Scientists have discovered for the first time how blue-green algae, which can be seen as a slimy green slime in stagnant waters, river beds and on seashores, weave themselves into large web-like structures. A team from Nottingham Trent University and Loughborough University has discovered the physical mechanism underlying the geometric patterns formed by cyanobacteria, one of the oldest and most widespread life forms on Earth, which played a key role in the evolution of our planet.

Research with a Ph.D. students Mixon Faluweki and Ian Kamman are co-authors and published in the journal Physical Examination Letters.

Ancient cyanobacteria were the first life form to develop photosynthesis and were responsible for delivering oxygen to the Earth’s environment, thus laying the foundation for the emergence of complex life forms as we know them today.

Modern cyanobacteria continue to play an important role in maintaining the composition of the modern atmosphere and oceans. To help them survive, many species have also evolved long chains of cells that crawl along surfaces and assemble into vast networks of tightly woven filaments over hours or days.

But until now, the origin of these mesh or web-like patterns has puzzled scientists.

Using advanced microscopy techniques, simulations and theoretical models, the researchers discovered how interactions between filaments bring them together and form structures. They found that if cyanobacteria are present at high enough density, they begin to organize into a network-like pattern following just a few simple rules.

As bacteria move, they bump into each other. In most cases the threads pass over or under each other, but sometimes one of them deviates and turns to move next to the other. These two threads follow each other for a while before one of them separates.

These interactions lead to the formation of aligned filament bundles that organize denser colonies into branched networks. The researchers developed a model that successfully predicted the typical density and scale of the resulting patterns, including movement and undulations in the shape of the filaments. The team says the findings pave the way for future research into how different types of bacteria self-organize to form structures.

This could improve our understanding of how bacterial biofilms—communities of bacteria that attach themselves to surfaces and to each other—form. This information is critical given their central role in processes as diverse as human infection, environmental degradation, and bioengineering.

Dr Marco Mazza, Associate Professor of Applied Mathematics at Loughborough University, said: “We have shown that cyanobacterial colony formation patterns can be understood as the cumulative result of cells acting independently through simple interactions.

“When applied carefully, modern tools of non-equilibrium statistical mechanics can provide robust predictions even in living systems.”

Professor of physics at Nottingham Trent University’s School of Science and Technology. Lucas Goering said: “Cyanobacteria are among the most widespread and oldest organisms on Earth, they created photosynthesis. They are also probably the first organisms to experiment with multicellularity.

“This extremely important but modest microorganism is involved in processes of global importance, such as oxygen and nitrogen balance. Despite its importance in the development of complex life, a mechanism to explain its collective behavior has not yet been discovered.” Source