Welcome to the plastisphere, the realm of plastic microbes: ‘It’s a new ecosystem on the planet’

Life may have arrived on Earth from outer space. Under the panspermia hypothesis, the first microorganisms could have traveled aboard fragments of asteroids or comets. Those pioneers would have prepared the ground so that, gradually, conditions on our planet became as suitable for life as they are today. At present, there is no corner of our home that living things have not adapted to.

Even plastic. For decades, and in front of our eyes, this new substrate has been colonized and reshaped. As if it were a new planet to invade, life follows the roadmap that has always worked for it: pioneers arrive, begin to alter the terrain, make it increasingly hospitable, and gradually the rest of the inhabitants move in. Over time, almost every microscopic organism joins the party (and even some macroscopic ones). At the entrance, a sign reads: Welcome to the plastisphere.

The origin of the plastisphere

“For decades we knew that living organisms could settle on plastic, but it wasn’t until we had the tools to analyze samples at the molecular level that we discovered the immense diversity of microorganisms that make their home on it.” If the term plastisphere had a mother, it would be microbiologist Linda Amaral‑Zettler. Together with her husband Erik Zettler and Tracy J. Mincer, she published, in 2013, the first scientific paper that named this new plastic ecosystem.

The plastisphere concept encompasses all the living things that live on plastic and the relationships they form among themselves and with the substrate. These new communities have been described mainly in aquatic environments (though they also exist on land) and on microplastics — small fragments of the material under five millimeters in diameter (although they appear on plastics of all sizes).

The very nature of plastic materials, which repel water, makes microorganisms comfortable on them and encourages the formation of biofilms (organized microbial communities). Once that film of life is established, it becomes easier for other organisms to settle on the plastic. “Microbes able to form biofilms are the pioneers, but the variety of organisms that later colonize plastic is astonishing. Today it is impossible to know all the species,” Amaral‑Zettler notes.

This researcher’s story with the relationship between life and plastics began in 2004, when she joined an international project to produce a census of microscopic marine life. During her research she kept finding microplastics. However, the Amaral‑Zettler story that best illustrates what the plastisphere is happened much later and involves a buoy that was floating in the middle of the South Atlantic. That beacon had been released in 2004 by Argentine researchers to measure ocean currents and, after its useful life ended, it had drifted away a few months later.

Made from a very durable plastic polymer (acrylonitrile butadiene styrene, or ABS), the buoy was in perfect condition when Amaral‑Zettler and Doug Wilson, researchers at the Royal Netherlands Institute for Sea Research, found it in January 2019. The identification number, 39257, was clearly legible, which allowed them to trace the beacon’s origin and route. And the instruments in their Dutch laboratory opened the door to the immense variety of life living on the buoy.

“They are true hitchhikers of plastic,” Amaral‑Zettler says. And it is precisely in that dispersal ability — granted by plastic to microorganisms that naturally have little mobility — that the risks of the plastisphere lie.

From Barcelona to the Ciénaga Grande de Santa Marta

Every year, between January and March, hundreds of scientists gather in Antarctica. They use the austral summer months to study the frozen continent in every possible way. For several years now, plastic and the plastisphere have played an increasingly important role on those expeditions. Because there, thousands of miles from the nearest city, among penguins and whales, there is also a lot of human waste.

“Research indicates that most of the plastics we find here come from activities taking place in Antarctica itself, such as life at research stations and tourism,” explains Pere Monràs i Riera, who took part in the Spanish polar expeditions in 2023 and 2024 to study the plastisphere. “And those plastics are also being colonized by Antarctic microbial communities.”

So far, among the plastisphere samples analyzed in Antarctica, no pathogenic bacteria have been found for humans or animals, although any bacterial proliferation has the potential to alter the biology and chemistry of its environment.

However, the story is very different closer to human civilization. A study of the plastisphere in waters of the Barcelona metropolitan area, published in 2023, concluded that plastic‑dwelling microbial communities are rich in pathogenic bacteria and antibiotic resistance genes. In particular, it noted that fecal bacteria of the genus Vibrio (some of whose species are dangerous to humans) can colonize microplastic biofilms and then travel with them to uncontaminated areas.

Across the Atlantic, in the Ciénaga Grande de Santa Marta, a vast coastal lagoon in the Colombian Caribbean, another study led by the Colombian Institute for Marine and Coastal Research (INVEMAR) and the University of Barcelona identified 1,760 genera of bacteria on microplastics collected from the waters, sediments, and fish of the lagoon. This could pose a direct risk to human health, but it also multiplies the risk of disease spread to aquatic species — many of which are consumed by people — and can disrupt the microscopic balances of those ecosystems.

“The plastisphere is a new biome, a new ecosystem on the planet, a new niche to be exploited by life,” Monràs i Riera concludes. “And we are only beginning to understand its implications.” Meanwhile, the colonization of plastic, as if it were the conquest of a distant planet, continues its course.

Sign up for our weekly newsletter to get more English-language news coverage from EL PAÍS USA Edition