Lactobacillus delbrueckii subsp. bulgaricus
(until 2014 known as Lactobacillus bulgaricus
) is one of several bacteria
used for the production of yogurt
. It is also found in other naturally fermented products. First identified in 1905 by the Bulgarian
doctor Stamen Grigorov
, the bacterium feeds on lactose
to produce lactic acid
, which is used to preserve milk.
can be found naturally in the gastrointestinal tract of mammals living in Bulgaria, but one specific strain, Lactobacillus bulgaricus GLB44
, is extracted from the leaves of the Galanthus nivalis
(snowdrop flower) in Bulgaria as well. The bacterium is also grown artificially in many other countries.
It is a gram-positive
rod that may appear long and filamentous. It is non-motile
and does not form spores. It is regarded as aciduric or acidophilic
, since it requires a low pH
(around 5.4–4.6) to grow effectively. The bacterium has complex nutritional requirements.
On October 18, 2012, during the International Conference on "Biodiversity Conservation and Education for Sustainable Development - Learning to Conserve Biodiversity in a Rapidly Changing World" held at Hyderabad during CoP-11, Jayanthi Natarajan
, India's Minister of State for Environment and Forests, announced it as the National Microbe for India. The microbe was selected by children who had visited the Science Express
Biodiversity Special, a train which has been visiting various stations across the country.http://southasia.oneworld.net/news/now-india-has-a-national-microbe
Use in industry
is commonly used alongside Streptococcus thermophilus
as a starter for making yogurt
. The two species work in synergy, with L. d. bulgaricus
producing amino acids from milk proteins, which are then used by S. thermophilus
. Both species produce lactic acid
, 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.http://www.medicinalfoodnews.com/vol01/issue5/kalab.htm While fermenting milk, L. d. bulgaricus
, one of the main yogurt aroma components. Some strains of L. d. bulgaricus
, such as L. bulgaricus GLB44
, also produce bacteriocin
s, which have been shown to kill undesired bacteria in vitro
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.
was first identified in 1905 by Stamen Grigorov
, who named it Bacillus bulgaricus
, a professor at the Pasteur Institute
in Paris, researched the relationship between the longevity of Bulgarians
and their consumption of yogurt. He had the idea that aging is caused by putrefactive activity, or proteolysis
, by microbes that produce toxic substances in the intestine.
Proteolytic bacteria such as clostridia
, which are part of the normal intestinal flora, produce toxic substances including phenols
s by digestion of protein
s. These compounds are responsible for what Metchnikoff called intestinal auto-intoxication
, which, according to him, was the cause of the physical changes associated with old age, a concept that has no scientific basis. It was already known at that time that fermentation with lactic acid bacteria
inhibits the deterioration of milk because of its low pH
Metchnikoff's research also noted that rural populations in Southeastern Europe
and the Russian steppes daily consume milk fermented with lactic acid bacteria and live relatively longer than other populations. Based on these data Metchnikoff proposed that consumption of fermented milk seeds the intestine with harmless lactic acid bacteria increasing intestinal acidity and suppressing the growth of proteolytic bacteria.
is a constituent in VSL#3
. This proprietary, standardized, formulation of live bacteria may be used in combination with conventional therapies to treat ulcerative colitis
and requires a prescription.