What seems like a colorful flower here is actually the work of bacteria. The microbes become artists under certain conditions – and form fascinating floral patterns as they grow.
Whether in the ground, in water or on and in our bodies: microbes – especially bacteria – roam almost everywhere on earth. In the laboratory, microbiologists usually examine individual species in isolation from one another. But in nature, many different bacterial species inhabit the same space and interact with one another.
Researchers around Liyang Xiong from the University of California at San Diego have now observed that true works of art can be created through such teamwork. For a study, they had mixed bacteria of the species Escherichia coli and Acinetobacter baylyi on an agar plate. Normally, E. coli bacteria cannot move and spread well on this nutrient medium. But with the help of the very mobile A. baylyi microbes, they succeeded very well. They practically drove along with these bacteria, as the team explains.
The special feature: The growing colony of the two types of bacteria formed a flower-like pattern over time. “I immediately noticed the beauty of this pattern and wondered how these bacterial cells become artists,” reports Xiong. In order to get to the bottom of the secret of flower formation, the researchers carried out further analyzes. It became apparent that the pattern formation has its origin at the outer boundaries of the expanding colony – and is related to the concentration of the E. coli bacteria.
Where less of the immobile microbes accumulate, the friction is lower and the colony progresses faster. In contrast, this happens more slowly in areas with many E. coli bacteria. In this way, the typical petal shapes are created. According to the researchers, such patterns are likely to form whenever mobile bacteria are mixed with immobile bacteria that have a higher growth rate. “Pattern formation in bacteria has been researched for a long time. So far, however, most studies have focused on the dynamics of a tribe’s colonies, ”says Xiong’s colleague Lev Tsimring.