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''Lactobacillus'' is a
genus Genus ( plural genera ) is a taxonomic rank used in the biological classification of living and fossil organisms as well as viruses. In the hierarchy of biological classification, genus comes above species and below family. In binomial nom ...
of
Gram-positive In bacteriology, gram-positive bacteria are bacteria that give a positive result in the Gram stain test, which is traditionally used to quickly classify bacteria into two broad categories according to their type of cell wall. Gram-positive bact ...
, aerotolerant anaerobes or microaerophilic, rod-shaped, non-
spore In biology, a spore is a unit of sexual or asexual reproduction that may be adapted for dispersal and for survival, often for extended periods of time, in unfavourable conditions. Spores form part of the life cycles of many plants, algae, ...
-forming
bacteria Bacteria (; singular: bacterium) are ubiquitous, mostly free-living organisms often consisting of one biological cell. They constitute a large domain of prokaryotic microorganisms. Typically a few micrometres in length, bacteria were am ...
. Until 2020, the genus ''Lactobacillus'' comprised over 260 phylogenetically, ecologically, and metabolically diverse species; a taxonomic revision of the genus assigned lactobacilli to 25 genera (see below). ''Lactobacillus'' species constitute a significant component of the human and animal
microbiota Microbiota are the range of microorganisms that may be commensal, symbiotic, or pathogenic found in and on all multicellular organisms, including plants. Microbiota include bacteria, archaea, protists, fungi, and viruses, and have been found ...
at a number of body sites, such as the
digestive system The human digestive system consists of the gastrointestinal tract plus the accessory organs of digestion (the tongue, salivary glands, pancreas, liver, and gallbladder). Digestion involves the breakdown of food into smaller and smaller compone ...
, and the female genital system. In women of European ancestry, ''Lactobacillus'' species are normally a major part of the vaginal microbiota. ''Lactobacillus'' forms
biofilm A biofilm comprises any syntrophic consortium of microorganisms in which cells stick to each other and often also to a surface. These adherent cells become embedded within a slimy extracellular matrix that is composed of extracellular po ...
s in the vaginal and
gut microbiota Gut microbiota, gut microbiome, or gut flora, are the microorganisms, including bacteria, archaea, fungi, and viruses that live in the digestive tracts of animals. The gastrointestinal metagenome is the aggregate of all the genomes of the gut mi ...
, allowing them to persist during harsh environmental conditions and maintain ample populations. ''Lactobacillus'' exhibits a mutualistic relationship with the human body, as it protects the host against potential invasions by
pathogen In biology, a pathogen ( el, πάθος, "suffering", "passion" and , "producer of") in the oldest and broadest sense, is any organism or agent that can produce disease. A pathogen may also be referred to as an infectious agent, or simply a g ...
s, and in turn, the host provides a source of nutrients. Lactobacilli are among the most common
probiotic Probiotics are live microorganisms promoted with claims that they provide health benefits when consumed, generally by improving or restoring the gut microbiota. Probiotics are considered generally safe to consume, but may cause bacteria-host i ...
found in food such as yogurt, and it is diverse in its application to maintain human well-being, as it can help treat diarrhea, vaginal infections, and skin disorders such as eczema.


Metabolism

Lactobacilli are homofermentative, i.e. hexoses are metabolised by
glycolysis Glycolysis is the metabolic pathway that converts glucose () into pyruvate (). The free energy released in this process is used to form the high-energy molecules adenosine triphosphate (ATP) and reduced nicotinamide adenine dinucleotide (NADH ...
to lactate as major end product, or heterofermentative, i.e. hexoses are metabolised by the
Phosphoketolase The enzyme phosphoketolase() catalyzes the chemical reactions :D-xylulose 5-phosphate + phosphate \rightleftharpoons acetyl phosphate + D-glyceraldehyde 3-phosphate + H2O () :D-fructose 6-phosphate + phosphate \rightleftharpoons acetyl phospha ...
pathway to lactate, CO2 and acetate or ethanol as major end products. Most lactobacilli are aerotolerant and some species respire if heme and menaquinone are present in the growth medium. Aerotolerance of lactobacilli is
manganese Manganese is a chemical element with the Symbol (chemistry), symbol Mn and atomic number 25. It is a hard, brittle, silvery metal, often found in minerals in combination with iron. Manganese is a transition metal with a multifaceted array of ...
-dependent and has been explored (and explained) in ''Lactiplantibacillus plantarum'' (previously '' Lactobacillus plantarum)''. Lactobacilli generally do not require
iron Iron () is a chemical element with symbol Fe (from la, ferrum) and atomic number 26. It is a metal that belongs to the first transition series and group 8 of the periodic table. It is, by mass, the most common element on Earth, right in ...
for growth. The
Lactobacillaceae The ''Lactobacillaceae'' are a family of lactic acid bacteria. It is the only family in the lactic acid bacteria which includes homofermentative and heterofermentative organisms; in the ''Lactobacillaceae,'' the pathway used for hexose fermentati ...
are the only family of the lactic acid bacteria (LAB) that includes homofermentative and heterofermentative organisms; in the ''Lactobacillaceae'', homofermentative or heterofermentative metabolism is shared by all strains of a genus. ''Lactobacillus'' species are all homofermentative, do not express pyruvate formate lyase, and most species do not ferment pentoses. In ''L. crispatus'', pentose metabolism is strain specific and acquired by lateral gene transfer.


Genomes

The genomes of lactobacilli are highly variable, ranging in size from 1.2 to 4.9 Mb (megabases). Accordingly, the number of protein-coding genes ranges from 1,267 to about 4,758 genes (in ''Fructilactobacillus sanfranciscensis'' and ''Lentilactobacillus parakefiri'', respectively). Even within a single species there can be substantial variation. For instance, strains of ''L. crispatus'' have genome sizes ranging from 1.83 to 2.7 Mb, or 1,839 to 2,688
open reading frame In molecular biology, open reading frames (ORFs) are defined as spans of DNA sequence between the start and stop codons. Usually, this is considered within a studied region of a prokaryotic DNA sequence, where only one of the six possible readi ...
s. ''Lactobacillus'' contains a wealth of compound microsatellites in the coding region of the genome, which are imperfect and have variant motifs. Many lactobacilli also contain multiple plasmids. A recent study has revealed that plasmids encode the genes which are required for adaptation of lactobacilli to the given environment.


Species

The genus ''Lactobacillus'' comprises the following species: * ''
Lactobacillus acetotolerans ''Lactobacillus acetotolerans'' (New Latin 'vinegar-tolerating milk-bacillus') is a species of gram positive bacteria in the genus ''Lactobacillus''. Discovered in rice wine vinegar, it has a very high tolerance for acetic acid. It can tolerate ...
'' Entani et al. 1986 * '' Lactobacillus acidophilus'' (Moro 1900) Hansen and Mocquot 1970 (Approved Lists 1980) * "''Lactobacillus alvi''" Kim et al. 2011 * '' Lactobacillus amylolyticus'' Bohak et al. 1999 * '' Lactobacillus amylovorus'' Nakamura 1981 * ''
Lactobacillus apis ''Lactobacillus'' is a genus of Gram-positive, aerotolerant anaerobes or microaerophilic, rod-shaped, non-spore-forming bacteria. Until 2020, the genus ''Lactobacillus'' comprised over 260 phylogenetically, ecologically, and metabolically dive ...
'' Killer et al. 2014 * "''Lactobacillus backi''" Bohak et al. 2006 * '' Lactobacillus bombicola'' Praet et al. 2015 * '' Lactobacillus colini'' Zhang et al. 2017 * '' Lactobacillus crispatus'' (Brygoo and Aladame 1953) Moore and Holdeman 1970 (Approved Lists 1980) * '' Lactobacillus delbrueckii'' (Leichmann 1896) Beijerinck 1901 (Approved Lists 1980) * '' Lactobacillus equicursoris'' Morita et al. 2010 * '' Lactobacillus fornicalis'' Dicks et al. 2000 * '' Lactobacillus gallinarum'' Fujisawa et al. 1992 * '' Lactobacillus gasseri'' Lauer and Kandler 1980 * '' Lactobacillus gigeriorum'' Cousin et al. 2012 * "''Lactobacillus ginsenosidimutans''" Jung et al. 2013 * '' Lactobacillus hamsteri'' Mitsuoka and Fujisawa 1988 * '' Lactobacillus helsingborgensis'' Olofsson et al. 2014 * '' Lactobacillus helveticus'' (Orla-Jensen 1919) Bergey et al. 1925 (Approved Lists 1980) * '' Lactobacillus hominis'' Cousin et al. 2013 * ''
Lactobacillus iners ''Lactobacillus iners'' is a species in the genus ''Lactobacillus''. It is a Gram-positive, catalase Catalase is a common enzyme found in nearly all living organisms exposed to oxygen (such as bacteria, plants, and animals) which catalyzes t ...
'' Falsen et al. 1999 * '' Lactobacillus intestinalis'' (ex Hemme 1974) Fujisawa et al. 1990 * ''
Lactobacillus jensenii ''Lactobacillus jensenii'' is a normal inhabitant of the lower reproductive tract in healthy women. ''L. jensenii'' makes up 23% of vaginal microflora that is naturally occurring. It is also found on the skins of grapes at the time of their ha ...
'' Gasser et al. 1970 (Approved Lists 1980) * "''Lactobacillus jinshani''" Yu et al. 2020 * ''
Lactobacillus johnsonii ''Lactobacillus johnsonii'' is a species in the genus ''Lactobacillus'' identified in 1980 by John L. Johnson, an American microbiologist and his associates. Its type strain is ATCC 33200. It is part of the healthy vaginal microbiota and has bee ...
'' Fujisawa et al. 1992 * '' Lactobacillus kalixensis'' Roos et al. 2005 * '' Lactobacillus kefiranofaciens'' Fujisawa et al. 1988 * ''
Lactobacillus kimbladii ''Lactobacillus'' is a genus of Gram-positive, aerotolerant anaerobes or microaerophilic, rod-shaped, non-endospore, spore-forming bacteria. Until 2020, the genus ''Lactobacillus'' comprised over 260 phylogenetically, ecologically, and metaboli ...
'' Olofsson et al. 2014 * '' Lactobacillus kitasatonis'' Mukai et al. 2003 * '' Lactobacillus kullabergensis'' Olofsson et al. 2014 * '' Lactobacillus melliventris'' Olofsson et al. 2014 * '' Lactobacillus mulieris'' Rocha et al. 2020 * ''
Lactobacillus nasalidis ''Lactobacillus'' is a genus of Gram-positive, aerotolerant anaerobes or microaerophilic, rod-shaped, non-spore-forming bacteria. Until 2020, the genus ''Lactobacillus'' comprised over 260 phylogenetically, ecologically, and metabolically dive ...
'' Suzuki-Hashido et al. 2021 * '' Lactobacillus panisapium'' Wang et al. 2018 * ''
Lactobacillus paragasseri ''Lactobacillus'' is a genus of Gram-positive, aerotolerant anaerobes or microaerophilic, rod-shaped, non-spore-forming bacteria. Until 2020, the genus ''Lactobacillus'' comprised over 260 phylogenetically, ecologically, and metabolically di ...
'' Tanizawa et al. 2018 * '' Lactobacillus pasteurii'' Cousin et al. 2013 * '' Lactobacillus porci'' Kim et al. 2018 * '' Lactobacillus psittaci'' Lawson et al. 2001 * "''Lactobacillus raoultii''" Nicaise et al. 2018 * ''
Lactobacillus rodentium ''Lactobacillus'' is a genus of Gram-positive, aerotolerant anaerobes or microaerophilic, rod-shaped, non-spore-forming bacteria. Until 2020, the genus ''Lactobacillus'' comprised over 260 phylogenetically, ecologically, and metabolically di ...
'' Killer et al. 2014 * '' Lactobacillus rogosae'' Holdeman and Moore 1974 (Approved Lists 1980) * '' Lactobacillus taiwanensis'' Wang et al. 2009 * "'' Lactobacillus thermophilus''" Ayers and Johnson 1924 * "''Lactobacillus timonensis''" Afouda et al. 2017 * '' Lactobacillus ultunensis'' Roos et al. 2005 * '' Lactobacillus xujianguonis'' Meng et al. 2020


Taxonomy

The genus ''Lactobacillus'' currently contains 44 species which are adapted to vertebrate hosts or to insects. In recent years, other members of the genus ''Lactobacillus'' (formerly known as the ''Leuconostoc'' branch of ''Lactobacillus'') have been reclassified into the genera ''
Atopobium ''Atopobium'' is a genus of Actinomycetota, in the family Coriobacteriaceae. ''Atopobium'' species are anaerobic, Gram-positive rod-shaped or elliptical bacteria found as single elements or in pairs or short chains. '' Atopobium vaginae'' was d ...
'', '' Carnobacterium'', ''
Weissella ''Weissella'' is a genus of gram-positive bacteria placed within the family Lactobacillaceae, formerly considered species of the ''Leuconostoc paramesenteroides'' group. The morphology of ''Weissella'' species varies from spherical or lenticul ...
'', '' Oenococcus'', and '' Leuconostoc''. The '' Pediococcus'' species '' P. dextrinicus'' has been reclassified as a ''Lapidilactobacillus dextrinicus'' and most lactobacilli were assigned to '' Paralactobacillus'' or one of the 23 novel genera of the ''Lactobacillaceae.'' Two websites inform on the assignment of species to the novel genera or species (http://www.lactobacillus.uantwerpen.be/; http://www.lactobacillus.ualberta.ca/).


Phylogeny

The currently accepted taxonomy is based on the
List of Prokaryotic names with Standing in Nomenclature List of Prokaryotic names with Standing in Nomenclature (LPSN) is an online database that maintains information on the nomenclature, naming and Taxonomy (biology), taxonomy of prokaryotes, following the taxonomy requirements and rulings of the In ...
and the phylogeny is based on whole-genome sequences.


Human health


Vaginal tract

The female genital tract is one of the principal colonisation sites for human microbiotic, and there is interest in the relationship between their presence and human health, with a domination by a single species being correlated with general welfare and good outcomes in pregnancy. In around 70% of women, a ''Lactobacillus'' species is dominant, although that has been found to vary between American women of European origin and those of African origin, the latter group tending to have more diverse vaginal microbiota. Similar differences have also been identified in comparisons between Belgian and Tanzanian women.


Interactions with pathogens

Lactobacilli produce
hydrogen peroxide Hydrogen peroxide is a chemical compound with the formula . In its pure form, it is a very pale blue liquid that is slightly more viscous than water. It is used as an oxidizer, bleaching agent, and antiseptic, usually as a dilute solution (3 ...
which inhibits the growth and
virulence Virulence is a pathogen's or microorganism's ability to cause damage to a host. In most, especially in animal systems, virulence refers to the degree of damage caused by a microbe to its host. The pathogenicity of an organism—its ability to ...
of the fungal pathogen '' Candida albicans'' ''
in vitro ''In vitro'' (meaning in glass, or ''in the glass'') studies are performed with microorganisms, cells, or biological molecules outside their normal biological context. Colloquially called " test-tube experiments", these studies in biology a ...
'' and ''
in vivo Studies that are ''in vivo'' (Latin for "within the living"; often not italicized in English) are those in which the effects of various biological entities are tested on whole, living organisms or cells, usually animals, including humans, and p ...
''. In vitro studies have also shown that lactobacilli reduce the pathogenicity of ''C. albicans'' through the production of organic acids and certain metabolites. Both the presence of metabolites, such as sodium butyrate, and the decrease in environmental pH caused by the organic acids reduce the growth of
hypha A hypha (; ) is a long, branching, filamentous structure of a fungus, oomycete, or actinobacterium. In most fungi, hyphae are the main mode of vegetative growth, and are collectively called a mycelium. Structure A hypha consists of one or ...
e in ''C. albicans'', which reduces its pathogenicity. Lactobacilli also reduce the pathogenicity of ''C. albicans'' by reducing ''C. albicans'' biofilm formation. Biofilm formation is reduced by both the competition from lactobacilli, and the formation of defective biofilms which is linked to the reduced hypha growth mentioned earlier. On the other hand, following
antibiotic An antibiotic is a type of antimicrobial substance active against bacteria. It is the most important type of antibacterial agent for fighting bacterial infections, and antibiotic medications are widely used in the treatment and prevention ...
therapy, certain ''Candida'' species can suppress the regrowth of lactobacilli at body sites where they cohabitate, such as in the gastrointestinal tract. In addition to its effects on ''C. albicans'', ''Lactobacillus'' sp. also interact with other pathogens. For example, ''
Limosilactobacillus reuteri ''Limosilactobacillus reuteri'' is a lactic acid bacterium found in a variety of natural environments, including the gastrointestinal tract of humans and other animals. It does not appear to be pathogenic and may have health effects. Discove ...
'' (formerly ''Lactobacillus reuteri'') can inhibit the growth of many different bacterial species by using glycerol to produce the antimicrobial substance called reuterin. Another example is '' Ligilactobacillus salivarius (''formerly ''Lactobacillus salivarius''), which interacts with many pathogens through the production of salivaricin B, a bacteriocin.


Probiotics

Fermentive bacteria like lactic acid bacteria (LAB) produce hydrogen peroxide which protects themselves from oxygen toxicity. The accumulation of hydrogen peroxide in growth media, and its antagonistic effects on ''
Staphylococcus aureus ''Staphylococcus aureus'' is a Gram-positive spherically shaped bacterium, a member of the Bacillota, and is a usual member of the microbiota of the body, frequently found in the upper respiratory tract and on the skin. It is often posit ...
'' and '' Pseudomonas'', have been demonstrated by researchers. LAB cultures have been used as starter cultures to create fermented foods since the beginning of the 20th century.
Elie Metchnikoff Elie and Earlsferry is a coastal town and former royal burgh in Fife, and parish, Scotland, situated within the East Neuk beside Chapel Ness on the north coast of the Firth of Forth, eight miles east of Leven. The burgh comprised the linked ...
won a Nobel prize in 1908 for his work on LAB. Lactobacilli administered in combination with other
probiotic Probiotics are live microorganisms promoted with claims that they provide health benefits when consumed, generally by improving or restoring the gut microbiota. Probiotics are considered generally safe to consume, but may cause bacteria-host i ...
s benefits cases of irritable bowel syndrome (IBS), although the extent of efficacy is still uncertain. The probiotics help treat IBS by returning homeostasis when the gut microbiota experiences unusually high levels of opportunistic bacteria. In addition, lactobacilli can be administered as probiotics during cases of infection by the ulcer-causing bacterium Helicobacter pylori. ''Helicobacter pylori'' is linked to cancer, and antibiotic resistance impedes the success of current antibiotic-based eradication treatments. When probiotic lactobacilli are administered along with the treatment as an
adjuvant In pharmacology, an adjuvant is a drug or other substance, or a combination of substances, that is used to increase the efficacy or potency of certain drugs. Specifically, the term can refer to: * Adjuvant therapy in cancer management * Analgesi ...
, its efficacy is substantially increased and side effects may be lessened. Also, lactobacilli are used to help control urogenital and vaginal infections, such as
bacterial vaginosis Bacterial vaginosis (BV) is a disease of the vagina caused by excessive growth of bacteria. Common symptoms include increased vaginal discharge that often smells like fish. The discharge is usually white or gray in color. Burning with urinati ...
(BV). ''Lactobacilli'' produce bacteriocins to suppress pathogenic growth of certain bacteria, as well as lactic acid and H2O2 (hydrogen peroxide). Lactic acid lowers the vaginal pH to around 4.5 or less, hampering the survival of other bacteria, and H2O2 reestablishes the normal bacterial microbiota and normal vaginal pH. In children, lactobacilli such as ''Lacticaseibacillus rhamnosus'' (previously '' L. rhamnosus'') are associated with a reduction of atopic eczema, also known as
dermatitis Dermatitis is inflammation of the skin, typically characterized by itchiness, redness and a rash. In cases of short duration, there may be small blisters, while in long-term cases the skin may become thickened. The area of skin involved c ...
, due to anti-inflammatory
cytokine Cytokines are a broad and loose category of small proteins (~5–25 kDa) important in cell signaling. Cytokines are peptides and cannot cross the lipid bilayer of cells to enter the cytoplasm. Cytokines have been shown to be involved in au ...
s secreted by this probiotic bacteria. In addition, lactobacilli with other probiotic organisms in ripened milk and yogurt aid development of immunity in the mucous intestine in humans by raising the number of LgA (+).


Oral health

Some lactobacilli have been associated with cases of dental caries (cavities).
Lactic acid Lactic acid is an organic acid. It has a molecular formula . It is white in the solid state and it is miscible with water. When in the dissolved state, it forms a colorless solution. Production includes both artificial synthesis as well as nat ...
can corrode teeth, and the ''Lactobacillus'' count in saliva has been used as a "caries test" for many years. Lactobacilli characteristically cause existing carious lesions to progress, especially those in coronal caries. The issue is, however, complex, as recent studies show probiotics can allow beneficial lactobacilli to populate sites on teeth, preventing streptococcal pathogens from taking hold and inducing dental decay. The scientific research of lactobacilli in relation to oral health is a new field and only a few studies and results have been published. Some studies have provided evidence of certain ''Lactobacilli'' which can be a probiotic for oral health. Some species, but not all, show evidence in defense to dental caries. Due to these studies, there have been applications of incorporating such probiotics in chewing gum and lozenges. There is also evidence of certain ''Lactobacilli'' that are beneficial in the defense of periodontal disease such as gingivitis and periodontitis.


Food production

Lactobacilli comprise most food fermenting lactic acid bacteria and are used as starter cultures in industry for controlled fermentation in the production of
wine Wine is an alcoholic drink typically made from Fermentation in winemaking, fermented grapes. Yeast in winemaking, Yeast consumes the sugar in the grapes and converts it to ethanol and carbon dioxide, releasing heat in the process. Different ...
,
yogurt Yogurt (; , from tr, yoğurt, also spelled yoghurt, yogourt or yoghourt) is a food produced by bacterial fermentation of milk. The bacteria used to make yogurt are known as ''yogurt cultures''. Fermentation of sugars in the milk by these bac ...
,
cheese Cheese is a dairy product produced in wide ranges of flavors, textures, and forms by coagulation of the milk protein casein. It comprises proteins and fat from milk, usually the milk of cows, buffalo, goats, or sheep. During productio ...
,
sauerkraut Sauerkraut (; , "sour cabbage") is finely cut raw cabbage that has been fermented by various lactic acid bacteria. It has a long shelf life and a distinctive sour flavor, both of which result from the lactic acid formed when the bacteria ...
, pickles,
beer Beer is one of the oldest and the most widely consumed type of alcoholic drink in the world, and the third most popular drink overall after water and tea. It is produced by the brewing and fermentation of starches, mainly derived from ce ...
,
cider Cider ( ) is an alcoholic beverage made from the fermented juice of apples. Cider is widely available in the United Kingdom (particularly in the West Country) and the Republic of Ireland. The UK has the world's highest per capita consumption, ...
,
kimchi ''Kimchi'' (; ko, 김치, gimchi, ), is a traditional Korean side dish of salted and fermented vegetables, such as napa cabbage and Korean radish. A wide selection of seasonings are used, including '' gochugaru'' (Korean chili powder), ...
,
cocoa Cocoa may refer to: Chocolate * Chocolate * ''Theobroma cacao'', the cocoa tree * Cocoa bean, seed of ''Theobroma cacao'' * Chocolate liquor, or cocoa liquor, pure, liquid chocolate extracted from the cocoa bean, including both cocoa butter an ...
, kefir, and other fermented foods, as well as
animal feeds Animal feed is food given to domestic animals, especially livestock, in the course of animal husbandry. There are two basic types: fodder and forage. Used alone, the word ''feed'' more often refers to fodder. Animal feed is an important input to ...
and the bokashi soil amendment. ''Lactobacillus'' species are dominant in yogurt, cheese, and sourdough fermentations. The antibacterial and antifungal activity of lactobacilli relies on production of bacteriocins and low molecular weight compounds that inhibits these microorganisms.
Sourdough Sourdough or sourdough bread is a bread made by the fermentation of dough using wild lactobacillaceae and yeast. Lactic acid from fermentation imparts a sour taste and improves keeping qualities. History In the ''Encyclopedia of Food Microbio ...
bread is made either spontaneously, by taking advantage of the bacteria naturally present in flour, or by using a "starter culture", which is a symbiotic culture of
yeast Yeasts are eukaryotic, single-celled microorganisms classified as members of the fungus kingdom. The first yeast originated hundreds of millions of years ago, and at least 1,500 species are currently recognized. They are estimated to constit ...
and lactic acid bacteria growing in a
water Water (chemical formula ) is an inorganic, transparent, tasteless, odorless, and nearly colorless chemical substance, which is the main constituent of Earth's hydrosphere and the fluids of all known living organisms (in which it acts as ...
and
flour Flour is a powder made by grinding raw grains, roots, beans, nuts, or seeds. Flours are used to make many different foods. Cereal flour, particularly wheat flour, is the main ingredient of bread, which is a staple food for many cul ...
medium Medium may refer to: Science and technology Aviation * Medium bomber, a class of war plane * Tecma Medium, a French hang glider design Communication * Media (communication), tools used to store and deliver information or data * Medium ...
. The bacteria metabolize sugars into lactic acid, which lowers the pH of their environment and creates the signature sourness associated with yogurt, sauerkraut, etc. In many traditional
pickling Pickling is the process of preserving or extending the shelf life of food by either anaerobic fermentation in brine or immersion in vinegar. The pickling procedure typically affects the food's texture and flavor. The resulting food is cal ...
processes, vegetables are submerged in
brine Brine is a high-concentration solution of salt (NaCl) in water (H2O). In diverse contexts, ''brine'' may refer to the salt solutions ranging from about 3.5% (a typical concentration of seawater, on the lower end of that of solutions used for ...
, and salt-tolerant lactobacilli feed on natural sugars found in the vegetables. The resulting mix of salt and lactic acid is a hostile environment for other microbes, such as
fungi A fungus ( : fungi or funguses) is any member of the group of eukaryotic organisms that includes microorganisms such as yeasts and molds, as well as the more familiar mushrooms. These organisms are classified as a kingdom, separately fr ...
, and the vegetables are thus preserved—remaining edible for long periods. Lactobacilli, especially pediococci and '' L. brevis'', are some of the most common beer spoilage organisms. They are, however, essential to the production of sour beers such as Belgian
lambic Lambic () is a type of beer brewed in the Pajottenland region of Belgium southwest of Brussels and in Brussels itself since the 13th century. Types of lambic beers include gueuze, kriek lambic and framboise. Lambic differs from most other be ...
s and American wild ales, giving the beer a distinct tart flavor.


See also

* Lactobacillus L. anticaries * Lactic acid fermentation * MRS agar * '' Pediococcus'' * Probiotics * Proteobiotics *
Carbon monoxide-releasing molecules Carbon monoxide-releasing molecules (CORMs) are chemical compounds designed to release controlled amounts of carbon monoxide (CO). CORMs are being developed as potential therapeutic agents to locally deliver CO to cells and tissues, thus overcomin ...


References


External links

*
Lactobacillus at Milk the Funk Wiki''Lactobacillus'' at Bac''Dive'' - the Bacterial Diversity Metadatabase
{{Authority control Lactobacillaceae Food science Gut flora bacteria Garde manger Gram-positive bacteria Bacteria genera