The previously unknown enzymes of the mutant bacteria can break down the plastic into simple components, which can then be used to make new high quality bottles. Out of 100,000 candidates, the choice fell on an organism that composts leaves effectively.
The widely available plastic processing technique nowadays allows for the processing of rubbish into clothes or carpets at most, notes “The Guardian”. Carbios, the French company behind this breakthrough in recycling, intends to use this new technique on an industrial scale. Its partners include Pepsi and L’Oréal. Although the commercial nature of this venture is no secret, even independent experts see the discovery as a big step forward.
- The biological recycling of PET bottles (polyethylene terephthalate, one of the most widely used plastics – ed.) on a mass scale is becoming a reality. This is a big step forward in terms of speed and efficiency. There is potential to reduce our dependence on oil, reduce greenhouse gas emissions and energy consumption. It encourages the collection and processing of plastic waste,” said Professor John McGeehan of Portsmouth University, director of the university’s Centre for Enzyme Innovation.
Professor McGeehan was one of the scientists who in 2018 accidentally created an enzyme that breaks down plastic into the chemical “blocks” that make it. In his opinion, Carbios was one of the leading companies working on the use of enzymes to break down polyethylene terephthalate garbage.
Billions of tons of plastic garbage cover the Earth from the poles to the depths of the oceans. It is particularly dangerous for the marine biosphere. Current estimates put its global annual production at 359 million tonnes. There are between 150 and 100 million tonnes in dumps. PET packaging is the lion’s share, about 70 million tonnes.
Although environmentalists would like to reduce the production and use of plastics as much as possible, companies like Carbios consider recycling to be an economically feasible and practical solution. The technical side of the process carried out by Carbios’ bioengineers, described in Nature magazine, was made possible by the discovery in 2012 of a bacteria that likes to eat old leaves.
- All in all, it was quite forgotten, but out of 100,000 proven microorganisms, it was the 201-F6 b strain of Ideonella sakaiensis bacteria that proved to be the most effective enzymes to recover the base material for the re-setting of plastic of a quality equal to that obtained in petrochemical processes (from crude oil – ed.),” explained Professor Alain Marty from the University of Toulouse, head of the scientific team in Carbios, to the daily newspaper “The Guardian”.
As we read in “Nature”, Prof. Marty and his colleagues managed to achieve a process of stable depolymerization (breaking the plastic into base components, monomers – ed.) with “almost ideal for the rapid decomposition of temperature 72 degrees Celsius”. The process, which lasted 10 hours, was completed with 90% efficiency.
The enzyme needed to break down the plastic into a new one that can be synthesised later will be produced from mushrooms by Novozymes, a company cooperating with Carbios. It is said that the use of enzymes for the subsequent synthesis of PET generates only 4% of the costs incurred in the creation of “virgin” plastic from crude oil.
However, recycled bottles will be slightly more expensive than those made from crude oil. This is because PET plastic has to be collected, cleaned, dried, ground and heated before it can be used, and only then can it be broken down by enzymes.
Carbios Vice President Martin Stephan assures you that it will still be profitable, because today even lower quality plastic bottles, created in a less efficient recycling process, are sold for large sums. Although we may not like it, the world simply needs new packaging. The French company wants to introduce its technology into mass production by 2025.