Leuconostoc lactis explained

Leuconostoc lactis is a species of lactic acid bacteria that performs fermentation in acidic conditions, like those found in dairy products such as cheese and yogurt, and tend to culture best at moderate temperatures around 30°C.[1] [2] [3] L. lactis typically produces volatile butter-like compounds that are typically used in fermented dairy products, as well as dextran-like exopolysaccharide in sourdough.

Microbiology

Leuconostoc lactis is a Gram-positive, non-motile, lactic acid bacterium that thrive best in acidic conditions and moderate temperatures.[2] [1] L. lactis is capable of acidifying culture media through lactose fermentation to pH levels of 4.0-4.1, and milk to levels below 5.4.[4] The availability of citrate to co-metabolize with lactose allows for L. lactis to maintain an intercellular pH of above 6.0 when lactose concentrations are high.[4] The maintenance of higher pH within the bacterial cell is important for the function of lactate dehydrogenase, and the Km for pyruvate and NADH, as well as the Vmax of the enzyme decreases by up to 30 fold as the intercellular pH drops from 8.0-5.0.[5]

Due to the acidic conditions that arise from the cultivation of the bacteria, L. lactis is often a starter culture for the fermentation of dairy products into products like cheese and sour cream. L. lactis is one of the most commonly found bacterial cultures in regions like Romania that heavily depend on fermented dairy products.[6]

Pathology

Certain subspecies of L. lactis have the potential to produce glycosyltransferase, which allows for a variety of oligosaccharides and gluco-oligosaccharides to be produced. These macromolecules can be recognized and responded to by mammalian immune systems. These oligosaccharides have been found to increase several notable immune response factors, such as phosphorylated P38, ERK1/2, and JNK.[7]

Leuconostoc lactis is found in a variety of fermenting vegetable and dairy products. The bacteria can also become an opportunistic pathogen with intrinsic resistance to traditional antibiotics like vancomycin and teicoplanin.[8] There has been at least one recorded case of a 4 year old patient presenting an acute fever with no other symptoms. Blood culture revealed L. lactis infection and the administered treatment consisted of intravenous ceftriaxone and gentamicin, and subsequent oral amoxicillin.

Notes and References

  1. Holland . R. . Liu . S.-Q. . Lactic Acid Bacteria Leuconostoc spp. . Encyclopedia of Dairy Sciences . 2011 . 2 . 138-142 . 10.1016/B978-0-12-374407-4.00267-3 . 9780123744074 . 9 December 2023.
  2. Web site: Leuconostoc lactis LL76 is an anaerobe, mesophilic human pathogen that was isolated from raw milk. . BacDiv . Leibniz Institute . 9 December 2023.
  3. Ah Kim . Seul . Han Bae . Jae . Seong . Hyunbin . Soo Han . Nam . Development of Leuconostoc lactis–Specific Quantitative PCR and its Application for Identification and Enumeration in Fermented Foods . Food Analytical Methods . 5 February 2020 . 16 . 9–10 . 992–999 . 10.1007/s12161-020-01720-8 . 211038773 . 8 December 2023.
  4. Hache . Caroline . Cachon . Rémy . Waché . Yves . Belguendouz . Talal . Riondet . Christophe . Deraedt . Andries . Diviès . Charles . Influence of Lactose-Citrate Co-metabolism on the Differences of Growth and Energetics in Leuconostoc lactis, Leuconostoc mesenteroides ssp.mesenteroides and Leuconostoc mesenteroides ssp.cremoris . Systematic and Applied Microbiology . December 1999 . 22 . 4 . 507–513 . 10.1016/S0723-2020(99)80002-2 . 10794137 . 9 December 2023.
  5. Fitzgerald . Richard J. . Doonan . Shawn . Mckay . Larry L. . Cogan . Timothy M. . Intracellular pH and the role of D-lactate dehydrogenase in the production of metabolic end products by Leuconostoc lactis . Journal of Dairy Research . August 1992 . 59 . 3 . 359–367 . 10.1017/S0022029900030636 . 1401357 . 22702514 . 9 December 2023.
  6. Zamfir . Medana . Vacanneyt . Marc . Makras . Lefteris . Vaningelgem . Frederik . Lefebvre . Karen . Pot . Bruno . Swings . Jean . De Vuyst . Luc . Biodiversity of lactic acid bacteria in Romanian dairy products . Systematic and Applied Microbiology . 11 September 2006 . 29 . 6 . 487–495 . 10.1016/j.syapm.2005.10.002 . 16919730 . 9 December 2023.
  7. Lee . Sulhee . Song . In Ho . Young-Seo . Park . In Vivo and In Vitro Study of Immunostimulation by Leuconostoc lactis-Produced Gluco-Oligosaccharides . Molecules . 2019 . 24 . 21 . 3994 . 10.3390/molecules24213994 . 31694180 . 6864623 . free .
  8. Azghar . Ali . Azizi . Manal . Mohammed . Lahmer . Benaissa . Elmostapha . Ben Lahlou . Yassine . Benajiba . Noufissa . Elouennass . Mostafa . Maleb . Adil . n A very rare case of bacteraemia in a 4-year-old girl with osteopetrosis with probable Leuconostoc lactis infection . Access Microbiology . 13 October 2023 . 5 . 10 . 000439 . 10.1099/acmi.0.000439 . 37970073 . 10634485 . 9 December 2023.

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