Enzymatic Degradation of Man-Made Plastics

In order to meet UK Government targets to recycle 65% of household waste by 2035, and achieve zero avoidable waste by 2050, new solutions for recycling and treatment of plastic waste are needed. Since 2011, Professor Bugg's research group has discovered several bacterial enzymes (dye-decolorising peroxidases, multicopper oxidases, manganese superoxide dismutase) which are able to oxidise the naturally occurring polymer lignin, via oxidative cleavage of ether C-O and C-C bonds. The aim of the project is to investigate whether these enzymes show activity for breakdown of man-made plastics. The project will involve:
1. Testing of recombinant bacterial lignin-degrading enzymes for enzyme-catalysed breakdown of different types of man-made plastics. Analytical methods such as HPLC and LC-MS will be used to detect the release of low molecular weight products, GPC will be used to analyse changes in polymer molecular weight, and changes in microscopic structure will be studied by SEM and TEM.
2. Treatment of man-made plastics by microbial lignin-degrading bacterial strains will also be investigated. Testing of single strains and consortia of different microbial strains will be tested, and screening for new soil microbes able to degrade the materials will be carried out.
3. Study of the mechanism of polymer breakdown, using kinetic analysis, and probing reaction intermediates.
4. Scale-up of polymer breakdown. The conversion yield will be optimised via testing of different biotransformation conditions. The possibility of recycling components of the plastics into new materials will be investigated.