Toward a Biosynthetic Route to Sclareol and Amber Odorants

Toward a Biosynthetic Route to Sclareol and Amber Odorants

Laurent Daviet

Biotechnology Department, Corporate R&D Division, FIRMENICH SA, Geneva, Switzerland

Ambergris, a waxy substance excreted by the intestinal tract of the sperm whale, has been a highly prized fragrance ingredient for millenia. Because of supply shortage and price inflation, a number of ambergris substitutes have been developed by the fragrance industry. One of the key olfactory components and most appreciated substitutes of ambergris, Ambrox is produced industrially by semisynthesis from sclareol, a diterpene- diol isolated from Clary sage. In the present work, we report the cloning and functional characterization of two diterpene synthases that act sequentially in sclareol biosynthesis from the universal geranyl geranyl pyrophosphate (GGPP) precursor. Furthermore, we reconstructed the sclareol biosynthetic pathway in bacterial platform strains engineered to overproduce GGPP. Peak titers of 400 mg/L and 1.5 g/L were obtained by cultivation in shake flasks and bench-scale bioreactors, respectively. Our work provides a basis for the development of an alternative, sustainable, and cost-efficient route to sclareol and other diterpene analogues.