You can often smell the scent of earth after the rain, and guess what it comes from?

Fungi and algae in the soil.

After the rain we smell the aroma of damp earth, which comes from geosmin, which is a metabolic byproduct of microorganisms such as actinomycetes and blue-green algae, which break down dead or decaying organic matter into simple compounds, one of which is called geosmin and helps to create an "earthy taste".

When the raindrops fall to the ground, they envelop the gas and form many small bubbles, and when the gas hits our faces, we smell the fragrance of the earth.

After a light rain, you can feel the fragrance of the earth even more

Geosmin is an alcohol, and like other alcohols, alcohol molecules tend to release strong odors during volatilization, such as the more common alcohol. Humid weather helps to increase actinomycetes activity and form more geoodorins, so we can feel the scent of the earth more after a light rain.

In fact, after a light rain, in addition to the smell of earth, we often smell other fresh smells, such as the smell of essential oils volatilized by plants after the rain, which will also form a familiar and pleasant aroma.

The above content reference: Popular Science China - The secret actinomycete of the earthy fragrance.

After heavy rain, the air becomes moist and has a fresh, earthy smell. When we smell it, we often feel very relaxed. But what is this fresh, earthy taste?

It turns out that the soil is full of actinomycetes, molds, cyanobacteria, and filamentous fungi. Some of the volatile organic compounds (VOCs) produced by these microorganisms contribute to the odor of the soil. Rainwater causes puddles to form on the ground, and these organisms from the soil can seep into the puddles and form a thin film on the surface of the water.

As the rain continues, tiny bubbles form in the puddles, bringing organic matter and tiny dirt particles into the air.

Studies have found that humans and many animals can smell diosmin and 2-methylisoamyl alcohol even at very low concentrations in the air. Streptomyces is the most common actinomycete found in soil. Almost all streptomycetes contain the gene for the production of diosmin, and nearly half of all streptomyces contain the gene for the synthesis of 2-methylisothyl alcohol.

When Streptomyces enters the reproductive stage, it produces a large number of progeny spores.

After the organic matter enters the soil, it can produce a thin film on the water surface, and when the trickle hits the water surface, there will be a large number of bubbles to burst, and at the same time the rupture can also disperse the organic matter and soil particles in the air, as we just said, microorganisms can emit the smell of 2-methylisopropanol and the soil, but let's smell the smell of the soil after the rain, these are the elements of the air. Actinomycetes are one of nature's best chemists because of their ability to make a wide variety of molecules, known as special metabolites, from which many antibiotics are produced.

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No, because the soil is rich in molds, filamentous fungi and cyanobacteria, as well as actinomycetes, volatile compounds produced by these organisms after rain, thus giving off what we think of as the fragrance of earth.

It is indeed the fragrance of the earth, because when the rain falls on the ground, it mixes with the smell of the land, and the air after the rain is very fresh.

In fact, it is not the fragrance of the earth at all, but the smell produced by some fungi, which is the metabolite of these fungi.

After rain, you can often smell the "earthy fragrance", which comes from the bacteria and algae in the soil.

After the rain we smell the aroma of damp earth.

This smell comes from geosmin, a volatile substance with an earthy odor, which is a product of the metabolism of actinomycetes, blue-green algae, and other microorganisms.

The soil is moist when it rains, and as the rain stops, the water in the soil will slowly evaporate, and geosmin will be released along with the water, and when this water enters our nose, we will smell this natural smell.

The scent of the soil comes from a type of bacteria called actinomycetes in the soil.

Actinomycetes are single-celled organisms, and those strangely shaped filaments are its hyphae. Its body covers a large space by growing a large number of hyphae, which is very beneficial for finding food. Actinomycetes can release a chemical that allows us to smell the scent of earth as soon as we get closer.

Extended information: After the rain, the fragrance in the earth is clearer:

Actinomycetes generally prefer to live in warm, humid environments. When the soil dries, its hyphae grow spores on its head. The spore has a very thick spore wall that protects it from being destroyed when there is a lack of water.

The original actinomycetes die gradually, but leave behind spores, which, once encountering the right conditions, germinate and grow into actinomycetes.

When it rains, the rain washes away the soil, and the actinomycete spores that are buried in the soil on these sunny days are adsorbed in small droplets of moist air and spread around. When they are inhaled into the nostrils, we can feel the fragrance of the earth.

Question 1: When it rains, the rain washes away the soil, and the actinomycete spores buried in the soil on a sunny day are dispersed with small droplets in the moist air. When they are inhaled into our nostrils, we feel an earthy scent.

And because the longer the land is dry, the more actinomycete spores exist, so the fragrance of the soil after rain is especially obvious after a long drought.

Question 2: The first line-drawing sentence uses an analogy to illustrate the actinomycetes vividly. (The line-drawn sentence compares actinomycetes to "a tree" or "a piece of grass", and uses an analogy to illustrate the article.) ）

Question 3: It is a treasure trove for the production of antibiotics, which can be used to make monosodium glutamate for flavoring, and is now a convenient material for scientists to study biological development and cell differentiation. , Question 4:

The title generally hints at the main content of the article. The title of this article, "Where does the smell of the earth come from?", is a question that the reader should think about the answer to such a question, so as to attract the reader to read the article.

Question 2: Analysis of test questions: Answer from the aspect of explanation method, point out the explanation method and what problem is illustrated, and use evaluation language such as "vividly explain".

Question 3: Test question analysis: Grasp the central sentence of the first sentence of the two paragraphs and summarize it.