A club-shaped bacterium

Corynebacterium glutamicum is the Microbe of the Year 2025. This bacterium produces amino acids that would fill a freight train stretching across Germany. Corynebacterium glutamicum is considered a “hidden champion” among bacteria, an unknown world market leader: The bacterium produces 3.5 million tonnes of the flavouring agent sodium glutamate every year, as well as many other amino acids and proteins for food and animal feed. The Association for General and Applied Microbiology (VAAM) honours Corynebacterium glutamicum as a Microbe of the Year of great industrial importance.

A savoury taste, called ‘umami’, was the trigger for the isolation of Corynebacterium glutamicum: in 1956, two Japanese researchers were specifically looking for bacteria that produce such a taste. Similar to the flavours sweet, sour, salty and bitter, there are special sensory cells on the tongue for umami. Sodium glutamate triggers this savoury taste and is found naturally in ripe tomatoes, Parmesan cheese and ham, for example. It is used as a seasoning - especially in Asian cuisine and in ready-made products.

When Corynebacterium glutamicum was identified as naturally secreting glutamate, the industrial production of sodium glutamate from microorganisms began. Today, the bacteria produce over 3.5 million tonnes per year worldwide - the equivalent of a freight train with 50,000 wagons and a length of over 850 kilometres.

Umami taste and more products

Scientific institutes and companies in Germany have been researching this fascinating Microbe of the Year for around 40 years. They are using specific genetic engineering methods and new approaches in synthetic biology to produce a wide range of other products with this microbe in addition to amino acids. These include health-promoting natural substances, antioxidants, and antimicrobial peptides.

To avoid wasting valuable food as a basis for amino acid production, researchers modified Corynebacterium glutamicum so that it can alternatively utilise residues from biodiesel production or plant waste, such as orange peel. This reduces our dependence on fossil fuels and enables a bioeconomic cycle from renewable resources. Intensive research into corynebacteria provides the basis for further exciting applications.

The corynebacteria owe their name to their club shape - coryne in Greek. This is due to the uneven growth of the cell walls at both ends of the bacterium: During growth, new cell wall material is initially incorporated preferentially at one end of the cell. In addition, a multi-layered, very stable and water-repellent cell envelope protects the bacteria from harmful substances. The special cell envelope also leads to an unusual division: the daughter cells snap open on one side, creating a characteristic V-shape.

Research model for drugs

Corynebacterium glutamicum, naturally living in soil, is not only robust and productive, but also completely harmless to humans. Many other Corynebacterium species that live on our skin, for example, are also harmless, if not beneficial for our microbiome. However, some relatives are quite different: Corynebacterium diphtheriae killed around 50,000 children across Germany every year until the end of the 19th century. Other Corynebacterium species found in animals also possess toxins - with the risk of transferring dangerous diseases in humans. Corynebacteria are also related to Mycobacterium tuberculosis, causing pulmonary tuberculosis, which kills 1.5 million people worldwide every year. The similarities, for example in the cell wall structure, can be used to identify targets for new drugs with the help of the Microbe of the Year. Corynebacterium glutamicum thus covers the entire spectrum from tiny research object to industrial producer on a scale of millions of tons.

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