Synthetic Bacteria: From swarms to life-like materials

Friday 10 April 2026

Inspired by the collective dynamics of bacteria like E. coli and Bacillus subtilis, researchers at the University of Twente asked a simple but fundamental question: what happens when artificial swimmers are made rod-shaped rather than spherical, and how does shape control how they move as a group? "These dumb yet active rods follow only the laws of physics, which help to uncover the mechanics of collective bacterial behaviour," says Hanumantha Rao Vutukuri. Their findings appear on the cover of Science.

Biofilms are communities of microorganisms that cling to surfaces and resist removal. They form on medical implants and in water pipes, and are notoriously difficult to eliminate once established. Understanding how bacteria organise collectively is a precondition for learning how to disrupt them. That knowledge could reduce hospital-acquired infections and improve the safety of drinking-water systems.

The challenge of studying bacteria

Bacteria are more than just their shape. They sense their environment, respond to chemical signals, and adapt their behaviour in real time. That biological complexity makes it difficult to isolate the physical principles that drive collective motion. Labelling single cells without disrupting their behaviour is technically demanding, and the sheer density of a bacterial colony makes it hard to follow what any one cell is doing.

To get around these obstacles, Vutukuri’s team turned to synthetic colloidal rods. “We used synthetic rods because they are dumber than bacteria,” says Vutukuri. “They don’t sense food, they don’t respond to signals. It’s pure physics.” That simplicity is precisely the point: by stripping away biological complexity, the researchers could study the role of shape alone.

The sweet spot

Using light-driven synthetic rods, the team systematically varied the length and concentration of the particles and observed how their collective behaviour changed. The results reveal a clear pattern. Short rods cluster and phase separate. Very long rods swarm and flock. But rods with an intermediate aspect ratio do something richer: they produce active turbulence, a state of continuous, dynamic collective motion.

That finding points to an evolutionary logic. Motile bacteria may have evolved to operate within a shape-based sweet spot where collective mobility and adaptability are both optimised. E. coli sits squarely in that zone. Bacillus subtilis, which can grow considerably more elongated, does not exhibit the same turbulent collective behaviour and may be less effective at navigating through dense environments like biofilms.

Non-equilibrium physics

Beyond its biological relevance, the study establishes a general framework for understanding shape-dependent collective dynamics in active matter. It also opens the way to more realistic theoretical and simulation models and offers design rules for programmable active materials.

About the researchers

Hanumantha Rao Vutukuri leads the Active Soft Matter Group (https://www.activesoftmatter.nl/home) in the Faculty of Science and Technology, MESA+, BRAINS Institute, the University of Twente. The study was carried out by Yogesh Shelke, Anpuj Nair S, and Vutukuri, with support from the Netherlands Organisation for Scientific Research (NWO) and the European Research Council, which awarded Vutukuri a Consolidator Grant (no. 101171050-SynthAct3D) for this research programme. The paper ‘Shape Anisotropy Governs Organization of Active Rods: Swarming, Turbulence, Flocking, and Jamming’ was published in Science on 9 April 2026.

DOI: 10.1126/science.ady7618