The microbes living on and in your skin enjoy shelter, moisture and the chemical building blocks they need for growth. Their turf is valuable, and they will fight to defend it.

Like most microbes typically found on skin, these bacteria don’t harm us, and they may protect us from treacherous intruders. Here, rod-shaped bacteria called Bacillus subtilis (purple) are locked in battle with a fungus that causes athlete’s foot (green). Like many kinds of bacteria, Bacillus subtilis cells can collect in orderly chains to form biofilms—cooperative communities that may improve self-defense. These rod-shaped cells have formed a blockade and are spewing toxic chemicals—a bold attack on an advancing colony of fungus.

The bacteria shown in this exhibition model, Bacillus subtilis, produce chemicals that kill other bacteria, as well as fungus. One strain releases an antibacterial blend called bacitracin—an ingredient in many over-the-counter antibiotic ointments. Under the right conditions, the population of Bacillus subtilis cells can double in about two hours!

Learn more amazing tales of your microbiome in the exhibition, The Secret World Inside You, open through August 2016.