Lactobacillus

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Lactobacillus
Lactobacillus acidophilus (after Gram stain)

Lactobacillus acidophilus (after Gram stain )

Systematics
Domain : Bacteria (bacteria)
Department : Firmicutes
Class : Bacilli
Order : Lactic acid bacteria (Lactobacillales)
Family : Lactobacillaceae
Genre : Lactobacillus
Scientific name
Lactobacillus
Beijerinck 1901 emend. Haakensen et al. 2009

Lactobacillus is a genus of gram-positive , mostly rod-shaped bacteria fromthe Lactobacillaceae family . The word is also written " Germanized " Laktobazillus ( plural : Laktobazillen). Lactobacillus belongs to the lactic acid bacteria together with other types of bacteria ; they all produce lactic acid by fermentation .

Lactobacillus - types are important for the food industry. They are used for the production of dairy products and beer specialties such as Berliner Weisse and Leipziger Gose . As opportunistic pathogens, with the exception of immunosuppressed patients, they usually do no harm to people themselves; they are non-pathogenic .

With regard to their characteristics , the representatives of the genus Lactobacillus do not form a uniform group, therefore individual species are combined into subgroups. Within the system, it can be observed that individual species are newly added or no longer belong to the genus. This led to an expanded description of the genus in 2009.

Origin of the designation

The generic name refers to the occurrence and appearance , lactis from Latin stands for “milk” and bacillus (Lat.) Means “small stick”, Lactobacillus is consequently a rod-shaped bacterium in milk.

features

Appearance

Lactobacillus is a typical genus for a lactic acid bacterium. The representatives of the genus are gram-positive bacteria, they do not form persistent forms like endospores and in most cases are not capable of active movement. The types of Lactobacillus are predominantly rod-shaped , the cells occur individually or in chains. However, curved and helical (e.g. Lactobacillus curvatus ) variants can also occur. After the assignment of different species, which were initially classified in other genera, there are now also some cocci and bacterial forms between cocci and rods among the lactobacilli.

On solid, carbohydrate-containing nutrient media , the cells grow into colonies , which in Lactobacilli are typically quite small. In L. paralimentarius, for example , the diameter of the colonies is between 0.8 and 1.5 mm.

Growth and metabolism

As representatives of the lactic acid bacteria, lactobacilli grow anaerobically but aerotolerantly, i. that is, they grow in the presence of atmospheric oxygen, but do not need oxygen for their metabolism . They are catalase negative and oxidase negative. However, they are able to form cytochromes when cultured on nutrient media containing heme or blood . In this case they show a positive reaction in the oxidase test. In the case of Lactobacillus , however, there are also some species that absolutely do not tolerate oxygen. L. aviarius and L. ruminis are examples of these species, which are designated as obligately anaerobic . Another characteristic of lactobacilli is the need for complex growth factors and amino acids in cultivation.

The temperatures suitable for cultivation are in the range of 30–40 ° C for most species, so Lactobacillus is one of the mesophilic organisms. Some Lactobacillus species also grow well at 45 ° C. This thermophilic tendency is used to subdivide the genus and is important for use in the food industry. The optimal pH value for growth is a slightly acidic pH value (pH 5 to 6), with acidic pH values ​​up to pH 4 also being tolerated. The lactic acid produced lowers the pH of the nutrient medium, provided it does not contain any buffering additives. Some Lactobacillus species produce up to 2.3% lactic acid in nutrient media rich in carbohydrates.

Lactic acid fermentation

Lactobacilli can use various carbohydrates for energy production in one fermentation . A characteristic of fermentation (fermentation) is that the substrates are broken down without oxygen. The typical fermentation product for lactic acid bacteria is lactic acid , which is why this metabolic pathway is called lactic acid fermentation . A distinction is made between homofermentative and heterofermentative types. Homofermentative types produce almost exclusively lactic acid from glucose through fermentation, while heterofermentative types produce not only lactic acid, but also other end products to a significant extent, mostly ethanol and carbon dioxide , sometimes also acetic acid . The heterofermentatives usually lack the enzyme aldolase .

The representatives of the genus Lactobacillus do not form a uniform group in this regard. Lactobacillus delbrueckii subsp. Belongs to the homofermentative species . bulgaricus , the typical metabolic pathway is explained there. The following table gives an overview of the lactic acid fermentation of some Lactobacillus species.

Homofermentative species or subspecies Heterofermentative species or subspecies
Lactobacillus acidophilus Lactobacillus bifermentans
Lactobacillus alimentarius Lactobacillus brevis
Lactobacillus casei Lactobacillus fermentum
Lactobacillus delbrueckii subsp. bulgaricus Lactobacillus oryzae
Lactobacillus delbrueckii subsp. delbrueckii Lactobacillus panis
Lactobacillus delbrueckii subsp. lactis Lactobacillus paracasei
Lactobacillus helveticus Lactobacillus parabuchneri
Lactobacillus plantarum Lactobacillus paralimentarius (formerly Lactobacillus kimchii )
Lactobacillus salivarius Lactobacillus rhamnosus

Chemotaxonomic Features

Many lactobacilli produce bacteriocins , poisonous proteins or peptides that are secreted by bacteria and kill other (competing) types of bacteria or hinder their growth. Bacteriocins produced by various Lactobacillus species include: a. Lactacin-F and Bavaricin-A. Lactobacillus plantarum forms various plantaricins (A, S, T, and Plantaricin-SIK).

Lactobacillus is one of the gram-positive bacteria with a low GC content (the proportion of the nucleobases guanine and cytosine ) in the bacterial DNA . Lactobacillus species also show a high degree of variability with regard to this characteristic; the GC content is between 32 and 53  mol percent . Lactobacillus mali, for example, has a GC content of 32-34 mol percent, while a GC content of 53-56 mol percent has been determined for Lactobacillus panis . Usually the content of guanine and cytosine in the DNA does not vary so strongly within a bacterial genus, which confirms that the lactobacilli form a rather heterogeneous group.

Occurrence

In addition to milk and dairy products , the species of Lactobacillus occur in or on plants; some form part of the natural intestinal flora of humans and other animals. Lactobacilli have been isolated from all parts of the digestive tract of humans, including the stomach.

The species Bifidobacterium bifidum , which used to belong to the lactobacilli, occurs in the intestines of adults and (breast-fed) infants. The obligatory anaerobic bacterium is an important part of the intestinal flora. The term bifidus flora generally stands for the entirety of the different bifidobacteria species in the human intestine. Specifically, the intestinal flora of babies breastfed with breast milk is referred to here.

Lactobacillus salivarius and Lactobacillus ruminis belong to the autochthonous intestinal flora of humans. Autochthonous bacteria are regularly detectable within the respective habitat. L. salivarius and L. ruminis are therefore "permanent residents" of the human intestine. The species Lactobacillus paracasei , L. brevis , L. fermentum , L. plantarum and L. rhamnosus only occur temporarilyin the intestine.

In the stomachs of various animals such as mice, pigs and rats, lactobacilli form layers of cells that are connected to the epithelial cells of the stomach. Lactobacillus amylovorus , L. johnsonii and L. reuteri are the most common in the digestive tract of pigs . Furthermore, some lactobacilli form dense layers on the epithelium in the crop of birds, especially the species L. salivarius .

Lactobacillus reuteri forms antibiotic substances and is used commercially as a probiotic in poultry farming, for example to prevent salmonella infections. The intestinal bacterium from the animal world, for which the Swedish company BioGaia has applied for a patent, isalso used in human medicine, where it is used as an agent for dental health, as an anti-diarrheal agent for small children and as a stomach agent to combat Helicobacter pylori . The bacterium, which is used in factory farming to save synthetic antibiotics, spreads very quickly in the human digestive tract after ingestion and can stay there not only in the intestine, but also in the acidic environment of the stomach. It can be transmitted through breast milk, i.e. it infects babies and can be found in raw milk products. Since 2018, after a study on genetically modified mice, L. reuteri has been suspected of being able to migrate from the digestive tract to the liver. There it is said totriggerthe autoimmune disease systemic lupus erythematosus . Migration to other organs is normally an exclusion criterion for the use of probiotics. The immunobiologist Martin Kriegel, who uncovered the scandal, found L. reuteri not only in the liver of mice, which developed systemic lupus as a result , but also in the liver of lupus patients. The researcher recommends those affectedto include resistant starch in their diet in orderto displace L. reuteri with less dangerous types of bacteria.

Different types of Lactobacillus form the so-called Döderlein bacteria or Döderlein rods. The Döderlein bacteria are part of the natural vaginal flora in women. Fermentation causes the bacteria in the vagina to create an acidic environment, protecting the vagina from other disease-causing bacteria that cannot tolerate low pH. The species most frequently identified in various studies include Lactobacillus crispatus , L. iners , L. gasseri, and L. jensenii . Earlier it was Lactobacillus acidophilus determined as dominant species in the vaginal flora of healthy women.

The site of Lactobacillus selangorensis (formerly Paralactobacillus selangorensis ) is a Malaysian food ingredient called Chili bo .

Furthermore, lactobacilli can be isolated from many plant surfaces, this being the case with intact, but also with decomposing plant parts. For example, L. brevis , L. delbrueckii , L. fermentum and L. plantarum have been detected there.

Systematics

External system

Lactobacillus is a type genus of the family Lactobacillaceae and the order Lactobacillales. The family currently (2013) comprises three genera: Lactobacillus , Pediococcus and Sharpea . Genetic and cell morphological studies by Haakensen u. a. on the species initially classified as Pediococcus dextrinicus showed that it is better assigned to the Lactobacilli , in addition to the renaming of the species to Lactobacillus dextrinicus , this also led to an expanded description of the genus Lactobacillus in 2009 .

Internal system

The genus Lactobacillus includes numerous (around 80) species. Currently (2013) 218 Lactobacillus species and subspecies are listed by the Leibniz Institute DSMZ - German Collection of Microorganisms and Cell Cultures GmbH in the Prokaryotic Nomenclature up-to-date (“Prokaryotic nomenclature up to date”). This compilation includes all names validly published according to the Bacteriological Code and takes into account the validation list of the International Journal of Systematic and Evolutionary Microbiology . In the case of other species, the assignment to other genera is suggested.

Because of the diversity within the genus, it is to be expected that reclassification will result in new species being added or no longer belonging to the genus, and that new Lactobacillus species will be described anew . In order to structure the rather heterogeneous group of lactobacilli, a division into three subgroups has proven successful:

features Group 1
Lactobacillus casei / Pediococcus group		 Group 2
Lactobacillus delbrueckii group		 Group 3
Lactobacillus brevis group
Lactic acid fermentation homofermentative homofermentative heterofermentative
Lactic fermentation products Lactic acid is the main product,
no gas formation from glucose 		Lactic acid is the main product,
no gas formation from glucose		 About 50% of lactic acid is formed from glucose,
and carbon dioxide (CO 2 ) and ethanol are also produced
Influence of temperature on growth Growth at 15 ° C, growth at 45 ° C variable Growth at 45 ° C but not at 15 ° C variable
Typical species L. casei, L. aviarius, L. curvatus, L. mali, L. plantarum, L. ruminis, L. salivarius L. delbrueckii, L. acidophilus, L. amylolyticus, L. crispatus, L. helveticus L. brevis, L. buchneri, L. fermentum, L. kefiri, L. paracasei, L. rhamnosus

A selection of the types of Lactobacillus :

Industrial importance

Lactic acid fermentation is mainly used in the food industry in the manufacture of dairy products such as cheese and yoghurt . Without lactic acid bacteria there would be practically no dairy products. But they are also involved in the production of other acidified food and feed. In addition to the Lactobacillus species, other types of bacteria are usually also involved.

Types of Lactobacillus and Pediococcus are also known to be pests in beverage production. The formation of lactic acid and other products leads to undesirable acidification and changes in taste, e.g. B. in beer , wine and fruit juices . Even with heated drinking milk ( long-life milk , pasteurized milk ), the lactobacilli are undesirable if they get back into the product through contamination after heating.

See also

literature

  • Bacteria: Firmicutes, Cyanobacteria . In: Martin Dworkin, Stanley Falkow, Eugene Rosenberg, Karl-Heinz Schleifer, Erko Stackebrandt (Eds.): The Prokaryotes, A Handbook of the Biology of Bacteria . 3. Edition. tape 4 . Springer Verlag, New York, USA 2006, ISBN 978-0-387-25494-4 .
  • Helmut H. Dittrich (Hrsg.): Microbiology of food, beverages. Behr, Hamburg 1999. ISBN 3-86022-113-2
  • Helmut H. Dittrich (Hrsg.): Microbiology of food, meat and meat products. Behr, Hamburg 1996. ISBN 3-86022-236-8

Web links

Commons : Lactobacillus  - collection of images, videos and audio files

Individual evidence

  1. ^ Marianne Abele-Horn: Antimicrobial Therapy. Decision support for the treatment and prophylaxis of infectious diseases. With the collaboration of Werner Heinz, Hartwig Klinker, Johann Schurz and August Stich, 2nd, revised and expanded edition. Peter Wiehl, Marburg 2009, ISBN 978-3-927219-14-4 , p. 264.
  2. ↑ a b c M. Haakensen, CM Dobson, JE Hill, B. Ziola: Reclassification of Pediococcus dextrinicus (Coster and White 1964) back 1978 (Approved Lists 1980) as Lactobacillus dextrinicus comb. nov., and emended description of the genus Lactobacillus. In: International journal of systematic and evolutionary microbiology. Volume 59, Pt 3, March 2009, pp. 615-621, ISSN  1466-5026 . doi : 10.1099 / ijs.0.65779-0 . PMID 19244449 .
  3. ↑ Der Kleine Stowasser, Latin-German school dictionary, edited by Dr. Michael Petschenig . B. Freytag Verlag, Munich 1971, ISBN 3-486-13402-7 .
  4. ↑ a b V.BD Skerman, Vicki McGowan, PHA Sneath (ed.): Approved Lists of Bacterial Names (Amended) . 2nd Edition. ASM Press, Washington (DC), USA 1989, ISBN 978-1-55581-014-6 .
  5. ↑ a b c d e Michael T. Madigan, John M. Martinko, Jack Parker: Brock Mikrobiologie. German translation edited by Werner Goebel. 1st edition. Spektrum Akademischer Verlag GmbH, Heidelberg / Berlin 2000, ISBN 3-8274-0566-1 .
  6. ↑ a b c d Gunther Müller: Fundamentals of food microbiology . 6th edition. Steinkopff Verlag, Darmstadt 1986, ISBN 3-7985-0673-6 , p. 59-61, 178 .
  7. ↑ a b J. H. Yoon, SS Kang u. a .: Lactobacillus kimchii sp. nov., a new species from kimchi. In: International journal of systematic and evolutionary microbiology. Volume 50 Pt 5, September 2000, pp. 1789-1795, ISSN  1466-5026 . PMID 11034488 .
  8. ↑ a b c d J. J. Leisner, M. Vancanneyt, J. Goris, H. Christensen, G. Rusul: Description of Paralactobacillus selangorensis gen. Nov., Sp. nov., a new lactic acid bacterium isolated from chili bo, a Malaysian food ingredient. In: International journal of systematic and evolutionary microbiology. Volume 50 Pt 1, January 2000, pp. 19-24, ISSN  1466-5026 . PMID 10826783 .
  9. ↑ a b c d e Hans G. Schlegel, Christiane Zaborosch: General microbiology . 7th edition. Thieme Verlag, Stuttgart / New York 1992, ISBN 3-13-444607-3 , p. 100 f., 296-304 .
  10. ^ A b Walter P. Hammes, Christian Hertel: The Genera Lactobacillus and Carnobacterium. In: The Prokaryotes, A Handbook of the Biology of Bacteria . Volume 4. Bacteria: Firmicutes, Cyanobacteria. Edited by Martin Dworkin, Stanley Falkow, Eugene Rosenberg, Karl-Heinz Schleifer, Erko Stackebrandt. 3. Edition. Springer, New York 2006. ISBN 978-0-387-25494-4
  11. ↑ M. Tohno, M. Kitahara et al. a .: Lactobacillus oryzae sp. nov., isolated from fermented rice grain (Oryza sativa L. subsp. japonica). In: International journal of systematic and evolutionary microbiology. Volume 63, Pt 8, August 2013, pp. 2957-2962, ISSN  1466-5034 . doi : 10.1099 / ijs.0.048918-0 . PMID 23378109 .
  12. ↑ a b B. G. Wiese, W. Strohmar, FA Rainey, H. Diekmann: Lactobacillus panis sp. nov., from sourdough with a long fermentation period. In: International journal of systematic bacteriology. Volume 46, Number 2, April 1996, pp. 449-453, ISSN  0020-7713 . PMID 8934903 .
  13. ↑ D. Sohier, E. Jamet et al. a .: Polyphasic approach for quantitative analysis of obligately heterofermentative Lactobacillus species in cheese. In: Food microbiology. Volume 31, Number 2, September 2012, pp. 271-277, ISSN  1095-9998 . doi : 10.1016 / j.fm.2012.01.009 . PMID 22608233 .
  14. ↑ Y. Cui, C. Zhang, Y. Wang, J. Shi, L. Zhang, Z. Ding, X. Qu, H. Cui: Class IIa Bacteriocins: Diversity and New Developments. In: International journal of molecular sciences. Volume 13, Number 12, 2012, pp. 16668-16707, ISSN  1422-0067 . doi : 10.3390 / ijms131216668 . PMID 23222636 . PMC 3546714 (free full text).
  15. ↑ GW Tannock, K. Munro et al. a .: Analysis of the fecal microflora of human subjects consuming a probiotic product containing Lactobacillus rhamnosus DR20. In: Applied and environmental microbiology. Volume 66, Number 6, June 2000, pp. 2578-2588, ISSN  0099-2240 . PMID 10831441 . PMC 110584 (free full text).
  16. Jump up ↑ J. Walter, C. Hertel, GW Tannock, CM Lis, K. Munro, WP Hammes: Detection of Lactobacillus, Pediococcus, Leuconostoc, and Weissella species in human feces by using group-specific PCR primers and denaturing gradient gel electrophoresis. In: Applied and environmental microbiology. Volume 67, Number 6, June 2001, pp. 2578-2585, ISSN  0099-2240 . doi : 10.1128 / AEM.67.6.2578-2585.2001 . PMID 11375166 . PMC 92910 (free full text).
  17. ↑ Impact of diet intervention on autoimmunity in mice. Retrieved January 21, 2019 .
  18. ^ MA Antonio, SE Hawes, SL Hillier. The identification of vaginal Lactobacillus species and the demographic and microbiologic characteristics of women colonized by these species. In: The Journal of Infectious Diseases . Chicago 180.1999, pp. 1950-1956. PMID 10558952 ISSN  0022-1899
  19. ^ A. Vásquez, T. Jakobsson, S. Ahrné, U. Forsum, G. Molin: Vaginal lactobacillus flora of healthy Swedish women. In: Journal of clinical microbiology. Volume 40, Number 8, August 2002, pp. 2746-2749, ISSN  0095-1137 . PMID 12149323 . PMC 120688 (free full text).
  20. ↑ M. Haakensen, V. Pittet, B. Ziola: Reclassification of Paralactobacillus selangorensis Leisner et al. 2000 as Lactobacillus selangorensis comb. nov. In: International journal of systematic and evolutionary microbiology. Volume 61, Pt 12, December 2011, pp. 2979-2983, ISSN  1466-5034 . doi : 10.1099 / ijs.0.027755-0 . PMID 21296926 .
  21. ↑ JP Euzéby, Aidan C. Part: Family Lactobacillaceae. (No longer available online.) In: List of Prokaryotic names with Standing in Nomenclature (LPSN) . Formerly in the original ; Retrieved October 20, 2013 .  ( Page no longer available , search in web archives )  Info: The link was automatically marked as defective. Please check the link according to the instructions and then remove this notice.@1@ 2Template: Dead Link / www.bacterio.net  
  22. ^ Prokaryotic Nomenclature Up-to-date. In: Website of the Leibniz Institute DSMZ - German Collection of Microorganisms and Cell Cultures GmbH . Retrieved October 21, 2013 .
  23. ^ JP Euzéby, Aidan C. Parte: Genus Lactobacillus. (No longer available online.) In: List of Prokaryotic names with Standing in Nomenclature (LPSN) . Archived from the original on August 17, 2013 ; Retrieved October 21, 2013 . Info: The archive link was inserted automatically and has not yet been checked. Please check the original and archive link according to the instructions and then remove this notice. @1@ 2Template: Webachiv / IABot / www.bacterio.net