Lactobacillus delbrueckii subsp. bulgaricus
Lactobacillus delbrueckii subsp. bulgaricus | |
---|---|
Lactobacillus delbrueckii subsp. bulgaricus from a sample of yogurt. Numbered ticks are 11 μm apart. | |
Scientific classification | |
Domain: | Bacteria |
Phylum: | Bacillota |
Class: | Bacilli |
Order: | Lactobacillales |
Family: | Lactobacillaceae |
Genus: | Lactobacillus |
Species: | |
Subspecies: | L. d. subsp. bulgaricus
|
Trinomial name | |
Lactobacillus delbrueckii subsp. bulgaricus (Orla-Jensen 1919) Rogosa & Hansen 1971 Weiss et al. 1984
| |
Synonyms[2] | |
|
Lactobacillus delbrueckii subsp. bulgaricus is the main
It is a
First identified in 1905 by the
Use
Lactobacillus delbrueckii subsp. bulgaricus is commonly used alongside Streptococcus thermophilus[8] as a starter for making yogurt. The Lb. bulgaricus 2038 strain has been used for decades for yogurt fermentation. The two species work in synergy, with L. d. bulgaricus producing amino acids from milk proteins, which are then used by S. thermophilus.[8] This relationship is considered to be symbiotic. Both species produce lactic acid,[8] which gives yogurt its tart flavor and acts as a preservative. The resulting decrease in pH also partially coagulates the milk proteins, such as casein, resulting in yogurt's thickness.[9][10] While fermenting milk, L. d. bulgaricus produces acetaldehyde, one of the main yogurt aroma components.[10] Some strains of L. d. bulgaricus, such as L. bulgaricus GLB44, also produce bacteriocins,[11] which have been shown to kill undesired bacteria in vitro. The viability of Lactobacillus delbrueckii subsp. bulgaricus is extremely important in that it is necessary for it to be efficient at fermentation and to effectively keep the food products it produces from spoiling. Freeze-drying is the preferred method of preserving the viability of the cells, but not all cells survive this process.[4]
Due to its usefulness in natural fermentation processes, specifically in how it makes fermented food products out of cow's milk, it has great economic importance. Some of the biggest importers of the bacterium are Japan, the United States, and the European Union.
It has also been considered a contaminant of beer due to its homofermentative production of lactic acid, an off-flavor in many styles of beer. In other styles of beer, however, lactic acid bacteria can contribute to the overall appearance, aroma, taste, and/or mouthfeel, and generally produce an otherwise pleasing sourness.[12]
History
Lactobacillus delbrueckii subsp. bulgaricus was first identified in 1905 by Stamen Grigorov, who named it Bacillus bulgaricus.[1]
Proteolytic bacteria such as
Metchnikoff's research also noted that rural populations in
Lactobacillus bulgaricus is a constituent in
In 2012 it was declared India's national microbe.[15][16]
Taxonomic history
In bacterial taxonomy, the basionym for L. d. bulgaricus was "Thermobacterium bulgaricum" Orla-Jensen 1919. The entity became Lactobacillus bulgaricus in 1973 with the work of Rugosa and Hansen, and was reclassified as a subspecies under Lactobacillus delbrueckii in 1984.[2]
Research
Quantification in cow's milk cheese via real-time polymerase chain reaction assay
In 2017, there was a study involving the development of a real-time polymerase chain reaction (
Effects on antigenicity of milk proteins
A study in 2012 posed the question of whether or not Lactobacillus delbrueckii subsp. bulgaricus had any effect on the antigenicity of four kinds of milk proteins, being
Subcellular membrane fluidity under cold and osmotic stress
The efficiency of lactic acid bacteria cryopreservation is not consistent and may lead to cell death. Lactobacillus delbrueckii subsp. bulgaricus has adapted to defend against cold stress. The way most cells react to the cold is by changing the fluidity of the cellular membrane, but this particular bacterium has acquired different tactics to fight against cold stress. The first way to cope with the cold is to increase viscosity by taking in compounds such as disaccharides, polysaccharides, amino acids and antioxidants. The second strategy used is performed by inducing active responses during the fermentation or post-fermentation processes. By modifying these it will change the temperature, pH and medium composition. This results in specific metabolic pathways becoming active, with the synthesis of cold shock proteins.[18]
Survival during freeze-drying processes
In 2017, a study was done to see the effects of six different substances on the growth and freeze- drying of Lactobacillus. Using Lactobacillus as starter cultures for the dairy industry depends on the number of viable and active cells. Currently, the preferred method to preserve the bacterial cells is through freeze-drying, however this also results in some strains being killed. This is due to various complications of freeze-drying, including the formation of ice crystals, loss of membrane fluidity, and the denaturation of important macromolecules. Regardless, freeze-drying has been used for decades in microbiological research as a way to store and stabilize cultures. Six substances, being sodium chloride, sorbitol, mannitol, mannose, monosodium glutamate, and betaine were tested to determine if they had any effect on the survivability of the cells after freeze-drying. Three of the six substances added had a positive effect on the growth and freeze-drying of Lactobacillus, being sodium chloride, sorbitol, and sodium glutamate. The results suggest that these substances have protective effects on Lactobacillus delbrueckii subsp. bulgaricus in small concentrations, but have little effect or even some harmful effects in higher concentrations. The optimal concentrations for sorbitol, sodium chloride and sodium glutamate for the desired protective effects were 0.15%, 0.6%, and 0.09% respectively. This was shown to increase cell viability drastically.[4]
Immunotherapy for cancer
According to Helen Nauts from Cancer Research Institute, on a monograph reviewing the effects of bacterial infections on multiple types of cancer, Ivan Bogdanov, a Bulgarian physician, allegedly produced a vaccine consisting of lactobacillus bulgaricus and used it to treat two patients with myeloma, inducing remission in the two cases, one dying 18 months later due to influenza, and another living 45 months (survival median at the time was about 12–18 months).[19] However, references are internal documents and conversations among hospitals; there's no mention in English medical literature. An article from a commercial site and an alleged documentary are available (in Bulgarian).[20]
References
- ^ a b "Dr Stamen Grigorov Foundation". Retrieved 2013-01-08.
- ^ a b "Subspecies: Lactobacillus delbrueckii subsp. bulgaricus". lpsn.dsmz.de.
- ^ ISSN 0001-7213.
- ^ doi:10.17306/J.AFS.2017.0512.)
{{cite journal}}
: CS1 maint: multiple names: authors list (link - PMID 21264216.
- ^ Grigoroff, Stamen, 1905. Étude sur une lait fermentée comestible. Le "Kissélo mléko" de Bulgarie. Revue Médicale de la Suisse Romande. Genève. Georg&G., Libraires-Éditeurs. Librairie de L'Université.
- PMID 17257163.
- ^ .
- ^ "From Milk to Yogurt-an Electron Microscope Story". Archived from the original on 2010-12-20. Retrieved 2011-03-19.
- ^ .
- S2CID 19284421.
- ^ Priest, FG (2002). Brewing Microbiology. Springer. pp. 185–202.
- ^ Anukam, Kingsley C.; et al. "Probiotics: 100 years (1907–2007) after Elie Metchnikoff's Observation" (PDF). Archived from the original (PDF) on 2012-10-04. Retrieved 2013-01-08.
- PMID 16576567.
- ^ "Now, India has a National Microbe!". Owsa. Archived from the original on 2019-11-27. Retrieved 2017-08-22.
- ^ "Education for Biodiversity Conservation CoP-11, Hyderabad". Press Information Bureau Government of India. Press Information Bureau Government of India Ministry of Environment, Forest and Climate Change. 18 October 2012. Retrieved 3 May 2019.
The Minister also announced the National Microbe for India which was selected by children who had visited the Science Express Biodiversity Special, a train which has been visiting various stations across the country. Voting for the National Microbe took place in these stations and the children have selected the Lactobacillus (Lactobacillus delbrueckii subsp. bulgaricus) to be the National Microbe for India
- .
- S2CID 23484383.
- ^ Nauts, Helen C. (1975). "Multiple Myeloma: Beneficial Effects of Acute Infections Or Immunotherapy (Bacterial Vaccines)" (PDF). Cancer Research Institute. Archived from the original (PDF) on 2022-10-23.
{{cite journal}}
: Cite journal requires|journal=
(help) - ^ "БЪЛГАРСКОТО ЛЕКАРСТВО ПРОТИВ РАК" (in Bulgarian). Retrieved 2022-12-20.
Bibliography
- Grigoroff, Stamen (1905). "Etude sur le lait fermenté comestible : le 'Kissélo-mléko' de Bulgarie". Revue Médicale de la Suisse Romande (in French). Genève: Libraires-Éditeurs. Librairie de L’Université. OCLC 717162535.
- Balows A, Truper HG, Dworkin M, Harder W, Schleifer KH (1992). "70". The Prokaryotes : A Handbook on the Biology of Bacteria (2nd ed.). New York: Springer-Verlag. p. 1547. OCLC 23767548.
External links
- Goudarzi, Sara (9 June 2006). "Yogurt Culture Evolves". LiveScience. Archived from the original on August 29, 2008. Retrieved 2013-01-14.
- Type strain of Lactobacillus delbrueckii subsp. bulgaricus at BacDive - the Bacterial Diversity Metadatabase
- "Lactobacillus delbrueckii". microbewiki.kenyon.edu – Microbe Wiki. Retrieved 2019-11-14.