When your umbrella decides to turn over on its own, when it gets a little cold and wet and stressful, there’s something incredible about the rain. Probably enjoyed from the security inside the house (good news for you lockdown), everyone prefers a fresh scent that fills the air after a good shower. And, as it happens, there may be a scientific reason for this. A group of researchers in Australia have discovered that a group of bacteria produces a compound that emits a “rain odor”, which is intended to lure animals and help spread bacteria. Those cheeky chappies.
The study, published in the journal Nature Microbiology, examined the effects of the presence of Streptomyces on the behavior of animals within dry distances, such as insects. Streptomyces is the largest group of Actinobacteria with over 500 species within the genus. These are usually found in soil and rotting plants, releasing the earthly odor that we all just can’t get enough of, it’s actually a compound that they call geosmin release more noticeable water for us after rain. Leading researchers Klas Flärdh and colleagues at Monash University decided to investigate the effects of this tempting odor on a combination of field and laboratory experiments. They wanted to find out if the smell of Streptomyces was attractive to arthropods in the soil.
Field trap analysis revealed that the springs were attracted by the earthly scent of Zeus Pisces. They further investigated the attraction under lab settings and found that the springtails were using their antennas to pick up perfume. During their investigation, they noticed that the bacteria-fed insects stuck to their bodies with bacterial spores. When they enter the soil, they carry these seeds with them, spreading them from the surface and the germinated seeds as they defecate.
The authors suggest that this dispersion is for the bacteria that make geosmin and the environmental benefits of the enticing odor that comes with it. By accidentally and accidentally coating themselves with bacteria to feed the animals, Streptomyces can spread far and wide behind a springtail (or digestive tract) at sunset. So, if you feel a bit intense and isolated from nature, make sure the window cracks next time it rains and breathe deeply.