22 Terrifying Facts You Didn’t Know About Bacteria

The smell of the air after a storm is caused by Geosmin, a chemical released by dead soil bacteria. Humans are hyper sensitive to it, capable of detecting it at a concentration of 5 parts per trillion. It's theorized that in our evolutionary past this helped us seek out water.

Scientists at UCLA noticed that "time and time again" people suffered their first experience with anxiety or depression right after stomach illnesses. They did brain scans after patients ate probiotics, and found that stomach bacteria actually directly affected the connectivity of the brain.

About 95% of serotonin in humans is produced in the gastrointestinal tract which is lined with a hundred million nerve cells, or neurons, that are influenced by bacteria. The inner workings of the digestive system don’t just help digest food, but also guide moods and emotions.

Blowing out birthday candles increases bacteria on the cake by 1,400%.

During the American Civil War some soldier's wounds glowed blue. Soldiers whose wounds glowed had better chance of surviving, and so the glow was called “Angel’s Glow”. Now it is known that the luminescence comes from bacteria that produce antibiotics and that live in nematodes.

Breast milk contains sugars which aren't digestible by human infants, but which serve as food for desirable gut bacteria.

Scientists have invented ‘poop pills’, which are capsules that contain only bacteria from donors' poo which are used to treat gut infections. They have no scent, taste and are as effective as traditional fecal transplants while being much cheaper.

Bathroom hand dryers suck fecal bacteria from the room and spray it directly on your hands.

The mitochondria in our cells, which generate energy, are ancient bacteria that had a symbiotic relationship with other single-cell organisms and developed around 1.5 billion years ago.

Bacteria will feed on a decaying body underwater and create gas, which causes the body to float to the surface. However, Lake Superior's cold temperatures inhibit bacterial growth and the bodies tend to sink and never resurface.