A team of Japanese researchers led by Shosuke Yoshida (Department of Applied Biology, Kyoto Institute of Technology, Kyoto) has identified a bacterium species Ideonella sakaiensis 201-F6 that can break down the plastic called polyethylene terephthalate or PET. PET is considered highly biodegradation resistant and till now only two fungi could be identified that can degrade it. This is the first report in which a bacteria able to breakdown PET could be identified.
The bacteria were screened by using 250 contaminated samples obtained from PET bottle recycling site. The microorganisms that could utilize PET as carbon source for growth were selected. In the first stage of research a microbial consortium capable of degrading the PET films was identified. It degraded the PET film surface at 30 degree C. In the second stage they separated the bacteria species Ideonella sakaiensis 201-F6 from the consortium. It took 6 weeks to this bacterium to almost completely degrade the film surface at the same temperature. The bacterium uses two enzymes in this process. In the two step process the PET is converted back into the monomers it is made i.e. into Ethylene glycol and terephthalic acid.
PET has been littering the environment for the last 70 years and, in 2013, 56 million tonnes of PET were produced worldwide. Since PET came into being only 70 years ago, a pertinent question is how this distinct bacterium evolved or naturally selected in the environment. Also, is not clear what natural processes were at play for the two unique enzymes capable of breaking down PET in sequential steps to evolve.