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Microbe ‘housekeepers’ clean up seaside

microscope image of clean polyethylene fragments

Tiny fragments of plastic waste can absorb toxic chemicals which are transported to marine animals when ingested. Researchers investigating the attachment of microbes to small fragments of a plastic commonly used for shopping bags found that the plastic was rapidly colonised by multiple species of bacteria that congregated together to form a `biofilm´ on its surface. Above, a microscope image of clean polyethylene fragments. (Credit: U. Sheffield)

SHEFFIELD (UK)—Marine life could be protected from the lethal effects of plastic pollution by coastal microbes that interact with waste in the seabed.

A new DNA-based study shows that the combination of marine microbes that can grow on plastic fragments varies significantly from microbial groups that colonise surfaces in the wider environment, raising the possibility that the plastic-associated microbes have different activities that could contribute to the breakdown of these plastics or the toxic chemicals associated with them.

Plastic waste is a long-term problem as its breakdown in the environment can take thousands of years. Over time, the size of plastic fragments in the sea decreases as a result of exposure to natural forces.

Tiny fragments of 5mm or less are called “microplastics” and are particularly dangerous as they can absorb toxic chemicals which are transported to marine animals when ingested.

“300 million tons of plastic are produced globally each year with significant proportions reaching the marine environment,” says Mark Osborn, senior lecturer in the Department of Animal and Plant Sciences University of Sheffield.

“Our research is revealing the potential for marine microbes to colonise plastics and to potentially degrade these key environmental pollutants.”

Researchers investigated the attachment of microbes to small fragments of polyethylene—a plastic commonly used for shopping bags and found that the plastic was rapidly colonised by multiple species of bacteria that congregated together to form a `biofilm´ on its surface.

Interestingly, the biofilm was only formed by certain types of marine bacteria that may have the potential to degrade plastics or plastic-associated pollutants.

The group now plans to investigate how the microbial interaction with microplastics varies across different habitats within the coastal seabed—research which they believe could have huge environmental benefits.

“Plastics form a daily part of our lives and are treated as disposable by consumers,” says Jesse Harrison, a PhD student in Sheffield’s Department of Animal and Plant Sciences. “As such, plastics comprise the most abundant and rapidly growing component of man-made litter entering the oceans.

“Microbes play a key role in the sustaining of all marine life and are the most likely of all organisms to break down toxic chemicals, or even the plastics themselves.

“This kind of research is also helping us unravel the global environmental impacts of plastic pollution.”

University of Sheffield news: www.shef.ac.uk/mediacentre/index.html

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