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Plastic waste is an emerging problem of the 20th century. Polyethylene terephthalate (PET), a synthetic polyester, is used industrially in bottle packaging and textiles, due to its durability and resistance to damage. Vast accumulation of PET over the last decades has resulted in increase of microplastics and nanoplastics in the oceans, which affect marine but also human life. Plastic bioremediation is expected to offer a carbon-neutral alternative to that problem.The identification of novel PET-degrading enzymes, such as PETase and MHETase from Idionella sakaiensis 201-F6, is a promising alternative for biological treatment of PET waste.

In this study, several strains harbouring a chimera of MHETase: DuraPETase or DuraPETase(engineered version of PETase) were created in Synechocystis sp. PCC 6803, that will provide insight into plastic degradation by cyanobacteria. Synechocystis managed to express DuraPETase under Ptrc and PpsbA2 promoter in a self-replicative vector and in the genome. Purification of DuraPETase from Synechocystis yielded 1mg/ml of protein, which showed enzymatic activity towards a synthetic analogue, p-NPA, but also commercial PET film, as demonstrated by the detection of terephthalic acid (the degradation product) through high performance liquid chromatography after 14 days.

These results indicate the potential of using cyanobacteria for industrial applications, coupling carbon assimilation from the environment through photosynthesis with plastic bioremediation. Further research is needed to optimize the system so that it is applicable in industrial applications.