Sina Weidenweber and Ulrich Ermler from the Max Planck Institute for Biophysics in Frankfurt liaised with Robert Marmulla and Jens Harder from the Max Planck Institute for Marine Microbiology in Bremen to search for another attractive alternative. The research scientists examined the microbial processing of plant fragrances and essential oils, which – chemically speaking – are terpenes / monoterpenes and monoterpene alcohols. What are involved here are natural hydrocarbon compounds with ten carbon atoms, and the basic structure with five carbon atoms can be used as the preliminary stage for plastics production .
Let us take a look at the chemical details first: sorry about this, but a few basic scientific facts are essential here. Terpenes / monoterpenes are the main component of such essential oils as eucalyptus oil or peppermint oil. Monoterpenes are produced naturally in plants; the secondary plant substances are made by metabolism and carry out different functions. Released as volatile fragrances, plants use them to attract pollinators or to fend off enemies.
What is known so far is that monoterpenes are produced within the plant and in bacteria in the course of sufficiently understood metabolic processes. The transformation of a terpene called geraniol that smells like roses, for example, into coriandrol ((S)-linalool) that smells like coriander and then into myrcene, that gives hops their unmistakable smell, does not happen by itself, however; it requires the use of a catalyst instead.
What a catalyst does is to attach itself to a compound, thus modulating its chemical properties in such a way that Mother Nature needs to invest less energy and effort into changing / metabolising said compound. The catalyst remains completely unchanged during this process and can carry out its assignment over and over again elsewhere.
Enzymes take over the assignment of biocatalysts in bacteria, plants and animals. What is involved in the above-mentioned example of the transformation of geraniol into myrcene is called linalool dehydratase isomerase. The scientists write , however, that this enzyme is also able to produce such basic substances as isoprene or butadiene from different products of fermentation processes. Dier Biotechnologie, for example, produces active substances, that are normally produced by the human, animal or plant organism, in large fermentation plants with the help of modified bacteria, fungi or yeasts. Basic materials for manufacturing plastics will be joining the list of biotechnological products too in future.
Sina Weidenweber and her colleagues have at least taken a major step in this direction by succeeding in clarifying the structure of the enzyme linalool dehydratase isomerase and the way in which it bonds to molecules. The scientists conclude that the catalytic capabilities of linalool dehydratase isomerase at any rate make it eminently suitable for this assignment. It is reported that numerous patent applications have been filed and patents obtained in the meantime for use of this enzyme in the production of butadiene and isoprene on the basis of the discovery of the enzyme by research scientists from Bremen in 2010.
 Sina Weidenweber, Robert Marmulla, Ulrich Ermler and Jens Harder, X-ray structure of linalool dehydratase/isomerase from Castellaniella defragrans reveals enzymatic alkene synthesis, FEBS Letters 2016, doi 10.1002/1873-3468.12165