Lactobacillus rhamnosus

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Lactobacillus rhamnosus
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Lactobacillus rhamnosus

Systematics
Department : Firmicutes
Class : Bacilli
Order : Lactic acid bacteria (Lactobacillales)
Family : Lactobacillaceae
Genre : Lactobacillus
Type : Lactobacillus rhamnosus
Scientific name
Lactobacillus rhamnosus
( Hansen 1968) Collins et al. 1989

Lactobacillus rhamnosus is a probiotic lactic acid bacterium that is used in probiotics . It was previously considered a subspecies of Lactobacillus casei . The species includes numerous phyla . The genome of one strain was completely sequenced in 2009.

features

Appearance

Lactobacillus rhamnosus is a gram - positive, medium - length, rod-shaped bacterium. A single cell is 2.0-4.0 µm long and 0.8-1.0 µm wide. In light microscopic image individual cells and cell chains found. The bacterium has no flagella for active movement and cannot form persistent forms such as endospores .

Growth and metabolism

L. rhamnosus is a typical representative of the genus Lactobacillus , it grows anaerobically but aerotolerant. The temperatures usually used for cultivation are in the range from 30 to 37 ° C. The bacterium is characterized by its tolerance to a wide temperature range, growth takes place at 15 ° C (with some strains even at 10 ° C) as well as at 45 ° C.

L. rhamnosus belongs to group 3 ( Lactobacillus brevis group) of the lactobacilli. The heterofermentative lactic acid fermentation is typical for them. Glucose is fermented to L - (+) - lactic acid, other fermentation products are carbon dioxide and ethanol . In addition to D- glucose, L. rhamnosus can also utilize numerous other carbohydrates , e.g. B. the monosaccharides D - fructose , D - mannose , D - tagatose , galactose , ribose and rhamnose (noted in the species name). Furthermore, the sugar alcohols mannitol and sorbitol can be broken down, as well as some disaccharides , for example lactose (milk sugar), maltose , trehalose and cellobiose .

Some enzymes that are used in the metabolism to break down certain substrates are detected in a colorful series in order to identify a bacterium. It is noticeable that Lactobacillus rhamnosus does not have many of these enzymes. He has neither catalase nor oxidase . Neither does it possess the enzyme urease , which enables urea to be broken down , nor the arginine dihydrolase to split ammonia from the amino acid arginine . The enzyme β-galactosidase is present and enables it to grow in milk using the lactose it contains, and it is also able to hydrolyze esculin .

genetics

The genome of numerous strains of the bacterium has already been completely sequenced . The first sequencing took place in 2009 on Lactobacillus rhamnosus GG ATCC 53103. The genome has a size of 3010 kilobase pairs (kb), which is about 65% of the genome size of Escherichia coli , but significantly more than that of Lactobacillus delbrueckii subsp. bulgaricus (1865 kb). 2913 proteins are annotated . In the years that followed, other strains were genetically examined, with similar results. The bacterial strains examined came from human faeces , but starter cultures used in the dairy industry were also examined.

The results of the sequencing show a GC content (the proportion of the nucleobases guanine and cytosine ) in the bacterial DNA of about 47 mol percent, which is comparable to the GC content of L. delbrueckii (49–51 mol percent) and significantly more than L. acidophilus , whose GC content in the DNA is 34–37 mol percent.

Pathogenicity

By Biostoffverordnung in connection with the TRBA 466 is L. rhamnosus the risk group  associated with the second Microorganisms in this risk group are defined in the Biological Agents Ordinance as "biological agents that can cause illness in humans and pose a risk to employees [...]". However, apathogenic strains of L. rhamnosus have been used in the food industry for a long time. This fact is taken into account by a note in the classification in risk group 2: Strains that have been safely handled in technical application for many years are classified in risk group 1. Endocarditis caused by the bacterium was reported in one case .

Occurrence

L. rhamnosus occurs in milk and milk products , and has also been found in wastewater and human faeces . Occasionally its occurrence in the intestine - as a component of the intestinal flora of humans - can be detected, so it is not a permanent intestinal inhabitant.

Systematics

External system

L. rhamnosus was previously considered a subspecies of Lactobacillus casei and was named L. casei subspecies rhamnosus . Studies from 1989 showed that there are considerable differences in chemotaxonomic traits compared to other L. casei subspecies. The genetic investigations using DNA-DNA hybridization also confirmed clear differences, whereupon L. rhamnosus was delimited as a separate species.

Internal system

More than 20 bacterial strains of this species are known, the genome of which has already been partially researched using DNA sequencing. As a type strain is L. rhamnosus ATCC 7469 (= NCDO 243) viewed.

etymology

The generic name can be traced back to the occurrence and appearance of the bacterial cells, lac from Latin means milk, while bacillus (Latin) refers to the rod-shaped shape. The species name refers to the ability of the bacterium to break down the monosaccharide rhamnose.

meaning

Lactobacillus rhamnosus is a probiotic lactic acid bacterium. The bacterium is for the relief of antibiotic-associated diarrhea used. A positive effect on respiratory infections is suspected in children. In addition, the bacterium has a positive effect on the human urogenital system by protecting it from pathogens.

One strain of bacteria used in probiotics is Lactobacillus rhamnosus DR20. It was used in a long-term test to investigate the extent to which the composition of the intestinal flora of humans changes when the probiotic preparation is consumed regularly. The study published in 2000 came to the conclusion that L. rhamnosus can be detected in the faeces during the phase of daily consumption, i.e. is part of the intestinal flora. This temporary occurrence in the intestines (and in the feces) is explained by the consumption of the probiotic, so the bacteria pass through the digestive tract . Such strains are regarded as allochthonous bacteria, while autochthonous bacteria are regularly detectable within the respective habitat. It was also found that the composition of the lactobacilli population changed during the test phase and the number of enterococci also increased. However, these effects are only temporary and could no longer be clearly recognized at the end of the 3-month phase in which the probiotic was no longer consumed.

The beneficial effect of the probiotic lactic acid bacteria on the immune system was investigated in animal experiments on mice and was confirmed. The extent to which these results can be transferred to humans is part of the discussion about the health-promoting effects of probiotics.

Individual evidence

  1. ↑ a b c d e f M. D. Collins, BA Phillips, P. Zanoni: Deoxyribonucleic acid homology studies of Lactobacillus casei, Lactobacillus paracasei sp. nov., subsp. paracasei and subsp. tolerans, and Lactobacillus rhamnosus sp. nov., comb. nov. Archived from the original on May 15, 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. In: Int. J. Syst. Bacteriol. . 39, No. 2, 1989, pp. 105-108. Retrieved September 24, 2013. @1@ 2Template: Webachiv / IABot / ijs.sgmjournals.org
  2. ↑ Gunther Müller: Fundamentals of food microbiology . 6th edition. Steinkopff Verlag, Darmstadt 1986, ISBN 3-7985-0673-6 , p. 178 .
  3. ↑ a b c Lactobacillus rhamnosus. In: National Center for Biotechnology Information (NCBI) Genome website . Retrieved October 22, 2013 .
  4. ↑ a b Lactobacillus rhamnosus GG ATCC 53103. In: Website Genomes Online Database (GOLD) . Retrieved October 22, 2013 .
  5. ↑ Lactobacillus rhamnosus R0011. In: Website Genomes Online Database (GOLD) . Retrieved October 22, 2013 .
  6. ↑ Michael T. Madigan, John M. Martinko, Jack Parker: Brock Microbiology. German translation edited by Werner Goebel. 1st edition. Spektrum Akademischer Verlag GmbH, Heidelberg / Berlin 2000, ISBN 3-8274-0566-1 , p. 563.
  7. ↑ a b TRBA 466: Classification of prokaryotes (bacteria and archaea) into risk groups. In: Website of the Federal Institute for Occupational Safety and Health (BAuA). May 4, 2012, accessed March 9, 2013 .
  8. ^ Text of the Biological Agents Ordinance - BioStoffV at juris. Retrieved September 15, 2013.
  9. ↑ A. Avlami, et al .: Lactobacillus rhamnosus endocarditis complicating colonoscopy. In: Journal of Infection . Volume 42, Number 4, May 2001, pp. 283-285, ISSN  0163-4453 . doi : 10.1053 / jinf.2001.0793 . PMID 11545575 .
  10. 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).
  11. ↑ Taxonomy Browser Lactobacillus rhamnosus. In: National Center for Biotechnology Information (NCBI) website . Retrieved October 22, 2013 .
  12. ↑ M. Kumpu, et al .: Milk containing probiotic Lactobacillus rhamnosus GG and respiratory illness in children: a randomized, double-blind, placebo-controlled trial. In: European Journal of Clinical Nutrition. Volume 66, Number 9, September 2012, pp. 1020-1023, ISSN  1476-5640 . doi : 10.1038 / ejcn.2012.62 . PMID 22692023 .
  13. ↑ CL Abad, N. Safdar: The role of lactobacillus probiotics in the treatment or prevention of urogenital infections - a systematic review. In: Journal of Chemotherapy . Volume 21, Number 3, June 2009, pp. 243-252, ISSN  1973-9478 . PMID 19567343 . (Review).
  14. ↑ 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).
  15. ↑ HS Gill, KJ Rutherfurd, J. Prasad, PK Gopal: enhancement of natural and acquired immunity by Lactobacillus rhamnosus (HN001), Lactobacillus acidophilus (HN017) and Bifidobacterium lactis (HN019). In: The British journal of nutrition. Volume 83, Number 2, February 2000, pp. 167-176, ISSN  0007-1145 . PMID 10743496 .

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