History of the Bulgarian Yoghurt

in the beginning of the 20th century the famous Russian scientist, winner of the Nobel Prize, Ilya Mechnikov (1845-1916), working at Pasteur Institute – Paris, began researches on the causes of human aging. He found that during feeding the protein substances in food are degraded by the action of putrefactive intestine bacteria that cause poisoning of the body and early death. He proves that the only food that could restrict the development of putrefactive bacteria in the intestines is the Bulgarian yoghurt, by which is explained the largest number of healthy centenarians in Bulgaria.

At the time of the biological research of Ilya Mechnikov, the Bulgarian doctor, Mr. Stamen Grigorov, a student of medicine in his fourth academic year at the Geneva University, undertook a research on the Bulgarian yogurt and found that the cause of fermentation is due to one rod-line and one spherical bacteria. Notice of his discovery was published in “Revue Medicale De La Suisse Romande” issue 10 dated 20.10.1905, Genève.

Professor Ilya Mechnikov confirmed the discovery of Dr. Stamen Grigorov three years later. His assistants Koendi and Mikelson (1907) named the microorganism discovered by Grigorov – Bacillus bulgaricus (Grigorov), currently known under the Bergey’s Classification of Bacteria as Lactobacillus delbrueckii subsp.bulgaricus.
The distinctive difference of the Bulgarian starter cultures, which distinguishes them from the starter cultures used in other countries, is that the Bulgarian starters have a long lasting symbiotic relationship between Lactobacillus bulgaricus and Streptococcus thermophilus. Due to this symbiosis the Bulgarian yogurt is different in taste and aroma compared to yogurts produced with starter cultures, which were isolated outside our country.![182d45f91c1581fe9f23dbb4c1e6a1ae.jpg]
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For the past few years the studies conducted in Bulgaria on the Bulgarian yogurt starter cultures isolated from natural sources entered a new stage of development. “LB Bulgaricum” PLc has one of the richest collections of lactic acid strains in the world, over 800 ofLactobacillus delbrueckii subsp. Bulgaricus and Streptococcus thermophilus. With the aid of JICA program, funded by the Japanese government and experts from Meiji Milk – Japan, the Research Center of “LB Bulgaricum” PLc was supplied with modern devices for introduction of modern molecular genetic methods and analytical techniques aiding in the extensive research on the strains ofLactobacillus delbrueckii subsp.bulgaricus and Streptococcus tihermophilus, in order to be ensured consistency of the properties of the produced starter cultures. The methods based on species-specific protein composition of the cell such as (gel-electrophoresis of total cell proteins, SDS-PAGE), as well as features of its genome (restrictive polymorphism of the ribosomal genes, ARDRA; amplification of species-specific sections of the genome, PCR), enabled us to achieve a reliable identification of the cultures stored in LBB collection of starter cultures. With the aid of pulse electrophoresis (PFGE), revealing the individual profile of the genome of each strain, we were able to distinguishe several strains of Lactobacillus delbrueckii subsp.bulgaricus and Streptococcus thermophilus. For the first time at “LB Bulgaricum” PLc has been evaluated the genetic diversity of strains of Lactobacillus delbrueckii subsp.buigaricus and Streptococcus thermophilus isolated from homemade yogurt and plants from different regions of the country, which confirmed the rich variety of strains in Bulgaria.