Who was Stamen Grigorov?

Stamen Grigorov (27 October 1878 to 27 October 1945) was a Bulgarian physician and microbiologist who described the bacterium behind Bulgarian yoghurt in 1905, while working in Geneva. It was named Lactobacillus bulgaricus in honour of his homeland and is now called Lactobacillus delbrueckii subsp. bulgaricus.

Is Nestor's name day a public holiday?

No. A name day is a personal celebration, not an official public holiday, and our calendar data lists none for 27 October. If you know a Nestor, call in without an appointment, bring flowers and wish him честит имен ден.

Why does Bobov Dol celebrate on 27 October?

Bulgarian Wikipedia says only that the town day is celebrated on 27 October and does not give a reason. Bobov Dol is a coal-mining town in Kyustendil province with 3,963 inhabitants at the end of 2025.

On This Day in Bulgaria: Yoghurt scientist Stamen Grigorov is born (27 October), Shumen.UK

📅 ON THIS DAY IN BULGARIA, Tuesday 27 October

Anyone who has bought a pot of Bulgarian yoghurt can thank Stamen Grigorov, who was born on this day in 1878 and, by an odd coincidence, died on the same date 67 years later. A village in the far west now has a museum of yoghurt.

What happened on this day

Stamen Grigorov was born on 27 October 1878 in Studen Izvor, a village in Tran municipality in the far west, a long way from Shumen. Tran itself, Bulgarian Wikipedia says, lies close to the Serbian border. He studied natural sciences at Montpellier and took his medical doctorate at Geneva, where he became assistant to Professor Léon Massol and, Bulgarian Wikipedia says, studied the yoghurt his wife Darinka sent from Bulgaria. In 1905 he described the micro-organism that ferments it. It was named Lactobacillus bulgaricus in his homeland's honour and today carries the official name Lactobacillus delbrueckii subsp. bulgaricus (Grigoroff, 1905); Bulgarian Wikipedia calls him the first scientist to describe it. The Pasteur Institute in Paris had Ilya Mechnikov, a future Nobel laureate, check his report, and Mechnikov confirmed it and built his theory of ageing on it.

Grigorov was offered a professorship at Geneva and the directorship of the Pasteur Institute in São Paulo, among other posts, and refused them to come home at the end of 1905 as district doctor and hospital manager in Tran, where the hospital now bears his name. Picture a bacteriologist turning down a chair at Oxford to become the medical officer in a small border town and you have the measure of it. He began work on a tuberculosis vaccine, with an article in the Paris journal Presse Médicale on 29 December 1906, served as a military doctor in the Balkan War and the First World War, and fought a cholera epidemic near Petrich. His brother Hristo, wounded at Kaliman field in the Inter-Allied War, died of his wounds aged 32. After 1935 Grigorov continued his tuberculosis research in Italy, came home in 1944 and died in Sofia on 27 October 1945.

Today's name days

Nestor is the name celebrated today. Nestor of Thessalonica was an early Christian martyr who suffered in 306 in Thessaloniki alongside Demetrius, whose pupil, Bulgarian Wikipedia says, he was; in its account the emperor Maximian had Nestor beheaded with a sword and Demetrius run through with spears. If you know a Nestor, call in without an appointment, bring flowers and say честит имен ден (chesh-TEET ee-MEN den).

Towns celebrating today

Bobov Dol, in Kyustendil province, keeps 27 October as its town day. Bulgarian Wikipedia says the name comes from the bean-shaped valley holding the original village, and that the economy is closely tied to underground and open-cast brown coal mining; with 3,963 inhabitants at the end of 2025 it is the province's third-largest town after Kyustendil and Dupnitsa.

Why this matters for British expats

Bulgaria's state has treated кисело мляко (KEE-se-lo MLYA-ko, "sour milk") as a national product since at least the 1950s: English Wikipedia says the state-owned yogurt company patented and promoted a specific blend of strains as an "official Bulgarian yoghurt", that the blend is still exported to producers in many countries, and that Grigorov's bacterium works with Streptococcus thermophilus in a symbiotic partnership. His home village has a Museum of Yoghurt in a restored house, a glacier on Brabant Island in Antarctica carries his name, and Google gave him a Doodle on 27 October 2020. If you are driving west to see the museum, pack for the weather: Tran is where the lowest temperature measured in Bulgaria, -38.3 °C, was recorded in the winter of 1947, and our weather guide has the seasons in full. For the Bulgarian to go with the shopping, start with our phrasebook.

Sources and further reading

This piece draws on the Bulgarian Wikipedia entry on Stamen Grigorov, read alongside the English entry and Wikipedia's pages on Lactobacillus delbrueckii subsp. bulgaricus, Nestor of Thessalonica, Bobov Dol and Tran. The two Grigorov pages differ on where he finished school and on his tuberculosis work, so I have left the disputed details out.