International Journal of Enology and Viticulture

Full Length Research Paper

Characterization of a cytochrome P450 monooxygenase gene involved in the biosynthesis of geosmin in Penicillium expansum

Muhammad Hussnain Siddique^1,2, Thierry Liboz^1,2, Nafees Bacha³, Olivier Puel⁴, Florence Mathieu^1,2 and Ahmed Lebrihi^1,2,5*

¹Université de Toulouse, INPT-UPS, Laboratoire de Génie Chimique, avenue de l’Agrobiopole, 31326 Castanet-Tolosan Cedex, France.

²Le Centre national de la recherche scientifique (CNRS), Laboratoire de Génie Chimique, 31030 Toulouse, France.

³Centre of Biotechnology and Microbiology, University of Peshawar, Pakistan.

⁴Institut National de la Recherche Agronomique (INRA), Laboratoire de Pharmacologie Toxicologie, 31931 Toulouse, France.

⁵Université Moulay Ismail, Marjane 2, BP 298, Meknes, Morocco.

Accepted 14 February, 2019

Abstract

Geosmin is a terpenoid, an earthy-smelling substance associated with off-flavors in water and wine. The biosynthesis of geosmin is well characterized in bacteria, but little is known about its production in eukaryotes, especially in filamentous fungi. The origin of geosmin in grapevine is largely attributable to the presence of Penicillium expansum on grapes. Herein, we describe the characterization of “gpe1”, a gene encoding a cytochrome P450 monooxygenase probably involved in the biosynthesis of geosmin in this species. A gpe1 knockout mutant of P. expansum M2230 lost the capacity to produce geosmin, while the genetically complemented mutant restored it. The deduced gpe1 protein sequence shows identities with other cytochrome P450 monooxygenases involved in diterpene biosynthesis. These enzymes catalyze the addition of hydroxyl groups to the diterpene compounds. gpe1 protein could work in the same way, with sesquiterpenes as substrates. This gene seems to be only present in geosmin-producing Penicillium species. To our knowledge, this is the first characterization of a fungal gene encoding an enzyme involved in geosmin biosynthesis.

Key words: Penicillium expansum, cytochrome P450 monooxygenase, geosmin.