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Lactococcus
Scientific classification
Kingdom: Bacteria
Division: Firmicutes
Class: Bacilli
Order: Lactobacillales
Family: Streptococcaceae
Genus: Lactococcus
Schleifer et al. 1986
Species

L. garvieae
L. lactis
L. piscium
L. plantarum
L. raffinolactis

Lactococcus is a genus of lactic acid bacteria that were formerly included in the genus Streptococcus Group N1[1]. They are known as homofermentors meaning that they produce a single product, lactic acid in this case, as the major or only product of glucose fermentation. Their homofermentative character can be altered by adjusting cultural conditions like pH, glucose concentration, and nutrient limitation. They are gram-positive, catalase negative, non-motile cocci that are found singly, in pairs, or in chains. The genus contains strains known to grow at or below 7˚C[2].

Five species of Lactococcus are currently recognized along with three subspecies. They are:
L. lactis
L. lactis subsp. lactis
L. lactis subsp. cremoris
L. lactis subsp. hordniae
L. garvieae
L. plantarum
L. raffinolactis
L. piscium

These organisms are commonly used in the dairy industry in the manufacture of fermented dairy products like cheeses. They can be used in single strain starter cultures, or in mixed strain cultures with other lactic acid bacteria such as Lactobacillus and Streptococcus. 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[3]. 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[4]. Lactococci are currently being used in the biotechnology industry. They are easily grown at industrial scale up on cheap whey based media. As food grade bacteria they are used in the production of foreign proteins that are applied to the food industry.

References

  1. ^ Schleifer KH, Kraus J, Dvorak C, Kilpper-Balz R, Collins MD, Fischer W (1985). "Transfer of Streptococcus lactis and related streptococci to the genus Lactococcus gen. nov". Syst. Appl. Microbiol. 6: 183–195. ISSN 0723-2020.  
  2. ^ , James M. Modern Food Microbiology, 4th ed. Van Nostrand Reinhold, 1992
  3. ^ de Vos, W.M. Simons, GFM. Genetics and Biotechnology of Lactic Acid Bacteria. eds. Gasson, M.J. de Vos, W.M. Gene Cloning and Expression Systems in Lactococci. Blackie Academic & Professional, 1994. pg. 52 – 53.
  4. ^ Kok, Jan. Genetics and Molecular Biology of Streptococci, Lactococci, and Enterococci.. eds Dunny, Gary M. Cleary, P. Patrick. McKay, Larry L. Special Purpose Vectors for Lactococci. American Society for Microbiology, 1991. pg. 97
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Wikispecies

Up to date as of January 23, 2010

From Wikispecies

Taxonavigation

Main Page
Superregnum: Bacteria
Regnum: Bacteria
Phylum: Firmicutes
Classis: Bacilli
Ordo: Lactobacillales
Familia: Streptococcaceae
Genus: Lactococcus
Species: L. garvieae - L. lactis - L. piscium - L. plantarum - L. raffinolactis


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