I am a bubble player

Dr. Fangchao Song

My fellow SLAM participants Lauren and Megan gave wonderful talks showing bacteria are all around the world and influence the health of the earth and each of us as well. However, it’s very difficult to understand the function of the bacterial community, since it typically contains thousands of species, millions of cells. And they talk with each other.

Interactions affect function. Like us, in our labs, we either collaborate with each other or (hopefully not) fight for authorship, equipment, or cookies! Interactions also influence productivity. People try so hard to study bacterial interactions by isolating each individual species and pairwise mixing them together to see how they interact.

However, there are two challenges. First, we are not able to isolate all the species. Second, even if we have all of them, we need to do millions of experiments to test all the interactions. I can tackle these challenges using a simple idea. Bubbles!

When you pour a little bath soap into water and stir it, you get millions of bubbles in seconds, Similarly, I mix bacterial solution, oil, and surfactant, then stir, and I get millions of liquid bubbles. These bubbles randomly capture some bacteria together and separate them from other bacteria in other bubbles. It allows us to test millions interactions in parallel without isolating any single species.

It is pretty, but there is still a problem, The bubble sizes are not uniform, which means big bubbles have more cells and small bubbles have less cells. It creates difficulties when testing pairwise interactions because we need two cells in each bubble.

To achieve this, I made a microfluidic chip, a small chip with designed microscale channels in it. Using it, I can make eight million uniform-sized bubbles in an hour, and have on average two cells in each bubble.

This is just a start. I also designed another chip to merge bubbles with reagent, which allows me to identify the interaction in each individual bubble from the whole mix. Since the size of the bubbles is the same as the diameter of your hair, instead of using millions of plastic tubes and tons of medium, all the bubbles are in a small tube. And the small tube can let us know all the pairwise interactions and the functions of the bacterial community. Small bubbles could help with answering big questions.

I am Fangchao, I am a bubble player."