title: The microbial community of Vetiver root and its involvement into essential oil biogenesis.
abstract: Vetiver is the only grass cultivated worldwide for the root essential oil, which is a mixture of sesquiterpene alcohols and hydrocarbons, used extensively in perfumery and cosmetics. Light and transmission electron microscopy demonstrated the presence of bacteria in the cortical parenchymatous essential oil-producing cells and in the lysigen lacunae in close association with the essential oil. This finding and the evidence that axenic Vetiver produces in vitro only trace amounts of oil with a strikingly different composition compared with the oils from in vivo Vetiver plants stimulated the hypothesis of an involvement of these bacteria in the oil metabolism. We used culture-based and culture-independent approaches to analyse the microbial community of the Vetiver root. Results demonstrate a broad phylogenetic spectrum of bacteria, including alpha-, beta- and gamma-Proteobacteria, high-G+C-content Gram-positive bacteria, and microbes belonging to the Fibrobacteres/Acidobacteria group. We isolated root-associated bacteria and showed that most of them are able to grow by using oil sesquiterpenes as a carbon source and to metabolize them releasing into the medium a large number of compounds typically found in commercial Vetiver oils. Several bacteria were also able to induce gene expression of a Vetiver sesquiterpene synthase. These results support the intriguing hypothesis that bacteria may have a role in essential oil biosynthesis opening the possibility to use them to manoeuvre the Vetiver oil molecular structure.
authors.affiliation: Institute of Genetics and Biophysics 'Adriano Buzzati-Traverso', Consiglio Nazionale delle Ricerche, via Pietro Castellino 111, 80131 Naples, Italy.
authors.forename: Luigi
authors.initials: L
authors.lastname: Del Giudice
authors.forename: Domenica Rita
authors.initials: DR
authors.lastname: Massardo
authors.forename: Paola
authors.initials: P
authors.lastname: Pontieri
authors.forename: Cinzia M
authors.initials: CM
authors.lastname: Bertea
authors.forename: Domenico
authors.initials: D
authors.lastname: Mombello
authors.forename: Elisabetta
authors.initials: E
authors.lastname: Carata
authors.forename: Salvatore Maurizio
authors.initials: SM
authors.lastname: Tredici
authors.forename: Adelfia
authors.initials: A
authors.lastname: Talà
authors.forename: Marco
authors.initials: M
authors.lastname: Mucciarelli
authors.forename: Veneta Ivanova
authors.initials: VI
authors.lastname: Groudeva
authors.forename: Mario
authors.initials: M
authors.lastname: De Stefano
authors.forename: Giovanni
authors.initials: G
authors.lastname: Vigliotta
authors.forename: Massimo E
authors.initials: ME
authors.lastname: Maffei
authors.forename: Pietro
authors.initials: P
authors.lastname: Alifano
mesh_terms: D001419:Bacteria / Q000145:classification* / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism*; D002244:Carbon / Q000378:metabolism; D049930:Chrysopogon / Q000166:cytology / Q000382:microbiology* / Q000648:ultrastructure; D004269:DNA, Bacterial / Q000737:chemistry / Q000235:genetics; D004275:DNA, Ribosomal / Q000737:chemistry / Q000235:genetics; D020869:Gene Expression Profiling; D020459:Genes, rRNA; D008853:Microscopy; D008854:Microscopy, Electron; D008969:Molecular Sequence Data; D009822:Oils, Volatile / Q000378:metabolism*; D010802:Phylogeny; D010940:Plant Proteins / Q000096:biosynthesis; D018517:Plant Roots / Q000166:cytology / Q000382:microbiology / Q000648:ultrastructure; D012329:RNA, Bacterial / Q000235:genetics; D012336:RNA, Ribosomal, 16S / Q000235:genetics; D017422:Sequence Analysis, DNA; D012689:Sequence Homology, Nucleic Acid; D012717:Sesquiterpenes / Q000378:metabolism
chemical_list: D004269:DNA, Bacterial; D004275:DNA, Ribosomal; D009822:Oils, Volatile; D010940:Plant Proteins; D012329:RNA, Bacterial; D012336:RNA, Ribosomal, 16S; D012717:Sesquiterpenes; D002244:Carbon