A team at Nottingham Trent University and Loughborough University has revealed the physical mechanism behind the geometric patterns formed of cyanobacteria, one of the oldest and most abundant forms of life on Earth, and which has played a pivotal role in the evolution of our planet.
Ancient cyanobacteria were the first life form to develop photosynthesis and are responsible for injecting oxygen into the Earth’s environment, thereby laying the foundation for the emergence of the complex life forms of today.
Modern cyanobacteria continue to play a key role in maintaining the composition of today’s atmosphere and oceans. To help it survive, many species also grow into long chains of cells that crawl across surfaces and weave together into large networks of closely-bundled filaments over hours or days. However, until now, the origin of these “reticulate” or web-like patterns has puzzled scientists.
Using advanced microscopy techniques, simulations and theoretical models, the researchers have revealed how interactions between the thread-like filaments cause them to bundle together and build structures.
They found that when cyanobacteria are present at a high enough density, they begin to organize into their reticulate pattern, as the result of a few simple rules.
As the bacteria move, they bump into each other. In most instances, filaments pass over or under each other, but occasionally one deflects and turns to travel alongside another. These two filaments follow each other for a while, before one splits away.
These interactions lead to the formation of bundles of aligned filaments which organize denser colonies into sprawling networks.
The researchers developed a model that successfully predicts the typical density and scale of the emergent patterns, including the movement and shape fluctuations of the filaments. They say the findings pave the way to inspiring future investigation of how different types of bacteria self-organize to form structures.
The research, for which PhD students Mixon Faluweki and Jan Cammann are co-lead authors, is published in the journal Physical Review Letters.