Plastic in the seas? A bacteria will eat it!

Humans produce and abandon far, far, far too much plastic in nature. To be precise, about 311 million tons per year, of which between 4.9 and 12.7 million end up in the seas and oceans. A very serious situation that is bound to worsen. Unless action is taken as soon as possible to improve waste disposal in coastal areas and adopt more efficient recycling systems, the amount of plastic in our seas could increase tenfold by 2025.

FROM JAPAN WITH FURY
The solution may come from the Japanese: a team of scientists from the Kyoto Institute of Technology and other Japanese research institutions has just isolated a species of bacterium, Ideonella sakaiensis, that can “devour” plastic, using it as a source of sustenance and growth, through the chemical action of just two enzymes. Ideonella is particularly fond of PET (polyethylene terephthalate), probably the most widely used plastic in the world (about 50 million tons are produced annually and it is used mainly for food purposes-bottles and containers for food and beverages-but also to make labels, battery casings, tubes and films.

THE DISCOVERY AND POSSIBLE APPLICATIONS
It reads in Repubblica: “The bacteria was uncovered by scientists by analyzing more than 250 samples taken from a PET bottle recycling site, and it is absolutely unique. Specifically, researchers at the Kyoto Institute of Technology, led by Shosuke Yoshida, identified the two key enzymes in the hydrolysis (i.e., breakdown, decomposition) reaction of plastics and described the process in detail. The first is called, very trivially, PETase, and is secreted by the bacterium when it adheres to plastic surfaces. The second is called MHET hydrolase, and it is the one responsible for breaking PET chains into smaller, “harmless” molecules, terephthalic acid and ethylene glycol. The process, the scientists add, is unfortunately quite slow – the complete degradation of a small PET film takes about six weeks at a temperature of 30 °C – but, nevertheless, “the discovery could have very important implications for plastics recycling, as well as for the study of the principles of enzyme evolution,” as Uwe T. Bornscheuer explains on the editorial accompanying the scientific article that appeared in Science. The research, of course, will go forward: in fact, the study authors plan to see if it is possible to use the bacteria to isolate terephthalic acid and reuse it for the production of new plastics, which would avoid the use of petroleum. As well as, of course, thoroughly understanding the mechanisms of plastic decomposition, with the aim of taking choral actions to clean up ecosystems“