A bio-industrial solutions company has developed a mutant bacterial enzyme that can break down polyethylene terephthalate (PET) plastic and transform it into new recycled plastic in just hours.

Researchers from Carbios have recovered an enzyme from compost composed of leaves and exposed that enzyme to mutations that can degrade the PET plastic, which is the kind used to manufacture plastic water bottles.

The enzyme broke down the PET into chemical building blocks, which could then be transformed into high-quality plastic bottles. The researchers reported that 90% of the plastic from bottles could be converted into durable plastic appropriate for re-use. Other methods of recycling typically produce just 30% of plastic appropriate for reuse and that plastic is generally weaker than the original product.

During testing, the Carbios team used the enzyme to break down one tonne of plastic waste bottles — 90% of which was reusable and transformed into food-grade plastic bottles with strength equal to that of its predecessors within 10 hours.

The Carbios team expects to bring the technology to market in five years.

The enzyme is detailed in the journal Nature.