A doctoral thesis on the topic of converting agricultural wastes into high-quality bioplastics could reach the first page of newspapers these days. Jean-Paul Meinjen, a researcher at the Technical University of Delft, Netherlands, will be presenting how he actually trained and selected bacteria in an evolutionary process that is not to be neglected by any means.
So far, turning sugar into plastics has been a rather expensive and inefficient process, resulting in large amounts of CO2 getting emitted. Meijnen’s proposed technique involves the use of a bacteria named Pseudomonas putida S12.
Although the bacteria have been successfully breaking down sugars obtained by the hydrolysis of lignocellulose, they have not been able to process two components resulted in the process of breakdown: xylose and arabinose. This failure led to the fact that 20 percent of the materials is left unused, and that is not what he wanted.
For that matter, Meijnen genetically modified the bacteria by inserting two genes from E.coli (a bacterium responsible for many diseases in humans). Thus he achieved getting the Pseudomonas putida S12 to produce enzymes that transformed xylose into a molecule that it could digest.
Because even this method proved inefficient and only 20% of the xylose was processed, Meijnen used an evolutionary process to train the bacteria, by selecting only the most efficient individuals for his further tests. His results were successful: “After three months of this improvement process, the bacteria could quickly digest all the xylose present in the medium. And surprisingly enough, these trained bacteria could also digest arabinose, and were thus capable of dealing with the three principal sugars in bio-wastes.”
The result of a previous project, a different strain of P. putida S12 that has been modified to produce para-hydroxybenzoate (pHB), has been modified to produce pHB, a biochemical used in cosmetics and pharmaceutical industries, from xylose and from other sources as glucose and glycerol.
I guess it’s not a long way to producing biodiesel with this technique…