A genetically tweaked microbe may be key to producing biodegradable plastic from plants.
University of Wisconsin-Madison students worked with soil bacteria N. Aromaticivorans, a type of soil bacteria that digests lignin, a polymer found in the cell walls of woody plants.
UW-Madison student Miguel Perez said: “Other microbes tried before may be able to digest a few types of aromatics found in lignin. When we met this microbe, it was already good at degrading a wide range of compounds. That makes this microbe very promising.”
In the course of its digestion process, N. Aromaticivorans turns aromatic compounds found in lignin into 2-pyrone-4, 6-dicarboxylic acid, or PDC. The scientists removed three genes from N. Aromaticivorans to make PDC the end point for the digestion process.
Bioengineers in Japan have used PDC to make a variety of materials that would have use in consumer products. The compound is similar to most common petroleum-based additive to PET polymers – found in plastic bottles and synthetic fibres.
As an alternative to plastic, PDC would break down naturally in the environment, and wouldn't leach hormone-mimicking compounds into water.
Apart from petroleum, lignin is the most abundant source of aromatic compounds on the planet. But the large and complex lignin molecule is also hard to break into useful constituent pieces. Currently, paper mills strip lignin from wood and discard it by burning it, as they have no use for it.
Daniel Noguera at UW-Madison said: “PDC is so difficult to make by existing routes. But if we’re making biofuels from cellulose and producing lignin – something we used to just burn – and we can efficiently turn the lignin into PDC, that potentially changes the market for industrial use of this compound.”
The team published their strategy in Green Chemistry.