title: Biosynthesis and identification of volatiles released by the myxobacterium Stigmatella aurantiaca.
abstract: The volatiles released by agar plate cultures of two strains of the myxobacterium Stigmatella aurantiaca (strains Sg a15 and DW4/3-1) were collected in a closed-loop stripping apparatus (CLSA) and analyzed by GC-MS. Large numbers of substances from different compound classes (ketones, esters, lactones, terpenes, and sulfur and nitrogen compounds) were identified; several of them are reported from natural sources for the first time. The volatiles 2-methyltridecan-4-one (17), its isomer 3-methyltridecan-4-one (20), and the higher homologue 2-methyltetradecan-4-one (18) were identified in the extracts of both strains and were synthesized. In addition, strain Sg a15 produced 2,12-dimethyltridecan-4-one (19), 2-methyltridec-2-en-4-one (23), and a series of phenyl ketones, among them 1-phenyldecan-1-one (14) and 9-methyl-1-phenyldecan-1-one (16), whereas strain DW4/3-1 emitted traces of 10-methylundecan-2-one (21). The biosynthesis of 14 and 16 was examined in feeding experiments with deuterated precursors carried out on agar plate cultures. The leucine-derived starter unit isovalerate was shown to be incorporated into 16, as was phenylalanine-derived benzoic acid into both 14 and 16. The results point to formation both of the phenyl ketones and of the structurally related aliphatic ketones through an unusual head-to-head coupling between a starter unit such as benzoyl-CoA and a fatty acyl-CoA, followed by decarboxylation.
authors.affiliation: Technische Universität Braunschweig, Institut für Organische Chemie, Hagenring 30, 38106 Braunschweig, Germany.
authors.forename: Jeroen S
authors.initials: JS
authors.lastname: Dickschat
authors.forename: Helge B
authors.initials: HB
authors.lastname: Bode
authors.forename: Silke C
authors.initials: SC
authors.lastname: Wenzel
authors.forename: Rolf
authors.initials: R
authors.lastname: Müller
authors.forename: Stefan
authors.initials: S
authors.lastname: Schulz
mesh_terms: D019817:Benzoic Acid / Q000378:metabolism; D005232:Fatty Acids, Volatile / Q000032:analysis / Q000096:biosynthesis* / Q000737:chemistry*; D008401:Gas Chromatography-Mass Spectrometry; D045782:Hemiterpenes; D015394:Molecular Structure; D010421:Pentanoic Acids / Q000378:metabolism; D020606:Stigmatella aurantiaca / Q000378:metabolism*
chemical_list: D005232:Fatty Acids, Volatile; D045782:Hemiterpenes; D010421:Pentanoic Acids; C008216:isovaleric acid; D019817:Benzoic Acid