New study shows microplastics are colonised by bacteria in natural environment, forming complex ‘biofilms’
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Less than five millimetres in size, microplastics are small but can wreak mighty havoc upon the environment. It is estimated that more than 125 trillion of these particles have accumulated in the ocean – from surface to seabed – and they have also been detected in soils, rivers, lakes, animals and the human body. Studies in animals and human cells suggest microplastic exposure could be linked to cancer, heart attacks and reproductive problems. So pervasive are microplastics that scientists estimate we consume about a credit card’s worth each week.
A new study, however, has found yet another means by which microplastics can pose an impact to human health. Some commonly-discarded plastic materials can become ‘platforms’ for bacterial communities to grow upon, particularly those responsible for antimicrobial resistance and diseases in both humans and animals.
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These particles then host microbial communities on their surface, forming complex biofilms known as the ‘Plastisphere’.
To come to their conclusions, researchers from Plymouth Marine Laboratory and the University of Exeter developed a structure that would allow five different substances (bio-beads, nurdles, polystyrene, wood and glass) to be secured along a waterway that was expected to decrease in pollution downstream.
After two months in the water, bacterial biofilms growing on each substance were analysed. The findings are stark: pathogens and antimicrobial-resistant bacteria (AMR) were found across all samples. In particular, polystyrene and nurdles (small plastic pellets used as the raw material for almost all plastic products) pose a greater AMR risk than other substances.
More than 100 unique antimicrobial-resistant genes were also found in microplastic biofilms, far more than those on natural (wood) or inert (glass) substances.
‘Our research shows that microplastics can act as carriers for harmful pathogens and antimicrobial-resistant (AMR) bacteria, enhancing their survival and spread,’ said lead author and PhD researcher with Plymouth Marine Laboratory, Dr Emily Stevenson. ‘This interaction poses a growing risk to environmental and public health and demands urgent attention.’
‘As this work highlights the diverse and sometimes harmful bacteria that grow on plastic in the environment, we recommend that any beach cleaning volunteer should wear gloves during clean-ups, and always wash their hands afterwards,’ said co-author Professor Pennie Lindeque.
