The orchestra of yeast and its fragrance show

Young woman smells a flower

Enzymes are playing the first violin, the cell is hosting a perfectly coordinated orchestra and reserachers are the composers? Instead of sounds they produce fragrances? Our musical thought experiment demonstrates the complex production processes of biotechnology with aromatics as an example.

Biological processes must fit together perfectly, similar to a clockwork. In a healthy cell every compound is available at the right time, at right amount and at right place. That is true for our human body as well as for microorganisms. Biotechnologists are eager to use the amazing skills of microorganisms to produce things that humans like: fluffy pastries and bread are produced with the help of yeast. How does “yeast” know, what we need for our processes? The answer is a complex interaction of a lot of molecular machines, called proteins and enzymes. Each protein has a specific task in the cell: some support the entry of nutrients, others utilize these nutrients for chemical reactions and still others produce molecules that cause the typical smell of yeast. The processes in a yeast cell are comparable to a well-coordinated orchestra.

The “sound” of fragrances

A well-known application field for yeast is also the production of ethanol in beer breweries. Since many, many years now, the tools of biotechnology enable biotechnologists to create new sounds in the orchestra – and get high-quality products out of it. Researchers at the Institute of Molecular Biotechnology at TU Graz and acib have shown numerous approaches so far. For example, they could produce the flavor of grapefruit in yeast or the fruity vanilla fragrance of the Heliotropa flower (heliotropin) in bacteria.

The show of enzyme solo artists

But do we need to engage a whole orchestra for a simple melody? A couple of enzymes perfectly work in a cell-free environment – most of them catalyse very simple reactions. If the only reaction partner is water, an enzyme plays the first and only violin. Unfortunately, for the key enzyme of heliotropin production this is not true: the reaction needs two biological energy carriers (ATP, NADPH). Until recently, it was impossible to conduct reactions like these outside of the cell. Researchers from the University of Freiburg have tuned their instruments (two enzymes called polyphosphate kinases) in a way that acib was successful in further using them and production isolable amounts of the aldehyde heliotropin for the first time without the use of living cells or big amounts of expensive energy carrier. The orchestra in this case included 5 enzymes, which filled the lab with a floral fragrance.

This work is based on
Strohmeier GA, Eiteljörg IC, Schwarz A, Winkler M: Enzymatic One-Step Reduction of Carboxylates to Aldehydes with Cell-free Regeneration of ATP and NADPH. 2019, Chemistry 25 (24), p 6119-6123.

Picture credits: Pexels