Determining the role played by bacteria in nature. bacteria

The message on the importance of bacteria in human life, summarized in this article, will tell you all about these organisms.

What is the importance of bacteria in nature?

Bacteria of the nodule species can absorb nitrogen from the air and enrich the soil with nitrogen substances. In general, bacteria destroy the complex substances of plant and animal corpses, absorb harmful excretions of organisms and waste. They play the role of orderlies, turning the leaves of shrubs and trees, above-ground shoots of perennials and herbaceous annuals into humus. Bacteria are a powerful biotic factor in nature, as they form not only humus, but also humus.

Speaking about the soil-forming work of bacteria, they created the first soil on the planet. And today its quality is completely dependent on these organisms.

What is the importance of bacteria in human life?

The positive significance of bacteria in human life lies in the fact that they are used in Food Industry. For example: a person makes extensive use of lactic acid bacteria, which feed on sugar in milk and form lactic acid. She, in turn, turns milk into curdled milk, and if it is cream, then into sour cream.

AT agriculture also not without bacteria. With their help, forage is ensiled and vegetables are fermented. Bacterial lactic acid also prevents food and vegetables from decomposing.

Man uses the activity of certain bacteria in the production of drugs, new foods, organic substances. They can produce strong antibiotics that suppress disease-causing organisms.

Negative value of bacteria in human life

Here's another thing about the importance of bacteria in human life - negative. Many of their species cause national economy harm, settling on products and spoiling them. There are bacteria that can spoil fishing nets, books and the rarest manuscripts in book depositories.

And for the person himself, they can also be harmful. Botulinum bacteria cause the most dangerous food poisoning leading to death - botulism. Bacilli accumulate in mushroom and meat products, releasing the poison botulinum.

There are also such types of pathogenic bacteria- salmonella (causes typhoid fever), shigella (causes dysentery), tuberculosis bacillus, clostridium (causes tetanus and gangrene), staphylococci and streptococci.

We hope that the report “The Importance of Bacteria in Human Life” helped you prepare for the lesson. And you can supplement the message "The importance of bacteria in life" through the comment form.

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

Over time, their structure became more complex, but even today bacteria are considered the most primitive unicellular organisms. Interestingly, some bacteria still retain the primitive features of their ancient ancestors. This is observed in bacteria that live in hot sulfur springs and anoxic silts at the bottom of reservoirs.

Most bacteria are colorless. Only a few are colored purple or green. But the colonies of many bacteria have a bright color, which is due to the release of a colored substance in environment or cell pigmentation.

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

Bacteria are classified as prokaryotes and are isolated into separate kingdom— Bacteria.

body shape

Bacteria are numerous and diverse organisms. They differ in form.

bacterium name	Bacteria shape	Bacteria image
cocci		spherical
Bacillus		rod-shaped
Vibrio		curved comma
Spirillum		Spiral
streptococci		Chain of cocci
Staphylococci		Clusters of cocci
diplococci		Two round bacteria enclosed in one slimy capsule

Ways of transportation

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

But movement is also inherent in many other bacteria that do not have flagella. So, bacteria covered with mucus on the outside are capable of sliding movement.

Some water and soil bacteria without flagella have gas vacuoles in the cytoplasm. There can be 40-60 vacuoles in a cell. Each of them is filled with gas (presumably nitrogen). By regulating the amount of gas in vacuoles, aquatic bacteria can sink into the water column or rise to its surface, while soil bacteria can move in soil capillaries.

Habitat

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

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

There is practically no place on Earth where bacteria would not be found, but in different quantities. The living conditions of bacteria are varied. Some of them need air 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.

Especially a lot of them in the soil. One gram of soil can contain hundreds of millions of bacteria.

In water: in the surface water layers of 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 assimilate food, synthesize vitamins.

External structure

The bacterial cell is dressed in a special dense shell - the 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 shell of a plant cell. It is permeable: through it, nutrients freely pass into the cell, and metabolic products go out into the environment. Bacteria often develop an additional protective layer of mucus, a capsule, over the cell wall. The thickness of the capsule can be many times greater than the diameter of the cell itself, but it can be very small. The capsule is not an obligatory part of the cell, it is formed depending on the conditions in which the bacteria enter. It keeps 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 is a dense immobile cytoplasm. It has a layered structure, there are no vacuoles, so various proteins (enzymes) and reserve nutrients are located in the very substance of the cytoplasm. Bacterial cells do not have a nucleus. In the central part of their cell, a substance is concentrated that carries hereditary information. Bacteria, - nucleic acid - DNA. But this substance is not framed in the nucleus.

The internal organization of a bacterial cell is complex and has its own specific features. The cytoplasm is separated from the cell wall by the cytoplasmic membrane. In the cytoplasm, the 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) are distinguished. The cytoplasm of bacterial cells often contains granules 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, DNA, is localized, not separated from the cytoplasm by a membrane. This is an analogue of the nucleus - the nucleoid. Nucleoid does not have a membrane, nucleolus and a set of chromosomes.

Nutrition methods

Bacteria are observed different ways nutrition. Among them are autotrophs and heterotrophs. Autotrophs are organisms that can independently form organic substances for their nutrition.

Plants need nitrogen, but they themselves cannot absorb nitrogen from the air. Some bacteria combine nitrogen molecules in the air with other molecules, resulting in substances 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 are formed on the roots of plants of the legume family and some other plants.

The roots provide the bacteria with carbohydrates, and the bacteria give the roots nitrogen-containing substances that can be taken up by the plant. Their relationship is mutually beneficial.

Plant roots secrete many 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 residues into substances available to the plant. This layer of soil is called the rhizosphere.

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

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

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

• infection of the root hairs;
• nodule formation process.

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

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

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

Metabolism

Bacteria differ from each other in metabolism. For some, it goes with the participation of oxygen, for others - without its participation.

Most bacteria feed on ready-made organic substances. Only a few of them (blue-green, or cyanobacteria) are able to create 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 apart, assemble their shell from these parts and replenish their contents (this is how they grow), and throw out unnecessary molecules. The shell and membrane of the bacterium allows it to absorb only the right substances.

If the shell and membrane of the 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. For the survival of bacteria, a shell is needed that allows the necessary substances to pass through, but not those that are not needed.

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

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

Bacteria, together with other groups of microorganisms, perform a huge chemical job. By transforming various compounds, they receive the energy and nutrients necessary for their vital activity. Metabolic processes, ways of obtaining energy and the need for materials to build the substances of their body in bacteria are diverse.

Other bacteria satisfy all the needs for carbon necessary for the synthesis of organic substances of the body due to not organic compounds. They are called autotrophs. Autotrophic bacteria are able to synthesize organic substances from inorganic ones. Among them are distinguished:

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, as an energy source for such synthesis, do not use sunlight, but the energy of chemical bonds that occur in the cells of organisms during the oxidation of some inorganic compounds— hydrogen sulfide, sulfur, ammonia, hydrogen, nitric acid, ferrous compounds of iron and manganese. Formed using this chemical energy they use organic matter to build their body cells. Therefore, this process is called chemosynthesis.

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

Iron bacteria convert ferrous iron to oxide. The formed iron hydroxide settles and forms the so-called swamp iron ore.

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

A characteristic feature of hydrogen bacteria is the ability to switch to a heterotrophic lifestyle when provided with organic compounds and in 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 into 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 is split in their organisms and gives 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, hydrogen sulfide is a hydrogen donor (occasionally - carboxylic acids), while green plants have water. In those and others, the splitting and transfer of hydrogen is carried out due to the energy of absorbed solar rays.

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

6CO 2 + 12H 2 S + hv → C6H 12 O 6 + 12S \u003d 6H 2 O

The biological significance of chemosynthesis and bacterial photosynthesis on a planetary scale is relatively small. Only chemosynthetic bacteria play a significant role in the sulfur cycle in nature. Absorbed by green plants in the form of salts of sulfuric acid, sulfur is restored and becomes part of protein molecules. Further, during the destruction of dead plant and animal residues by putrefactive bacteria, sulfur is released in the form of hydrogen sulfide, which is oxidized by sulfur bacteria to free sulfur (or sulfuric acid), which forms sulfites available for plants in the soil. Chemo- and photoautotrophic bacteria are essential in the cycle of nitrogen and sulfur.

sporulation

Spores form inside the bacterial cell. In the process of spore formation, a bacterial cell undergoes a series of biochemical processes. The amount of free water in it decreases, enzymatic activity decreases. This ensures the resistance of spores to adverse environmental conditions ( high temperature, high salt concentration, drying, etc.). Spore formation is characteristic of only a small group of bacteria.

Disputes are not a mandatory stage life cycle bacteria. Sporulation begins only with a lack of nutrients or the accumulation of metabolic products. Bacteria in the form of spores long time be at rest. Bacterial spores withstand prolonged boiling and very long freezing. When favorable conditions occur, the dispute germinates and becomes viable. Bacterial spores are adaptations for survival in adverse 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 elongation of the cell, a transverse septum is gradually formed, and then the daughter cells diverge; in many bacteria, under certain conditions, cells after division remain connected in characteristic groups. In this case, depending on the direction of the division plane and the number of divisions, different forms. Reproduction by budding occurs in bacteria as an exception.

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 is able to form a mass that can fill all the seas and oceans. A simple calculation shows that 72 generations (720,000,000,000,000,000,000 cells) can be formed per day. If translated into weight - 4720 tons. However, this does not happen in nature, since most bacteria quickly die under the action of sunlight, during drying, lack of food, heating up to 65-100ºС, as a result of the 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) appear to be attached to the bacterial wall and, when elongated, the bacteria diverge to the sides (5.6). First, the nucleotide divides, then the cytoplasm.

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

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

DNA is transported from one bacterium to another via the jumper (3). Once in one bacterium, DNA molecules intertwine, stick together in some places (4), after which they exchange sections (5).

The role of bacteria in nature

Circulation

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

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

soil formation

Since bacteria are distributed almost everywhere and are found in huge numbers, they largely determine the various processes that occur in nature. In autumn, the leaves of trees and shrubs fall, the above-ground grass shoots die off, old branches fall off, and from time to time the trunks of old trees fall. All this gradually turns into humus. In 1 cm 3. 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 taken up from the soil by plant roots.

Some soil bacteria are able to absorb nitrogen from the air, using it in life processes. These nitrogen-fixing bacteria live on their own or take up residence in the roots of leguminous plants. Having penetrated into the roots of legumes, these bacteria cause the growth of root cells and the formation of nodules on them.

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

Thanks to their symbiosis with nodule bacteria, legumes enrich the soil with nitrogen, helping to increase yields.

Distribution in nature

Microorganisms are ubiquitous. The only exceptions are the craters of active volcanoes and small areas in the epicenters of exploded volcanoes. atomic bombs. Neither low temperatures Antarctica, nor boiling jets of geysers, nor saturated solutions salts in salt basins, neither strong insolation of mountain peaks, nor severe radiation nuclear reactors do not interfere with the existence and development of microflora. All living beings constantly interact with microorganisms, being often not only their storages, but also distributors. Microorganisms are the natives of our planet, actively developing the most incredible natural substrates.

Soil microflora

The number of bacteria in the soil is extremely large - hundreds of millions and billions of individuals in 1 gram. They are much more abundant in soil than in water and air. Total bacteria in soils is changing. The number of bacteria depends on the type of soil, their condition, the depth of the layers.

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

Soil microflora is very diverse. Different physiological groups of bacteria are found here: putrefactive, nitrifying, nitrogen-fixing, sulfur bacteria, etc. among them there are aerobes and anaerobes, spore and non-spore forms. Microflora is one of the factors of 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 - natural environment where microorganisms grow in abundance. Most of them enter the water from the soil. A factor that determines the number of bacteria in water, the presence of nutrients in it. The cleanest are the waters of artesian wells and springs. Open reservoirs and rivers are very rich in bacteria. The greatest number of bacteria is found in the surface layers of water, closer to the shore. With increasing distance from the coast and increasing depth, the number of bacteria decreases.

Pure water contains 100-200 bacteria per 1 ml, while contaminated water contains 100-300 thousand or more. There are many bacteria in the bottom silt, especially in the surface layer, where the bacteria form a film. There are a lot of sulfur and iron bacteria in this film, which oxidize hydrogen sulfide to sulfuric acid and thereby prevent fish from dying. There are more spore-bearing forms in the silt, while non-spore-bearing forms predominate in the water.

In terms of species composition, the water microflora is similar to the soil microflora, but specific forms are also found. Destroying various wastes that have fallen into the water, microorganisms gradually carry out the so-called biological purification of water.

Air microflora

Air microflora is less numerous than soil and water microflora. Bacteria rise into the air with dust, may stay there for some time, and then settle to 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 geographical area, terrain, season, dust pollution, etc. each speck of dust is a carrier of microorganisms. Most bacteria in the air over industrial enterprises. Air countryside cleaner. The cleanest air is over forests, mountains, snowy spaces. The upper layers of the air contain fewer germs. In the air microflora there are many pigmented and spore-bearing bacteria that are more resistant than others to ultraviolet rays.

Microflora of the human body

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

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

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

Bacteria in the cycling

Microorganisms in general and bacteria in particular big role in the biologically important cycles of substances on Earth, carrying out chemical transformations that are completely inaccessible to either plants or animals. Various stages of the cycle of elements are carried out by organisms of different types. The existence of each separate 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 paramount role in supplying the necessary forms of nitrogen to various biosphere organisms in terms of nutritional needs. Over 90% of total nitrogen fixation is due to the metabolic activity of certain bacteria.

The carbon cycle

Biological conversion of organic carbon into carbon dioxide, accompanied by the reduction of molecular oxygen, requires joint metabolic activity a variety of microorganisms. Many aerobic bacteria carry out the complete oxidation of organic substances. Under aerobic conditions, organic compounds are initially broken down by fermentation, and organic fermentation end products are further oxidized by anaerobic respiration if inorganic hydrogen acceptors (nitrate, sulfate, or CO2) are present.

Sulfur cycle

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

The iron cycle

In some water bodies, fresh water 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 marsh iron ores and water sources rich in iron salts.

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

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

MBOU secondary school №85 Naumova Ekaterina 2G

BACTERIA. THE ROLE OF BACTERIA IN NATURE AND HUMAN LIFE

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MUNICIPAL BUDGET GENERAL EDUCATIONAL INSTITUTION OF THE CITY OF ULYANOVSK

SECONDARY SCHOOL №85

TOPIC OF RESEARCH WORK:

"BACTERIA. ROLE OF BACTERIA IN NATURE

AND HUMAN LIFE"

Completed by: 2nd grade student G

Naumova Ekaterina

Work manager:

Makarenko Elena Nikolaevna

Ulyanovsk, 2013

Maintaining…………………………………………………………..…………………................................ ..3

1. Bacteria are the most ancient inhabitants of the Earth………………………….……………………...3

1. Nutrition and habitat of bacteria…………………………….……………………….3

1. The role of bacteria…………………………….………………………………………………..3

1. Vital activity in nature………………………………………………………..4

1. Help in human life……………………………….………………………………4

1. Wayward defenders………………………….……………………………………...4

1. The harm of bacteria……….…………………………………………………………...…….4

Application. Practical work ………………………………….………………………5

Conclusion……………………………………………………………………………….……6

Literature…………………………………………………………………………….…….…7

Introduction.

And in the depths of the seas, and in the soil under our feet, myriads of tiny creatures live. Bacteria are the smallest organisms on earth. If you put one of them on the tip of a needle and enlarge the needle to the size ballistic missile, then the bacterium could hardly be seen on its tip with the naked eye. But these babies are the most on the planet. One teaspoon of ordinary garden soil contains at least five billion bacteria, and the skin healthy person there are usually ten times as many of them as there are cells in his entire body. Fortunately, most bacteria do not harm us.

I became curious and wanted to learn more about these mysterious organisms.

The purpose of my work:get acquainted with the world of bacteria hidden from us. Find out what benefits such tiny organisms can bring. Conduct an experiment with milk, using the example of bifidobacteria, and see what changes occur in the course of their life.

1 . Bacteria are the most ancient inhabitants of the Earth.

Bacteria appeared on Earth before all other living beings. Petrified bacteria found in rocks that are 3.5 billion years old! Surprisingly, these ancient organisms continue to exist today. Since bacteria are very small, we do not notice them. But, as in the days of their origin, they continue to do important and necessary work in nature.

2. Nutrition and habitat of bacteria.

Bacteria are organisms made up of one cell. These organisms can feed various substances: dead plants and animals, metals, oil, even plastic. They are widely distributed in nature: they are found in soil, water, plants, humans and animals. Bacteria can live everywhere. They can be found among polar ice and in the craters of volcanoes, at the height of the clouds and at the bottom of the deepest seas. Bacteria adapt quickly to any changes.

3. The role of bacteria.

The role of bacteria is great. Some micro-organisms are harmful to us, but most are of great benefit, ensuring the cycle of substances in nature. There are bacteria that, before plants, learned how to make nutrients with the help of sunlight and were the first to release oxygen into the air.

1. Vital activity in nature.

Bacteria recycle waste, without them our planet would turn into a big dump.

Bacteria create mineral reserves: iron ore, oil, sulfur - from which many useful things are made.

1. Help in a person's life.

Many bacteria help a person: they make medicines, purify the soil, cook food products. Some make curdled milk, yogurt, cottage cheese, cheese. Others - sauerkraut. Still others - prepare vinegar. Without such skilled helpers, life would be more difficult for us.

1. Wayward defenders.

Bacteria play a huge role in sustaining life on our planet and protecting us from disease.

Our body is inhabited by more than 100 trillion bacteria: they are always present on the skin, in respiratory tract, in the digestive tract. After a thorough wash, we are freed from the billions of bacteria that are on the surface of the body, but even more of them remain. Usually these permanent residents are very useful: they displace dangerous microbes from the occupied space.

However, they serve faithfully only where they are supposed to. Once in the wrong place, these guards turn from friends into enemies. For example, Staphylococcus aureus is harmless as long as it lives on the nasal mucosa. Once inside the body, say through a wound, it becomes dangerous, causing ear infections. Food poisoning.

1. Damage to bacteria.

But not all bacteria help people, there are some that cause disease. They enter our body along with dirty water, unwashed fruits and vegetables. To protect yourself from them, you need to wash your hands before eating, dress properly, and get vaccinated.

Application

Practical work. useful transformation.

Target: observe and see what happens.

Equipment:

• milk;

• boiled water;

• one bottle of bifidumbacterin;

• transparent glass;

• tea spoon;

• small saucepan.

Progress:

1. I pour milk into a saucepan. Under the control of my parents, I put it on an electric stove, waiting for the milk to boil.

1. As soon as the milk boils, I remove the pan from the stove and wait until the milk becomes warm. Pour warm milk into a glass.

1. I ask for help from my parents to open a bottle of bifidumbacterin. In this bottle I add 4 teaspoons of boiled water at room temperature. In order for the contents of the vial to dissolve, the vial must be closed with a stopper and shaken thoroughly. Leave for a few minutes until the contents are completely dissolved.

1. After that, the liquid from the bottle is poured into a glass of milk. Mix well and leave the glass in a conspicuous place.

1. Milk in a glass after adding bifidobacteria remained the same white, liquid, not transparent as before they were combined.

1. I stirred the milk with bacteria every 3 hours.

1. And only the next day, exactly 24 hours later, the milk changed. It remained the same white, not transparent, but turned into kefir, a semi-liquid consistency. It tasted like a very delicate and tasty drink that my mother always makes and gives us to drink when we are sick and take antibiotics.

Conclusion.

Having conducted the experiment, I was convinced that changes do occur in milk under the influence of bacteria. As a result of their vital activity, a fermented milk product is obtained, very tasty and healthy. This is how various fermented milk products are obtained: yogurt, yogurt, cottage cheese, sour cream, cheese. These foods are useful for people of all ages without exception. Hence the conclusion that the role of bacteria in human life is very great.

Having become acquainted with the activity of these microorganisms and having learned their benefits, it seems to me that without them we simply could not live.

Used Books:

1. Living world. Danilova M.N., Lazareva O.N. - Yekaterinburg: U - Factoria, 2001 - p. eleven,

118, 119.

2. Milk and dairy products. Kuchenev P.V. - 3rd edition, M .: Rosselkhozizdat, 1985 -

pp. 46, 54.

3. My first scientific experiments. Publisher: Kristina - new century, 2003, p. - 31.

The word “bacteria” first of all brings to mind terrible microbes that are responsible for almost everything - from the banal flu to cancer as a consequence of the disease. So what is the true significance of bacteria in nature and human life? Let's start with the fact that it was bacteria, according to the opinion of scientists that has not yet been refuted, were the first organisms that appeared on our planet. And if these "discoverers" did not release oxygen, then poor humanity would have no chance of survival. Even more, if the bacteria had not attended to the creation of protein as such, then the presence of protein life (including us) could be safely forgotten!

Bacterial cells were the first inhabitants of the Earth and it was they who created all of nature.

According to the official version of history, bacteria appeared on Earth several billion years ago, and then for about a billion years no one prevented them from enjoying life in splendid isolation. In comparison with the history of mankind, numbering some hundreds of thousands of years, this is a huge period. During this time, microorganisms have learned to adapt to the environment, changing their structure, and to change the environment, adapting it to their needs.

The vitality of bacteria is incomparable, perhaps, with any living organism on Earth. They live:

• in ocean depths under tremendous pressure;
• in conditions of arctic cold, and retain the ability to exist after defrosting;
• in hot springs at temperatures of a hundred degrees (and even more!);
• in the human stomach, resisting the action of hydrochloric acid;
• in the vents of underwater volcanoes, where three (minimum) aggressive factors converge simultaneously - temperature, pressure, poisonous gases;
• in the upper rarefied layers of the atmosphere, where it is already closer to cosmic cold than to warm earth;
• deep underground, they survive by eating sulfur compounds and washing down their dinner with oil, etc.

In a word, there is no such corner on our planet and in our body where bacteria would not be found. There is a theory that life appeared on Earth along with bacteria that arrived to us inside some fateful meteorite. This means that microorganisms have managed to survive in absolute vacuum and cosmic cold! And they not only survived, but retained the ability to reproduce, inhabited the entire planet, prepared the ground for the appearance of fungi and algae, which led to an increase in the diversity of life in nature and, as a result, to the emergence of mankind! And this is only the beginning of the answer to the question of what is the importance of bacteria in nature and in human life. In short, without them, there would be no us.

So who are they, bacteria?

In the second half of the 19th century, a new direction in science was formed - microbiology. This science appeared as a branch of medicine and studied the role of bacteria as pathogens. The founders of microbiology were Pascal, Mechnikov, Koch, Erlich and other doctors who were able to consider the connection between tiny creatures and human diseases. The current microbiology is not only concerned with medical problems, it plays a large role in industry (biotechnology) and in a relatively new branch of science - genetic engineering.

Microorganisms (or microbes) are considered to be all living organisms that cannot be seen with the naked eye (without a microscope). In nature, there are three domains (regions):

• viruses;
• protozoa and fungi;
• true bacteria.

Bacteria differ from other domains in their structure - they do not have a nucleus bounded by a membrane. Instead, they have a DNA molecule closed in a loop, which takes on the role of transferring genetic information from the mother cell to the daughter cell.

Bacteria are unicellular organisms with the simplest structure:

• the outer layer is the cell wall;
• thin inner layer - cytoplasmic membrane;
• internal gel-like substance - cytoplasm;
• the prototype of the nucleus (DNA molecule) is the nucleoid;
• "reserve" storage of information (RNA molecules) - ribosomes.

These are just the basic structures of a bacterial cell. Additional ones that appear depending on the functions of the cell or the conditions of its existence include capsules, pili, spores, plasmids, volutin grains and other adaptations developed over billions of years of evolution for the survival of bacteria as a species.

What will we eat...

The further the study of bacteria progressed, the more interesting the picture became. It turned out that the soil that feeds us all was also formed thanks to microorganisms. Not the last role, however, was played by water and air. But it was bacteria that started it.

Further more. Organic substances used by plants are also created by microorganisms (bacteria - producers). Moreover, they use inorganic compounds for this, and take energy from the reactions of photo- and chemosynthesis, that is, from sunlight and chemical transformations. But it is not enough to create organics, something else needs to be done with the dead remains. Otherwise, the planet would have turned into a waste food graveyard a long time ago (to put it mildly). Nature has appointed the same ubiquitous bacteria to the role of scavengers.

Some bacteria (decomposers or saprophytes) use waste organic residues and dead cells as food, decomposing them into simple and inorganic substances, which are then put back into use.

Thus the circle closes and nothing is wasted. The totality of transformations of chemical elements that make up all living beings is called the circulation of substances. This is a fundamental rule of nature, and it would not be possible without the help of such a tiny and, at first glance, defenseless cell.

... and how to breathe

The first reserves of oxygen on our planet also appeared thanks to bacteria. It sounds strange enough, but oxygen is just a byproduct of the food of photosynthetic microorganisms (phototrophs), so to speak, waste products.

Animals and humans also play a role in maintaining the balance of the atmosphere. The process of photosynthesis requires carbon dioxide, and this is exactly what is released during respiration and during combustion (think of our factories, factories and cars). The circle closes again and there are obvious advantages of the existence of a balanced system.

One more, no less necessary element- nitrogen. It is essential for proteins and nucleic acids, that is, it forms the basis of protein life. Animals and humans get this element from protein-rich foods. It can be of vegetable or animal origin. Animals take protein from plants, but how is it formed in the plants themselves?

There is a small problem here. There is a lot of nitrogen in the atmosphere of our planet (78% of the total volume), but plants cannot absorb it from the air on their own. The soil also contains nitrogen, but very little, and often in compounds that are not suitable for plants to eat. Our little friends come to the rescue, as usual. There is a special breed of bacteria (nitrogen-fixing) that convert nitrogen compounds into nitrates available to plants.

The role of nitrogen-fixing bacteria in nature is to help plants

So, the soil is ready, the atmosphere is created, there is a basis for protein life. After the preparatory work carried out by bacteria, fungi, algae and protozoa appear, increasing the diversity of life and bringing us closer to the Earth.

The basis of life

In the structure of a bacterial cell there are ribosomes (ribonucleoprotein particles). They are responsible for protein synthesis. There can be up to 90 thousand such small pieces in a cell! This shows how important ribosomes are to nature. What is their importance?

The role of ribosomes is the synthesis of protein from amino acids. The sequence of the process is written in the genetic information of RNA (not DNA!). And the catch is this - DNA cannot reproduce itself, it needs a catalyst (trigger), which is a protein. And protein, in turn, cannot be formed without DNA. There is a chicken-and-egg paradox.

It turned out that RNA can easily cope with all this ( ribonucleic acid), which forms the basis of ribosomes. It transmits information, works as a catalyst and transports amino acids, giving out the very valuable protein, the basis of our life.

Ribosome of a bacterial cell

These findings formed the basis of the theory of life "before DNA". Who knows, maybe after some time scientists will have to reconsider the theory of the origin of life on Earth?

Human + bacteria = symbiotic system

Man cannot survive without his bacteria, just as bacteria cannot survive without man. This symbiotic system was formed during huge amount time, and an improved and thoroughly tested version has reached our days.

The total weight of bacteria in the human body is about four kilograms. Approximately two of them are in the gastrointestinal tract. Bacteria cover our body with a kind of invisible cloak, making up normal microflora person. Each has its own, its main role is to protect a person from extraneous “stray” bacteria (if the immune system is in order), killing them or depriving them of food.

By the way, bacteria that live in the gastrointestinal tract play a huge role in the formation and maintenance of the immune system. If you treat them with due respect and do not poison them with harmful food and toxins, then the result will not be slow to affect.

The role of beneficial bacteria in human immunity

Digestion in the human body is impossible without bacteria living in the intestines (not to be confused with the stomach). These microorganisms produce vitamins and enzymes, without which our body will not be able to absorb even the freshest and most healthy food. Oddly enough, but one of these bacteria is E. coli, the one that is responsible for many dangerous diseases. It's all about proportions. As long as the amount of E. coli is normal, a person feels great, but it is worth creating suitable conditions for her, as she will seize power and loudly declare herself.

Not only E. coli, but also many other bacteria, called opportunistic pathogens, exist in the human body without causing harm until a certain time. The trigger mechanism can be a decrease in immunity (injury, illness), an unhealthy lifestyle, bad habits, stress.

Not everything is so rosy

Now a little about the cons. Bacteria are not always pink and fluffy. It is to them that we owe many diseases, and until we have learned to detect them and at least somehow fight them, then the most terrible epidemics, such as smallpox, plague or cholera.

In the stomach of more than half of humanity, the recently discovered bacterium Helicobacter pylori lives. Scientists who proved the guilt of this "criminal" in intestinal diseases (ulcers, gastritis) were even awarded Nobel Prize so important was this study.

And just the other day, information appeared that in the stomach (or rather, its remains) of the famous Tyrolean ice man Ötzi (a mummy found in the Alps in 1991), who lived 5300 years ago, traces of Helicobacter DNA were found. Today, several strains of this bacterium are distinguished, each tied to its own region: African, Asian and a hybrid of these two - European. It turned out that the strain of bacteria in Ötzi's body is of Asian origin, although it should have been European. The discovery calls into question the history of the settlement of Europe and the time frame for the settlement of peoples.

How are viruses different from bacteria

It turns out that bacteria not only took care of the creation of life on our planet, they continue to actively patronize humanity, forcing them to take care of their health and maintain a balance in nature. In an effort to survive themselves, they help the survival of mankind. And even when people decide to go into space, bacteria will follow them.

Distributed everywhere: in the air, in water, in soil, in living organisms. Bacteria have been found even at the bottom of the ocean at a depth of several kilometers, in thermal springs, the water temperature of which reaches 90 degrees, in oil-bearing formations, that is, they are able to exist in conditions where other living organisms do not occur at all.

Thanks to the vital activity of soil bacteria, together with other organisms - plants, fungi - soil fertility is ensured. In 1 gram of black soil contains about 10 billion bacteria. They decompose organic matter left over from dead animals and plants that enter the soil. Due to this, inorganic substances are formed, which can later be used by other organisms, including plants, and carbon dioxide is released, which plants need for photosynthesis. A large amount of humus is formed by bacteria when fertilizing the soil with manure, when cultivating perennial and annual herbaceous plants, in which numerous roots die off. In the presence of oxygen in the soil, bacteria in a short period of time are subjected to the transformation of humus into minerals for plant nutrition, including cultivated ones.

In order to ensure Better conditions for the vital activity of beneficial soil bacteria in agriculture, soil is cultivated and fertilized. Due to the loosening of the topsoil, moisture is retained and the soil is enriched with air, which is necessary both for the life of cultivated plants and for soil bacteria. Also, the application of manure feeds not only cultivated plants, but also bacteria.

Cyanobacteria and some soil bacteria are able to assimilate nitrogen from the air and convert it into a form available for use by plants. Nodule bacteria are one such group of bacteria. They settle on the roots of legumes and some other plants (sea buckthorn, mulberry). Nodule bacteria are able to assimilate nitrogen from the air and produce organic nitrogen-containing substances, enriching the soil with them.

Assimilated organic substances, bacteria ensure the purification of water bodies. But they can also provoke the reverse process - "water bloom". Cyanobacteria, green and purple sulfur bacteria, together with plants, form the reserves of organic substances in nature, forming them from inorganic compounds. And cyanobacteria also release free oxygen into the atmosphere, which all living creatures breathe. Deposit formation natural gas and oil also occurred involving certain types of bacteria.

Life on Earth is impossible without the vital activity of bacteria, since they participate in the cycle of substances in nature, carrying out chemical transformations that are not available to either animals or plants.