After a heavy rain, a fresh earthy smell will fill the air. How did this earthy smell come from? It turns out that the soil contains a lot of actinomycetes, slime bacteria, cyanobacteria and filamentous fungi, these microorganisms produce some volatile organic compounds (VOCs) to constitute the taste of the soil. Among them, the most common ones are geosmin (a natural terpenoid) and 2-methylisotitol (2-MIB).
The study found that this odor is very beneficial for some small animals that live in the soil. For example, the Collembola (a small arthropod, commonly known as the hopper) can feed on actinomycetes and fungi in the soil. Their tentacles can capture these odor molecules, and then determine the location of these microorganisms.
However, the latest article published in “Nature-Microbiology” shows that the actinomycetes that seem to be eaten by the reptiles because of their odor, are actually Jumping insects are also used, and the smell is their “bait”.
In the experiment, the researchers used gas chromatography to analyze a volatile organic compound produced by an actinomycete, Streptomyces coelicolor. Subsequently, they observed the response of the springtail to these small molecule compounds, and found that not only earth odorin, some intermediate products of synthetic earth odorin, and by-product big root geraniene-D, can cause electrophysiological reactions on the antennae of springhopper. In addition, the volatile organic compounds produced by Streptomyces coelicolor have a clear attraction to springtails, but have no obvious impact on other insects.
Streptomyces produces a large number of progeny spores when it enters the breeding period. The researchers found that when Streptomyces produce these volatile compounds, it is precisely the time when the spores they produce begin to spread. Therefore, when the attracted springer came to eat these streptomyces, it inadvertently acted as a medium to help the spores spread.
In addition to the body surface that can help spread spores, excreta produced by the springworm after feeding on Streptomyces can also promote the spread of Streptomyces spores. The researchers collected the excrement of the springworm and washed away the spores attached to the body surface. They found that 70.8% of the hopping feces particles contained live Streptomyces spores. This finding also confirms that although Streptomyces are ingested by the springtail, their spores can still survive in the intestinal tract of the springtail and spread again.
Some studies have confirmed that Streptomyces can produce a variety of metabolites harmful to invertebrates. Therefore, when other animals in the soil, such as Caenorhabditis elegans, sense these earthy small molecules, they generally try to escape. But it ’s interesting to use Streptomyces asThe only food source of springtails is not “poisoned”.
Researchers have found that the genome of the springtail contains multiple gene clusters related to detoxification mechanisms, so they can be exposed to soil containing various toxic substances. The multiple antibiotics produced by Streptomyces can also help the springtail to kill pathogens in the body. Considering that both trichomoniasis and streptomyces are highly abundant in soil, the researchers speculate that these two types of organisms formed this special “mutually beneficial” relationship long ago. (According to “Global Science”)