Microbial Bioremediation of Plastics

Plastic waste, especially from polyethylene terephthalate, or PET, is one of the most persistent pollutants.

PET is made of repeating units of terephthalic acid and ethylene glycol, forming a durable, semi-crystalline structure.

Ideonella sakaiensis is a bacterium capable of degrading PET and using its monomers as a carbon and energy source.

This bacterium produces two key enzymes: polyethylene terephthalate hydrolase, or PETase, and mono (2-hydroxyethyl) terephthalate hydrolase, or MHETase. Together, they break down PET into its monomers.

PETase hydrolyzes the PET polymer into mono(2-hydroxyethyl) terephthalic acid, or MHET.

Occasionally, this step releases bis(2-hydroxyethyl) terephthalate or BHET as a minor intermediate, which can also be hydrolyzed by PETase into MHET.

MHETase then breaks down MHET into ethylene glycol and terephthalic acid, which are metabolized by the bacterium.

However, this process is slow and inefficient, often taking years to partially degrade a single plastic bottle.