The secret of earthy fragrance – actinomycetes

　　 After a shower, we can always smell an “earth fragrance” in the air. This smell is fresh and natural, and people can’t help but take two more breaths. So where does the “scent” come from?
　　 In fact, in the sparse and porous soil, there is a special substance containing “earth smell”, called “geosmin”. When the raindrops fall to the ground, it will wrap the gas and form many small bubbles. When the gas blows, we will smell the fragrance of the soil.
　　 Geosmin, also known as chosamidine and 2-dimethyl isozolol. In the 1940s, chosamidine and 2-dimethylisotanol were successively extracted from the fermentation broth of actinomycetes. Therefore, actinomycetes were initially considered to be the main source of geosmin. But later, some scholars confirmed that some eukaryotic algae, such as diatoms, are also important sources of chosamidine and 2-dimethylisocamphenol.
　　 Geosmin is an alcohol, just like other alcohols, alcohol molecules tend to release strong odors during the volatilization process, such as the more common alcohol. Wet weather helps to increase the activity of actinomycetes and form more geosmin, so after a light rain, we can feel the fragrance of the earth more.
　　 It is worth noting that the role of actinomycetes is not only to provide “earth fragrance”, but also plays a vital role in the medical community. For example, a large part of the production of antibiotics comes from actinomycetes, and there are about 4,200 kinds of antibiotics produced by actinomycetes, which are proper “treasure bacteria”.

　　 There are many plants in nature, and many of them have their own unique flavors. Some flowers are fragrant, and some trees are fragrant. Smell is a language of plants, which can show its state and reflect its growth wisdom.
　　 Some people think that the smell of plants can be roughly divided into five types: invitation language, warning language, expulsion language, help language and response language. Let’s introduce them in turn.
　　 The first is the invitation language, which is not difficult to understand. For example, the smell of flowers, insect-pollinated flowers emit a special smell to attract insects such as bees. Different plants emit different odors, and the insects they attract will also be different, some like fragrance, and some like stench. For bees, the scent of flowers is the first element that attracts them. Coincidentally, when the melons and fruits of the plant are ripe, they will also emit an attractive fragrance to attract birds and beasts. When the birds and beasts eat the fruit, the seeds of the plant will be scattered everywhere, and the plant will complete the task of reproduction based on its own taste.
　　 The second is warning language, which is generally a coup used by plants to prevent themselves from being eaten by animals. The smell they emit may make some animals reluctant to eat.
　　 Once again, it is the driving language, which is similar to the warning language. It is all to prevent yourself from being eaten up. For example, when the stems and leaves of some plants are bitten by insects, they emit a bad smell to protect themselves. .
　　 Then there is the distress language and the response language, which is a dynamic and friendly process. When some plants are attacked by a large number of insects, they will send out distress signals to the surrounding plants of the same species. When the surrounding plants smell the distress odor, they will not ignore it. They will also emit a repelling odor when they are not violated, so that the insects are forced to retreat. This behavior of emitting an odor without being attacked is called response language.
　　 The fragrance of the flower comes from an oil cell in the petals, which secretes a steady stream of fragrant, fragrant oils. Aromatic oils are volatile and are released along with moisture when the flowers are in full bloom. There are also some flowers, although they cannot secrete aromatic oils, but the glycosides contained in their cells can also emit fragrance after being decomposed by enzymes. But aromatic oils are not only produced in flowers. Strictly speaking, aromatic oils are secondary substances in the metabolic process of plants. They are formed in the special organs of plants – oil glands and glandular hairs, and are secreted by these organs. . Therefore, as long as these organs are present, aromatic oils can be secreted. The parts of the plant body that contain aromatic oils are different, some are in the trunk, some are in stems and leaves, some are in flowers, fruits and seeds, and some are in roots and underground stems.

　　 In weightlifting competitions, we noticed that almost all weightlifters roared like a lion before raising the bar. What’s the matter?
　　 In addition to cheering for oneself, the main function is to encourage athletes to exert greater strength. Because weightlifters often take a deep breath before roaring, they will close their mouths immediately after roaring, and at the same time, the chest, abdomen, and waist will be strongly contracted, which will cause the pressure in the chest and abdominal cavity to rise sharply in an instant. , and the athlete’s limbs and back muscles also have solid support points, which is convenient for exerting greater power and lifting heavy objects.