|
|Section2= |Section7= }} Geosmin is an organic compound with a distinct earthy flavor and aroma produced by a type of Actinobacteria, and is responsible for the earthy taste of beets and a contributor to the strong scent (petrichor) that occurs in the air when rain falls after a dry spell of weather or when soil is disturbed.〔(The earth's perfume ), ''Protein Spotlight'', Issue 35, June 2003.〕 In chemical terms, it is a bicyclic alcohol with formula , a derivative of decalin. Its name is derived from the Greek γεω- "earth" and ὀσμή "smell". == Production == Geosmin is produced by the gram-positive bacteria ''Streptomyces'', a genus of Actinobacteria in the order Actinomycetales, and released when these microorganisms die. Communities whose water supplies depend on surface water can periodically experience episodes of unpleasant-tasting water when a sharp drop in the population of these bacteria releases geosmin into the local water supply. Under acidic conditions, geosmin decomposes into odorless substances. In 2006, the biosynthesis of geosmin by a bifunctional ''Streptomyces coelicolor'' enzyme was unveiled. A single enzyme, geosmin synthase, converts farnesyl diphosphate to geosmin in a two-step reaction. ''Streptomyces coelicolor'' is the model representative of a group of soil-dwelling bacteria with a complex lifecycle involving mycelial growth and spore formation. Besides the production of volatile geosmin, it also produces many other complex molecules of pharmacological interest; its genome sequence is available at the Sanger Institute.〔(【引用サイトリンク】publisher=Sanger Institute )〕 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「geosmin」の詳細全文を読む スポンサード リンク
|