 2023

Bacteria can use plastic waste as a food source, and it’s not as good as it sounds: ScienceAlert

Plastic pollution is out of control every year, more than 8 million tons Of synthetic polymers enter the ocean, some of them sink to the groundBack to the beachor collect in stuckBig part It is not easy to calculate.

All that missing plastic is a mystery, but some researchers suspect that hungry microbes are partly responsible.

Experiments in the lab have now shown that a type of marine bacteria known as Rhodococcus ruberIt can slowly decompose and digest the plastic it is made of Polyethylene (PE).

largely used in packaging, Polyethylene is the most widely produced plastic in the world, and while it is not clear whether Roper On these litters in the wild, the new research confirms that they are able to do at least that.

Previous studies have found strains Roper They float in dense cellular membranes on marine plastic. Moreover, the initial search in 2006 I suggested plastic underneath Roper It was collapsing at a faster rate than usual.

The new study confirms that this is the case.

“This is the first time we’ve demonstrated in this way that bacteria actually digest plastic into carbon dioxide and other molecules.” Says Microbial ecologist Maaike Goudriaan of the Royal Netherlands Institute for Marine Research (NIOZ).

To simulate the natural ways that plastic decomposes at the ocean’s surface, Guderian and her colleagues exposed their plastic samples to ultraviolet light and placed them in artificial seawater.

“UV treatment was necessary because we already know that sunlight partially degrades plastic into bacteria bite-sized pieces,” she says. Explain Guderian.

After that, the team introduced a strain of Roper to the scene.

By measuring the levels of a carbon isotope released from the degrading plastic called carbon-13, the authors estimated that the polymers in their experiments degrade at a rate of 1.2% per year.

The team can’t be sure how much the ultraviolet lamp degraded the plastic compared to the microbial activity, but it’s clear that bacteria played a role. Bacterial samples after the experiment showed films of carbon-13-enriched fatty acids.

Plastic decay rate determined in the current study very slow to completely solve the problem of plastic pollution in our oceans, but points to where some of our planet’s lost plastic might have gone.

“Our data shows that sunlight can therefore degrade a significant amount of all the floating plastic that has been littering the oceans since the 1950s,” Says Microbiologist Annalisa Delre.

Microbes can then come in and digest some of the sun’s leftovers.

Since 2013, researchers have been doing just that warned It’s possible that microbes thrive on the plastic patches in the ocean, forming an artificial ecosystem that has come to be known as the plastisphere.

There is even evidence to suggest that some of these microbial communities Adapts To eat different types of plastic.

Previous studies have identified specific bacteria and fungi, on the earth And in the seaIt looks like it’s eating plastic. But while this knowledge can help us better Recycle our waste Before it ends up in the wild, its other uses are controversial.

Some scientists have suggested shooting plastic chewing equivalents at pollution hotspots, such as A large garbage patch in the Pacific Ocean.

others I’m not sure this is a good idea. engineered enzymes And bacteria Deconstructing plastic might sound like a great way to make our waste disappear, but some experts worry about unintended side effects to natural ecosystems and food webs.

After all, breaking plastic isn’t necessarily a good thing. Microplastics are much more difficult to clean than large pieces, and these small residues can infiltrate food webs. Filter feeders, for example, may accidentally pick up small pieces of plastic before microbes do.

in study In 2020, every sample of seafood tested at an Australian market contained microplastics.

What it does to human or animal health completely unknown.

“Prevention is much better than cleaning.” Argues Guderian.

“And only we humans can do that.”

The study has been published in Marine Pollution Bulletin.