An article published in the journal “Green Chemistry” describes the possibility of using bacteria of the species Novosphingobium aromaticivorans to produce a plastic material starting from wood processing waste following some genetic modifications. A team of researchers worked on this bacterium, which in nature can already digest many parts of lignin, improving its ability to produce a substance known as PDC on which bioplastic materials are already based upon but with production difficulties that could be overcome using these bacteria.
The species Novosphingobium aromaticivorans is part of a group of bacteria known for their biodegradative and biosynthetic capabilities, which made some of them useful in the field of biotechnology. This species was originally known as Sphingomonas aromaticivorans, part of a genus of bacteria with very different characteristics. For this reason, in 2001 it was divided into four new genera including Novosphingobium.
Lignin is an organic polymer that is found mainly in the cell wall of certain plant cells and in particular in wood. Their presence is a problem for example in the processing of wood to produce paper with the consequence that it becomes a waste of that processing. This compound is the major source along with petroleum of organic compounds on Earth, precisely the food preferred by Novosphingobium aromaticivorans, which was first isolated in a soil that was contaminated with petroleum products and consequently was rich in those compounds.
Other bacteria digest some aromatic compounds, Novosphingobium aromaticivorans can digest almost all those present in different parts of lignin producing smaller aromatic hydrocarbons. This was already an excellent starting point because in the course of its digestion it produces 2-pyrone-4-6-dicarboxylic acid, commonly known by the acronym PDC, a potential precursor of polyester that in particular in Japan is already used to produce a number of bioplastic materials.
The problem so far was to produce PDC in the amounts needed to make it a low-cost industrial product and the exploitation of these bacteria could be the solution. Researchers at the University of Wisconsin at Madison and the Great Lakes Bioenergy Research Center (GLBRC) eliminated three genes of Novosphingobium aromaticivorans making PDC the final product of this bacterium’s digestion instead of an intermediate compound.
Now at least 59% of the digested lignin is transformed into PDC, with the possibility of using waste from paper production to produce this material. Compared to equivalent compounds derived from petroleum, not only it has the advantage of being sustainable but it’s also biodegradable. The presence of plastics, often in microscopic fragments, is becoming a huge problem because now there’s a huge amount in the seas and consequently it’s increasingly present in the food chain with a growing damage to marine ecosystems. Biodegradable materials could have a truly huge positive ecological impact and PDC could greatly contribute to the solution of this problem.
The authors of this research think they can further improve the ability of Novosphingobium aromaticivorans to produce PDC with further genetic tweaking. According to Professor Daniel Noguera of GLBRC, one of the authors of this research, if the pace of production will be fast enough, a new industry could be created thanks to this type of biotechnology.
