The new process comes from the U.S. Sandia National Laboratories. Here microbiologists and chemists have shown how a new technology, based on bioengineered bacteria, has the potential to produce economically feasible products derived from renewable plant sources.
The process involves converting tough plant matter, called lignin. Lignin is a class of complex organic polymers that form important structural materials in the support tissues of vascular plants and some algae. The potential to convert lignin into material that can be used for other purposes has been of interest to scientists for decades, however the costs of doing so have tended to be prohibitive. The new approach involved examining the mechanisms of lignin degraders and then bioengineering a type of Escherichia coli bacteria into an efficient and productive bioconversion cell factory.
To ‘coax’ the E. coli into breaking down lignin, the researchers constructed a fermentor and add a designed inducer into the fermentation broth. This was an organic compound called vanillin, which is a phenolic aldehyde. Synthetic vanillin is used more often than natural vanilla extract as a flavoring agent in foods, beverages, and pharmaceuticals.
When the vanillin in the fermentation broth activates the enzymes, the E. coli begin to convert the vanillin into catechol, which is the desired platform chemical. The trick is not to allow the vanillin levels to become too high or else they prove toxic to the bacteria.
Once lignin has been broken down it produces energy. It also provides “platform chemicals“, which are the starting chemicals for conversion into nylon, plastics, pharmaceuticals and other economically valuable products.
The new process has been published in the journal Proceedings of the National Academy of Sciences, with the research paper titled “Toward engineeringE. coliwith an autoregulatory system for lignin valorization.”
