Article: Lactobacillus

?Lactobacillus
Lactobacillus bacteria (around vaginal squamous epithelial cell)
Scientific classification
Kingdom: Bacteria Division: Firmicutes Class: Bacilli Order: Lactobacillales Family: Lactobacillaceae Genus: Lactobacillus Beijerinck 1901
Species
L. acidophilus L. bulgaricus L. casei L. delbrueckii L. fermentum L. plantarum L. reuteri etc.

Lactobacillus is a genus of Gram-positive facultative bacteria. They are a major part of the Lactic acid bacteria group, named as such because most of its members convert lactose and other simple sugars to lactic acid. They are common and usually benign, even necessary, inhabitants of humans and other animals. In humans they are present in the vagina and the gastrointestinal tract, and are an important genus of the gut flora. Many species are prominent in decaying plant material. The production of lactic acid makes its environment acidic which inhibits the growth of some harmful bacteria.

Some Lactobacillus species are used industrially for the production of yogurt, sauerkraut, pickles, and other fermented foods, such as silage. Sourdough bread is made using a "starter culture" which is a symbiotic culture of yeast and lactic acid bacteria growing in a water and flour medium. Some yogurt drinks contain Lactobacillus bacteria as a dietary supplement. Korean kimchi is also made using lactic acid fermentation techniques. Many lactobacilli are unique among living things as they do not require iron for growth and have an extremely high hydrogen peroxide tolerance. Lactobacilli, especially L. casei and L. brevis, are some of the most common beer spoilage organisms.

Several members of the genus have had their genome sequenced.

Many lactobacilli are unusual in that they operate using homofermentative metabolism (that is, they produce only lactic acid from sugars) and are aerotolerant despite the complete absence of a respiratory chain. This aerotolerance is manganese-dependent and has been explored (and explained) in Lactobacillus plantarum.

See also

• Lactic acid bacteria
• Kombucha