Bacteria aggregate on surfaces to form dense communities, which can develop into biofilms that shield against antibiotics. This crowding drains their food reserves rapidly but, surprisingly, we discovered that ‘active carpets’ of motile microbes can replenish resources by creating strong currents that transport food and oxygen.
Figure: A star-like pattern of bacteria generates vortex flows that draw in nutrients. Image courtesy of Dr. A Mathijssen.
Each bacterium produces small flows by swimming with its flagella. These whorls are amplified when the cells organise themselves into specific patterns. Large vortices then emerge, which can span distances even beyond the colony size. We calculated the flow strengths generated by these patterns and predict that this co-operative nutrient transport can sustain microbial activity.
Our results contribute to understanding how single cells assemble to function collectively, a fundamental pillar of biology. Conversely, new technology to disturb these replenishing flows could prevent bacterial biofilm formation, reducing the need to apply biocides while lowering chances of infection.
Figure: Nutrient particles (shown in colours) are attracted to a dynamic cluster of bacteria (shown in black). Image courtesy of Dr. A Mathijssen.