Élie Metchnikoff
The first discovered probiotic was a certain strain of bacillus in Bulgarian yogurt, called Lactobacillus bulgaricus. The discovery was made in 1905 by Bulgarian physician and microbiologist Stamen Grigorov. The modern-day theory is generally attributed to Nobel laureate Élie Metchnikoff, who postulated that yoghurt-consuming Bulgarian peasants lived longer.