''Lactococcus'' is a

genus Genus ( plural genera ) is a taxonomic rank used in the biological classification of extant taxon, living and fossil organisms as well as Virus classification#ICTV classification, viruses. In the hierarchy of biological classification, genus com ...

lactic acid bacteria Lactobacillales are an order of gram-positive, low-GC, acid-tolerant, generally nonsporulating, nonrespiring, either rod-shaped (bacilli) or spherical (cocci) bacteria that share common metabolic and physiological characteristics. These bacte ...

that were formerly included in the genus ''Streptococcus'' Group N1. They are known as homofermenters meaning that they produce a single product,

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 natu ...

in this case, as the major or only product of

glucose Glucose is a simple sugar with the molecular formula . Glucose is overall the most abundant monosaccharide, a subcategory of carbohydrates. Glucose is mainly made by plants and most algae during photosynthesis from water and carbon dioxide, using ...

fermentation Fermentation is a metabolic process that produces chemical changes in organic substrates through the action of enzymes. In biochemistry, it is narrowly defined as the extraction of energy from carbohydrates in the absence of oxygen. In food ...

. Their homofermentative character can be altered by adjusting environmental conditions such as pH, glucose concentration, and nutrient limitation. They are

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 bacte ...

catalase Catalase is a common enzyme found in nearly all living organisms exposed to oxygen (such as bacteria, plants, and animals) which catalyzes the decomposition of hydrogen peroxide to water and oxygen. It is a very important enzyme in protecting t ...

-negative, non-

motile Motility is the ability of an organism to move independently, using metabolic energy. Definitions Motility, the ability of an organism to move independently, using metabolic energy, can be contrasted with sessility, the state of organisms th ...

cocci A coccus (plural cocci) is any bacterium or archaeon that has a spherical, ovoid, or generally round shape. Bacteria are categorized based on their shapes into three classes: cocci (spherical-shaped), bacillus (rod-shaped) and spiral ( of whi ...

that are found singly, in pairs, or in chains. The genus contains strains known to grow at or below 7˚C. Twelve species of ''Lactococcus'' are currently recognized. They are: *''

Lactococcus chungangensis ''Lactococcus'' is a genus of lactic acid bacteria that were formerly included in the genus ''Streptococcus'' Group N1. They are known as homofermenters meaning that they produce a single product, lactic acid in this case, as the major or only pr ...

'' *''

Lactococcus formosensis ''Lactococcus'' is a genus of lactic acid bacteria that were formerly included in the genus ''Streptococcus'' Group N1. They are known as homofermenters meaning that they produce a single product, lactic acid in this case, as the major or only pr ...

'' *''

Lactococcus fujiensis ''Lactococcus fujiensis'' is a Gram-positive and facultatively anaerobic bacterium from the genus ''Lactococcus'' which has been isolated from the leaves of Chinese cabbage from Fujinomiya is a city located in central Shizuoka Prefecture, Jap ...

'' *''

Lactococcus garvieae ''Lactococcus garvieae'' is a known fish pathogen affecting saltwater fish in the Far East, specifically in rainbow trout, Japanese yellowtail, Cobia (''Rachycentron canadum'') and grey mullet (''Mugil cephalus''). This bacteria causes lesions i ...

'' **''L. garvieae subsp. garvieae **''L. garvieae subsp. bovis *''

Lactococcus hircilactis ''Lactococcus hircilactis'' is a Gram-positive and non- spore-forming bacterium from the genus ''Lactococcus'' which has been isolated from raw goat milk in Valtellina in Italy Italy ( it, Italia ), officially the Italian Republic, ) or t ...

'' *''

Lactococcus lactis ''Lactococcus lactis'' is a Gram-positive bacterium used extensively in the production of buttermilk and cheese, but has also become famous as the first genetically modified organism to be used alive for the treatment of human disease. ''L. lact ...

'' **''L. lactis'' subsp. ''cremoris'' **''L. lactis'' subsp. ''hordniae'' **''L. lactis'' subsp. ''lactis'' **''L. lactis'' subsp. ''tructae'' *''

Lactococcus laudensis ''Lactococcus laudensis'' is a Gram-positive and non- spore-forming bacterium from the genus ''Lactococcus'' which has been isolated from raw cow milk from Val Trompia in Italy Italy ( it, Italia ), officially the Italian Republic, ) or t ...

'' *''

Lactococcus nasutitermitis ''Lactococcus nasutitermitis'' is a bacterium from the genus ''Lactococcus ''Lactococcus'' is a genus of lactic acid bacteria that were formerly included in the genus ''Streptococcus'' Group N1. They are known as homofermenters meaning that t ...

'' *''

Lactococcus piscium ''Lactococcus piscium'' is a known fish 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 ...

'' *''

Lactococcus plantarum ''Lactococcus'' is a genus of lactic acid bacteria that were formerly included in the genus ''Streptococcus'' Group N1. They are known as homofermenters meaning that they produce a single product, lactic acid in this case, as the major or only pr ...

'' *''

Lactococcus raffinolactis ''Lactococcus'' is a genus of lactic acid bacteria that were formerly included in the genus ''Streptococcus'' Group N1. They are known as homofermenters meaning that they produce a single product, lactic acid in this case, as the major or only pr ...

'' *''

Lactococcus taiwanensis ''Lactococcus'' is a genus of lactic acid bacteria that were formerly included in the genus ''Streptococcus'' Group N1. They are known as homofermenters meaning that they produce a single product, lactic acid in this case, as the major or only pr ...

'' These organisms are commonly used in the

dairy industry A dairy is a business enterprise established for the harvesting or processing (or both) of animal milk – mostly from cows or buffaloes, but also from goats, sheep, horses, or camels – for human consumption. A dairy is typically located on a ...

in the manufacture of fermented dairy products such as cheeses. They can be used in single-strain starter cultures, or in mixed-strain cultures with other lactic acid bacteria such as ''

Lactobacillus ''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 diver ...

'' and ''

Streptococcus ''Streptococcus'' is a genus of gram-positive ' (plural ) or spherical bacteria that belongs to the family Streptococcaceae, within the order Lactobacillales (lactic acid bacteria), in the phylum Bacillota. Cell division in streptococci occurs ...

''. Special interest is placed on the study of ''L. lactis'' subsp. ''lactis'' and ''L. lactis'' subsp. ''cremoris'', as they are the strains used as starter cultures in industrial dairy fermentations. Their main purpose in dairy production is the rapid acidification of milk; this causes a drop in the pH of the fermented product, which prevents the growth of spoilage bacteria. The bacteria also play a role in the flavor of the final product. Lactococci are currently being used in the

biotechnology Biotechnology is the integration of natural sciences and engineering sciences in order to achieve the application of organisms, cells, parts thereof and molecular analogues for products and services. The term ''biotechnology'' was first used b ...

industry. They are easily grown at industrial scale on whey-based media. As food-grade bacteria, they are used in the production of foreign

proteins Proteins are large biomolecules and macromolecules that comprise one or more long chains of amino acid residues. Proteins perform a vast array of functions within organisms, including catalysing metabolic reactions, DNA replication, respo ...

that are applied to the food industry.

Diseases

Lactococcosis refers to a group of disorders caused by the bacterium

L. garvieae Carl Linnaeus (; 23 May 1707 – 10 January 1778), also known after his Nobility#Ennoblement, ennoblement in 1761 as Carl von Linné#Blunt, Blunt (2004), p. 171. (), was a Swedish botanist, zoologist, taxonomist, and physician who formalise ...

. Most "Lacto" species dwell on the bodies of humans and animals, and while they do not cause serious problems in higher animals, they do cause chronic illnesses in lower animals, particularly fish.Rao, S, Chen, M-Y, Sudpraseart, C, et al. Genotyping and phenotyping of Lactococcus garvieae isolates from fish by pulse-field gel electrophoresis (PFGE) and electron microscopy indicate geographical and capsular variations. J Fish Dis. 2022; 45: 771– 781. https://doi.org/10.1111/jfd.13601

References

{{Taxonbar, from=Q134274 Streptococcaceae Cheese Bacteria genera