359 million tons of plastics are produced annually worldwide and 50–200 million tons of plastics gets accumulated in landfill or in the natural environment. The most abundant polyester plastic, Polyethylene terephthalate (PET) is produced annually with an estimate of almost 70 million tons worldwide. PET plastic bottles are a popular choice for packaging soft drinks. These pet plastics are mainly recycled through thermomechanical process. However, this method of recycling results in a loss of mechanical properties of PET, thus making it a poor monomer for reuse. Consequently, lots of PET monomers are lost as waste when we try to reuse them to make brand new bottles. Because of this limitation, scientists have been trying to find a solution. Breaking down of PET using enzymes have been reported but show limited productivity. This is most likely because PET is extremely difficult to hydrolyse because of the high ratio of aromatic terephthalate units present in them.
Scientists at Carbios and the Toulouse Biotechnology Institute 1 (TBI) have engineered a PET hydrolase that can recycle plastic in just a few hours. The enzyme can break down 90 percent of pet polymer in just 10 hours. “This highly efficient, optimized enzyme outperforms all pet hydrolase reported so far, including an enzyme from the bacterium ideonella sakaiensis strain 201-F6” writes the researchers in a paper published in Nature
The new enzyme was first spotted in a heap of composted leaves back in 2012. “It had been completely forgotten, but it turned out to be the best,” Alain Marty at the Université de Toulouse, France and the chief science officer at Carbios, told The Guardian.
Carbios is a green chemistry company in industrial development stage with a focus on discovering and developing enzymatic bioprocesses to reinvent the lifecycle of plastics. Carbios partnered with Pepsi and L’oreal to help develop the technology. They have filed a patent for the invention.