Module 3: Degradation

Description | Design | Construction | Characterisation | Modelling | Results | Conclusions

Description

As an alternative to the Aggregation system, we are developing another solution – Degradation of plastic. This will focus on Polyethylene degradation, for which numerous bacteria and fungi have been found to be capable of degrading. Certain multi-copper enzymes have been found to degrade polyethylene and polypropylene, and we are looking in particular at an enzyme called Laccase that has been found to degrade polyethylene in a number of bacteria and fungi.

Laccases in fact exhibit an ‘extraordinary’ range of substrates. This is due to the conserved copper binding sites that couple the oxidation reactions of a reducing susbtrate to the cleavage of a dioxygen bond. As such, the oxidoreductase is able to catalyse redox reactions for various substrates.

This suggests that the enzymatic activity of laccase oxidises the polyethylene macromolecule. As such, it is thought that a series of oxidation reactions catabolised by laccase is responsible for plastic degradation.

The laccase system (BBa_K729002) will be driven by a strong constitutive promoter (BBa_J23119) - we expect overexpression of the protein to allow laccase to leak into the extracellular medium.