It turns out that not only we, the people, the aroma of moist earth and recent rain seems attractive. The smell that bears his own name petrichor comes from organic compounds geosmin produced by the microbes – including bacteria-Streptomyces (Streptomyces). It is known that the Streptomyces secrete a substance when they die, and that different creatures, including humans, have a special reaction. The question is, why is this happening?
To understand the role geosmin in the soil environment inhabited by the bacteria, an international group of researchers wondered whether a smell streptomycetes live in the soil arthropods. Their guesses were confirmed when the network field traps with bait from Streptomyces coelicolor, scientists discovered colonies of springtails (Collembola) tiny arthropods living in organic media. The team then conducted a number of experiments already in the laboratory. And it turned out that these kids are big fans geosmin. And Streptomyces fulfill for them the role of food.
What bacteria is beneficial to be eaten by arthropods? Streptomyces in many respects similar to filamentous fungus. Being ready to breed, it creates spores, which are spread newborn bacteria. Only here to spread the media and this mission falls on the springtails. They feed on colonies of Streptomyces and spread their spores through fecal balls and transfer to its hydrophobic body skin.
The conclusion is simple: the production of bacteria geosmin is an integral part of the process of sporulation. This is the end of the life cycle involving arthropods of the soil, which will spread spores to start all over again. So next time you feel the smell of the rain, unable to remember that this pleasant fragrance – a sign of the whole circle of life, which is very close to us.