Bacterium may help answer mystery of ‘missing’ plastic in the seas

A bacterium has been discovered that can digest plastic, and its discovery goes some way to explaining why there is significantly less plastic in the oceans than models predict.¹

A team from the Royal Netherlands Institute for Sea Research started their investigation with a polyethylene plastic that contained carbon-13. When the bacterium Rhodococcus ruber was exposed to this plastic the carbon dioxide that was evolved contained carbon-13, meaning that the bacterium had metabolised the plastic.

The isotope was also found in the bacterium’s fatty acids, showing that it had not only metabolised the plastic, but also incorporated its breakdown products. The scientists calculated that R. Ruber  can break down about 1% of the available plastic in the oceans per year into carbon dioxide and other harmless substances. But the researchers acknowledge that this  could be an underestimate as they only monitored the carbon-13 in the carbon dioxide produced, and not in other metabolites produced by the bacterium.