Marine microbes digest plastic

Gwyneth Dickey Zaikab -

Specialist bacteria seem to be eating the plastic garbage we throw into the ocean. But whether they're cleaning up our poisons or just passing them back up the food chain remains to be seen.

The ocean contains vast amounts of plastic, mostly as tiny shards floating just beneath the surface. Under an electron microscope, each scrap of "plastic confetti" becomes "an oasis, a reef of biological activity," says marine microbiologist Tracy Mincer of the Woods Hole Oceanographic Institution in Massachusetts.

Mincer and his colleagues examined bits of fishing line, a plastic bag and a plastic nurdle (a pre-production plastic pellet) fished out of the Sargasso Sea, an area of the North Atlantic where currents cause debris to accumulate. The region as a whole contains more than 1,100 tonnes of plastic.

Scanning electron microscopy revealed bacteria-like cells living in pits in the plastic, as if they were eating the surface away.

"They look like you took a hot barbecue briquette and threw it into snow," says Mincer. "You see this melting bit all around the outside of the cells, and they're just burrowing into the plastic."

Microbes have been found digesting plastic in landfills, he says, but this is the first evidence of marine bacteria breaking down plastic in the ocean. The work was presented the 5th International Marine Debris Conference in Honolulu, Hawaii, on 24 and 25 March.

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T. Mincer/G. Proskurowski

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