Oenococcus oeni
Oenococcus oeni
Oenococcus oeni is a Gram-positive bacterium from the order of the lactic acid bacteria ( Lactobacillaceae ). This bacterium was counted to 1995 to the genus Leuconostoc, Oenococcus is today but next kitaharae the only member of the genus Oenococcus. Characteristic of these bacteria is the lactic acid fermentation, fermentative metabolism, in which lactic acid occurs as the final product. Oenococcus oeni, like all genres of Leuconostocaceae family, obligate heterofermentative. Addition of lactic acid occur in this case, other waste products such as CO2, acetate (acetic acid) and ethanol (alcohol), while in the homofermentative lactic acid fermentation, lactic acid is produced exclusively. Oenococcus oeni Man is used in the winemaking process.
Features
Oenococcus oeni is acidophilic, that shows good growth at a low pH. The cells are kokkenförmig. Oenococcus oeni tolerated large amounts of alcohol ( ethanol) and can be cultured in media with 10% ethanol content.
Use by humans
Oenococcus oeni occurs naturally in fruit mash. This microorganism is used in wine production, because it has the ability to convert by the lactic fermentation of malic acid into lactic acid ( malolactic fermentation). Thus, the acidity of the wine is reduced, which thus gets a milder taste.
Formation of diacetyl
Oenococcus oeni can citrate form diacetyl, a compound with a typical butter taste. In low concentrations it contributes to the flavor, in larger quantities but it spoils the wine.
Systematics and evolution
The genus Oenococcus together with Leuconostoc and Weissella the family Leuconostocaceae. These genera are within the phylogeny together with other genera such as Lactobacillus, Lactococcus, Enterococcus and Carnobacterium (all typical lactic acid bacteria) to the so-called " Clostridium branch " (English: Clostridium branch ) provided, so they are evolutionarily closely related. Oenococcus oeni addition since 2006 the nature of Oenococcus kitaharae provided to the genus Oenococcus.
Oenococcus oeni is further away due to the 16S rRNA tests compared to species of Leuconostoc and Weis screen on the phylogenetic branch, and seems to vary more in at Weissella and Leuconostoc more conserved points of the rRNA. Oenococus oeni thus appears to have a particularly rapid rate of evolution. This is called a tachytelischen evolution rate, the contrast is the bradytelische rate, so extremely slowly progressive changes in evolution. However, the assumption of a rate of Oenococcus oeni tachytellischen evolution has been called into question.