“A tiny microbe one day could devour the millions of metric tons of polyethylene terephthalate, or PET, that pile up in landfills each year”.
A research work carried out by a group of Japanese scientists, led by Kohei Oda of Kyoto Institute of Technology and Kenji Miyamoto of Keio University, have discovered a bacterium which eats PET. PET is a kind of plastic used to make water bottles, peanut butter jars, etc. Therefore, a huge amount of PET needs to be produced every year (more than 45 million of tons). It can be recycled: PET heads the list of most recycled plastics in USA. Nevertheless, the recycling rate only reach about 31%, while at the European Union it’s close to 50%. Even then, a huge amount of PET fills dumping sites every year. The PET-eating bacterium was found in a sample from a bottle recycling facility in Sakai, Japan; it was called Ideonella sakaiensis. It was not the first discovery of an organism capable of breaking down plastic, but I. Sakaiensis seems to be more efficient. This bacterium uses two different enzymes. The first one, called PETase, break the PET down into the intermediate mono terephthalic acid, MHET. The second one, known as MHETase, hydrolyzes MHET into ethylene glycol and monomers terephthalic acid. Possible purposes for this bacterium might be decontaminate PET-polluted areas or produce a new polymer which doesn’t use starting materials based on petrol. Currently the I. Sakaiensis is not prepared for solving the PET contamination problem around the world, because it prefers to eat amorphous PET than the crystalline one, and this last PET type is the used one at production, and because the enzymatic process is too slow. Shosuke Yoshida, the study’s first author, thinks that the bacterium will be useful if it’s modified for accelerating the process or PET is pretreated for extending the polymer’s amorphous areas.