Lactobacillus delbrueckii subsp. bulgaricus

Lactobacillus delbrueckii subspecies bulgaricus (until 1984 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, it is named after Bulgaria. It is a Gram-positive rod that may appear long and filamentous. It is also non-motile, and it does not form spores. This bacterium 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, including the inability to ferment any sugar except lactose^{[citation needed]} , from which it produces lactic acid, which helps to preserve yogurt. It is often helpful to sufferers of lactose intolerance, whose digestive systems lack the enzymes to break down lactose to simpler sugars. While fermenting milk, it produces acetaldehyde, which is one of the main yogurt aroma components.

Some of the biggest importers of the bacterium are Japan, USA, and the EU.

History of Lactobacillus Bulgaricus

In the early 20th century, the Russian scientist Ilya Metchnikoff - one of the founders of modern immunology - linked the longevity of the Bulgarian people to the consumption of yoghurt. Metchnikoff, at that time a professor at the Pasteur Institute in Paris, produced the notion that the aging process results from the activity of putrefactive (proteolytic) microbes producing toxic substances in the bowels. Proteolytic bacteria such as clostridia, which are part of the normal gut flora, produce toxic substances including phenols, indols and ammonia from the digestion of proteins. According to Metchnikoff these compounds were responsible for what he called "intestinal auto-intoxication", which caused the physical changes associated with old age. It was at that time known that milk fermented with lactic-acid bacteria inhibits the growth of proteolytic bacteria because of the low pH produced by the fermentation of lactose. Metchnikoff had also observed that certain rural populations in Europe, for example in Bulgaria and the Russian Steppes who lived largely on milk fermented by lactic-acid bacteria were exceptionally long lived. Based on these facts, Metchnikoff proposed that consumption of fermented milk would "seed" the intestine with harmless lactic-acid bacteria and decrease the intestinal pH and that this would suppress the growth of proteolytic bacteria.

Metchnikoff even reported that the special kind of Lactobacilli in samples of Bulgarian yogurt was the only bacterium that had never damaged the human organism. Even though he made that discovery, Professor Metchnikoff was not aware who the real founder of that special bacillus was. The answer to his question dates back to 1905 when the Bulgarian Dr. Stamen Grigorov, discovered a special kind of Lactobacilli and called them Lactobacillus Bulgaricus.

The B. lactis bulgaricus is one of a widely distributed group of lactic acid-producing organisms which do not proliferate in laboratory media. Scientists believe that these bacilli modify the intestinal flora, thus limiting auto-intoxication and its train of arteriosclerotic changes which lead to premature senility.

Nowadays, Lactobacillus Bulgaricus is used to sour milk (produce yogurt), given as a remedy, used in treatments, etc. The administration of yogurt products is very beneficial and it gradually taking the place of protein food for improving nutrition. LB can also be taken in tablet form although the best way to benefit from its qualities is through yogurt consumption.

References

• Grigoroff, Stamen Étude sur une lait fermenté comestible. Le “Kissélo mléko” de Bulgarie. Revue Médicale de la Suisse Romande. Genéve. Georg&G., Libraires-Éditeurs. Librairie de L’Université. 1905
• A. Balows, H.G.Truper, M. Dworkin, W. Harder, K.H.Schleifer (1991). The Prokaryotes, 2nd Edition, A Handbook on the Biology of Bacteria, Chapter 70, pg 1547. 

External links

• Yogurt Culture Evolves
• Lactobacillus bulgaricus on the web

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