Big bacterium. Bacteria

Dwarfs and giants among bacteria

Bacteria are the smallest living organisms and are the most common form of life on Earth. Ordinary bacteria are about 10 times smaller than a human cell. Their size is about 0.5 microns, and they can only be seen with a microscope. However, it turns out that the world of bacteria also has its dwarfs and giants. One of these giants is considered to be the bacterium Epulopiscium fishelsoni, the size of which reaches half a millimeter! That is, it reaches the size of a grain of sand or a grain of salt and can be seen with the naked eye.

With the help of sulfur pearls, nature came up with an amazing solution to the critical size problem: bacteria are hollow. Inside there is a huge container, 50 times larger than the cytoplasm, the living part of the cell. Like the peel of an orange, cellulose surrounds the living part of the cavity.

Bacteria have taken up residence in the world in a variety of fantastic ways. Of all creatures, the oft-forgotten single-celled ones are the most successful - and yet are often used by humans to re-evaluate themselves as the crown of evolution. The bacteria live in human kidney stones and in the intestines of worms, in the air, in boiling geysers and in the ice of Antarctica. Some bring suffering such as plague, cholera or tuberculosis throughout the world, others help plants grow or people digest, others feed on oil, the seas are polluted, some are even resistant to strong radioactivity.

Reproduction of Epulopiscium

Research was carried out at the Cornwall Academy to determine the reasons for such large sizes. As it turned out, the bacterium stores 85,000 copies of DNA. By comparison, human cells contain only 3 copies. This cute creature lives in the digestive tract of the tropical reef fish Acanthurus nigrofuscus (surgeonfish).

The sulfur pearl plays an important role in the natural cycle of matter in Namibia, and this role formally caused its gigantism. It feeds on sulfur compounds abundant in the sediment that is their home. In order to digest sulfur, bacteria, like animal metabolism, depend on oxygen - they urgently need nitrates. But this does not exist in the hostile sauce in which Thiomargarita namibiensis lives.

This dilemma did not break the protozoan, but it made it a giant: every few months, when a storm hits the sea, nitrate-rich water also briefly penetrates bacteria in the depths. The sulfur pearl can now store in its cavity the precious nitrate, which it uses in abundance for a short time; she manages the reserves, like a diver who takes compressed air with him into the depths.

Common types of bacteria are very small and primitive, they have no organs and feed through their membranes. Nutrients are distributed evenly throughout the body of the bacteria, so they must be small. In contrast, Epulopiscium copies its DNA many times, distributes copies evenly along the shell, and they receive sufficient nutrition. This structure gives it the ability to instantly respond to external stimuli. The way it divides is also different from other bacteria. If ordinary bacteria simply divide in half, then it grows two cells inside itself, which after its death simply come out.

Because the largest bacterium on Earth can also store sulfur, it can go months without food - a feathered Namibian pearl - and then simply stop the air and wait for better times. Today we know that the Namibian Sulfur Pearl not only has many close relatives in other marine areas, but also plays an important ecological role: these bacteria can cause the formation of rocks with high phosphorus content. This reduces the amount of phosphate in seawater so that it is no longer available as a nutrient to other living things.

Namibian sulfur pearl

However, even this far from small bacterium cannot compare with the largest bacterium in the world, which is considered Thiomargarita namibiensis, otherwise known as the “Namibian sulfur pearl” is a gram-negative marine bacterium discovered in 1997. Not only does it consist of just one cell, but it also lacks a supporting skeleton, just like eukaryotes. The dimensions of Thiomargarita reach 0.75-1 mm, which allows it to be seen with the naked eye.

Thus, the formation of these rocks counteracts the excessive enrichment of the oceans with phosphate. Most bacteria are usually very small and can only be detected with a microscope. But giant forms have emerged in several groups of bacteria. They are more than hundreds of times larger than ordinary bacteria and are easily recognized by the naked eye. The largest known bacteria belong to the group of sulfur bacteria. These bacteria can be recognized by bright gray sulfur inclusions, which cause the sulfur bacteria to be oxidized by sulfide to sulfur and further sulfated to produce energy.

According to the type of metabolism, Thiomargarita is an organism that receives energy as a result of reduction-oxidation reactions and can use nitrate as the final object that receives electrons. The cells of the Namibian sulfur pearl are immobile, and therefore the nitrate content can fluctuate. Thiomargarita can store nitrate in a vacuole, which occupies about 98% of the entire cell. At low nitrate concentrations, its contents are used for respiration. Sulfides are oxidized by nitrates to sulfur, which collects in the internal environment of the bacterium in the form of small granules, which explains the pearl color of Thiomargarita.

To do this, they use either oxygen or nitrate. Breathing nitrate is also a cause of unusual size. The cells of giant bacteria consist mainly of large, membrane-enclosed vacuoles in which they can store high concentrations of nitrate.

By storing nitrate for respiration and sulfur as an energy source, giant bacteria can survive for a long time in unfavorable external conditions.

Facing Namibia, the seabed contains much more sulphides than other coastal areas, which obviously benefits this giant with its corresponding large nitrate reservoir. In addition, Namibia's particularly soft seabed is regularly churned by large-scale methane outbreaks. Since its discovery 14 years ago, the bacteria have gained notoriety and have been included in the Guinness Book of World Records and featured on a Namibian stamp.

Study of Thiomargarita

Research conducted recently has shown that Thiomargarita namibiensis may not be an obligate, but a facultative organism that obtains energy without the presence of oxygen. She is capable of oxygen respiration if there is enough of this gas. Another distinctive feature of this bacterium is the possibility of palintomic division, which occurs without an increase in intermediate growth. This process is used by Thiomargarita namibiensis in stress conditions caused by starvation.

Of course, after the discovery in Namibia, the search for Thiomargarite began in other sulfide-rich marine areas, and indeed, very similar bacteria could be found elsewhere, but nowhere in such numbers and with so many different forms as off the coast of Namibia. Only recently has it been possible to genetically study this diversity of expressions. In addition, two other previously unknown genera were discovered, now named Thiopilula and Thiophysa.

Sulfur bacteria and the phosphorus cycle

Although it has also been found on the seabed off the coast of Chile and Costa Rica, it is found there only as a solitary chamber and does not produce the typical pearl necklaces to which Tiomargarita owes its name.

In the huge cells of sulfur bacteria there is enough space to store substances. Not only sulfur for energy supply and nitrate as an oxidizing agent, but also phosphate can accumulate in the cell as a kind of energy storage in the form of polyphosphate in large quantities. In coastal areas, where particularly large numbers of sulfur bacteria live, rocks with a high phosphorus content, so-called phosphorites, are also formed.

The bacterium was discovered in the bottom sediments of the flattened continental margin, near the Namibian coast, by Heide Schulz, a German biologist and her colleagues in 1997, and in 2005, in the cold cludes of the bottom of the Gulf of Mexico, they discovered a similar strain, which confirms the widespread distribution of the Namibian sulfur pearl .

In ancient rocks that come from marine, coastal areas, you can often find fossils shaped like sulfur bacteria. Taken together, this suggests that for a long time large sulfur bacteria could play a direct role in the phosphorus cycle of the sea, which favors the formation of phosphorites. The question now arises about the conditions under which phosphate rocks are formed, since this process reduces the amount of dissolved phosphate available in seawater as a nutrient for all living organisms.

Victor Ostrovsky, Samogo.Net

Bacteria are the first “inhabitants” of our planet. These primitive, nuclear-free microorganisms, most of which consisted of only one cell, subsequently gave rise to other, more complex forms of life. Scientists have studied more than ten thousand of their species, but about a million more remain unexplored. The standard size of a representative of the microcosm is 0.5-5 microns, but the largest bacterium has a size of more than 700 microns.

Therefore, increased phosphorus production means less growth for all organisms in the long term. In fact, there appears to be a direct connection between phosphite formation and large sulfur bacteria. The result is the phosphorus-rich mineral apatite, and the first step towards the formation of phosphorites is taken.

The seabed off the coast of Namibia is so rich in phosphorites that they are even useful as raw materials for the fertilizer industry. We suspect that similar mechanisms also apply to thiomargarita.

Bacteria are the oldest form of life on Earth

Bacteria can have a spherical, spiral, or spherical shape. They can be found everywhere, they densely inhabit water, soil, acidic environments, and radioactive sources. Scientists find living single-celled microorganisms in permafrost conditions and in erupting lava from volcanoes. You can see them using a microscope, but some bacteria grow to gigantic sizes, completely changing a person’s understanding of the microcosm.

It is not yet known why sulfide causes phosphate release. In fact, however, it can be seen that both today and throughout Earth's history, phosphorites formed in highly sulfide seafloors. We therefore suspect that these and similar bacteria play an important role in the marine phosphorus cycle and likely contributed to the formation of phosphorite in the geological past. What advice does a health expert give if we ask her questions about how to easily and inexpensively avoid bacteria growth? "Hand washing" by Dr Eckerley, British hygienist.

After all, pathogens are especially fond of appearing and often appear in places where they are not expected. It's no surprise that 65% of all colds, 50% of all diarrheal illnesses and 80% of all food-related gastrointestinal illnesses come from clean households. Not in the bathroom, but in the kitchen. In most households, fecal bacteria is 200 times more likely to be detected.

Thiomargarita namibiensis, Namibian sulfur pearl, is the name of the largest bacteria known to man. You don't need a microscope to see it; its length is 750 microns. The giant of the microcosm was discovered by a German scientist in the bottom waters during an expedition on a Russian scientific vessel.

Epulopiscium fishelsoni lives in the intestines of surgeonfish and is 700 microns in length. The volume of this bacterium is 2000 times the volume of a standard-sized microorganism. The large, single-celled organism was originally found inside surgeonfish that inhabit the Red Sea, but has since been found in other fish species in the Great Barrier Reef area.
Spirochetes are bacteria with long, spiral cells. Very mobile. They live in water, soil or other nutritious medium. Many spirochetes are causative agents of serious human diseases, while other varieties are saprophytes - they decompose dead organic matter. These bacteria can grow to a length of 250 microns.
Cyanobacteria are the oldest microorganisms. Scientists have found products of their vital activity that are more than 3.5 billion years old. These single-celled organisms are part of oceanic plankton and produce 20-40% of the oxygen on Earth. Spirulina is dried, ground and added to food. Oxygenic photosynthesis is characteristic of algae and higher plants. Cyanobacteria are the only single-celled organisms that produce oxygen during photosynthesis. It was thanks to cyanobacteria that a large supply of oxygen appeared in the Earth's atmosphere. The cell width of these bacteria varies from 0.5 to 100 microns.

Actinomycetes live in the intestines of most invertebrates. Their diameter is 0.4-1.5 microns. There are pathogenic forms of actinomycetes that live in dental plaque and in the human respiratory tract. Thanks to actinomycetes, humans also experience the specific “smell of rain.”
Beggiatoa alba. Proteobacteria of this genus inhabit places rich in sulfur, fresh rivers and seas. The size of these bacteria is 10x50 microns.
Azotobacter has a diameter of 1-2 microns, lives in slightly alkaline or neutral environments, plays an important role in the nitrogen cycle, increases soil fertility and stimulates plant growth.
Mycoplasma mycoides is a causative agent of pulmonary diseases in cows and goats. These cells have a size of 0.25-0.75 microns. Bacteria do not have a hard shell; they are protected from the external environment only by a cytoplasmic membrane. The genome of this type of bacteria is one of the simplest.

Archaea are not bacteria, but like them, they consist of a single cell. These single-celled organisms have been isolated near thermal underwater springs, inside oil wells and under the icy surface of northern Alaska. Archaea have their own developmental evolution and differ from other life forms in some biochemical features. The average size of an archaea is 1 micron.

Build your immune system - and cleanse it regularly

Good immune defense is mainly intestinal. So good intestinal protection is responsible for our health. Therefore, it is advisable to build up your intestinal flora through a good diet. Fluid and hygienic conditions must be obtained for the remaining 20 percent. The dirtiest household items include kitchen sponges and rags, cutting boards, countertops, drains, doorknobs and toothbrushes.

Humid and warm is the ideal climate for breeding. In addition, bacteria are very easily transported from one place to another using textiles. It is best to use separate textiles and replace them frequently. Dry regularly: Most bacterial strains cannot survive in dry conditions. Good tip: You can disinfect sponges by washing them in the dishwasher.

Theoretically, the minimum size of a single-celled microorganism is 0.15-0.20 microns. With a smaller size, the cell will not be able to reproduce its own kind, since it will not accommodate biopolymers in the required composition and quantity.

The role of bacteria in nature

More than a million species of different single-celled microorganisms coexist in the human body. Some of them are extremely useful, others can cause irreparable damage to health. The baby receives the first “portion” of bacteria at birth - during passage through the mother’s birth canal and in the first minutes after birth.

Cuts and cracks in boards provide a large breeding ground for bacteria. Again, be careful not to cross-contaminate: do not use raw meat or raw fish without sanitizing. To keep your cutting board completely clean, we recommend using this cleaning agent: Mix 1 teaspoon of chlorine bleach with 200 ml of water. Drain the board and let it dry. You can also put cutting boards in the dishwasher.

Biggest challenge: Clean work surfaces only with seemingly clean textiles. If you use the same dirty cloths and kitchen sponges on different dishes, this increases the risk of germs. Regular disinfection helps. Even drains provide bacteria with a humid climate. You get them clean with soda or baking soda and a toothbrush. This way, stains, stubborn dirt and even odors can easily be put to flight. Plums can also be cured regularly.

If a child is born by cesarean section, the baby's body is populated with unrelated microorganisms. As a result, his natural immunity decreases, and the risk of allergic reactions increases. By the age of three, most of the child’s microbiome is mature. Each person has his own unique set of microorganisms inhabiting him.

From hand to hand: bacteria love door handles. If the penis is still sore, the mini-pests are even happier. Especially in this case: wash your hands regularly. Antibacterial soaps should be avoided in any case because they are real shells that kill all bacterial strains. Natural soap is a healthier alternative.

Various bacterial strains

You should change every three months. Not only because of bacteria, but also because you break down the brushes over time. Despite all the described “household confusion”: bacteria are not bad in themselves. There are good and bad strains of bacteria, and most people can easily cope with both strains. Normal households are colonized with healthy bacterial flora.

Bacteria are used by humans in the production of medicines and food. They break down organic compounds, purifying them and turning dirty waste into harmless water. Soil microorganisms produce nitrogen compounds necessary for plant growth. Single-celled organisms actively process organic matter and carry out the circulation of substances in nature, which is the basis of life on our planet.

Bacteria are the oldest group of organisms currently existing on Earth. The first bacteria probably appeared more than 3.5 billion years ago and for almost a billion years they were the only living creatures on our planet. Since these were the first representatives of living nature, their body had a primitive structure.

Over time, their structure became more complex, but to this day bacteria are considered the most primitive single-celled organisms. It is interesting that some bacteria still retain the primitive features of their ancient ancestors. This is observed in bacteria living in hot sulfur springs and anoxic mud at the bottom of reservoirs.

Most bacteria are colorless. Only a few are purple or green. But the colonies of many bacteria have a bright color, which is caused by the release of a colored substance into the environment or pigmentation of cells.

The discoverer of the world of bacteria was Antony Leeuwenhoek, a Dutch naturalist of the 17th century, who first created a perfect magnifying microscope that magnifies objects 160-270 times.

Bacteria are classified as prokaryotes and are classified into a separate kingdom - Bacteria.

Body Shape

Bacteria are numerous and diverse organisms. They vary in shape.

Name of the bacterium	Bacteria shape	Bacteria image
Cocci		Ball-shaped
Bacillus		Rod-shaped
Vibrio		Comma-shaped
Spirillum		Spiral
Streptococci		Chain of cocci
Staphylococcus		Clusters of cocci
Diplococcus		Two round bacteria enclosed in one mucous capsule

Methods of transportation

Among bacteria there are mobile and immobile forms. Motiles move due to wave-like contractions or with the help of flagella (twisted helical threads), which consist of a special protein called flagellin. There may be one or more flagella. In some bacteria they are located at one end of the cell, in others - at two or over the entire surface.

But movement is also inherent in many other bacteria that lack flagella. Thus, bacteria covered on the outside with mucus are capable of gliding movement.

Some aquatic and soil bacteria lacking flagella have gas vacuoles in the cytoplasm. There may be 40-60 vacuoles in a cell. Each of them is filled with gas (presumably nitrogen). By regulating the amount of gas in the vacuoles, aquatic bacteria can sink into the water column or rise to its surface, and soil bacteria can move in the soil capillaries.

Habitat

Due to their simplicity of organization and unpretentiousness, bacteria are widespread in nature. Bacteria are found everywhere: in a drop of even the purest spring water, in grains of soil, in the air, on rocks, in polar snow, desert sands, on the ocean floor, in oil extracted from great depths, and even in the water of hot springs with a temperature of about 80ºC. They live on plants, fruits, various animals and in humans in the intestines, oral cavity, limbs, and on the surface of the body.

Bacteria are the smallest and most numerous living creatures. Due to their small size, they easily penetrate into any cracks, crevices, or pores. Very hardy and adapted to various living conditions. They tolerate drying, extreme cold, and heating up to 90ºC without losing their viability.

There is practically no place on Earth where bacteria are not found, but in varying quantities. The living conditions of bacteria are varied. Some of them require atmospheric oxygen, others do not need it and are able to live in an oxygen-free environment.

In the air: bacteria rise to the upper atmosphere up to 30 km. and more.

There are especially many of them in the soil. 1 g of soil can contain hundreds of millions of bacteria.

In water: in the surface layers of water in open reservoirs. Beneficial aquatic bacteria mineralize organic residues.

In living organisms: pathogenic bacteria enter the body from the external environment, but only under favorable conditions cause diseases. Symbiotic live in the digestive organs, helping to break down and absorb food, and synthesize vitamins.

External structure

The bacterial cell is covered with a special dense shell - a cell wall, which performs protective and supporting functions, and also gives the bacterium a permanent, characteristic shape. The cell wall of a bacterium resembles the wall of a plant cell. It is permeable: through it, nutrients freely pass into the cell, and metabolic products exit into the environment. Often, bacteria produce an additional protective layer of mucus on top of the cell wall - a capsule. The thickness of the capsule can be many times greater than the diameter of the cell itself, but it can also be very small. The capsule is not an essential part of the cell; it is formed depending on the conditions in which the bacteria find themselves. It protects the bacteria from drying out.

On the surface of some bacteria there are long flagella (one, two or many) or short thin villi. The length of the flagella can be many times greater than the size of the body of the bacterium. Bacteria move with the help of flagella and villi.

Internal structure

Inside the bacterial cell there is dense, immobile cytoplasm. It has a layered structure, there are no vacuoles, therefore various proteins (enzymes) and reserve nutrients are located in the substance of the cytoplasm itself. Bacterial cells do not have a nucleus. A substance carrying hereditary information is concentrated in the central part of their cell. Bacteria, - nucleic acid - DNA. But this substance is not formed into a nucleus.

The internal organization of a bacterial cell is complex and has its own specific characteristics. The cytoplasm is separated from the cell wall by the cytoplasmic membrane. In the cytoplasm there is a main substance, or matrix, ribosomes and a small number of membrane structures that perform a variety of functions (analogues of mitochondria, endoplasmic reticulum, Golgi apparatus). The cytoplasm of bacterial cells often contains granules of various shapes and sizes. The granules may be composed of compounds that serve as a source of energy and carbon. Droplets of fat are also found in the bacterial cell.

In the central part of the cell, the nuclear substance is localized - DNA, which is not delimited from the cytoplasm by a membrane. This is an analogue of the nucleus - a nucleoid. The nucleoid does not have a membrane, a nucleolus, or a set of chromosomes.

Eating methods

Bacteria have different feeding methods. Among them there are autotrophs and heterotrophs. Autotrophs are organisms that are capable of independently producing organic substances for their nutrition.

Plants need nitrogen, but cannot absorb nitrogen from the air themselves. Some bacteria combine nitrogen molecules in the air with other molecules, resulting in substances that are available to plants.

These bacteria settle in the cells of young roots, which leads to the formation of thickenings on the roots, called nodules. Such nodules form on the roots of plants of the legume family and some other plants.

The roots provide the bacteria with carbohydrates, and the bacteria provide the roots with nitrogen-containing substances that can be absorbed by the plant. Their cohabitation is mutually beneficial.

Plant roots secrete a lot of organic substances (sugars, amino acids and others) that bacteria feed on. Therefore, especially many bacteria settle in the soil layer surrounding the roots. These bacteria convert dead plant debris into plant-available substances. This layer of soil is called the rhizosphere.

There are several hypotheses about the penetration of nodule bacteria into root tissue:

through damage to epidermal and cortex tissue;
through root hairs;
only through the young cell membrane;
thanks to companion bacteria producing pectinolytic enzymes;
due to stimulation of the synthesis of B-indoleacetic acid from tryptophan, always present in plant root secretions.

The process of introduction of nodule bacteria into root tissue consists of two phases:

infection of root hairs;
process of nodule formation.

In most cases, the invading cell actively multiplies, forms so-called infection threads and, in the form of such threads, moves into the plant tissue. Nodule bacteria emerging from the infection thread continue to multiply in the host tissue.

Plant cells filled with rapidly multiplying cells of nodule bacteria begin to rapidly divide. The connection of a young nodule with the root of a legume plant is carried out thanks to vascular-fibrous bundles. During the period of functioning, the nodules are usually dense. By the time optimal activity occurs, the nodules acquire a pink color (thanks to the leghemoglobin pigment). Only those bacteria that contain leghemoglobin are capable of fixing nitrogen.

Nodule bacteria create tens and hundreds of kilograms of nitrogen fertilizer per hectare of soil.

Metabolism

Bacteria differ from each other in their metabolism. In some it occurs with the participation of oxygen, in others - without it.

Most bacteria feed on ready-made organic substances. Only a few of them (blue-green, or cyanobacteria) are capable of creating organic substances from inorganic ones. They played an important role in the accumulation of oxygen in the Earth's atmosphere.

Bacteria absorb substances from the outside, tear their molecules into pieces, assemble their shell from these parts and replenish their contents (this is how they grow), and throw unnecessary molecules out. The shell and membrane of the bacterium allows it to absorb only the necessary substances.

If the shell and membrane of a bacterium were completely impermeable, no substances would enter the cell. If they were permeable to all substances, the contents of the cell would mix with the medium - the solution in which the bacterium lives. To survive, bacteria need a shell that allows necessary substances to pass through, but not unnecessary substances.

The bacterium absorbs nutrients located near it. What happens next? If it can move independently (by moving a flagellum or pushing mucus back), then it moves until it finds the necessary substances.

If it cannot move, then it waits until diffusion (the ability of molecules of one substance to penetrate into the thicket of molecules of another substance) brings the necessary molecules to it.

Bacteria, together with other groups of microorganisms, perform enormous chemical work. By converting various compounds, they receive the energy and nutrients necessary for their life. Metabolic processes, methods of obtaining energy and the need for materials for building the substances of their bodies are diverse in bacteria.

Other bacteria satisfy all their needs for carbon necessary for the synthesis of organic substances in the body at the expense of inorganic compounds. They are called autotrophs. Autotrophic bacteria are capable of synthesizing organic substances from inorganic ones. Among them are:

Chemosynthesis

The use of radiant energy is the most important, but not the only way to create organic matter from carbon dioxide and water. Bacteria are known that use not sunlight as an energy source for such synthesis, but the energy of chemical bonds occurring in the cells of organisms during the oxidation of certain inorganic compounds - hydrogen sulfide, sulfur, ammonia, hydrogen, nitric acid, ferrous compounds of iron and manganese. They use the organic matter formed using this chemical energy to build the cells of their body. Therefore, this process is called chemosynthesis.

The most important group of chemosynthetic microorganisms are nitrifying bacteria. These bacteria live in the soil and oxidize ammonia formed during the decay of organic residues to nitric acid. The latter reacts with mineral compounds of the soil, turning into salts of nitric acid. This process takes place in two phases.

Iron bacteria convert ferrous iron into oxide iron. The resulting iron hydroxide settles and forms the so-called bog iron ore.

Some microorganisms exist due to the oxidation of molecular hydrogen, thereby providing an autotrophic method of nutrition.

A characteristic feature of hydrogen bacteria is the ability to switch to a heterotrophic lifestyle when provided with organic compounds and the absence of hydrogen.

Thus, chemoautotrophs are typical autotrophs, since they independently synthesize the necessary organic compounds from inorganic substances, and do not take them ready-made from other organisms, like heterotrophs. Chemoautotrophic bacteria differ from phototrophic plants in their complete independence from light as an energy source.

Bacterial photosynthesis

Some pigment-containing sulfur bacteria (purple, green), containing specific pigments - bacteriochlorophylls, are able to absorb solar energy, with the help of which hydrogen sulfide in their bodies is broken down and releases hydrogen atoms to restore the corresponding compounds. This process has much in common with photosynthesis and differs only in that in purple and green bacteria the hydrogen donor is hydrogen sulfide (occasionally carboxylic acids), and in green plants it is water. In both of them, the separation and transfer of hydrogen is carried out due to the energy of absorbed solar rays.

This bacterial photosynthesis, which occurs without the release of oxygen, is called photoreduction. Photoreduction of carbon dioxide is associated with the transfer of hydrogen not from water, but from hydrogen sulfide:

6СО 2 +12Н 2 S+hv → С6Н 12 О 6 +12S=6Н 2 О

The biological significance of chemosynthesis and bacterial photosynthesis on a planetary scale is relatively small. Only chemosynthetic bacteria play a significant role in the process of sulfur cycling in nature. Absorbed by green plants in the form of sulfuric acid salts, sulfur is reduced and becomes part of protein molecules. Further, when dead plant and animal remains are destroyed by putrefactive bacteria, sulfur is released in the form of hydrogen sulfide, which is oxidized by sulfur bacteria to free sulfur (or sulfuric acid), forming sulfites in the soil that are accessible to plants. Chemo- and photoautotrophic bacteria are essential in the nitrogen and sulfur cycle.

Sporulation

Spores form inside the bacterial cell. During the process of sporulation, the bacterial cell undergoes a number of biochemical processes. The amount of free water in it decreases and enzymatic activity decreases. This ensures the resistance of the spores to unfavorable environmental conditions (high temperature, high salt concentration, drying, etc.). Sporulation is characteristic of only a small group of bacteria.

Spores are an optional stage in the life cycle of bacteria. Sporulation begins only with a lack of nutrients or accumulation of metabolic products. Bacteria in the form of spores can remain dormant for a long time. Bacterial spores can withstand prolonged boiling and very long freezing. When favorable conditions occur, the spore germinates and becomes viable. Bacterial spores are an adaptation to survive in unfavorable conditions.

Reproduction

Bacteria reproduce by dividing one cell into two. Having reached a certain size, the bacterium divides into two identical bacteria. Then each of them begins to feed, grows, divides, and so on.

After cell elongation, a transverse septum gradually forms, and then the daughter cells separate; In many bacteria, under certain conditions, after dividing, cells remain connected in characteristic groups. In this case, depending on the direction of the division plane and the number of divisions, different shapes arise. Reproduction by budding occurs as an exception in bacteria.

Under favorable conditions, cell division in many bacteria occurs every 20-30 minutes. With such rapid reproduction, the offspring of one bacterium in 5 days can form a mass that can fill all seas and oceans. A simple calculation shows that 72 generations (720,000,000,000,000,000,000 cells) can be formed per day. If converted into weight - 4720 tons. However, this does not happen in nature, since most bacteria quickly die under the influence of sunlight, drying, lack of food, heating to 65-100ºC, as a result of struggle between species, etc.

The bacterium (1), having absorbed enough food, increases in size (2) and begins to prepare for reproduction (cell division). Its DNA (in a bacterium the DNA molecule is closed in a ring) doubles (the bacterium produces a copy of this molecule). Both DNA molecules (3,4) find themselves attached to the wall of the bacterium and, as the bacterium elongates, move apart (5,6). First the nucleotide divides, then the cytoplasm.

After the divergence of two DNA molecules, a constriction appears on the bacterium, which gradually divides the body of the bacterium into two parts, each of which contains a DNA molecule (7).

It happens (in Bacillus subtilis) that two bacteria stick together and a bridge is formed between them (1,2).

The jumper transports DNA from one bacterium to another (3). Once in one bacterium, DNA molecules intertwine, stick together in some places (4), and then exchange sections (5).

The role of bacteria in nature

Gyre

Bacteria are the most important link in the general cycle of substances in nature. Plants create complex organic substances from carbon dioxide, water and mineral salts in the soil. These substances return to the soil with dead fungi, plants and animal corpses. Bacteria break down complex substances into simple ones, which are then used by plants.

Bacteria destroy complex organic substances of dead plants and animal corpses, excretions of living organisms and various wastes. Feeding on these organic substances, saprophytic bacteria of decay turn them into humus. These are a kind of orderlies of our planet. Thus, bacteria actively participate in the cycle of substances in nature.

Soil formation

Since bacteria are distributed almost everywhere and occur in huge numbers, they largely determine various processes occurring in nature. In autumn, the leaves of trees and shrubs fall, above-ground shoots of grasses die, old branches fall off, and from time to time the trunks of old trees fall. All this gradually turns into humus. In 1 cm3. The surface layer of forest soil contains hundreds of millions of saprophytic soil bacteria of several species. These bacteria convert humus into various minerals that can be absorbed from the soil by plant roots.

Some soil bacteria are able to absorb nitrogen from the air, using it in vital processes. These nitrogen-fixing bacteria live independently or settle in the roots of legume plants. Having penetrated the roots of legumes, these bacteria cause the growth of root cells and the formation of nodules on them.

These bacteria produce nitrogen compounds that plants use. Bacteria obtain carbohydrates and mineral salts from plants. Thus, there is a close relationship between the legume plant and the nodule bacteria, which is beneficial to both one and the other organism. This phenomenon is called symbiosis.

Thanks to symbiosis with nodule bacteria, leguminous plants enrich the soil with nitrogen, helping to increase yield.

Distribution in nature

Microorganisms are ubiquitous. The only exceptions are the craters of active volcanoes and small areas at the epicenters of exploded atomic bombs. Neither the low temperatures of Antarctica, nor the boiling streams of geysers, nor saturated salt solutions in salt pools, nor the strong insolation of mountain peaks, nor the harsh irradiation of nuclear reactors interfere with the existence and development of microflora. All living beings constantly interact with microorganisms, often being not only their repositories, but also their distributors. Microorganisms are natives of our planet, actively exploring the most incredible natural substrates.

Soil microflora

The number of bacteria in the soil is extremely large - hundreds of millions and billions of individuals per gram. There are much more of them in soil than in water and air. The total number of bacteria in soils changes. The number of bacteria depends on the type of soil, their condition, and the depth of the layers.

On the surface of soil particles, microorganisms are located in small microcolonies (20-100 cells each). They often develop in the thickness of clots of organic matter, on living and dying plant roots, in thin capillaries and inside lumps.

The soil microflora is very diverse. Here there are different physiological groups of bacteria: putrefaction bacteria, nitrifying bacteria, nitrogen-fixing bacteria, sulfur bacteria, etc. among them there are aerobes and anaerobes, spore and non-spore forms. Microflora is one of the factors in soil formation.

The area of development of microorganisms in the soil is the zone adjacent to the roots of living plants. It is called the rhizosphere, and the totality of microorganisms contained in it is called the rhizosphere microflora.

Microflora of reservoirs

Water is a natural environment where microorganisms develop in large numbers. The bulk of them enters the water from the soil. A factor that determines the number of bacteria in water and the presence of nutrients in it. The cleanest waters are from artesian wells and springs. Open reservoirs and rivers are very rich in bacteria. The largest number of bacteria is found in the surface layers of water, closer to the shore. As you move away from the shore and increase in depth, the number of bacteria decreases.

Clean water contains 100-200 bacteria per ml, and polluted water contains 100-300 thousand or more. There are many bacteria in the bottom sludge, especially in the surface layer, where the bacteria form a film. This film contains a lot of sulfur and iron bacteria, which oxidize hydrogen sulfide to sulfuric acid and thereby prevent fish from dying. There are more spore-bearing forms in silt, while non-spore-bearing forms predominate in water.

In terms of species composition, the microflora of water is similar to the microflora of soil, but there are also specific forms. By destroying various waste that gets into the water, microorganisms gradually carry out the so-called biological purification of water.

Air microflora

The microflora of the air is less numerous than the microflora of soil and water. Bacteria rise into the air with dust, can remain there for some time, and then settle on the surface of the earth and die from lack of nutrition or under the influence of ultraviolet rays. The number of microorganisms in the air depends on the geographical zone, terrain, time of year, dust pollution, etc. each speck of dust is a carrier of microorganisms. Most bacteria are in the air above industrial enterprises. The air in rural areas is cleaner. The cleanest air is over forests, mountains, and snowy areas. The upper layers of air contain fewer microbes. The air microflora contains many pigmented and spore-bearing bacteria, which are more resistant than others to ultraviolet rays.

Microflora of the human body

The human body, even a completely healthy one, is always a carrier of microflora. When the human body comes into contact with air and soil, various microorganisms, including pathogenic ones (tetanus bacilli, gas gangrene, etc.), settle on clothing and skin. The most frequently exposed parts of the human body are contaminated. E. coli and staphylococci are found on the hands. There are over 100 types of microbes in the oral cavity. The mouth, with its temperature, humidity, and nutrient residues, is an excellent environment for the development of microorganisms.

The stomach has an acidic reaction, so the majority of microorganisms in it die. Starting from the small intestine, the reaction becomes alkaline, i.e. favorable for microbes. The microflora in the large intestines is very diverse. Each adult excretes about 18 billion bacteria daily in excrement, i.e. more individuals than people on the globe.

Internal organs that are not connected to the external environment (brain, heart, liver, bladder, etc.) are usually free of microbes. Microbes enter these organs only during illness.

Bacteria in the cycle of substances

Microorganisms in general and bacteria in particular play a large role in the biologically important cycles of substances on Earth, carrying out chemical transformations that are completely inaccessible to either plants or animals. Different stages of the cycle of elements are carried out by organisms of different types. The existence of each individual group of organisms depends on the chemical transformation of elements carried out by other groups.

Nitrogen cycle

The cyclic transformation of nitrogenous compounds plays a primary role in supplying the necessary forms of nitrogen to organisms of the biosphere with different nutritional needs. Over 90% of total nitrogen fixation is due to the metabolic activity of certain bacteria.

Carbon cycle

The biological transformation of organic carbon into carbon dioxide, accompanied by the reduction of molecular oxygen, requires the joint metabolic activity of various microorganisms. Many aerobic bacteria carry out complete oxidation of organic substances. Under aerobic conditions, organic compounds are initially broken down by fermentation, and the organic end products of fermentation are further oxidized by anaerobic respiration if inorganic hydrogen acceptors (nitrate, sulfate, or CO 2 ) are present.

Sulfur cycle

Sulfur is available to living organisms mainly in the form of soluble sulfates or reduced organic sulfur compounds.

Iron cycle

Some freshwater bodies contain high concentrations of reduced iron salts. In such places, a specific bacterial microflora develops - iron bacteria, which oxidize reduced iron. They participate in the formation of bog iron ores and water sources rich in iron salts.

Bacteria are the most ancient organisms, appearing about 3.5 billion years ago in the Archean. For about 2.5 billion years they dominated the Earth, forming the biosphere, and participated in the formation of the oxygen atmosphere.

Bacteria are one of the most simply structured living organisms (except viruses). They are believed to be the first organisms to appear on Earth.

Life on our planet began with bacteria. Scientists believe that this is where it all ends. There is a joke that when aliens studied the Earth, they could not understand who its real owner was - a person or a bacillus. The most interesting facts about bacteria are selected below.

A bacterium is a separate organism that reproduces by division. The more favorable the habitat, the sooner it divides. These microorganisms live in all living things, as well as in water, food, rotten trees, and plants.

The list is not limited to this. The bacilli survive well on objects that have been touched by humans. For example, on a handrail in public transport, on the handle of a refrigerator, on the tip of a pencil. Interesting facts about bacteria were recently discovered from the University of Arizona. According to their observations, “sleeping” microorganisms live on Mars. Scientists are confident that this is one of the proofs of the existence of life on other planets; in addition, in their opinion, alien bacteria can be “revived” on Earth.

The microorganism was first examined in an optical microscope by the Dutch scientist Antonius van Leeuwenhoek at the end of the 17th century. Currently, there are about two thousand known species of bacilli. All of them can be divided into:

harmful;
useful;
neutral.

At the same time, the harmful ones usually fight with the beneficial and neutral ones. This is one of the most common reasons why a person gets sick.

The most interesting facts

In general, single-celled organisms participate in all life processes.

Bacteria and people

From birth, a person enters a world full of various microorganisms. Some help him survive, others cause infections and diseases.

The most curious interesting facts about bacteria and people:

It turns out that the bacillus can either completely cure a person or destroy our species. Currently, bacterial toxins already exist.

How did bacteria help us survive?

Here are some more interesting facts about bacteria that benefit humans:

some types of bacilli protect people from allergies;
with the help of bacteria you can dispose of hazardous waste (for example, petroleum products);
Without microorganisms in the intestines, a person would not survive.

How to tell kids about bacilli?

Children are ready to talk about bacilli at the age of 3-4 years. To convey the information correctly, it is worth telling interesting facts about bacteria. For children, for example, it is very important to understand that there are evil and good microbes. That the good ones can turn milk into fermented baked milk. And also that they help the tummy digest food.

Attention needs to be paid to evil bacteria. Tell them that they are very small, so they are not visible. That when they enter the human body, there are quickly a lot of microbes, and they begin to eat us from the inside.

The child must know to prevent the evil microbe from entering the body:

Wash your hands after going outside and before eating.
Don't eat a lot of sweets.
Get vaccinated.

The best way to demonstrate bacteria is through pictures and encyclopedias.

What should every student know?

With an older child, it is better to talk not about germs, but about bacteria. It is important to give reasons for interesting facts for schoolchildren. That is, when talking about the importance of hand washing, you can tell that 340 colonies of harmful bacilli live on toilet handles.

You can find information together about which bacteria cause tooth decay. And also tell the student that chocolate in small quantities has an antibacterial effect.

Even a primary school student can understand what a vaccine is. This is when a small amount of virus or bacteria is introduced into the body and the immune system defeats it. This is why it is so important to get vaccinated.

Already from childhood, an understanding should come that the country of bacteria is a whole world that has not yet been fully studied. And as long as these microorganisms exist, the human species itself exists.

Dwarfs and giants among bacteria

Reproduction of Epulopiscium

Namibian sulfur pearl

Study of Thiomargarita

Victor Ostrovsky, Samogo.Net

Bacteria are the oldest form of life on Earth

Thiomargarita namibiensis, Namibian sulfur pearl, is the name of the largest bacteria known to man. You don't need a microscope to see it; its length is 750 microns. The giant of the microcosm was discovered by a German scientist in the bottom waters during an expedition on a Russian scientific vessel.

Epulopiscium fishelsoni lives in the intestines of surgeonfish and is 700 microns in length. The volume of this bacterium is 2000 times greater than the volume of a standard-sized microorganism. The large, single-celled organism was originally found inside surgeonfish that inhabit the Red Sea, but has since been found in other fish species in the Great Barrier Reef area.
Spirochetes are bacteria with long, spiral cells. Very mobile. They live in water, soil or other nutritious medium. Many spirochetes are causative agents of serious human diseases, while other varieties are saprophytes - they decompose dead organic matter. These bacteria can grow to a length of 250 microns.
Cyanobacteria are the oldest microorganisms. Scientists have found products of their vital activity that are more than 3.5 billion years old. These single-celled organisms are part of oceanic plankton and produce 20-40% of the oxygen on Earth. Spirulina is dried, ground and added to food. Oxygenic photosynthesis is characteristic of algae and higher plants. Cyanobacteria are the only single-celled organisms that produce oxygen during photosynthesis. It was thanks to cyanobacteria that a large supply of oxygen appeared in the Earth's atmosphere. The cell width of these bacteria varies from 0.5 to 100 microns.

Actinomycetes live in the intestines of most invertebrates. Their diameter is 0.4-1.5 microns. There are pathogenic forms of actinomycetes that live in dental plaque and in the human respiratory tract. Thanks to actinomycetes, humans also experience the specific “smell of rain.”
Beggiatoa alba. Proteobacteria of this genus inhabit places rich in sulfur, fresh rivers and seas. The size of these bacteria is 10x50 microns.
Azotobacter has a diameter of 1-2 microns, lives in slightly alkaline or neutral environments, plays an important role in the nitrogen cycle, increases soil fertility and stimulates plant growth.
Mycoplasma mycoides is a causative agent of pulmonary diseases in cows and goats. These cells have a size of 0.25-0.75 microns. Bacteria do not have a hard shell; they are protected from the external environment only by a cytoplasmic membrane. The genome of this type of bacteria is one of the simplest.

The role of bacteria in nature

If a child is born by caesarean section, the baby’s body is colonized by unrelated microorganisms. As a result, his natural immunity decreases and the risk of allergic reactions increases. By the age of three, most of the child’s microbiome is mature. Each person has his own unique set of microorganisms inhabiting him.

Bacteria are used by humans in the production of medicines and food products. They break down organic compounds, purifying them and turning dirty waste into harmless water. Soil microorganisms produce nitrogen compounds necessary for plant growth. Single-celled organisms actively process organic matter and carry out the circulation of substances in nature, which is the basis of life on our planet.