Biology project on the topic: "The role of lactic acid bacteria in human life." Bacteria Biology Project Bacteria in Human Life Biology Project

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Text content of presentation slides: Biology project on the topic: “Bacteria. Variety of bacteria. The place and importance of bacteria on the planet Earth "The project was prepared by the teacher of biology of the Crimean school of I-III levels Tomko N. R.

style.rotation The goal of the project: to understand the origin of bacteria and their specific features, to study the beneficial and negative role of bacteria in human life and in nature, to learn about the settlement of bacteria on the planet Earth. Project objectives: to define and give the concept of the term bacteria; study the structure of bacteria; to increase knowledge about bacteriological human diseases and methods for their prevention; learn about the process of sporulation in bacteria. The subject of the study was bacteria, their variety and peculiarity.

Bacteria are the smallest of the organisms with a cellular structure; their sizes range from 0.1 to 10 µm. A typical printing point can accommodate hundreds of thousands of medium-sized bacteria. Bacteria can only be seen through a microscope, so they are called micro-organisms, micro-organisms are the study of microbiology. The part of microbiology that studies bacteria is called bacteriology. The beginning of this science was laid by Anthony van Leeuwenhoek in the 17th century.

Bacteria belong to prokaryotes. These are the simplest, smallest and most widespread organisms that have existed on earth for more than 2 billion years, but at the same time they are constantly so different from other living organisms that they are isolated in a special kingdom. There are not many places in the world that are devoid of bacteria. They live in water, soil, air, inside and on the surface of the bodies of animals and plants.

Bacteria are the oldest known organisms. Traces of the vital activity of bacteria belong to the Archean and date back to 3.5 billion years. There is no nucleus in the bacterial cell, the chromosomes are not separated from the cytoplasm by the nuclear membrane, but are freely located in it. In addition, a number of organelles are absent in the bacterial cell. Outside, the cell membrane is surrounded by a cell wall.
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The structure of a bacterial cell
Features of bacteria Unlimited ability to settle on the planet There is practically not a single substance on Earth that could not be decomposed by bacteria In the course of evolution, bacteria learned to live in the human body (normal cohabitants and pathogenic (pathogenic) bacteria)

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Most bacteria can use almost any organic compound as an energy source, even substances used to destroy them (for example, penicillin, which kills many bacteria). This is due to the fact that bacteria can live both in the presence of oxygen in the environment and in its absence.

The top layer of soil contains millions of bacteria per 1 g, that is, approximately 2 tons per hectare.

Settlement of bacteriaSome flexibacteria actively multiply in hot geysers at a temperature of 90 degrees CelsiusMany species of bacteria inhabit the soils of the Sahara desert and the ice of Antarctica and also live on the ocean floor at a depth of 4 km

Settlement of bacteria Sulfate-reducing bacteria - in oil-bearing rocks, at a depth of 500-700 m Halophilic bacteria (genus Halobacterium) - in saturated salt solutions In nuclear reactors

REPRODUCTION OF BACTERIA Under favorable conditions, bacterial cells multiply very quickly, dividing in two. If a cell doubles every half hour, then it can produce 281474976710656 descendants per day. And some bacteria can multiply even faster. Reproduction is prevented by the sun's rays and the products of their own vital activity.

style.rotation Bacteria are widely used in the food industry. Bacteria are used to leach ores (primarily copper and uranium), to treat wastewater from organic remains, in the processing of silk and leather, to control agricultural pests, and to produce medicines (for example, interferon).

The rapid multiplication of lactic acid bacteria in milk leads to the fact that it turns sour in a matter of hours.
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Spore formation Under unfavorable conditions, such as lack of water, many bacteria go dormant. The cell loses water, shrinks somewhat, and remains dormant until water reappears. Some species survive periods of drought, heat, or cold in the form of spores. The formation of spores in bacteria is not a way of reproduction, since each cell produces only one spore and the total number of individuals does not increase. Under favorable conditions (in humid conditions), the spore germinates. The spores are very resistant: they can withstand prolonged drying, boiling for several hours, dry heating up to 140 C. Some spores can withstand temperatures of -245 C. They are also resistant to the action of toxic substances and remain viable for a long time. So, anthrax sticks remain viable, remaining in the form of spores for 30 years.

Survival of bacteria when dried Vibrio cholerae up to 2 days Plague bacillus up to 8 days Diphtheria bacillus up to 30 days Typhoid bacillus up to 70 days Tuberculosis bacillus up to 90 days Staphylococcus bacillus up to 90 days

The positive significance of bacteria is determined by their participation in many biological processes, especially in the circulation of substances in nature. Bacteria, as a result of their vital activity, are able to decompose complex organic compounds into simple inorganic substances, which are again used by green plants. Bacteria are able to decompose proteins, carbohydrates, fats. A number of substances formed by bacteria as a result of metabolism are very valuable for humans. The activity of bacteria is used in various industries and agriculture.
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At present, bacteria are becoming extremely important as producers of many biologically active substances (antibiotics, amino acids, vitamins, etc.) used in medicine, veterinary medicine, and animal husbandry. Without the participation of bacteria, the processes that occur during the preparation of leather for tanning, maceration of flax and hemp fibers are impossible. Humans also use bacteria to treat wastewater: when the wastewater is slowly passed over gravel and sand, solid particles settle and, under the action of various bacteria, turn into a material that, after drying, is used as fertilizer. When passing through sand and gravel, disease-causing bacteria die and are digested by putrefactive bacteria.
In laboratories, bacteria are grown on a special nutrient medium. Millions of bacteria form colonies of various colors and shapes.

Pathogenic bacteria Epidemic cerebrospinal meningitis, dangerous for its complications, is caused by small cocci of the genus Neisseria. Many cocci are the causative agents of pneumonia and cause damage to the heart valves.

Pathogenic bacteria Diphtheria (corynebacteria), tuberculosis and leprosy (mycobacteria) and many other diseases are caused by the development of the microbe-causative agent in its habitat - in cells, tissues and organs of the human. Severe diseases are caused by spore-forming bacteria, among them gas gangrene (Gl. perfringens), tetanus (Gl. tetani), anthrax (Bac. anthracis), etc.

Causative agents of intestinal diseases Dysentery bacillus Typhoid fever pathogen Salmonellosis pathogen Vibrio cholerae

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Respiratory tract pathogens Diphtheria bacillus Pneumococcus Koch's bacillus

The causative agents of especially dangerous infections The causative agents of the plague The causative agents of leprosy The causative agents of the ulcer The doctor's suit worn during the outbreak of the plague in Marseille in 1720

Intermediate hosts of pathogenic bacteria make up a reservoir (center) of diseases from which epidemics often develop. These are many insects, nematodes (worms), animals (rodents are especially dangerous), birds and even humans (bacillus and virus carriers, while remaining healthy, are dangerous to others)

Anthrax carriers

Plague carriers

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Fight against pathogenic bacteria Barriers preventing colonization of bacteria: 1) the skin is protected from the colonization of microbes by fatty acids; 2) the mucous membrane of the nose and eyes - lysozyme (an enzyme that destroys the cell walls of bacteria); 3) blood - by phagocytes and antibodies;

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The fight against pathogenic bacteria Compliance with the rules of personal hygiene Vaccinations and vaccinesUV light and ionizing radiation Antibiotics and other drugs Oxidizing substances (iodine, chlorine, hydrogen peroxide) Heat treatment (pasteurization, boiling, sterilization)

NORMAL CABIN IN THE ORGANISMS OF THE MOUTH CAVITY - the bulk of bacteria in plaque (in 1 g - about 250 million) These are streptococci, lactobacilli, corynebacteria, actinomycetes, etc.

NORMAL PARTNERS IN THE ORGANISMS IN the digestive tract (large intestine) - symbiotic bacteria - bifidobacteria, lactobacilli, etc. There are few bacteria in the small intestine, as they are killed by hydrochloric acid of the stomach

NORMAL CABIN IN THE ORGANISM skin - bacteria make up the normal microflora of the skin
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Spirochetes from dental plaqueE. coli

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Tetanus coliEscherichia coli

Significance of bacteria in nature Soil bacteria participate in the formation of coal, oil, peat, etc. Putrefactive bacteria decompose organic substances into inorganic ones, making them available to plants. Nitrifying and nitrogen fixing bacteria are involved in the nitrogen cycle. As a result of the activity of putrefactive bacteria, the earth is cleared of the corpses of animals and plants, which also ensures soil fertility.

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Interesting factsIrish scientists have discovered a new type of bacteria that protects the human body from stress and depression There are more than 500 types of microbes in the human body Brown University researchers have discovered a new type of bacteria that can kill HIV There are about 40,000 bacteria in the human mouth The total weight of bacteria living in the human body is two kilograms A person excretes over 17 trillion microbes per day with stools, and by weight they make up a third of dry stools.

Thank you for your attention!
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Passport of project work.

Project name " Bacteria in our life

Project leader - I.A. Shtreker, teacher of biology and chemistry, MBOU secondary school No. 24, town. Kaz.

The subject of study is biology, within which the work is carried out.

Academic disciplines are close to the topic of the project: history, informatics.

Age 13

Project Type: Research

Target

Empirically confirm the importance of our living conditions for the growth and development of bacteria.

Tasks

1. To study the effect of bacteria on dairy products;

2. To study methods of combating pathogenic bacteria;

3. Study hygiene rules.

I, Maria Zhuravleva, decided to investigate the effect of bacteria on milk and potatoes and make a presentation on the topic "Bacteria in our life." I decided to make this presentation and defend it at a school environmental conference.

My work plan:

Topic selection.

Search for information

Study

Making a presentation

5. Protection of the project.

What are microbes?! Where did they come from and what do they look like? We hear on TV and on the radio, read in newspapers and on the Internet that bacteria and microbes are harmful organisms and they live in the environment around us - air, soil, water - from where they then get on objects, clothes, hands, food , in the mouth, intestines.

The size of microbes is so small that they are measured in thousandths and even millionths of a millimeter. Microbes can only be seen with an optical or electron microscope. They can cause various diseases, poisonings. Therefore, it is necessary to comply with sanitary and hygienic requirements.

There are a huge number of microbes, but which ones live in us ?! How do they differ and do they even exist?

In total, scientists counted 500 species of bacteria in the samples.

Hypothesis: I want to make sure there are bacteria on our hands. And do you really need to wash your hands to protect yourself from bacteria?

Relevance: Do bacteria exist on our hands?

Problem: ways to protect against bacteria.

Discovery history

Seeing the microbe became possible after the invention of the microscope. The first to see and describe microorganisms was the Dutch naturalist Anthony van Leeuwenhoek (1632-1723), who designed a microscope that magnified up to 300 times. Through a microscope, he examined everything that came to hand: water from a pond, various infusions, blood, plaque, and much more. In the objects he viewed, he found the smallest creatures, which he called "living animals". He established spherical, rod-shaped and convoluted forms of microbes. Leeuwenhoek's discovery laid the foundation for the emergence of microbiology.

The French chemist Louis Pasteur (1822-1895) was the first to study bacteria and their properties. He proved that microbes are the cause of fermentation and decay, capable of causing disease.

Great merit in the development of microbiology II Mechnikov (1845-1916). He also identified human diseases caused by bacteria. He organized the first bacteriological station in Russia. The name of Mechnikov is associated with the development of a new direction in microbiology - immunology - the doctrine of the body's immunity to infectious diseases (immunity).

Habitat

Bacteria are the very first living things that appeared on our planet.
Bacteria live almost everywhere where there is water, including hot springs, the bottom of the world's oceans, and also deep inside the earth's crust. They are an important link in the metabolism in ecosystems.

There is practically no place on Earth where bacteria are found. They live in the ice of Antarctica at a temperature of -83 Celsius and in hot springs (volcano or desert), where the temperature reaches +85 or +90 Celsius. Especially a lot of them in the soil. One gram of soil can contain hundreds of millions of bacteria.
The number of bacteria is different in the air of ventilated and unventilated rooms. So, in the classroom after airing before the start of the lesson, bacteria are 13 times less than before airing.

1.3. What are bacteria. Bacteria are both beneficial and harmful.

Many animals need bacteria to live. For example, plants are known to serve as food for ungulates and rodents. The bulk of any plant is fiber (cellulose). But it turns out that bacteria that live in special sections of the stomach and intestines help animals digest fiber.

We know putrefactive bacteria spoil food. But this harm that they bring to man is nothing compared to the benefits that they bring to nature as a whole. These bacteria can be called "natural orderlies". By decomposing proteins and amino acids, they support the cycle of substances in nature.

Yogurt, cheese, sour cream, butter, kefir, sauerkraut, pickled vegetables - all these products would not exist if there were no lactic acid bacteria. Man has been using them since ancient times. By the way, curdled milk is digested three times faster than milk - in an hour the body completely digests 90% of this product. Without lactic acid bacteria, there would be no silage for livestock feed.

The structure of bacteria

The structure depends on the mode of life and nutrition of the microorganism. Bacteria can be rod-shaped (bacilli), spherical (cocci) and spiral (spirilla, vibrios, spirochetes) shape.

How do they infect us?? Contagious (infectious) diseases have been known since ancient times. The most severe of them (plague, cholera, smallpox) often took on a mass distribution, caused a wholesale pestilence, as a result of which flourishing cities turned into vast cemeteries.

In addition to these especially dangerous infections, there are still many other infectious diseases that can cause epidemics - these are dysentery, typhoid fever and paratyphoid fever, typhus and relapsing fever, brucellosis, these diseases arise through dirty products and hands. The method of infection is the transfer of the pathogen into the respiratory tract through the air around us. The causative agents of many infectious diseases are excreted by a sick organism from the affected respiratory tract (nose, pharynx, bronchi, lungs). When a sick person speaks, coughs, sneezes, he throws out the smallest splashes into the surrounding air - droplets of infected sputum or nasal mucus. In this way, microbes-causative agents easily penetrate, along with contaminated air, into the nose, throat, and lungs of healthy people, where the further development of the disease occurs. Such an "air" or "drip" path of movement of infectious microbes is observed when healthy people are infected with influenza, scarlet fever, measles, diphtheria, whooping cough, smallpox, and mumps.

Survey-observation.

I interviewed 20 people how they wash their hands before eating, 19 people know that they need to wash their hands with soap before eating - this is 98% of students. After the work done, I was interested in the question: “How often do students wash their hands before eating?”. During the break, I began to observe at the entrance to the dining room, do the students wash their hands?

Result:

When asked students, “Do they know that it is necessary to wash their hands before eating?”, 98% of students answered that they know and understand why this is necessary.

Having observed the schoolchildren at the entrance to the dining room, I found out that about 8 people wash their hands without soap before eating, and 12 people did not wash their hands.

Conclusion: it is not enough to know, you also need to apply knowledge in order to maintain your health.

My experiences.

I washed, peeled the potato tuber, cut it into 2 shares, soaked it in a soda solution, cooked it, cooled it. I made 2 glass jars with lids sterile, put the potato share in jar No. 1 with dirty hands, and the potato share in No. 2 jar washed with soapy hands. Banks put in a warm place. As a result, after 4 days, the potatoes that I took with dirty hands were densely covered with bacterial colonies, and in jar No. 2, the potatoes were partially covered with colonies.

Conclusion: there are a lot of bacteria on dirty hands.

Experience No. 2 (with milk)

Obtaining curdled milk from milk.

I took 1 glass of fresh milk, put it in a warm place the next day I got yogurt

Getting sour cream from cream.

I took 1 glass of cream and put it in a warm place, a day later I got sour cream

Conclusion: In this way, I was convinced that beneficial bacteria help make many delicious foods.

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 into the environment or pigmentation of the cells.

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 separated into a 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 purest 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, mouth, limbs, and 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 disease. 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 cells, a substance carrying hereditary information is concentrated. 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 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, 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 have different ways of feeding. 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 that have emerged 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 at the expense of inorganic 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 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 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, thus 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 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 (occasionally carboxylic acids) is a hydrogen donor, and in green plants it is 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, 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), 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.

Spores are not an essential stage in the life cycle of bacteria. Sporulation begins only with a lack of nutrients or the accumulation of metabolic products. Bacteria in the form of spores can remain dormant for a long time. 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 arise. 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 influence of sunlight, 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 absorbed 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 detonated atomic bombs. Neither the low temperatures of the Antarctic, nor the boiling jets of geysers, nor saturated salt solutions in salt pools, nor the strong insolation of mountain peaks, nor the harsh radiation of nuclear reactors 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. The total number of bacteria in soils varies. 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 is a natural environment where microorganisms grow in large numbers. 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, can stay there for a while, 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 the geographic area, terrain, season, dust pollution, etc. Each speck of dust is a carrier of microorganisms. Most bacteria in the air over industrial enterprises. The air in the countryside is 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 that are not connected to the 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 play an important role in the biologically important cycles of matter 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

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 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

Some fresh water reservoirs 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.

Problem: I decided to find out if bacteria are dangerous for humans?

Hypothesis: Bacteria can bring not only harm, but also benefit.

Object of study sour milk products and dirty hands.

Subject of study bacteria

Objective: study the characteristics of bacterial life and find out if they can be useful.

Research objectives:

1. Get acquainted with the characteristics of bacteria.

2. Find out where bacteria live.

3. Study the literature on the harm or benefit of bacteria.

Research methods:

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MBOU "Kozul Secondary School No. 2"

Bacteria - my enemies or friends?

Research

Performed:

Yurkova Lada

student 6 "B" class

Supervisor:

Kukartseva Svetlana Vladimirovna,

biology teacher

village Kozulka, 2015

Introduction ……………………………………………………………………………..3

I. Literature analysis...…………………………………………….4

I.1 Brief characteristics of bacteria ........................ ……………………………………………………………………………………………………………………………………………………………………….

I.2. The human body and bacteria......................………………………………………..8

I.3. Behavior of bacteria under different conditions .........……………………………..8

I.4. Amazing abilities of bacteria? .............................................. ................ eight

Conclusions on Chapter I .............................................. ..................................................

II.Experimental part ……………………………………………………..8

II.1 Influence of bacteria on lactic acid products ..............................................

II.2 Benefits of good hygiene ....................................................................... ........

II.3 Questionnaire ............................................................... ..................................................

Conclusions on Chapter II ............................................... ................................................. .

Conclusion ………………………………………………………………………...

Literature ………………………………………………........................... .....

Applications ………………………………………………………………………..

INTRODUCTION

Relevance of the topic:

"Moydodyr" K.I. Chukovsky is one of my childhood favorite books. And I always wondered why the crocodile, Moidodyr, washcloths, soap were angry at the dirty. This boy was just funny. My mother very often tells me that I need to wash my hands with soap after the street, be sure to wash fruits and vegetables before eating. She warned that some microbes would get into my body, and I could get sick. It was interesting to me. Why can I get sick? What are these microbes? How can they harm me? Where do they come from? Are all microbes harmful to humans? Who are these microbes and where are they, if I don’t see them at all. Maybe mom made it all up? But it turns out that we are surrounded by a whole world of invisible creatures that arose on the planet many billions of years ago, survived all the changes that took place on Earth: volcanic eruptions, the Ice Age, the death of many prehistoric animals. These creatures are called bacteria. They are both useful and harmful to humans and animals. In order to imagine what we are dealing with, I decided to learn more about them.

When we talked about bacteria in biology class, I became interested, and I decided to get to know the mysterious world of microorganisms in more detail. Now I have learned a lot about them and am ready to tell.

Problem : I decided to find out if bacteria are dangerous for humans?

Hypothesis: Bacteria can bring not only harm, but also benefit.

Object of studysour milk products and dirty hands.

Subject of study bacteria

Objective: study the characteristics of bacterial life and find out if they can be useful.

Research objectives:

1. Get acquainted with the characteristics of bacteria.

2. Find out where bacteria live.

3. Study the literature on the harm or benefit of bacteria.

Research methods:

Search - collection of information and literature on a given topic;

Research - information processing;

Practical - the implementation of the experience;

Questionnaire

I Analysis of literary sources

I.1 BRIEF CHARACTERISTICS OF BACTERIA.

Our magical planet Earth is full of secrets and mysteries. Blue, green, yellow, red, white - these are all habitats. In every point of the Earth there is a huge number of mysteries. And one of the mysteries is the creatures living on it. They are diverse: these are huge baobab trees, these are giant animal whales, huge elephants. And we are people, beings endowed with a great gift of reason. We think. With the help of the mind, a person makes discoveries and tries to uncover the secrets of nature.

For thousands of years, man has been ill, and did not know the cause of the disease. Primitive people had their own explanation for this - they believed that evil spirits cause the disease. It was only at the beginning of the 19th century that man invented the microscope. This is a device that helped a person discover another mystery of nature - the world of the smallest organisms - bacteria. In 1865 Louis Pasteur proved that microbes are the cause of disease. They are the smallest single-celled microorganisms visible only under a microscope. Before a person could see bacteria, he had to face the results of their activity. For example, when milk turns sour, dough rises, wine ferments, and dead plants and animals decompose. Thus, when talking about bacteria, many people immediately think of harmful organisms that carry diseases. But the fact is that many different types of bacteria are beneficial to living organisms, including humans.

Today we know that bacteria are everywhere - in the air, water, food, the bottom of the ocean, hot springs, deep inside the earth's crust, on our skin and even inside us.

Microbiology is the study of microorganisms. The name of science comes from the Greek word "MIKROS" - small. Modern microbiology is divided into: general, technical, agricultural, sanitary, medical, radiation, space.

The most widely accepted theories about the origin of life on Earth are that microorganisms were the first living organisms to emerge through evolution.¹

Microorganisms are divided into several groups: BACTERIA, YEAST, MOLDS, VIRUSES.

BACTERIA - single-celled organisms related to prokaryotes. About 3000 species of bacteria are known. Their sizes are microscopic, from 1 to 10 microns, width from 0.2 to 1 microns. Most bacteria are one cell, but physiologically they are an integral organism, perfectly arranged biochemically.

Bacteria have three shapes: spherical, rod-shaped, and curved or convoluted. Most microbes breathe air - these are aerobes. For others, the air is harmful - these are anaerobes. Microbes are divided into pathogenic (disease-causing) and non-pathogenic. Most infectious diseases are caused by bacteria. In the environment around us: air, soil, water - there are many microorganisms, from where they get on objects, clothes, hands, food, mouth, intestines.

Like all living things, microorganisms feed and reproduce. Microbes do not have special digestive organs. Nutrients enter microorganisms through the cell membrane. Therefore, for the development of microbes, foods containing a lot of water - milk, broths, meat, fish, etc. - are a good nutrient medium. Bacteria do not have male and female individuals. Bacteria reproduce by division. In addition to the nutrient medium, a favorable temperature (37-40 degrees) is necessary. Once in favorable conditions, microbes begin to multiply rapidly by dividing.

At temperatures above 50 degrees, most bacteria die. The bacterium consists of one cell, it is surrounded by a coating - a "membrane" that does not allow water to pass through. Inside the bacterium is a substance called "protoplasm", but there is no single center, or nucleus.

Bacteria are able to move, although they do not have limbs. The bacterium is covered with a mucous membrane, which changes its shape, sometimes forming fibrous processes. Some bacteria move with their help, others - by contracting the cell itself, like worms.

I. 2. THE HUMAN BODY AND BACTERIA.

Microorganisms play a crucial role in the circulation of substances and maintaining balance in the Earth's biosphere. Bacteria cause decay of dead plants and animals on land and in water. Without these bacteria, the earth would be covered with various dead material. Processing complex substances, bacteria decompose them into simple ones. These substances are returned to the soil, air and water, where they can be used by plants and animals.

Bacteria are essential to sustain life. For example, nitrogen-containing bacteria live in the soil and help turn this nitrogen into substances that plants need. Humans eat these plants.

Bacteria play an important role in the human digestive process. These bacteria break down food into particles. At the same time, they produce vitamins, proteins, carbohydrates that the body uses to build itself.

Thanks to the activity of microbes, cabbage is fermented, dough, kefir, cheese, butter are prepared. Bacteria are necessary in the fermentation process in the production of cottage cheese, vinegar, wine, beer. The same process is used in the industrial production of paints, plastics, cosmetics and confectionery. Bacteria are needed in the production of leather, the removal of shells from coffee and cocoa beans, and the separation of fibers in the textile industry.

So, there are many varieties of microbes, and they live in whole colonies. Naturally, living in the human body, they must protect their master, and not harm him.

What is the intestines of a healthy person, that is, the population of this organ? In the intestines, 99% of microbes are disinterested helpers of a person. They are called permanent microflora. Among them there are the main, basic microorganisms - these are bifidobacteria and bacteroids. But there are also accompanying bacteria - these are E. coli, lactobacilli, enterococci. Under certain conditions, representatives of the normal microflora, in addition to bifidobacteria, have the ability to cause diseases. However, there are more dangerous microbes in the intestines, they are no more than 1%. These are staphylococci and fungi. But while they are in the minority, they work for the benefit of the body. They are called opportunistic pathogens. Why are we talking mostly about the gut? The digestive tract is not uniform in composition and number of microorganisms. The esophagus does not have a permanent microflora at all and practically repeats the microflora of the oral cavity. Staphylo-, pneumo- and streptococci constantly live on the mucous membrane of the nasopharynx. For the vital activity of microorganisms, a good environment is plaque on the teeth, food debris between them. The abundant development of microbes in the mouth leads to the rapid multiplication of food residues, while the chemical products of this decay accumulate, which destroy the enamel of the teeth and lead to the development of caries. Therefore, it is so important to systematically brush your teeth, rinse your mouth after each meal.

The microbial spectrum of the stomach is poor and is represented by lactobacilli, streptococci, heliobacteria and acid-resistant yeast-like fungi. The microflora of the small intestine is not numerous and in the duodenum it is represented by streptococci, lactobacilli and veillonella; in other departments, the number of microbes is higher, and even more bacteria are found in the ileum, in which, in addition to the listed microorganisms, Escherichia coli lives. But the largest number of microbes lives in the large intestine. It is estimated that a person excretes over 17 trillion microbes per day with stools, and by weight they make up a third of dry stools. If you take only intestinal bacteria, and collect them in one pile and weigh them, you get about 3 kilograms!

I.3. BEHAVIOR OF BACTERIA UNDER DIFFERENT CONDITIONS

IS THERE LIFE IN BOILING WATER?

Until recently, it was believed that all, even the most persistent, bacteria die in boiling water, but nature, as always, refuted this belief. At the bottom of the Pacific Ocean, superhot springs with water temperatures from 250 to living organisms feel great in boiling water: bacteria, giant worms, various mollusks and even some types of crabs. This discovery seemed incredible. After all, most plants and animals die at body temperatures above 40 degrees, and most bacteria - at 70 degrees. Only a few bacteria are able to survive at 85 degrees C, and the bacteria living in sulfur springs were considered the most resistant. They can exist at t - 105C. But this was already the limit.

IS THERE LIFE IN ICE?

There are bacteria that live in ice. Freezing may stop the growth of bacteria, but will not completely kill them. They will be inactive for a while. Found bacteria in frozen salt deposits, which are hundreds of millions of years old. These bacteria, when studied, came to life.

BACTERIA IN SPACE

“Scientists have suspected for a long time that something bad is happening on starships and space stations, astronauts got sick too often. Of the 29 astronauts, 15 fell victim to bacterial or viral infections during their flight. The suspicions of scientists were further strengthened when it turned out that on the Mir space stations and the ISS, seemingly harmless bacteria began to chew all kinds of structural materials with pleasure, which led to accelerated corrosion.

All this prompted biologists to come to grips with the study of the behavior of microorganisms in space. In 2006 on the shuttle Atlantis, a group of salmonella went on a space trip in a securely insulated container. Bacteria stayed in space for only 24 hours, but this time was more than enough for them. Upon returning to Earth, it turned out that their infectiousness, compared with the control group, had increased three times. For a whole year, astrobiologists have been trying to understand what caused the increase in the aggressiveness of Salmonella. In space, Salmonella activated a section of DNA that controls the work of 160 genes. In addition, Salmonella began to combine, forming a thin layer - a biofilm, which makes any microorganisms extremely dangerous. It is interesting that earlier on Earth such behavior was not characteristic of Salmonella. Some experts consider weightlessness to be the cause of the mutation, others to cosmic radiation.”

Over the long years of operation, the Mir space station has become a real testing ground for testing many technical solutions. It was on the "Mir" that we managed to study small space stowaways and learn how to deal with them.

The microbes that inhabit space objects behave as if they have a specific purpose. It is simple: using all available nutrients, perform one of the main natural functions - to be fruitful and multiply. Getting on a variety of materials, microbes quickly master

and start eating. As a result, the materials favored by voracious invisibles change color, their strength, sealing properties, dielectric and other characteristics decrease.

Over the course of twenty years of research, scientists have discovered 250 types of microorganisms that live inside manned spacecraft. All samples of microorganisms grown in space are stored at the Institute of Biomedical Problems in sealed ampoules - scientists do not know how they will behave in the earth's environment. There is another reason for keeping space mutants in a protected area. According to experts, if you take a microorganism grown in space that used metal as part of its existence, and continue to cultivate it, increasing the metal content in its environment, you can potentially get a biological weapon that can literally gobble up a tank or a helicopter.

“The situation related to the navigation window of the Soyuz spacecraft, which spent half a year in orbit, is of particular interest. Crew members noted a deterioration in the visibility of the porthole. After the ship returned to Earth, research was carried out. The presence of mycelium of mold fungi was noted on the central porthole made of heavy-duty quartz glass, as well as on the enamel coating of the titanium frame. In one case, a growing colony of the fungus was clearly visible. Along the growth lines of the mycelium, the glass was, as it were, etched.

I.4. THE AMAZING ABILITY OF BACTERIA

Currently, scientists are looking for alternative fuel, replacing oil, gas, coal with a safer - biological, more environmentally friendly. Scientists at the University of Texas have created a new kind of microbe that produces cellulose, which in turn can be converted into ethanol and other biofuels. With the help of salt water, blue-green algae, along with cellulose, also release glucose and sucrose, which is used to produce biofuels.

However, bacteria can participate in technological progress. After all, their ability to destroy almost any material can be turned to the benefit of man. Microorganisms may well be used in the processing of waste. Work is already underway to create bacteria that could decompose plastic. The fact is that plastic has no analogues in nature, so its decomposition process is very long. It is assumed that with the help of microorganisms, plastic can be broken down into water and methane, which can be used in heating and the chemical industry. Thus, malicious bacteria in the near future may turn into the most useful guardians of the environment.

Houseplants can improve people's health. In the flower zone, where there are many plants, special earth microbes have a special ability to neutralize volatile organic components that weaken human health. In the air of industrial cities, along with dust, there are millions of microorganisms. In a liter of air in a poorly ventilated room, there are about 500,000 dust particles. During the day, a person inhales about 10 thousand liters of air with dangerous and non-dangerous microbes.

The cleaner the air in public places, around human habitation and in rooms, the less a person gets sick. It is estimated that if you brush the vacuum cleaner over the surface of an object four times, then 50% of germs are removed. If hygiene is observed, brushing teeth, washing and washing hands with soap, as well as food, the likelihood of disease is reduced many times over.

Forests and parks are of great importance in the fight for clean air. Green spaces precipitate and absorb dust and release phytoncides that kill microbes.

CONCLUSIONS ON CHAPTER I..........................................................

II. experimental part

II.1. Influence of bacteria on dairy products

Raw milk was poured into 2 jars, and boiled milk was poured into the third jar. Covered

lids one jar with raw milk and one with boiled milk. Observation

carried out within 3 days. The results are as follows.

__________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________

II.2. The benefits of observing hygiene rules.

Two days before the experiment, we closed the Petri dishes with lids. A nutrient mixture was prepared: the washed potato tuber was peeled, cut in half and soaked for 2-3 hours in a 1% soda solution, then boiled and cut into slices. Then they put potato pieces on filter paper in Petri dishes (this is the nutrient medium for growing bacteria). They touched one plate with the finger of an unwashed hand, and the other with the finger of a washed hand, having previously washed their hands well with soap. The results were compared two days later.

During the first experiments and literature analysis, we found out that many traditional drinks and products, such as kefir, curdled milk, koumiss, sour cream, cottage cheese, cheese, would not exist without the activity of special lactic acid bacteria. These bacteria, getting into milk, begin to ferment and turn milk sugar into lactic acid. It not only adds flavor to drinks, but prevents them from being contaminated by other microbes. Lactic acid bacteria are not only found in milk. Many of them live on the leaves of bushes and trees, feeding on substances that are released during the death of plant tissues. These bacteria are found in various foods prepared with the help of fermentation, for example, in sauerkraut, pickles, pickled olives. Lactic acid bacteria are used in agriculture to preserve feed. Juicy tops of beets or other fodder plants are put into special pits and pressed. This process is called ensiling. After ensiling, a lot of lactic acid bacteria develop in the pressed mass, and lactic acid reliably protects the silage from decomposition, and the feed only gets better, as the bacteria enrich it with various useful substances.

The second experiment showed us that ............................................... ...........

II.3. Questionnaire

Target: analyze students' knowledge about bacteria

For this, a survey was conducted among students in grades 7-8 of the school, in which 66 people participated. Found out that they know about the existence of bacteria - 60 people, 6 people have never heard of them.

Most of the respondents (34 people) imagine bacteria as small, dirty and creepy - 5 people, the remaining 14 people do not represent them at all. (Appendix 2 ).

To the question "Where can bacteria live?" answered “everywhere” - 8 people, “on the body and in the body” - 10 people, “on the street and in different rooms” - 11 people, “nowhere” - 2 people.

According to the results of the survey "Can bacteria be useful?": "yes" - 37 people, "no" - 29 people.

Basically, all the students surveyed in our school (66 people) know about the rules of hygiene and that you need to wash vegetables and fruits before eating.

But when answering the question “Do you always follow the rules of hygiene?” 48 children gave a positive answer, 16 people do it often, and the remaining 2 people occasionally observe hygiene rules. (Annex 4)

Conclusion: 91% of respondents are aware of the existence of bacteria, but 44% of respondents believe that bacteria are not beneficial. 100% know the rules of hygiene, but 73% of children always follow them.

CONCLUSION

So, the topic I have considered allows us to say that bacteria are of great importance for humans. Man and bacteria are inseparable. Microbes can be both enemies and friends. In the air of industrial cities, along with dust, there are millions of microorganisms. During the day, we inhale a huge number of dangerous and non-dangerous microbes. Bacteria play a huge role in the purification of water contaminated with industrial and household waste. Many bacteria harm humans, animals and plants, being the causative agents of various diseases. In order for bacteria to be our friends and not enemies, we need to wash our hands with soap, wash our face, brush our teeth, wash vegetables and fruits, plant a lot of trees. Protect our planet, keep clean and breathe fresh air.

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annotation

Vasyankina Nina

Kulebaksky district, r.p. Gremyachevo, MBOU Gremyachevsky secondary school, 7 b "Amazing bacteria".

Leader: Drews Svetlana Andreevna, biology teacher. MBOU Gremyachevskaya school №1

The purpose of scientific work: to study the features of the structure and vital activity of bacteria, to determine their positive and negative impact on human life, to conduct laboratory work to detect bacteria.

Conducting method: abstract-research with practical work. The main results of the study: studied in detail the structure and vital activity of bacteria; determined the importance of bacteria in the biosphere and the national economy; carried out practical work on the detection of lactic acid bacteria, decay bacteria, studied their properties; I learned interesting facts about bacteria.

Introduction………………………………………………………………………………….4

Main part:

Discovery of a bacterial cell…………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………5

The structure and vital activity of bacteria……………………………………………..... 7

The importance of bacteria in the biosphere and the national economy…………………………..….10

Practical work “Detection of lactic acid bacteria, study of their properties”…………………………………………………………………………………..13

Interesting facts about bacteria…………………………………………………………………………16

Conclusion…………………………………………………………………………………..17

Conclusion……………………………………………………………………………….19

References…………………………………………………………………....20

Introduction

Chosen theme of the work "Amazing bacteria)" relevant, as much attention is currently paid to the study of microorganisms - bacteria and viruses, their impact on the human body. Scientists around the world are working to develop drugs against many infectious diseases.

Working on this topic, I set myself the following goal: study of the features of the structure and vital activity of bacteria, determination of their positive and negative impact on human vital activity.

To achieve this goal, I set myself the following tasks:

to study in detail the structure and vital activity of bacteria;

determine the importance of bacteria in the biosphere and the national economy;

to carry out practical work on the detection of lactic acid bacteria, putrefaction bacteria, to study their properties;

learn interesting facts about bacteria.

II. Main part

1. Discovery of a bacterial cell.

Bacteriology is the branch of microbiology that deals with the study of bacteria. Bacteria along with were among the first living organisms on Earth, appearing about 3.5 billion years ago.

Bacteria (dr. Greek - stick) - the kingdom of microorganisms, most often unicellular. Currently, about ten thousand species of bacteria have been described, and it is estimated that there are over a million of them.

Bacteria were first seen through an optical microscope and described in 1676 by the Dutch naturalist Anthony van Leeuwenhoek. Like all microscopic creatures, he called them "animalcules".

The name "bacteria" was introduced by Christian Ehrenberg in 1828. Louis Pasteur in the 1850s initiated the study of the physiology and metabolism of bacteria, and also discovered their pathogenic properties.

Until the 19th century, microbiology was a collection of disparate facts. The founders of microbiology as a science were the outstanding scientists of the 19th century, the French chemist L. Pasteur (1822-1895) and the Russian botanist L. S. Tsenkovsky (1822-1887). In 1862, Pasteur brilliantly proved that microorganisms do not arise spontaneously. He proved that contagious diseases are caused by various microbes. Pasteur prepared vaccines against rabies and anthrax. Tsenkovsky L.S. showed the proximity of bacteria with blue-green algae.

The development of methods for growing microbes on various solid nutrient media is associated with the name of the German physician R. Koch (1843-1910), who discovered the anthrax bacillus, vibrio cholerae and tubercle bacillus. After the work of L. Pasteur and R. Koch, microbiology was divided into a number of narrower specialties. There are general, agricultural, technical, veterinary and medical microbiology.

The works of S. N. Vinogradsky and V. L. Omelyansky played an important role in the development of general and soil microbiology. S. N. Vinogradsky established the fact of the assimilation of carbon dioxide by non-chlorophyll microorganisms, i.e., the ability to build one’s body entirely through the assimilation of inorganic substances. He proved the existence of anaerobic nitrogen-fixing bacteria; laid the foundation for the study of microorganisms inhabiting the soil. VL Omelyansky revealed the microbiological nature of the process of anaerobic decomposition of fiber. Of the researchers in the field of medical microbiology, D.K. Zabolotny, known for his work on the study of cholera and plague pathogens, should be noted.

Soviet microbiologists have done much to develop measures to prevent infectious diseases. Much has been done in the field of studying questions of general microbiology and in the application of microorganisms in industry and agriculture. Microbes are widely used to obtain alcohol, acetone, citric acid, yeast, and to obtain antibiotics. In agriculture, bacterial fertilizers are used to increase crop yields.

Main part

2. The structure and vital activity of bacteria.

Bacteria - These are the smallest prokaryotic organisms that have a cellular structure. Due to the microscopic size of cells from 0.1 to 10-30 microns, bacteria

According to the shape and features of cell association, several morphological groups of bacteria are distinguished: spherical (cocci), straight rod-shaped (bacilli), curved (vibrios), spirally curved (spirilla), etc. Cocci linked in pairs are called diplococci, connected in the form of a chain - streptococci, in the form of clusters - staphylococci, etc. Filamentous forms are less common.

Cell structure. The cell wall gives the bacterial cell a certain shape, protects its contents from the effects of adverse environmental conditions, and performs a number of other functions. The basis of the cell wall of bacteria (as well as all prokaryotes) is a special substance - murein (a polysaccharide combined with several amino acids). Many types of bacteria are surrounded by a mucous capsule, which serves as an additional protection for the cells.

The way the flagella are arranged is one of the characteristic features in the classification of motile forms of bacteria.

The plasma membrane does not differ in structure and function from the membrane of a eukaryotic cell. In some bacteria, the plasmalemma is able to form invaginations into the cytoplasm, called mesosomes. Redox enzymes are located on the folded membranes of mesosomes, and in photosynthetic bacteria they also have the corresponding pigments (including bacteriochlorophyll), due to which mesosomes are able to perform the functions of mitochondria, chloroplasts and other organelles, as well as participate in nitrogen fixation.

In the cytoplasm there are about 20 thousand ribosomes and one large circular double-stranded DNA molecule, the length of which is 700 or a thousand times the length of the cell itself. In addition, most types of bacteria in the cytoplasm also have small circular DNA molecules called plasmids. Membrane structures (organelles) characteristic of eukaryotic cells are absent in bacteria.

A number of water and soil bacteria lacking flagella have gas vacuoles in the cytoplasm. 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. Spare substances of a bacterial cell are polysaccharides (starch, glycogen), fats, polyphosphates, sulfur.

Forms of a bacterial cell.

spherical kinds - cocci. AT form spirals - spirilla. rod-shaped bacteria - bacilli.

Nutrition of bacteria.

Bacteria are divided into two groups according to the type of nutrition: autotrophic and heterotrophic. Autotrophic bacteria synthesize organic substances from inorganic ones. Depending on what energy autotrophs use to synthesize organic substances, photo- (green and purple sulfur bacteria) and chemosynthetic bacteria (nitrifying, iron bacteria, colorless sulfur bacteria, etc.) are distinguished. Heterotrophic bacteria feed on ready-made organic matter of dead remains: (saprotrophs) or living plants, animals and humans (symbionts).

Saprotrophs include decay and fermentation bacteria. The first break down nitrogen-containing compounds, the second - carbon-containing. In both cases, the energy necessary for their life activity is released.

Reproduction. Bacteria reproduce by simple binary cell division. This is preceded by self-doubling (replication) of the DNA molecule. Budding occurs as an exception.

With the formation of spores in a bacterial cell, the amount of free water decreases, enzymatic activity decreases, the protoplast shrinks and becomes covered with a very dense shell. Spores provide the ability to endure adverse conditions. They withstand prolonged drying, heating above 100°C and cooling to almost absolute zero. In the normal state, the bacteria are unstable when dried, exposed to direct sunlight, when the temperature rises to 65-80°C, etc.; Under favorable conditions, the spores swell, forming a new bacterial cell.

Despite the constant death of bacteria (eating them by protozoa, exposure to high and low temperatures, and other unfavorable factors), these primitive organisms have been preserved since ancient times due to the ability to rapidly reproduce (a cell can divide every 20–30 minutes), form spores, and are extremely resistant to environmental factors, and their ubiquitous distribution.

cyanobacteria.

We will get acquainted with bacteria - "herbs". A little bit of moisture, air and sun - that's almost all they need to live. Yes, and these bacteria do not look quite normal. So unusual, in fact, that scientists have long considered them to be… algae! But studies have shown that these "algae" do not have a nucleus, and therefore, they must be attributed to bacteria - prokaryotes. Because of their blue-green color, they are called cyanobacteria (cyanus is Greek for "blue").

Cyanobacteria live in a wide variety of places. Imagine a barren rock. From day to day they “bite off” the smallest grains from the stone. The stone is covered with cracks, into which the roots of the plant can launch, and eventually crumble into grains of sand. And the beginning of this was laid by cyanobacteria.

Do you have an aquarium in bloom? Did dark green flakes appear in it or plaque on the walls? Warning sign! Cyanobacteria appeared in the aquarium. Some cyanobacteria release substances poisonous to fish into the water. The processes of photosynthesis in cyanobacteria and eukaryotic organisms are carried out in a similar way. Their main storage carbohydrate is glycogen.

3. The importance of bacteria in the biosphere and the national economy.

The role of bacteria in the biosphere is great. Due to their vital activity, the decomposition and mineralization of organic matter of dead plants and animals occurs. The resulting simple inorganic compounds (ammonia, hydrogen sulfide, carbon dioxide, etc.) are involved in the general circulation of substances, without which life on Earth would be impossible. Bacteria, together with fungi and lichens, destroy rocks, thereby participating in the initial stages of soil-forming processes.

A special role in nature is played by bacteria that are able to bind free molecular nitrogen, which is inaccessible to higher plants. This group includes free-living Azotobacter and nodule bacteria that settle on the roots of leguminous plants. Penetrating through the root hair into the root, they cause a strong growth of root cells, which has the form of nodules. At first, bacteria live at the expense of the plant, and then they begin to fix nitrogen with the subsequent formation of ammonia, and from it - nitrites and nitrates. The resulting nitrogenous substances are sufficient for both bacteria and plants. In addition, some nitrites and nitrates are released into the soil, increasing its fertility. The amount of nitrogen fixed by nodule bacteria can reach 450–550 kg/ha per year.

Bacteria play a positive role in human economic activity. Lactic acid bacteria are used in the preparation of a variety of dairy products (sour cream, curdled milk, butter, cheese, etc.). They also help preserve food. Bacteria are widely used in modern biotechnology for the industrial production of lactic, butyric, acetic and propionic acids, acetone, butyl alcohol, etc. In the process of their vital activity, biologically active substances are formed - antibiotics, vitamins, amino acids. Finally, bacteria are an object of research in the field of genetics, biochemistry, biophysics, space biology, etc.

The negative role belongs to pathogenic or pathogenic bacteria. They are able to penetrate the tissues of plants, animals and humans and release substances that depress the body's defenses. Such pathogenic bacteria as the causative agent of plague, tularemia, anthrax, pneumococci in animals and humans are resistant to phagocytosis and antibodies. A number of other human diseases of bacterial origin are known, which are transmitted by airborne droplets (bacterial pneumonia, tuberculosis, whooping cough), through food and water (typhoid fever, dysentery, brucellosis, cholera), through sexual contact (gonorrhea, syphilis, etc.) .

Bacteria can also infect plants, causing them so-called bacterioses (spotting, wilting, burns, wet rot, tumors, etc.). Bacterioses are quite common in potatoes, tomatoes, cabbage, cucumbers, beets, legumes, and fruit trees.

Saprotrophic bacteria cause food spoilage. At the same time, along with the release of carbon dioxide, ammonia and energy, the excess of which causes heating of the substrate (for example, manure, wet hay and grain) up to its self-ignition, the formation of toxic substances also occurs. Therefore, in order to prevent spoilage of food products, a person creates conditions under which bacteria largely lose their ability to rapidly multiply, and sometimes die.

Lactobacilli and bifidobacteria live in the human body. They appear in our body from the first infancy and remain in it forever, complementing each other and solving serious problems. Lactobacilli and bifidobacteria enter into complex reactions with other microorganisms, easily suppress putrefactive and pathogenic microbes. As a result, lactic acid is formed, hydrogen peroxide - these are natural internal antibiotics. Thus, lactobacilli raise, restore the body's defenses and strengthen the immune system.

The beneficial functions of lactobacilli were first noticed by the Russian scientist Ilya Ilyich Mechnikov. The idea to use fermented milk products to normalize biochemical processes in the intestines and nourish the body as a whole belongs to him.

Bacteria cause food spoilage. Therefore, in order to prevent spoilage of food products, a person creates conditions under which bacteria largely lose their ability to rapidly multiply, and sometimes die. widespread fighting methods with bacteria are: drying of fruits, mushrooms, meat, fish, grains; their cooling and freezing in refrigerators and glaciers; pickling products in acetic acid; salting. When pickling cucumbers, tomatoes, mushrooms, sauerkraut due to the activity of lactic acid bacteria, an acidic environment is created that inhibits the development of bacteria. This is the basis of food preservation. The method is used to kill bacteria and preserve food. pasteurization—heating to 65°C for 10-20 min and sterilization method — boiling. High temperature causes the death of all bacterial cells. In addition, in medicine, the food industry, and agriculture for disinfection, i.e., to destroy pathogenic bacteria, iodine, hydrogen peroxide, boric acid, potassium permanganate, alcohol, formalin and other inorganic and organic substances are used.

Having studied various sources, I was convinced that all the materials confirm the hypothesis of my project that bacteria can be both harmful to humans and beneficial.

Practical work

Mini study

Having received information that bacteria are harmful and beneficial, it became interesting for me to look at them. To do this, I decided to conduct an experiment.

Description of the experiment.

In order to create a breeding ground for bacteria, I took a pot, put it on the stove and brought water to a boil. I added a bouillon cube and a spoonful of sugar to the water. Boil this mixture for a few minutes. She took the saucepan off the heat and let it cool. I brought the broth to class. I poured the same amount of broth into each of the previously prepared vessels. Then she coughed into one of the vessels, put her finger into the other, and did not touch the third vessel.

Sticker "Do not drink!" on each vessel she warned everyone that an experiment was underway. I wrapped the vessels in plastic wrap and put them in a warm place so that they would not interfere with anyone.

After a while, I checked what was happening with the broth. The liquid in the vessels became cloudy and began to emit an unpleasant odor, which is confirmation that there are bacteria in it.

After that, I took a few drops of liquid and tried to examine the bacteria with a magnifying glass. But this did not lead to a positive result - I did not see bacteria. Then I decided to resort to the help of another device - a light microscope.

At 200x magnification, I was able to see the bacteria in all the containers. I noticed that most of the bacteria were in the vessel into which I dipped my finger. This once again confirms the fact that bacteria live on our hands. And the least bacteria was in the third vessel. I would like to note that I was surprised by the small amount of bacteria in all containers, although they were in a warm place for several weeks. I think this is due to the presence of preservatives (substances that allow food not to spoil for a long time) in the bouillon cube.

"Detection of lactic acid bacteria, and the study of their properties"

For the first time, the benefits of fermented milk products were discussed at the beginning of the 20th century, when Ilya Mechnikov (Russian biologist, Nobel Prize winner) told the world about the beneficial properties of this product. In the course of his research, Mechnikov found out that our gastrointestinal tract, like fermented milk products, contains live microorganisms. They help the stomach to function successfully.

Target: to detect lactic acid bacteria, to study their properties.

Equipment and materials: microscope, slides, cover slips, test tubes, kefir, curdled milk, rotten potatoes, alcohol, methyl blue.

Working process.

Researching dairy products. To do this, you need to prepare smears of yogurt, kefir. I pour alcohol on an air-dry smear and hold for 1-2 minutes.

I paint with methylene blue. I examine preparations with an immersion lens. In a smear from curdled milk, diplococci will be visible, in kefir, sticks and yeast.

Experience 1. Spoilage of milk by putrefactive microbes. I add a few drops of liquid from a rotten potato to a test tube with milk and leave it in a warm place for 10-12 hours. As a result of the development of putrefactive bacteria, the milk protein will begin to dissolve and in 1-2 days it will completely dissolve with the release of foul-smelling gases.

Experience 2. Protection of milk from spoilage by lactic acid bacteria. I put putrefactive and lactic acid bacteria into a test tube with milk. As a source of lactic acid bacteria, you can take 1-2 ml of kefir. The development of lactic acid bacteria ensures the formation of lactic acid in milk, which inhibits the development of putrefactive bacteria. In a test tube, a normal clot of milk is obtained.

Conclusion: Dairy products contain three main types of beneficial bacteria: bifidobacteria, lactobacilli and enterobacteria. When we are healthy, the intestinal microflora includes probiotic lactic acid bacteria. It is precisely thanks to their work that all other microorganisms living in our gastrointestinal tract manage not only to coexist peacefully with each other, but also to work effectively for our benefit.

Conducting a survey

After I got acquainted with the information about bacteria and conducted my own mini-study, it became interesting for me to find out how much the guys who study with me own this information.

To this end, together with the class teacher, we compiled a survey questionnaire. We interviewed 24 students in our class.

The survey included questions about bacteria and their importance in human life (see Appendix)

After analyzing the results, I found out that:

know about the existence of bacteria - 100% of students;

know that bacteria can cause various human diseases - 100% of students;

95.8% of students know that not all bacteria are harmful to humans;

100% i.e. all students know that bacteria live in the human body, 75% believe that they help digest food and restore the body's defenses;

many guys know that a person uses bacteria in economic activities.

Interesting facts about bacteria.

Scientists have discovered the packaging structure of light-sensitive green bacteria molecules that helps organisms extremely efficiently convert sunlight into the chemical energy they need to live. The discovery may lead to the creation of a new generation of solar cells in the future, according to the authors of a study published in the journal Proceedings of the National Academy of Sciences.

The green bacteria studied by scientists use the energy of light to process sulfur or iron compounds, similar to how plants use sunlight in photosynthesis. At the same time, organisms are forced to be content with a very limited amount of sunlight, as they live in the waters of hot hydrothermal springs or in seas at a depth of more than 100 meters.

Japanese experts have created the world's first micromotor, which is powered by bacteria. Its main rotating component has a diameter of 20 millionths of a meter.

Bacteria and bacillus are one and the same. The first word is of Greek origin, and the second is of Latin origin.

There are bacteria that help clean your teeth. Scientists at the Swedish Karolinska Institute have crossed these bacteria with regular yogurt and are now trying to make a transgenic yogurt that will allow us not to brush our teeth.

The total weight of bacteria living in the human body is 2 kilograms.

There are about 40,000 bacteria in the human mouth. During a kiss, 278 different cultures of bacteria are transferred from one person to another. Luckily, 95 percent of them are harmless.

Conclusion

The role of prokaryotes in nature and human life is enormous. Bacteria, living in almost all environments, often determine the various processes occurring in nature. Bacteria were the first inhabitants of the Earth. The first bacteria arose on earth over 3 billion years ago.

Due to the influence of bacteria, the appearance and chemical composition of the Earth's shells have changed, and thanks to this, the emergence of other forms of life (for example, plants) has become possible. Thanks to bacteria, the living shell of the Earth, the biosphere, began to develop. Bacteria that came to land before plants took part in soil formation and created the conditions for plants to land on land. At present, the role of bacteria is also very large.

1. Soil bacteria - decay bacteria. They recycle dead organic matter. If it were not for these bacteria, then the surface of the earth would be covered with a thick layer of the remains of dead organisms. The cycle of substances in nature is provided by these bacteria. Decompose dead remains to mineral salts, which are absorbed by plants.

2. Nitrogen-fixing bacteria. They settle on the roots of leguminous crops (peas, alfalfa) and absorb nitrogen from the air, thereby enriching the soil with this element necessary for plant growth.

3. Lactic acid - used for the preparation of sour cream, kefir, fermented baked milk, cheese, sauerkraut, as well as for the production of silage.

4. E. coli - human companion. Lives in the intestines, helps break down milk sugar and produce vitamins.

5. Pathogenic bacteria - are the causative agents of many diseases such as: tuberculosis, plague, dysentery, tetanus.

6. While admiring the blue flames on your gas stove, remember the smallest workers who made natural gas for you. This is methanobacteria , they process bottom residues, resulting in the formation of marsh gas - methane, which we use in everyday life.

7. Biotechnology, genetic engineering - a branch of modern biology, where bacteria are also indispensable. By inserting the necessary genes into the nuclear substance of bacteria, scientists force them to produce insulin, a drug used in the treatment of diabetes.

Conclusion

We pass a verdict - bacteria live, because. without it, many processes will stop, and the ecological balance will be disturbed.

Ah, this habitat! All are interconnected by exchange, food chains, composition, structure, fate ...

In the thickets, and in the ridges, and in the villages, Where life breathes and moves, May there always be balance! Be afraid to disturb it!

Bibliography.

A.G. Elenevsky, M. A. Biology. Plants, fungi, bacteria. Bustard, 2001

Biology grade 6. Lesson plans according to the textbook by I.N. Ponomaryora. Author-compiler G.V. Cherednikov. Volgograd. "Teacher" 2008 pp.144-146

Biology 10-11 class. Lesson plans for studies by V.I. Sivoglazov. Author-compiler T.V.Zarudnyaya. Volgograd. "Teacher" 2008 Pages 70-71

General biology. Grade 9. V.B. Zakharov, A.G. Mustafin, Moscow. Enlightenment 2003. p. 44 - 46.

other referat s.allbest.ru›Biology and Natural Science›00000073.html

en.wikipedia.org›wiki/ bacteria

krugosvet.ru›enc/nauka_i_tehnika… BAKTERII.html

bigpi.biysk.ru›encicl/articles/00/1000056/…

slovari.yandex.ru›TSB› bacteria

bril2002.narod.ru›b11.html

vokrugsveta.ru›Telegraph›pulse/501

mikroby-parazity.ru›index.php…

Appendix

Variety of bacteria