Nature offers us several incredible and pleasant things such as the smell of rain. Surely it is a smell that brings you nostalgia and a feeling of passage of time and is to your liking. After a long time of drought, when the first drops of rain fall, you can perceive a somewhat sweet smell that sends the entire atmosphere and alerts us that the rainy season is approaching. However, the general population does not know what mechanism causes the air to take in this fragrance. The explanation for this is in a compound called geosmin which is responsible for this smell known by the name of petricor.
In this article we are going to tell you everything you need to know about geosmin, its characteristics and why it generates the smell of rain.
What is
When we talk about petricor we refer to the characteristic smell that the rain originates when it falls, especially after a long time of drought. This fragrance that intoxicates the entire atmosphere is due to a compound called geosmin. Geosmin is the compound in charge of secreting millions of bacteria when rain falls to the ground.
The main responsible for the generation of geosmin is the bacteria Streptomyces coelicolor. It is also known as Albert's bacteria. Along with other cyanobacteria and some fungi that live in the soil are those that are activated when the rain moistens the earth. Geosmin is not only present in the particles that float in the air after the arrival of the rains. It is also the substance that gives the characteristic smell of beets. We know that beets have an earthy smell that stands out as soon as they are opened.
Another of the places where we find geosmin is in the aroma of some wines.
Dispersion and action of geosmin
We are going to see what are the main mechanisms of action that geosmin has and how they disperse the air. For the first time scientists have focused on being able to explain the mechanism by which geosmin is able to disperse through the air. In order to explain this, a group of researchers have used high-speed cameras and fluorescent ink. They have used this to be able to film in detail what happens when the drops of water impact on a soil that is full of the bacteria mentioned above.
After making the recordings it was found that, when the drop of water fell, catches tiny air bubbles and smashes it to the ground. As soon as the drop of water stabilizes, the water bubbles rise to the surface and explode, projecting tiny jets that launch water particles into the air. It can be said that the same thing happens as when gas is released from a carbonated drink such as champagne or beer. These bubbles travel up through the boot to explode into the air when it reaches the surface.
Once it explodes, a small amount of aerosols is released from the ground that are responsible for the dispersion of the petricor aroma. Each of the particles is responsible for transporting thousands of bacteria that are capable of surviving up to an hour in the air. Thus, the petricor does not usually last much longer than this time. These bacteria are responsible for the smell of fresh earth that we notice when it rains.
Uses of geosmin bacteria
There are various studies that link these bacteria with other uses and utilities that can be given. Both geosmin and the bacteria that are secreted during the fall of the rain are harmless to humans. In addition, it is known that they are used to obtain a long list of drugs among which are antibacterial agents such as tetracycline, erythromycin, rifampin, or kanamycin, and antifungal substances such as nystatin.
Another use of the study of geosmin is achieved after the knowledge of the molecular bases and the biosynthesis of geosmin. Knowing how this compound works, those fans of good wine can be benefited and especially people who have a more sensitive to give. The presence of geosmin can be a real nightmare for wine producers, because the presence of these aromas can spoil the characteristics of the product. Thanks to the knowledge of the biosynthesis of this compound, some advice can be given on how to reduce or eliminate its presence in some wines in order to improve their quality.
Although it may not seem was related the palate of winemakers with the thirst of camels are completely related. The importance of this substance on a biological level is involved in the survival of camels in deserts. Geosmin is the molecule that was the signal to the camels that the water is close. And it is that some camels in the Gobi desert are capable of finding water more than 80 kilometers away. The fact that camels can find water from so far away is something that scientists have explained for many years.
With the discovery of geosmin and its characteristics, it can be a mechanism for animals to disperse the spores of these microorganisms in order to know where there is water.
It seems that in the desert, Streptomyces it releases geosmin in moist soil, which can be taken up by olfactory receptors in camels. It is thought that the aroma of geosmin may be a mechanism for animals to disperse the spores of these microorganisms. Thus, when camels drink water, they spread the spores wherever they go helping their spread. But this seemingly trivial compound, geosmin, can be a matter of life and death for camels. If the genetic mutation occurred in nature it would be terrible for these animals. In addition, not only are camels attracted to the smell of geosmin, but some worms and insects are also capable of targeting the emanations of these bacteria.
I hope that with this information you can learn more about geosmin and its characteristics.