The saliva of a human can be used to break down the plastic. A hydrolase was found in a database. In the journal Angewandte Chemie International Edition, they report on the discovery of a hydrolase that performs better than other known ones. The authors say that it could be used in plastic recycling or functionalizing plastic.
It is known that landfill sites and harbors are good places to find organisms that have adapted to consume or use plastic. Thesebacteria can break down PET into smaller Molecules. The first enzyme has been discovered by Chayasith Uttamapinant and his colleagues.
Humans may have evolved to digest microplastics because of the large amount of food they consume. The team uncovered the new hydrolase, which they named MG8, while searching a public metagenomic database containing samples from seawater and human saliva, and were able to attribute the likely source of the enzyme to Gram-negativebacteria that may reside in human saliva The strains found near the "Pacific trash vortex" are similar to the ones found in these organisms.
They modified a bacterium that can be cultured in laboratories in order to get enough material for their experiment. They were able to recover an active form of theidase from a denatured form that could be isolated in large quantities. This shows promise for scaling up in the future.
The team sees another use of MG8. With a small modification, it can bind to it in a way that is very effective. They replaced one of the naturally occurring amino acids with an unnatural one in order to achieve this. The modified enzymes stuck to the powder. It could be used as a vehicle for functionalizing PET surfaces, increasing the flexibility of PET in medical devices, and enhancing theVersatility of recycled PET.
Despite the promise of plastic recycling and functionalization, the team acknowledges that there is still work to be done. This hydrolase can't be used to make consumer- grade plastic with high crystallinity. Further research is needed to get to the stage where a whole plastic water bottle can be dissolved in a simple solution.
More information: Bhumrapee Eiamthong et al, Discovery and Genetic Code Expansion of a Polyethylene Terephthalate (PET) Hydrolase from the Human Saliva Metagenome for the Degradation and Bio‐Functionalization of PET, Angewandte Chemie International Edition (2022). DOI: 10.1002/anie.202203061 Journal information: Angewandte Chemie International Edition
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