Raspberry Ketone Accumulation in Nicotiana benthamiana and Saccharomyces cerevisiae by Expression of Fused Pathway Genes.

Raspberry ketone has generated interest in recent years both as a flavor agent and as a health promoting supplement. Raspberry ketone can be synthesized chemically, but the value of a natural nonsynthetic product is among the most valuable flavor compounds on the market. Coumaroyl-coenzyme A (CoA) is the direct precursor for raspberry ketone but also an essential precursor for flavonoid and lignin biosynthesis in plants and therefore highly regulated. The synthetic fusion of 4-coumaric acid ligase (4CL) and benzalacetone synthase (BAS) enables the channeling of coumaroyl-CoA from the ligase to the synthase, proving to be a powerful tool in the production of raspberry ketone in both N. benthamiana and S. cerevisiae. To the best of our knowledge, the key pathway genes for raspberry ketone formation are transiently expressed in N. benthamiana for the first time in this study, producing over 30 µg/g of the compound. Our raspberry ketone producing yeast strains yielded up to 60 mg/L, which is the highest ever reported in yeast.

Cichorium intybus L. Hairy Roots as a Platform for Antimicrobial Activity.

Industrial chicory is an important crop for its high dietary fibre content. Besides inulin, chicory taproots contain interesting secondary metabolite compounds, which possess bioactive properties. Hairy roots are differentiated plant cell cultures that have shown to be feasible biotechnological hosts for the production of several plant-derived molecules. In this study, hairy roots of industrial chicory cultivars were established, and their potential as a source of antimicrobial ingredients was assessed. It was shown that hot water extracts of hairy roots possessed antimicrobial activity against relevant human microbes, whereas corresponding chicory taproots did not show activity. Remarkably, a significant antimicrobial activity of hot water extracts of chicory hairy roots towards methicillin-resistant Staphylococcus aureus was observed, indicating a high potential of hairy roots as a host for production of antimicrobial agents.