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Bacteria chemosynthetic: examples. The role of chemosynthetic bacteria

How are the bacteria that chemosynthesize various substances organized and carried out? To answer these questions, it is necessary to deal with a number of biological concepts.

Characteristics of bacteria

First we find out who the bacteria are. This is the whole Kingdom of living nature. They are single-celled organisms of microscopic size, which are devoid of nuclei. But this does not mean that bacteria generally do not have structures responsible for the transfer of hereditary information. It simply has a more primitive organization. These are circular DNA molecules that are concentrated in a specific part of the cytoplasm called the nucleoid.

The essence of autotrophic nutrition

Chemosynthetic bacteria, examples of which will be considered in our article, independently produce organic substances. They are autotrophs, like plants. However, the latter use the energy of sunlight for this. The presence of green plastids of chloroplasts allows them to carry out the process of photosynthesis. Its essence lies in the formation of a glucose carbohydrate from inorganic substances - water and carbon dioxide. Another product of this chemical reaction is oxygen. Bacteria are also autotrophs. But they do not need sunlight to receive energy. They carry out another process - chemosynthesis.

What is chemosynthesis

Chemosynthesis is the process of formation of organic substances due to oxidation-reduction reactions. It is carried out in nature only prokaryotes. Chemosynthetic bacteria can use sulfur, nitrogen and iron compounds to synthesize organic compounds . This releases energy, which first accumulates in the ATP bonds, after which it can be used by bacteria cells.

Bacteria chemosynthetic: habitat

Since the life of chemotrophs does not depend on the presence of sunlight, the range of their distribution is quite wide. For example, serobacteria can live at great depths, sometimes being the only representatives of living beings. The habitat of these prokaryotes is most often soil, sewage and substrates rich in certain chemical compounds.

Iron Bacteria

To chemosynthetic bacteria include prokaryotes, changing the composition of iron compounds. They were discovered by the outstanding Russian microbiologist Sergei Nikolaevich Vinogradsky in 1950. This type of bacteria during the oxidation reaction changes the oxidation state of iron, making it trivalent. They live in fresh, and salt water. In nature, they carry out the circulation of iron in nature, and in industry they are used to produce pure copper. This kind of bacteria also refers to lithoautotrophs, capable of synthesizing some elements of their cells from the uleacid.


Bacteria, chemosynthesizing substances from sulfur compounds, can exist separately on the bottom of reservoirs or form a symbiosis with mollusks and marine invertebrates. As an oxidation source, they use hydrogen sulphide, sulfides, thionic acids or molecular sulfur. This type of bacteria was the main object in the discovery and study of the process of chemosynthesis. To this group of prokaryotes include some phototrophic prokaryotes. For example, such as purple or green sulfur bacteria.

Nitrifying bacteria

Nitrifying bacteria grow on the roots of leguminous plants. Chemosynthetic prokaryotes of this group oxidize ammonia to nitric acid. This reaction is carried out in several stages with the formation of intermediates. There are also nitrogen-fixing bacteria in the soil . They settle on the roots of leguminous plants. Introduced into the tissue of the subterranean organ, they form characteristic thickenings. Inside such formations a favorable environment is created for chemosynthesis to proceed. Symbiosis of plants with nodule bacteria is mutually beneficial. The former are provided by prokaryotes from organics obtained during photosynthesis. Bacteria are able to fix atmospheric nitrogen and convert it into a form that is accessible to plants.

Why is this process so important? After all, in the atmosphere, the nitrogen concentration is high enough and amounts to 78%. But in this form, plants can not absorb this substance. And nitrogen is necessary for plants to develop the root system. In this situation, nodule bacteria come to the aid , which turn it into a nitrate and ammonium form.

Thionic bacteria

Chemosynthetic bacteria are also thionic prokaryotes. Their source of energy are various sulfur compounds. This kind of bacteria restores them to sulfuric acid. This reaction is accompanied by a significant decrease in the hydrogen index of the medium. Thionic bacteria are part of the group of acidophils. These include organisms that can survive in conditions of high acidity. Such conditions are typical for marshes. Together with tianovym this group consists of milk and acetic bacteria, flagellates and rotifers.

Hydrogen bacteria

These kinds of prokaryotes are soil inhabitants. They oxidize molecular hydrogen to water with the release of energy. Such bacteria are also part of the group of thermophiles. This means that they are able to maintain viability at high temperatures, which can reach 50 degrees Celsius. This ability of hydrogen bacteria is due to the fact that they release special enzymes that function even in such conditions.

The role of chemosynthetic bacteria

Chemotrophs play a major role in the complex processes of transformation and cycling of the relevant chemicals in nature. Since hydrogen sulphide and ammonia are sufficiently toxic substances, there is a need to neutralize them. This is also done by chemotropic bacteria. In the course of chemical transformations, substances necessary for other organisms are formed, which makes possible their normal growth and development. Large deposits of iron and manganese ores at the bottom of the seas and marshes arise due to the activity of chemotrophs. Namely - iron bacteria.

Man has learned to use the unique properties of chemotrophs in his work. For example, with the help of sulfur bacteria, waste water is purified from hydrogen sulphide, protects metal and concrete pipes from corrosion, and the soil from acidification.

Thus, chemosynthetic bacteria are special prokaryotes capable of carrying out appropriate chemical reactions under anaerobic conditions. These organisms oxidize substances. The energy that is released during this process is first stored in ATP bonds, and then used for vital processes. The main ones are iron-, sulfur- and nitrogen-fixing bacteria. They live both in the water and in the soil environment. Chemotrophs are an indispensable link in the circulation of substances, provide living organisms with the necessary substances and are widely used by man in his economic and industrial activities.

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