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Lactobacillus is a genus of Gram-positive, facultative anaerobic or microaerophilic, rod-shaped, non-spore-forming bacteria.[1] They are a major part of the lactic acid bacteria group (i.e. they convert sugars to lactic acid). In humans, they constitute a significant component of the microbiota at a number of body sites. In women of European ancestry, Lactobacillus species are normally a major part of the vaginal microbiota.[2][3][4]

Lactobacillus
Lactobacillus sp 01.png
Lactobacillus near a squamous epithelial cell
Scientific classification
Domain: Bacteria
Phylum: Firmicutes
Class: Bacilli
Order: Lactobacillales
Family: Lactobacillaceae
Genus: Lactobacillus
Beijerinck 1901
Species

Contents

MetabolismEdit

Many lactobacilli operate using homofermentative metabolism (they produce only lactic acid from sugars), and some species use heterofermentative metabolism (they can produce either alcohol or lactic acid from sugars). They are aerotolerant despite the complete absence of a respiratory chain[citation needed]. This aerotolerance is manganese-dependent and has been explored (and explained) in Lactobacillus plantarum[citation needed]. Many species of this genus do not require iron for growth and have an extremely high hydrogen peroxide tolerance.[citation needed]

GenomeEdit

The genomes of Lactobacillus are highly variable, ranging in size from 1.2 to 3.3 Mb (megabases). Accordingly, the number of protein-coding genes ranges from 1,100 to about 3,200 genes.[5]

Lactobacillus contains a wealth of compound microsatellites in the coding region of the genome, which are imperfect and have variant motifs.[6]

TaxonomyEdit

The genus Lactobacillus currently contains over 180 species and encompasses a wide variety of organisms.[7] The genus is polyphyletic, with the genus Pediococcus dividing the L. casei group, and the species L. acidophilus, L. salivarius, and L. reuteri being representatives of three distinct subclades. The genus Paralactobacillus falls within the L. salivarius group. In recent years, other members of the genus Lactobacillus (formerly known as the Leuconostoc branch of Lactobacillus) have been reclassified into the genera Atopobium, Carnobacterium, Weissella, Oenococcus, and Leuconostoc. More recently, the Pediococcus species P. dextrinicus has been reclassified as a Lactobacillus species.[8] According to metabolism, Lactobacillus species can be divided into three groups:

Human healthEdit

Vaginal tractEdit

The female genital tract is one of the principal colonisation sites for human microbiota, and there is interest in the relationship between the composition of these bacteria 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.[2][3][4]

Interactions with other pathogensEdit

Lactobacillus species produce hydrogen peroxide which inhibits the growth and virulence of the fungal pathogen Candida albicans in vitro and in vivo.[9][10] Following antibiotic therapy, certain Candida species can suppress the regrowth of Lactobacillus species at body sites where they cohabitate, such as in the gastrointestinal tract.[9][10]

ProbioticsEdit

Lactobacillus species administered as a single probiotic agent is of no benefit in people with irritable bowel syndrome[11] or Crohn's disease.[12] When it is administered in combination with other probiotics, may help people with irritable bowel syndrome, although in a minority of cases may cause negative side effects, uncertainty remains around which type of probiotic works best, and around the size of the effect.[11] Lactobacillus and bifidobacteria probiotics can reduce clinical symptoms of pouchitis and cholangitis.[13] L. acidophilus is used to prevent necrotizing entercolitis and other neonatal infections.[14] Lactobacillus have been recently shown to counteract the long term side effect of exposure to antibiotics in early life in mice.[15]

Oral healthEdit

 
Dental caries

Some Lactobacillus species have been associated with cases of dental caries (cavities). Lactic acid 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.[16][17]

Food productionEdit

Some Lactobacillus species are used as starter cultures in industry for controlled fermentation in the production of yogurt, cheese, sauerkraut, pickles, beer, cider, kimchi, cocoa, kefir, and other fermented foods, as well as animal feeds. The antibacterial and antifungal activity of Lactobacillus species rely on production of bacteriocins and low molecular weight compounds that inhibits these microorganisms.[18]

Sourdough 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 and lactic acid bacteria growing in a water and flour medium. The bacteria metabolize sugars into lactic acid, which lowers the pH of their environment, creating a signature "sourness" associated with yogurt, sauerkraut, etc.

In many traditional pickling processes, vegetables are submerged in brine, and salt-tolerant Lactobacillus species 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, and the vegetables are thus preserved—remaining edible for long periods.

Lactobacilli, especially L. casei 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 lambics and American wild ales, giving the beer a distinct tart flavor.

See alsoEdit

ReferencesEdit

  1. ^ Makarova, K.; Slesarev, A.; Wolf, Y.; Sorokin, A.; Mirkin, B.; Koonin, E.; Pavlov, A.; Pavlova, N.; et al. (October 2006). "Comparative genomics of the lactic acid bacteria". Proc Natl Acad Sci U S A. 103 (42): 15611–6. PMC 1622870 . PMID 17030793. doi:10.1073/pnas.0607117103. 
  2. ^ a b Petrova, Mariya I.; Lievens, Elke; Malik, Shweta; Imholz, Nicole; Lebeer, Sarah (2015). "Lactobacillus species as biomarkers and agents that can promote various aspects of vaginal health". Frontiers in Physiology. 6. ISSN 1664-042X. doi:10.3389/fphys.2015.00081. 
  3. ^ a b Ma, Bing; Forney, Larry J.; Ravel, Jacques (20 September 2012). "Vaginal Microbiome: Rethinking Health and Disease". Annual Review of Microbiology. 66 (1): 371–389. ISSN 0066-4227. PMC 3780402 . PMID 22746335. doi:10.1146/annurev-micro-092611-150157. 
  4. ^ a b Fettweis, JM; Brooks, JP; Serrano, MG; Sheth, NU; Girerd, PH; Edwards, DJ; Strauss, JF; Jefferson, KK; Buck, GA (2014). "Differences in vaginal microbiome in African American women versus women of European ancestry". Microbiology. 160 (Pt 10): 2272–82. PMC 4178329 . PMID 25073854. doi:10.1099/mic.0.081034-0. 
  5. ^ Mendes-Soares, Helena; Suzuki, Haruo; Hickey, Roxana J.; Forney, Larry J. (2014-04-01). "Comparative Functional Genomics of Lactobacillus spp. Reveals Possible Mechanisms for Specialization of Vaginal Lactobacilli to Their Environment". Journal of Bacteriology. 196 (7): 1458–1470. ISSN 0021-9193. PMC 3993339 . PMID 24488312. doi:10.1128/JB.01439-13. 
  6. ^ Basharat, Z; Yasmin, A (2015). "Survey of compound microsatellites in multiple Lactobacillus genomes". Canadian Journal of Microbiology. 61 (12): 898–902. ISSN 0008-4166. doi:10.1139/cjm-2015-0136. 
  7. ^ http://www.bacterio.cict.fr/l/lactobacillus.html
  8. ^ (IJSEM, Paper in Press).
  9. ^ a b Wang ZK, Yang YS, Stefka AT, Sun G, Peng LH (April 2014). "Review article: fungal microbiota and digestive diseases". Aliment. Pharmacol. Ther. 39 (8): 751–766. PMID 24612332. doi:10.1111/apt.12665. In addition, GI fungal infection is reported even among those patients with normal immune status. Digestive system-related fungal infections may be induced by both commensal opportunistic fungi and exogenous pathogenic fungi. ...
    In vitro, bacterial hydrogen peroxide or organic acids can inhibit C. albicans growth and virulence61
    In vivo, Lactobacillus sp. can inhibit the GI colonisation and infection of C. albicans62
    In vivo, C. albicans can suppress Lactobacillus sp. regeneration in the GI tract after antibiotic therapy63, 64
     
  10. ^ a b Erdogan A, Rao SS (April 2015). "Small intestinal fungal overgrowth". Curr Gastroenterol Rep. 17 (4): 16. PMID 25786900. doi:10.1007/s11894-015-0436-2. Small intestinal fungal overgrowth (SIFO) is characterized by the presence of excessive number of fungal organisms in the small intestine associated with gastrointestinal (GI) symptoms. Candidiasis is known to cause GI symptoms particularly in immunocompromised patients or those receiving steroids or antibiotics. However, only recently, there is emerging literature that an overgrowth of fungus in the small intestine of non-immunocompromised subjects may cause unexplained GI symptoms. ... Fungal-bacterial interaction may act in different ways and may either be synergistic or antagonistic or symbiotic [29]. Some bacteria such as Lactobacillus species can interact and inhibit both the virulence and growth of Candida species in the gut by producing hydrogen peroxide [30]. Any damage to the mucosal barrier or disruption of GI microbiota with chemotherapy or antibiotic use, inflammatory processes, activation of immune molecules and disruption of epithelial repair may all cause fungal overgrowth [27]. 
  11. ^ a b Ford, Alexander C; Quigley, Eamonn M M; Lacy, Brian E; Lembo, Anthony J; Saito, Yuri A; Schiller, Lawrence R; Soffer, Edy E; Spiegel, Brennan M R; Moayyedi, Paul (2014). "Efficacy of Prebiotics, Probiotics, and Synbiotics in Irritable Bowel Syndrome and Chronic Idiopathic Constipation: Systematic Review and Meta-analysis". The American Journal of Gastroenterology. 109 (10): 1547–1561. ISSN 0002-9270. PMID 25070051. doi:10.1038/ajg.2014.202. 
  12. ^ Ghouri YA, Richards DM, Rahimi EF, Krill JT, Jelinek KA, DuPont AW (Dec 9, 2014). "Systematic review of randomized controlled trials of probiotics, prebiotics, and synbiotics in inflammatory bowel disease". Clin Exp Gastroenterol (Review). 7: 473–87. PMC 4266241 . PMID 25525379. doi:10.2147/CEG.S27530. 
  13. ^ Saez-Lara, Maria Jose; Gomez-Llorente, Carolina; Plaza-Diaz, Julio; Gil, Angel (2015). "The Role of Probiotic Lactic Acid Bacteria and Bifidobacteria in the Prevention and Treatment of Inflammatory Bowel Disease and Other Related Diseases: A Systematic Review of Randomized Human Clinical Trials". BioMed Research International. 2015: 1–15. ISSN 2314-6133. PMC 4352483 . PMID 25793197. doi:10.1155/2015/505878. 
  14. ^ Baucells, B.J.; Mercadal Hally, M.; Álvarez Sánchez, A.T.; Figueras Aloy, J. (2015). "Asociaciones de probióticos para la prevención de la enterocolitis necrosante y la reducción de la sepsis tardía y la mortalidad neonatal en recién nacidos pretérmino de menos de 1.500g: una revisión sistemática". Anales de Pediatría. ISSN 1695-4033. doi:10.1016/j.anpedi.2015.07.038. 
  15. ^ Leclercq, Sophie; Mian, Firoz M.; Stanisz, Andrew M.; Bindels, Laure B.; Cambier, Emmanuel; Ben-Amram, Hila; Koren, Omry; Forsythe, Paul; Bienenstock, John (2017). "Low-dose penicillin in early life induces long-term changes in murine gut microbiota, brain cytokines and behavior". Nature Communications. 8: 15062. doi:10.1038/ncomms15062. 
  16. ^ Twetman, S; Stecksén-Blicks, C (2008). "Probiotics and oral health effects in children". International Journal of Paediatric Dentistry. 18 (1): 3–10. PMID 18086020. doi:10.1111/j.1365-263X.2007.00885.x. 
  17. ^ Meurman, J. H.; Stamatova, I (2007). "Probiotics: Contributions to oral health". Oral Diseases. 13 (5): 443–51. PMID 17714346. doi:10.1111/j.1601-0825.2007.01386.x. 
  18. ^ Inglin, Raffael C. (2015). "High-throughput screening assays for antibacterial and antifungal activities of Lactobacillus species". Journal of Microbiological Methods. 114 (July 2015): 26–29. doi:10.1016/j.mimet.2015.04.011. 

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