Bioconversion of (+)-valencene in submerged cultures of the ascomycete Chaetomium globosum

• Published in: Applied microbiology and biotechnology Vol. 67; no. 4; pp. 477 - 483
• Main Authors: KASPERA, Rudiger, KRINGS, Ulrich, NANZAD, Tsevegsuren, BERGER, Ralf G
• Format: Journal Article
• Language: English
• Published: Berlin Springer 01-06-2005; Springer Nature B.V
• Subjects: Bioconversions. Hemisynthesis; Biological and medical sciences; Biotechnology; Biotechnology - methods; Chaetomium - growth & development; Chaetomium - metabolism; Chaetomium globosum; Culture Media; Detoxification; Epoxy Compounds - metabolism; Fundamental and applied biological sciences. Psychology; Magnetic Resonance Spectroscopy; Metabolites; Methods. Procedures. Technologies; Microbiology; Oxidation; Oxidation-Reduction; Sesquiterpenes - chemistry; Sesquiterpenes - metabolism; Fungi; Stereoselectivity; Chaetomium globosum; Submerged culture; Biotransformation; Sesquiterpenes; Ascomycetes; Thallophyta
• ISSN: 0175-7598; 1432-0614
• DOI: 10.1007/s00253-004-1794-0

Submerged cultures of the ascomycete Chaetomium globosum oxidised the exogenous sesquiterpene (+)-valencene to nootkatone via the stereoselective generation of alpha-nootkatol. Inhibition experiments suggested that the first introduction of oxygen, the rate-limiting step of the bioconversion, may have been catalysed by a cytochrome-P450-monooxygenase. However, nootkatone was not the final metabolite: further flavour-active and inactive, non-volatile oxidation products were identified. (+)-Valencene and the flavour-active mono-oxyfunctionalised transformation products, alpha-nootkatol, nootkatone, and valencene-11,12-epoxide accumulated preferably inside the fungal cells. Di- and poly-oxygenated products, such as nootkatone-11,12-epoxide, were found solely in the culture medium, indicating an active transport of these metabolites into the extracellular compartment during (+)-valencene detoxification. These metabolic properties may have contributed to the high tolerance of the fungus towards the exogenous hydrocarbon.