Leuconostocaceae
Oenococcus oeni
Leuconostocaceae constitute a family of Gram-positive bacteria from the order of Lactobacillales, a typical lactic acid bacteria. They do not form catalase (they are catalase - negative) and have, like all members of the tribe Firmicutes, a low GC content. They are facultative anaerobes, that is relatively insensitive to oxygen. All the three genera occur as mostly on oval cocci, however, is found in the genus Weissella also rod-shaped cells. Spore formation do not occur. Characteristic, as well as generally for the lactic acid bacteria, the fermentative metabolic pathway ( malolactic fermentation ) in which lactic acid is the final product. All classes of Leuconostocaceae here are obligate heterofermentative, i.e. in addition to lactic acid to occur, other waste products such as CO2, acetate (acetic acid) and ethanol.
Occurrence
All representatives of Leuconostocaceae need nutrient-rich environments in general. Are found in the genera often foods such as milk and milk products, meat and fish products, in spoiled. Other localities of Leuconostoc and Weissella are already decomposing plant residues, rare live plants. Leuconostoc this seems to be the predominant species in occurring on dead plant debris lactic acid bacteria.
Systematics and phylogeny
Genera of this family are:
- Fructobacillus Endo and Okada 2008
- Leuconostoc van Tieghem 1878
- Oenococcus Dicks et al. 1995
- Weissella Collins et al. 1994
By phylogenetic studies using comparisons of 16S rRNA and the 23S rRNA ( ribosomal RNA sh ), various species of the genus Leuconostoc too Weissella and Leuconostoc oenos to the genus Oenococcus and then combines these three genera in the family Leuconostocaceae. Leuconostoc, Oenococcus and Weissella are placed in the phylogeny to the so-called " Clostridium branch ". At this branch (English: Clostridium branch ) also include genera of typical lactic acid bacteria such as Lactobacillus, Lactococcus, Enterococcus and Carnobacterium. These genera are so closely related evolutionarily. In 2006, another type was provided to the genus Oenococcus, O. kitaharae Endo & Okada 2006.
It is interesting in connection with the genus Oenococcus evolution rate. Due to the 16S rRNA comparisons Oenococcus oeni appears to have a very rapid rate of evolution. One speaks of a tachytelischen in contrast to the slow rate of evolution bradytelischen. Oenococcus oeni is in comparison to the other two genera further away on the branch of the phylogenetic tree. Even when in Weissella and Leuconostoc rather conserved points of rRNA varies Oenococcus stronger. This Vermutumg however, was questioned again.
Relevance to humans
All members of this family play a major role in food processing. Leuconostoc especially in the production of dairy products ( fermented milk, butter milk, etc.). Leuconostoc is also important for silage production. Oenococcus plays in winemaking, the largest role among the lactic acid bacteria, by the Malo- lactate fermentation (English: " malolactic fermentation", MLF ) receives the wine a mildereren taste.
Species of Leuconostoc could cause earlier in the sugar industry by the so-called frog spawn fermentation also considerable damage. The description and naming of this genus of Van Tieghem in 1878 also resulted from the scientific study of these economic problems.