Bacteria can live in dense, diverse, and complex communities, sometimes in resource-limited environments. These communities include human and animal gut microbiomes, soil microbiomes, and plant-associated biofilms. Bacteria in these surface-attached communities can use social behaviors to navigate interactions with siblings and other organisms. 

Our goal is to harness bacteria's relative genetic simplicity and tractability to understand social behaviors. We study bacteria that work together to race across hard surfaces faster than any single cell could achieve alone. These shapeshifting, fast-moving bacteria live in various environments where their collective motility is required to invade niches, cause disease, and avoid death. Using a combination of molecular biology, biochemistry, and live-cell imaging, we investigate these bacteria at multiple scales, from molecular interactions to community dynamics. Explore some of our projects below.

Graphic describing the roles of the ids and rdn systems in P. mirabilis. IdsD disrupts collective swarming while RdnE acts as a DNA nuclease. Illustrated by Abby Knecht. 


How do bacteria recognize one another?

Bacteria in dense environments, like the human microbiome, respond to the actions of neighboring cells. Our goals are to understand how bacteria recognize their neighbors and respond accordingly on a molecular scale. Specifically, we study social recognition systems in the opportunistic pathogen, Proteus mirabilis, found in human guts and causes recurrent catheter-associated urinary infections. While these systems use the type VI secretion system for transfer between cells, they have unique mechanisms for social recognition. Read more at:


How do micro-scale interactions among cells lead to macro-scale behaviors?

Collective behavior in P. mirabilis and other bacteria is linked to fitness and virulence. We study how the interactions between bacteria can act as a form of micro-crowdsourcing and lead to changes in macro-scale behavior. Specifically, we focus on the collective motility of swarming, where bacteria travel centimeter-wide distances in direct coordination with their neighbors. Many questions abound about how this movement occurs and how social recognition impacts this coordination. To read more about our work in this area, see:

Image captured by E. Garling (2022).

"Bacterial World." Illustrated by Abby Knecht

Populations in nature

How do bacterial populations navigate their environments? 

A bacteria's ecosystem comprises many moving parts, including environmental factors like antibiotics and pH levels, host immune systems, phages, and other bacteria. As such, we study these fast-moving bacteria in their native environments to understand how they navigate these changing environments. We use a combination of publicly available metagenomes, collaboration with mouse facilities, and generating datasets ourselves.  Stay tuned for more. 

Methods development

How do we expand and develop technologies to answer questions in our system?

Diagram describing rdn gene mapping in metagenomes for Knecht A., Denise S., et al. (2023). Image by Daniel Utter.

Research Gallery

P. mirabilis colonies migrate as swarms on top of a rigid nutrient surface.  The pattern of concentric circles is characteristic.

Left: Each colony was isolated from a different person.  A visible line forms between the two colonies and is apparent at the movie's end.

Right: Each colony was isolated from the same person.  The two colonies form a single, coherent colony.

Movies taken by J. Austerman.

All images here are used for artistic purposes and are property of the Gibbs lab.