In the case of the streptomycetes are microbes, with a special importance for humans: made up Of representatives of these bacteria in 1943 was obtained, the antibiotic Streptomycin, which could have many of the dangerous pathogens in the place. The streptomycetes in order for us harmless bacteria that form in the soil fungal networks. They build organic Material, and as a result have a great importance for the cycle and the fertility of the soil. Hardly anyone knows, however, that you are also special for another reason: Everyone has perceived with the nose – they cause the typical smell of earth.

What is the smell?

Two volatile substances are known to be responsible: Geosmin and 2-methyl isoborneol (2-MIB). Studies have shown that the production of these two substances is widely used in the various representatives of the streptomycetes far. Geosmin and 2-MIB appear to have an important function – but what? The researchers Paul cups from the Swedish University of Agricultural Sciences in Alnarp are now investigating the suspicion that it is the attractants, which are aimed at the “nose” of the springtails (Collembola). This is mm-large member of the animals, which feed on rotting plant material and the microbes that grow on this substrate.

In the context of the study, the researchers conducted first of all preference Tests with spring by tails of the type

Folsomia candida

. As you report, choose the animal cells in Y-shaped experimental vessels for the junction, from the scent of streptomycetes-streamed Material. That Geosmin and 2-MIB are the attractants, the researchers have shown by the use of Streptomyces mutants that can form both substances. These versions were the tiny animals on the left and decided to go for the “normal”, apparently seductive fragrance Streptomyces ends of the samples. The Experiments showed that springtails Streptomyces Material as a food source appreciate: they assimilated the sample material to be greedy.

A further evidence of the importance of Geosmin and 2-MIB as an attractant subsequent electric provided physiological studies on the antennae of springtails: If the two fragrances were in the air, the researchers found characteristic reactions in the antennae of the animal. You have according to the results, a very fine nose for these substances, report mug and his colleagues.

springtails transport spores

next, the researchers devoted themselves to the study of the genes for Geosmin and 2-MIB in the streptomycetes. In the process, they were able to show that the activity of these genes is associated with the formation of spores in the germs. This means that you exude the scent, when they form resistant resting forms, which serve to spread. Fittingly, the scientists were able to show that springtails carry the spores on their bodies and also without prejudice to their excretions make, after you streptomycetes Material have eaten.

Becher and his colleagues, therefore, come to the conclusion: What we perceive as the typical earthy smell, is to use an attractant, the Streptomyces, to get the “ride sharing”. Springtails are suitable for this role very well, because they move around a lot. As the Name clarifies, you can carry a small jump fork at the back, far through the air and be carried by the Wind. So you can open up new spaces of life – and the Same applies thus also for its microscopic passengers – the streptomycetes.

source: Nature, doi: 10.1038/s41564-020-0697-x

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