One yogurt, 100 years of science

Since their discovery by biologist Elie Metchnikoff in the early 20th Century, the role of lactic ferments as part of a healthy diet has been widely confirmed. Let’s look back over a century of research serving human health.

Culture of intestinal bacteria // Nicola Fawcett (Own work) [CC BY-SA 4.0 (], via Wikimedia Commons

It’s a Holy Grail in the heart of Paris. The Biological Resource Centre at the Pasteur Institute Campus in city’s 15th arrondissement has been home to an amazing microscopic bestiary of bacteria and viruses for over 120 years.

Entrance to the Pasteur Museum, Paris  //  By Ab2804 (Own work) [CC BY-SA 3.0 (], via Wikimedia Commons

The ‘Pasteur Institute Collection’, as it’s also known, is a genuine hall of fame for microbes. This library of strains (the name given to a line of identical bacteria or viruses) created by doctor and biologist Jean Binot at the end of the 19th Century, now contains over 12,000 strains of different bacteria.

”The micro-organisms are frozen via lyophilisation with a view to preserving biodiversity,” explains Chantal Bizet, who heads the Pasteur Institute’s Biological Resources Centre.

Of course, not all of the strains carefully preserved at the Pasteur Institute are benign; microbes with names such as streptococci and salmonella rarely conjure a positive image.

These are the polar opposite to the many microbes, some of which remain unknown, that are our bodies’ allies, including the broad category of lactic ferments, used to produce yoghurts and fermented milks.

Regardless of whether they are feared or prized, the microbes in the collection all benefit from the Pasteur Institute’s know-how, which is recognised throughout the world. Danone has chosen to rely on that expertise in preserving a copy of its own collection.

One of the largest industrial strain libraries

What is the Danone Collection? “It contains almost 4,000 strains, 1,800 of which belong exclusively to us,” says Christine M’Rini, the Life Sciences R&D Director for Danone’s dairy products.

The strain library, one of the largest in the world, includes a star by the name of Bifidus ActiRegularis (B. Lactis CNCM I-2494). For most of us, this microbe is famous for its digestive properties, which are popular with consumers of Activia yoghurts. Each 125-gramme pot contains 4 billion microbes! For biologists, however, it is known for illustrating the surprising ability of lactic ferments to interact with the bacteria that are naturally present in the gut, for the benefit of our health.

It was Elie Metchnikoff the biologist born in Ukraine in 1845, who first noticed the benefits that these ferments could offer human health. Louis Pasteur invited Metchnikoff to his new Institute in 1888 to pursue his research. He was appointed as the Institute’s Director of Morphological Microbiology, and remained there until his death in 1916, having made a significant contribution to the Institute’s reputation.

Elie Metchnikoff (1845–1916) in front of his microscope c. 1900–1910 — Institut Pasteur

A visionary Nobel prize-winner

The Metchnikoff Theory, which won Metchnikoff the Nobel Prize for Physiology or Medicine in 1908, along with Paul Ehrlich from Germany, “in recognition for their work on immunity”, was a scientific breakthrough. Metchnikoff believed that certain lactic ferments could combat the harmful effects of certain bacteria in the gut, and that it was therefore possible to prolong life. This premise was initially based on the longevity observed among certain inhabitants of the Balkans, which was exceptional at the time. In fact, Elie Metchnikoff had observed that those inhabitants whose diet included a high amount of fermented dairy products lived longer.

“Metchnikoff made the assumption that ageing was probably due to the poisoning of the body by pathogenic micro-organisms in the large intestine,” says Michel Morange, the Director of the Cavaillès Centre for the History and Philosophy of Science at France’s Ecole Normale Supérieure. “[Metchnikoff] consequently recommended a specific way of eating, which was intended to change the microbial population in the large intestine, and so avoid poisoning.”

Bifidobacterium Lactis — Danone

The Russian scientist continued his research, and ultimately discovered a bacillus, lactobacillus bulgaricum, which was the ancestor of probiotics, or friendly bacteria (the literal meaning is life-promoting) in Bulgarian yoghurts.

More fundamentally, Metchnikoff had discovered the mechanism that these probiotics used to boost life. He had observed that some cells (not only lactic ferments, but also yeast and mould) could swallow others (undesirable microbes and toxins, etc.), destroy them, and prevent them from causing excessive damage to the body. This process is described as ‘phagocytosis’ — which we now know to be essential to our immune system.

Lactic ferments are the digestive system's allies

The biologist’s work cleared the way for a research field that is now booming, and aims to gain a better understanding of the role played by ‘microbiota’ (the bacteria, viruses, and parasites, etc. hosted by our intestine) in our longevity and health.

“Metchnikoff’s work paved the way for cellular immunology as we now know it,” says Laurent Loison, a Research Fellow in the History and Philosophy of Life Sciences at CNRS (French National Scientific Research Centre) who sees Elie Metchnikoff as the heir to the work undertaken by Louis Pasteur in the 19th century.

These discoveries fascinated a large number of scientists from the outset, as well as a certain Isaac Carasso, who was then a young industrial company owner from Thessaloniki. Hearing of Metchnikoff’s discoveries, Carasso soon realised its potential. He began selling his first yoghurts fermented with lactic bacteria that were carefully selected by Metchnikoff himself ‘on prescription’ in Barcelona chemists in 1919. This is how Danone was born. The idea of incorporating lactic ferments into our diet has since come a long way, to the point where in 2016, fermented foods even form part of the ‘the top ten current food trends’.

A collection of over 4,000 strains used for innovation purposes

For Danone, the benefits of natural ferments have not required proving for a long time. They form part of the brand’s DNA, which has been skilfully nurtured at the Group’s research and development laboratories. These include around 660 researchers in 40 countries working on R&D in fresh dairy products, and underline Danone’s claim that research is “the company’s greatest ally”.

For fermented products, researchers use that ally in three main areas, as Christine M’Rini, Danone’s Director of R&D for dairy products explains: “First, the aim is to help the intestine play its role in terms of the body’s overall health. This means helping the digestive tract and the microbiota, which are subject to the various sources of stress in modern life, to rediscover their balance. But also, it means boosting the p’s metabolic health. Consuming yoghurt encourages the prevention of major illnesses in the developed world, such as diabetes and obesity.”

The researchers can count on the valuable support provided by thousands of strains of bacteria. “All of the strains are different,” Christine M’Rini says. We are working on species in the large bifidus category, as well as on species in the large lactobacillus category. We are capable of finding specific factors within these categories, which have distinctive properties in terms of health, taste, and texture, etc.”

She continues: “However, no two strains within the same species are alike. It’s somewhat similar to human beings: we belong to the same species, but we nonetheless do not look like our neighbour. We have our own qualities and specific attributes. The same applies to the various bacilli in the same species. This is what we are working on, i.e. identifying the best specimens in order to subsequently make optimal use of them, so as to contribute to the development of new yoghurt ranges for health and enjoyment, taking dietary habits and desires into account.”

We bet that some of these specimens will end up in the Hall of Fame for micro-organisms that are good for health one day.