Shine on, you tiny diamond: Flavobacterium IR1 is the Microverse Microbe of the Year 2026

On the occasion of International Microorganism Day on September 17, the Cluster of Excellence “Balance of the Microverse” has named its Microbe of the Year 2026. This year’s title goes to Flavobacterium IR1, a marine bacterium whose cells produce brilliant, iridescent colours without using pigments.

Colour by structure

Flavobacterium IR1 is a non-pathogenic bacterium found in sediments in coastal ecosystems. It was first isolated by Dr Colin Ingham. Its long, rod-shaped cells can arrange themselves into densely packed hexagonal lattices. In doing so, they form ordered three-dimensional structures that interact with visible light at the nanoscale.

The result is striking: the colonies display vivid colours that change depending on the viewing angle. This phenomenon is known as structural colouration. Unlike chemical pigments, structural colour arises from the interaction of light with microscopic structures – similar to the shimmering colours of peacock feathers or beetle shells. IR1 has become an important model system for studying how such structures develop in living organisms.

Research in focus

At the Cluster of Excellence “Balance of the Microverse”, Samira Quanz and Marcel Bäcker are investigating the ecological significance of structural colouration in Flavobacterium IR1.

“We compare the original form of the bacterium with genetically modified variants that display different colours. This allows us to investigate what function structural colouration serves in the bacterium’s natural interactions with other microbes,” says Samira Quanz. “We suspect that the structure underlying the colour gives the bacteria a fitness advantage. For example, we observe that Flavobacterium IR1 grows better in the presence of other bacteria when it produces structural colouration, for instance on surfaces.”

The project is being carried out in ongoing collaboration with Dr Colin Ingham and the research group of Professor Silvia Vignolini at the Max Planck Institute of Colloids and Interfaces in Potsdam.

Potential far beyond the laboratory

Research on this fascinating microbe not only helps scientists better understand structural colour as a biological phenomenon. It also opens up perspectives for applications inspired by the bacterium’s unusual optical properties.

“The optical properties of Flavobacterium IR1 could open up new approaches to bio-based optical materials, for example biodegradable paints or artistic materials whose visual effects do not rely on chemical pigments. The bacterium also offers exciting ideas for living biosensors: changes in the environment could alter the bacterial structures and, consequently, their colour. Such visible signals could help make environmental changes easier to detect,” explains Marcel Bäcker.

A microbe in the spotlight

By naming Flavobacterium IR1 its Microbe of the Year 2026, the Cluster of Excellence “Balance of the Microverse” highlights how much there is still to discover about the hidden physical and ecological capabilities of microorganisms.

And IR1 is perfectly suited to the role: after all, an organism that knows how to shine should feel right at home in the spotlight.