Grigorov, born in Bulgaria in 1878, relocated to southern France to attend university and study natural science. When his instructing professor saw Grigorov’s superb logical ability, he advised Grigorov to pursue a career in medicine, which Grigorov heeded and went on to attend medical school at the University of Geneva.
In Geneva, Grigorov studied bacteriology under the tutelage of a professor who was considered the pioneer in the field at the time. Although Grigorov quickly rose to prominence in the new field and was recommended to the position of assistant professor at the University, he stopped receiving funds from his family at home and so had to go back to Bulgaria.
Although Grigorov initially planned on finishing his career as a researcher and spending the rest of his life in Bulgaria as a clinician, he got married and was blessed with the fortune of being able to resume his research in Geneva, thanks to the financial support of his wife’s family. As Grigorov was about to depart Bulgaria for Switzerland, his wife gave him yogurt contained in a traditional ロカットゥカ pot made in the village of ブスィンツィー, which was a neighboring community of her hometown. This gift from his wife would later bring Grigorov good fortune.
Upon returning to the University of Geneva, Grigorov wasted no time in investigating the bacteria squirming in the yogurt in the pot.

In 1905, when he was a fourth-year student at the University at the age of 27, after thousands of experiments Grigorov finally discovered that there were three anaerobic bacteria (those that eschew oxygen) in Bulgarian yogurt. After identifying the rod-shaped one as Bacille A, the spherical one as Micrococcque B, and the chained-rod-shaped one as Streptobacille C, Grigorov published his finding that they were responsible for promoting the fermentation of Bulgarian yogurt and for giving the distinctive acidity and flavor to the yogurt.

When his supervising professor saw this research result, the professor swiftly contacted his old acquaintance, Mechnikov, and Grigorov was invited by Mechnikov to travel to the Pasteur Institute to give a lecture. The lecture Grigorov gave, which was held in a large auditorium, was heard by a packed audience of scholars and scientists from various countries. In the lecture, Grigorov showed to the audience the bacteria he had discovered in the yogurt contained in the ロカットゥカ pot, with a microscope, while reportedly explaining how Bulgarian yogurt could help extend people’s lifespans with great enthusiasm. After the lecture, many scientists approached Grigorov and the Pasteur Institute to request permission to continue conducting the research, which Mechnikov agreed to and guaranteed it would go on.

Lactobacillus delbrueckii subsp. bulgaricus

In this year, Grigorov published his theory on the pathogenesis of appendicitis, which was considered a fatal disease at the time, in which he proved that it was caused by the abnormal propagation of a certain type of anaerobic bacteria. He received an award from the Faculty of Medicine at the University of Geneva for the achievement. After graduating the medical school, Grigorov returned to Bulgaria where he worked on applying scientific methods in medicine, as the head of a municipal hospital, for 20 years. In this particular period, Grigorov focused on studying tuberculosis and reportedly invented a vaccine to treat the disease.

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