If you are a microbe—or a person—it’s often not good to be surrounded by individuals just like you. This is a great lesson from our work on interactions between bacterial cells. The work itself is born from interactions between five scientists with different backgrounds.

Why did we decide to study interactions in bacterial communities? Because interactions shape the properties of bacterial communities. Bacterial communities are aggregates of cells living in contact with each other and moving little. Bacterial communities can be thought as systems composed of parts, the cells, connected via biochemical interactions. Every single cell interacts with its neighbors, which affect its growth and survival. The combined network of interactions between all cells determines the properties of the community, such as its growth and collective metabolic processes. To understand these collective properties, we need to reconstruct the network of interactions between cells.

If we take a single cell, how large is the neighborhood with which it interacts? Measuring this neighborhood seems to be the key to reconstruct the network of interactions in a community. We decided to build a new experimental system for growing microbial communities and measuring interactions between individual cells. We needed a variety of expertise to design a model bacterial community, build a new microfluidic device, perform time-lapse experiments, develop image analysis software and statistics, and build a mathematical model to interpret the results. Our little team became quickly diverse!

This work occupies a special place in my mind because it has been my personal bridge between physics and wet-lab biology. It shaped me into a Chimera, half physicist and half experimental biologist, which is the Chimera I like to be. This project was challenging, and it was made possible by interactions between five scientists with different backgrounds. Working together showed us that it is good to be surrounded by individuals different from you. Both for people, and for microbes.

Alma Dal Co

Mutualistic relationship: two Escherichia coli strains, shown in yellow and purple, grow inside a microfluidic chamber and mutually exchange beneficial compounds. Brighter colors indicate faster growth rates of cells. Cells closer to the mutualistic partner grow faster as they receive more of the beneficial compound from this partner. Yellow cells interact within a smaller neighborhood than purple cells.

Dive into our experiments:

Watch our communities: pic.twitter.com/DroXqhjoEN

Watch a 3D rendering of the microfluidic device: pic.twitter.com/m0S8G5OOGj