Have you ever noticed that every time dry earth becomes wet, whether after watering the plants or after a rain, it gives off a “wet earth” aroma?
This smell of "wet earth" is due to a chemical called geosmina, a Greek word that means “the aroma of the earth”. This substance is produced by the bacteria Streptomyces colicolor, a harmless bacterium that lives in almost all types of soil. When in contact with water, the geosmina activates, releasing the smell of wet earth.
Bacteria image Streptomyces colicolor, responsible for the aroma of wet earth.
Geosmine is also present in beetroot and fish, and is responsible for introducing the smell and taste of clay into these foods.
These bacteria are widely researched by scientists, being used in the composition of several antibiotics used in human and veterinary medicine. This bacteria is also present in numerous products that we use daily.
Geosmin is also present in sugar beets and fish.
In the desert, camels can find water thanks to the smell these bacteria give off. Releasing this smell, the bacteria attract camels, which, when drinking the water, leave spreading their spores to other places. Spores are structures produced by bacteria that allow them to reproduce elsewhere.
But camels are not the only ones to be attracted by the smell of “wet earth”, worms and insects are too. Researchers believe that some plants have flowers that give off geosmin and, because of that, insects and roundworms are attracted by the smell, thinking that there is water in that flower - thus helping with pollination from them.
Camels can find water thanks to the smell that bacteria give off.
by Paula Louredo
Graduated in Biology
