Genetically modified bacteria break down plastics in saltwater

Researchers have genetically engineered a marine microorganism to break down plastic in salt water. The modified organism can break down polyethylene terephthalate (PET), a contributor to microplastic pollution in oceans that is used in everything from water bottles to clothing.

The researchers worked with two species of bacteria. The first, Vibrio natriegens, thrives in saltwater and reproduces very quickly. The second, Ideonella sakaiensis, produces enzymes that enable it to break down and metabolize PET.

The researchers took the DNA from I. sakaiensis and incorporated its genetic sequence into a plasmid. Plasmids are genetic sequences that can replicate in a cell, independent of the cell's own chromosome. By introducing the plasmid containing the I. sakaiensis genes into V. natriegens bacteria, the researchers were able to get V. natriegens to produce the desired enzymes on the surfaces of their cells. The researchers then demonstrated that V. natriegens could break down PET in a saltwater environment at room temperature.

"This is the first time anyone has reported successfully getting V. natriegens to express foreign enzymes on the surface of its cells," says Nathan Crook, corresponding author of the paper on the work, published in the AIChE Journal, and a chemical and biomolecular engineer at North Carolina State University. The work was done with funding support from the U.S. National Science Foundation.

"From a practical standpoint, this is also the first genetically engineered organism that we know of that is capable of breaking down PET microplastics in saltwater," says Tianyu Li of NC State, first author of the paper.

The researchers acknowledged that additional hurdles must be addressed, but "breaking down the PET in saltwater was the most challenging" part of their work, according to Crook.