Lactococcus lactis

Lactococcus lactis
Scientific classification Edit this classification
Domain: Bacteria
Phylum: Bacillota
Class: Bacilli
Order: Lactobacillales
Family: Streptococcaceae
Genus: Lactococcus
Species:
L. lactis
Binomial name
Lactococcus lactis
(Lister 1873)
Schleifer et al. 1986
Subspecies

L. l. cremoris
L. l. hordniae
L. l. lactis
L. l. lactis bv. diacetylactis
L. l. tructae

Lactococcus lactis is a gram-positive bacterium used extensively in the production of buttermilk and cheese,[1] but has also become famous as the first genetically modified organism to be used alive for the treatment of human disease.[2] L. lactis cells are cocci that group in pairs and short chains, and, depending on growth conditions, appear ovoid with a typical length of 0.5 - 1.5 μm. L. lactis does not produce spores (nonsporulating) and are not motile (nonmotile). They have a homofermentative metabolism, meaning they produce lactic acid from sugars. They've also been reported to produce exclusive L-(+)-lactic acid.[3] However,[4] reported D-(−)-lactic acid can be produced when cultured at low pH. The capability to produce lactic acid is one of the reasons why L. lactis is one of the most important microorganisms in the dairy industry.[5] Based on its history in food fermentation, L. lactis has generally recognized as safe (GRAS) status,[6][7] with few case reports of it being an opportunistic pathogen.[8][9][10]

Lactococcus lactis is of crucial importance for manufacturing dairy products, such as buttermilk and cheeses. When L. lactis ssp. lactis is added to milk, the bacterium uses enzymes to produce energy molecules (ATP), from lactose. The byproduct of ATP energy production is lactic acid. The lactic acid produced by the bacterium curdles the milk, which then separates to form curds that are used to produce cheese.[11] Other uses that have been reported for this bacterium include the production of pickled vegetables, beer or wine, some breads, and other fermented foodstuffs like soymilk kefir, buttermilk, and others.[12] L. lactis is one of the best characterized low GC Gram positive bacteria with detailed knowledge on genetics, metabolism and biodiversity.[13][14]

L. lactis is mainly isolated from either the dairy environment, or plant material.[15][16][17] Dairy isolates are suggested to have evolved from plant isolates through a process in which genes without benefit in the rich milk were lost or downregulated.[14][18] This process, called genome erosion or reductive evolution, has been described in several other lactic acid bacteria.[19][20] The proposed transition from the plant to the dairy environment was reproduced in the laboratory through experimental evolution of a plant isolate that was cultivated in milk for a prolonged period. Consistent with the results from comparative genomics (see references above), this resulted in L. lactis losing or downregulating genes that are dispensable in milk and the upregulation of peptide transport.[21]

Hundreds of novel small RNAs were identified by Meulen et al. in the genome of L. lactis MG1363. One of them, LLnc147, was shown to be involved in carbon uptake and metabolism.[22]

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  5. ^ Integr8 – Species search results:
  6. ^ FDA. "History of the GRAS List and SCOGS Reviews". FDA. Retrieved 11 May 2012.
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  9. ^ Facklam RR, Pigott NE, Collins MD. Identification of Lactococcus species from human sources. Proceedings of the XI Lancefield International Symposium on Streptococci and Streptococcal Diseases, Siena, Italy. Stuttgart: Gustav Fischer Verlag; 1990:127
  10. ^ Mannion PT, Rothburn MM (November 1990). "Diagnosis of bacterial endocarditis caused by Streptococcus lactis and assisted by immunoblotting of serum antibodies". J. Infect. 21 (3): 317–8. doi:10.1016/0163-4453(90)94149-T. PMID 2125626.
  11. ^ "Bacteria Genomes - LACTOCOCCUS LACTIS". 2Can Karyn's Genomes. Archived from the original on 2008-01-12.
  12. ^ Shurtleff W, Aoyagi A (2004). "History of Fermented Soymilk and Its Products". www.soyinfocenter.com. Retrieved 2024-01-14.
  13. ^ Kok J, Buist G, Zomer AL, van Hijum SA, Kuipers OP (2005). "Comparative and functional genomics of lactococci". FEMS Microbiology Reviews. 29 (3): 411–33. doi:10.1016/j.femsre.2005.04.004. PMID 15936843.
  14. ^ a b van Hylckama Vlieg JE, Rademaker, JL, Bachmann H, Molenaar D, Kelly WJ, Siezen RJ (2006). "Natural diversity and adaptive responses of Lactococcus lactis". Current Opinion in Biotechnology. 17 (2): 183–90. doi:10.1016/j.copbio.2006.02.007. PMID 16517150.
  15. ^ Kelly WJ, Ward LJ, Leahy SC (2010). "Chromosomal diversity in Lactococcus lactis and the origin of dairy starter cultures". Genome Biology and Evolution. 2: 729–44. doi:10.1093/gbe/evq056. PMC 2962554. PMID 20847124.
  16. ^ Passerini D, Beltramo C, Coddeville M, Quentin Y, Ritzenthaler P, Daveran-Mingot ML, Le Bourgeois P (2010). "Genes but Not Genomes Reveal Bacterial Domestication of Lactococcus Lactis". PLOS ONE. 5 (12): e15306. Bibcode:2010PLoSO...515306P. doi:10.1371/journal.pone.0015306. PMC 3003715. PMID 21179431.
  17. ^ Rademaker JL, Herbet H, Starrenburg MJ, Naser SM, Gevers D, Kelly WJ, Hugenholtz J, et al. (2007). "Diversity analysis of dairy and nondairy Lactococcus lactis isolates, using a novel multilocus sequence analysis scheme and (GTG)5-PCR fingerprinting". Applied and Environmental Microbiology. 73 (22): 7128–37. Bibcode:2007ApEnM..73.7128R. doi:10.1128/AEM.01017-07. PMC 2168189. PMID 17890345.
  18. ^ Siezen RJ, Starrenburg MJ, Boekhorst J, Renckens B, Molenaar D, van Hylckama Vlieg JE (2008). "Genome-scale genotype-phenotype matching of two Lactococcus lactis isolates from plants identifies mechanisms of adaptation to the plant niche". Applied and Environmental Microbiology. 74 (2): 424–36. Bibcode:2008ApEnM..74..424S. doi:10.1128/AEM.01850-07. PMC 2223259. PMID 18039825.
  19. ^ Bolotin A, Quinquis B, Renault P, Sorokin A, Ehrlich SD, Kulakauskas S, Lapidus A, et al. (2004). "Complete sequence and comparative genome analysis of the dairy bacterium Streptococcus thermophilus". Nature Biotechnology. 22 (12): 1554–8. doi:10.1038/nbt1034. PMC 7416660. PMID 15543133.
  20. ^ van de Guchte M, Penaud S, Grimaldi C, Barbe V, Bryson K, Nicolas P, Robert C, et al. (2006). "The complete genome sequence of Lactobacillus bulgaricus reveals extensive and ongoing reductive evolution". Proceedings of the National Academy of Sciences of the United States of America. 103 (24): 9274–9. Bibcode:2006PNAS..103.9274V. doi:10.1073/pnas.0603024103. PMC 1482600. PMID 16754859.
  21. ^ Bachmann H, Starrenburg MJ, Molenaar D, Kleerebezem M, van Hylckama Vlieg JE (2012). "Microbial domestication signatures of Lactococcus lactis can be reproduced by experimental evolution". Genome Research. 22 (1): 115–24. doi:10.1101/gr.121285.111. PMC 3246198. PMID 22080491.
  22. ^ Meulen SB, Jong Ad, Kok J (2016-03-03). "Transcriptome landscape of Lactococcus lactis reveals many novel RNAs including a small regulatory RNA involved in carbon uptake and metabolism". RNA Biology. 13 (3): 353–366. doi:10.1080/15476286.2016.1146855. ISSN 1547-6286. PMC 4829306. PMID 26950529.