How a Biofilm’s Strange Shape Emerges From Cellular Geometry

In colloids as in biofilms, these interactions are governed by two opposing forces. One is repulsive: Two particles or two cells can’t physically occupy the same space at the same time. The other force is attractive. Cells are covered with sticky proteins that can fasten two cells together, much like the medium binding a colloid. If the repulsive force is stronger, cells don’t aggregate. But if the attractive force is stronger, it can spark the initial formation of a biofilm. What differentiates colloids from biofilms is growth, which a biofilm must balance between the horizontal and the vertical. It’s not unlike urban sprawl. Both Houston, Texas, and Queens, New York, house populations of around 2.3 million people, but they have completely different urban geometry. Around Houston, cheap and abundant land lets residents spread out, with mostly horizontal growth. Queens, on the other hand, is hemmed in by water and surrounding municipalities, so residents build more vertically. That’s ... Read full article.