Genetically tweaked microbe can make plastic from plants

MADISON, WISCONSIN — A genetically engineered microbe is the key to producing biodegradable plastics from a common plant waste material.

According to research from the University of Wisconsin-Madison, N. aromaticivorans is a type of soil bacteria that can digest lignin from plant cells and turn them into smaller hydrocarbons.

Lignin is a polymer found in the cell walls of woody plants, which although abundant, is difficult to break down. It has such little value that paper mills that have been stripping lignin from wood for centuries merely dispose of it in boilers.

During digestion, the bacteria turns lignin into 2-pyrone-4, 6-dicarboxylic acid, or PDC. By removing three genes from the microbe, University of Wisconsin-Madison scientists were able to make PDC the end point for the digestion process.

UWM researcher Miguel Perez says bioengineers in Japan used PDC to make a variety of materials for consumer products, and found it performs the same or better than petroleum-based additives in PET polymers, like plastic bottles or synthetic fibers.

As a plastic alternative, PDC would naturally break down in the environment, but wouldn't leach compounds as it degrades.

Researchers have so far managed to turn 59 percent of lignin's compounds into PDC, but suggest greater efficiency might be achieved with further gene-tweaking.

The study is published in the journal Green Chemistry.