REPORT on the topic:
Are bacteria friends or foes?
Safonov Alexey
3 "B" class
The human body is populated by millions of microorganisms that constitute normal microflora. They help fight various diseases, improve digestion, accelerating the absorption of nutrients from the intestines into the blood, and synthesize vitamins and other biologically active substances.
Spread of bacteria.
Bacteria exist anywhere and everywhere: in the food we eat, especially if it is sloppily prepared in dirty dishes; on unwashed vegetables and fruits. There are even more of them in the air we breathe, especially in dusty indoor air. There are many bacteria in water and soil. Bacteria can be found on all objects that we come into contact with: on door handles, on money, on the handrails of buses and trolleybuses, on the pages of books and notebooks.
Reproduction of bacteria.
The rate at which bacteria multiply is amazing. One bacterium turns into 2 in 15-20 minutes. If one bacterium, found in favorable conditions, could multiply freely, then in 2-3 days its offspring would fill all the seas and oceans of the Earth. What helps bacteria spread? What's stopping you?
Measures to combat bacteria. The multiplication of bacteria is helped by: warmth, moisture, darkness and good nutrition. They prevent bacteria from multiplying and destroy them: cold, dry room, sunlight, cleanliness, lack of food.
Ways of infection by pathogenic bacteria.
Each patient spreads around himself a large number of pathogenic bacteria. When you sneeze, droplets from your mouth are sprayed over a distance of 4-5 meters, and when you cough - up to 6-8 meters. You can become infected through the air, through a handshake.
Infection can occur through the patient’s belongings: dishes, towels, books, clothes, toys. Carriers of microbes can be dogs, cats, mice, rats, flies, lice, and mosquitoes.
Wounds, abrasions, and other skin damage are the gates through which microbes enter our organism.
Unwashed vegetables and fruits carry germs.
Interesting facts.
Most often our hands get dirty. Along with dirt and dust, many infectious germs accumulate on the hands. From the hands they are transferred to the face, eyes, lips, and into the mouth. Through dirty hands they become infected with worms, typhus and other diseases.
Even more germs accumulate under the nails.
The face is always open. A lot of dust, soot, and germs settle on it. They can fester and hurt your eyes.
A lot of dust and germs accumulate in the hair. To prevent enemy bacteria from attacking you, you need to wash your hands often, take a shower or bath, eat healthy food, and exercise.
What are the beneficial bacteria?
Foaming kvass, soft spongy bread - we would not have tried them if not for our friends - microorganisms. Let's find out together what beneficial bacteria are?
You have probably already paid attention to multi-colored spots of mold miraculously “blooming” on a forgotten crust of bread or in a jar of jam.
For children, this may indeed seem like a miracle: just yesterday a piece of bread looked completely normal, but today... it was covered with gray, yellow, and blue spots! “What is this?” Where did it come from? Is it possible to eat such bread?" asks the little why. Or maybe it started not with mold, but with illness: “I was completely healthy in the evening, but today?” Or a child saw his mother rolling out yeast dough: “Why does it squeak under the rolling pin?” Why does it come out of the bag? Who made the holes in the dough?" The children can't wait to find out everything!
But really, what do we really know about these and other microorganisms that surround us every day?
Let's debunk the myths
Most people are sure that germs cause only harm and they should be destroyed by all available means: from washing hands with antibacterial soap to treating every square centimeter of the apartment with chlorine-containing products. Someone even buys ultraviolet lamps for their children’s room, rubbing their hands with satisfaction: “Well, now hold on!” How will it be in a hospital: cleanliness and sterility!" But, meanwhile, scientists have long known that microbes, or, as they are more correctly called, microorganisms, are everywhere, so it is useless to fight them. They literally surround us and even abundantly populate our your native organism.
Many people wonder what beneficial bacteria are. Moreover, without microorganisms, life on Earth would be impossible at all!
Global cycle substances occur precisely with their active participation: if these little workers one day disappeared, the planet would very quickly be littered with the remains of dead plants and dead animals. It is they who return mineral substances that were once “removed” from it by plants to the soil, thus regulating its fertility. And what about the food products that are on our table every day?
But again, it was microorganisms who worked hard: they fermented milk into a variety of fermented milk products, made bread from yeast dough fluffy, better baked and easily digestible, preserved pickled and pickled products for us, even took care of our leisure time by makingalcoholic drinks , they tried to provide us with delicacies - for example, Roquefort and Camembert cheeses with noble mold. Cooks use citric acid extracted from mold fungi (which also belong to the microcosm), agronomists use bacterial preparations to combat diseases and pests of cultivated plants, livestock specialists prepare nutritious and long-lasting feed for farm animals (such as silage), pharmacists use a variety of antibiotics , vaccines, enzymes, vitamins... We encounter the end products of microbial activity several times a day, without even thinking about it.
And the invisible satellites, living on us and in us? There are, of course, unexpected visitors, but most of them are included in the honorary club “Normal Human Microflora”: microorganisms inhabit the skin and mucous membranes in large numbers, but most microbes live in the intestines, where they work for the benefit of the human body. Some produce enzymes, helping to more fully absorb nutrients from incoming food, others produce vitamins that are absorbed by the intestinal wall and used by the body - the host of all this fraternity. Still others (acidophilus and bifidobacteria, as well as E. coli) have antibiotic (i.e., suppressing vital activity) properties in relation to. to putrefactive and pathogenic microbes.
Now you understand what beneficial bacteria there are and why it is important to consume fermented milk products, especially those with the prefix “Bio” in the name (they contain, in addition to ordinary lactic acid bacteria, bifidobacteria)? Those of them that reach the intestines intact (and many will succeed in this), will remain there and temporarily take root for the benefit of man.
Fly in the ointment
However, not everything is so rosy. Like any creature in nature, microbes are diverse and do not fall under the definition of “absolutely harmful” or “absolutely beneficial.” We cannot discount the variety of and often dangerous infectious diseases - again they are to blame, invisible microorganisms. Of course, scientists have learned to fight many of them - in some places they have even won a victory on a planetary scale, with some a temporary truce has been concluded (for example, with leprosy, or, as it is otherwise called, with leprosy - the number of cases in the world is decreasing year by year, but it is too early to talk about a person’s victory over the disease). Other infectious agents still pose a serious danger, despite the modern level of development of medicine, for example, tuberculosis. And new diseases appear with sad regularity: just remember AIDS or swine flu (although many of them can be called new only conditionally - most often they are long-known to science, but are now changed, mutated microbes with new properties).
Besides that microorganisms cause various infectious diseases, many of them cause other damage to humans - for example, they lead to spoilage of food. Moreover, these often turn out to be the same friends: lactic acid bacteria ferment fresh milk; yeast leads to fermentation and souring of juices and fruits; mold... However, with mold everything is clear. Fortunately, people have learned to deal with this kind of trouble - it’s not for nothing that there are now many ways to preserve and sterilize products: from banal boiling to ultrasonic treatment, from simple drying to the addition of chemical preservatives that increase shelf life several times or even by an order of magnitude.
Who should you be afraid of?
To protect yourself from truly harmful microbes and make friends with useful (or harmless) ones, it is enough to follow simple, well-known rules: wash your hands before eating and after using the toilet, after returning home from anywhere, wash vegetables bought at the market or in a store and fruits, monitor the expiration dates of products, and during epidemics limit contact with possible carriers of infection. In general, no one has yet canceled the general rules of hygiene and sanitation, but it seems unnecessary to universally and regularly destroy germs at home. There are several reasons for this. Firstly, as mentioned, bacteria and mold spores are everywhere, so the benefit from the treatment does not last long. Secondly, not only harmful microbes are destroyed, but also all others (useful and indifferent to the body), but scientists have already proven that for the formation of normalchild's immunity Constant meetings with representatives of the microworld are necessary. And thirdly, disinfectants are usually quite aggressive substances that act not only on microorganisms, but also on householdanimals and humans .
Devyatkin Alexander
My parents gave me a microscope for my birthday. It's a toy, but very similar to the real thing. I looked at everything under a microscope: leaves of indoor plants, specks of dust, a drop of water and everything that came to hand. I was surprised and amazed by what I saw! How many new discoveries I have made for myself! To my great regret, I did not see any bacteria or microbes under the microscope. But I didn’t get upset for long. I took my books, encyclopedias and began to study them. Then I came up with a game. I “was” a real biology teacher, telling stories I had read and showing plant leaves under a microscope. Therefore, I did not choose the topic for the conference by chance. I myself was interested in learning about bacteria and telling others about it.
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Ministry of Education of the Saratov Region
Municipal secondary education
Institution Lyceum No. 37
Frunzensky district of Saratov
Bacteria
Creative work
student of grade 3 "B"
Devyatkin Alexander Igorevich
_______________________
Scientific supervisor
primary school teacher
Municipal educational institution "Lyceum No. 37"
Puzina Elena Valerievna
______________________
Saratov, 2010
Introduction page 3
1.Diversity of the surrounding world p.4
2.How are bacteria useful to humans? p.6
3. Brief characteristics of bacteria p. 7
4.The human body and bacteria. Enemies or friends? p.9
5.Is there life in boiling water? p.11
6.Bacteria in space p.12
7. The amazing abilities of bacteria p. 14
8. Bacteria fighters for health p. 15
Conclusion p.16
List of references p.17
INTRODUCTION
My parents gave me a microscope for my birthday. It's a toy, but very similar to the real thing. I looked at everything under a microscope: leaves of indoor plants, specks of dust, a drop of water and everything that came to hand. I was surprised and amazed by what I saw! How many new discoveries I have made for myself! To my great regret, I did not see any bacteria or microbes under the microscope. But I didn’t get upset for long. I took my books, encyclopedias and began to study them. Then I came up with a game. I “was” a real biology teacher, telling stories I had read and showing plant leaves under a microscope. Therefore, I did not choose the topic for the conference by chance. I myself was interested in learning about bacteria and telling others about it.
1.DIVERSITY OF THE AROUND WORLD
This is our magical planet Earth, full of secrets and mysteries. Blue, green, yellow, red, white - all of these are habitats on the planet. Every point on Earth contains 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, people, are creatures endowed with the great gift of reason. We think. With the help of reason, man makes discoveries and tries to uncover the secrets of nature.
For thousands of years man was sick and did not know the cause of the disease. Primitive people had their own explanation for this - they believed that the disease was caused by evil spirits. It was only at the beginning of the 19th century that man invented the microscope. This is a device that helped man discover another mystery of nature - the world of the smallest organisms - bacteria. In 1865 Louis Pasteur proved that germs are the cause of disease. They are tiny single-celled microorganisms visible only under a microscope.
Before a person could see bacteria, he had to deal with the results of their activity. For example, when milk sours, dough rises, wine ferments, and dead plants and animals decompose. Today we know that bacteria are everywhere - in the air, water, food, the ocean floor, hot springs, deep within the earth's crust, on our skin and even inside us.
The science of MICROBIOLOGY studies microorganisms. The name of the science comes from the Greek word “MIKROS” - small. Modern microbiology is divided into: general, technical, agricultural, sanitary, medical, radiation, space.
The most generally accepted theories about the origin of life on Earth say that microorganisms were the first living organisms to appear through the process of evolution.
2. WHAT ARE BACTERIA USEFUL TO HUMANS?
When people talk 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.
Microorganisms play a vital role in the circulation of substances and maintaining balance in the Earth's biosphere. Bacteria cause rotting of dead plants and animals on land and in water. Without these bacteria, the earth would be covered in various dead materials. By 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 convert this nitrogen into substances that plants need. And 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, which the body uses for its construction.
Thanks to the activity of microbes, cabbage is fermented, dough, kefir, cheese, and butter are prepared. Bacteria are necessary in the fermentation process in the production of cottage cheese, vinegar, wine, and beer. The same process is used in the industrial production of paints, plastics, cosmetics and confectionery. Bacteria are needed in production for the production of leather, removal of shells from coffee and cocoa beans, and separation of fibers in the textile industry.
3. BRIEF CHARACTERISTICS OF BACTERIA.
GROUPS OF MICROORGANISMS: Microorganisms are divided into several groups: BACTERIA, YEAST, MOLD FUNGI, VIRUSES.
BACTERIA are single-celled organisms that belong to prokaryotes. About 3,000 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, completely biochemically structured.
Bacteria have three shapes: spherical, rod-shaped, and curved or convoluted. Most microbes breathe air - they are aerobes. For others, the air is harmful - these are anaerobes. Microbes are divided into pathogenic (disease-causing) and non-pathogenic. The causative agents of most infectious diseases are bacteria. In our environment - air, soil, water - there are many microorganisms, from where they get onto 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, products containing a lot of water are a good nutrient medium - milk, broths, meat, fish, etc. Bacteria do not have male or female individuals. Bacteria reproduce by division. In addition to the nutrient medium, a favorable temperature (37-40 degrees) is required. Once in favorable conditions, microbes begin to rapidly multiply by fission. At temperatures above 50 degrees, most bacteria die. The bacterium consists of one cell; it is surrounded by a “membrane” coating that does not allow water to pass through. Inside the bacterium there 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 extensions of “flagella”. Some bacteria move with their help, others - by contracting the cell itself, like worms. The movement of bacteria was first described in the 19th century by Theodor Engelmann. He observed the accumulation of bacteria when various substances were added to the suspension. Taxis is a motor reaction of a bacterium. The movement of bacteria towards nutrients - sugar, amino acids, peptides, oxygen - is called “chemotaxis”. Photobacteria react to light - phototaxis. Thermotaxis response to temperature changes is also distinguished. Magnetotaxis helps bacteria navigate a magnetic field or find the seafloor.
4. HUMAN BODY AND BACTERIA. ENEMIES OR FRIENDS?
So, there are many varieties of microbes, and they live in entire colonies. Naturally, living in the human body, they must protect their owner and not harm him.
So, what is the intestine of a healthy person, that is, the population of this organ? In the intestines, 99% of microbes are selfless helpers of humans. They are called permanent microflora. Among them there are the main, main microorganisms - bifidobacteria and bacteroides. But there are also accompanying bacteria - these are Escherichia coli, lactobacilli, enterococci. Under certain conditions, representatives of normal microflora, except bifidobacteria, have the ability to cause diseases. However, there are more dangerous microbes in the intestines, 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 microbes. Why are we talking mostly about the intestines? The digestive tract is not homogeneous in composition and number of microorganisms. The esophagus has no permanent microflora at all and practically replicates the microflora of the oral cavity. Staphylo-, pneumo-, and streptococci constantly live on the mucous membrane of the nasopharynx. Plaque on teeth and food debris between them are a good environment for the life of microorganisms. The abundant development of microbes in the mouth leads to the rapid proliferation of food debris, while the chemical products of this decay accumulate, which destroy tooth enamel and lead to the development of caries. Therefore, it is so important to systematically brush your teeth and rinse your mouth after every 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 is represented by streptococci, lactobacilli and veillonella; in other sections the number of microbes is higher, and even more bacteria are found in the ileum, which, in addition to the listed microorganisms, contains E. coli. But the largest number of microbes lives in the large intestine. It is estimated that humans excrete over 17 trillion microbes per day in their stool, and by weight they account for a third of dry stool. If you take only intestinal bacteria, and collect them in one pile and weigh them, you will get about 3 kilograms!
5. IS THERE LIFE IN BOILING WATER?
Until recently, it was believed that boiling water killed all bacteria, even the most persistent ones, but nature, as always, refuted this belief. At the bottom of the Pacific Ocean, superhot springs with water temperatures from 250 to 400 degrees C were discovered, and it turned out that in this Living organisms thrive in boiling water: bacteria, giant worms, various shellfish 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 most resistant bacteria were considered to be those living in sulfur springs. 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 kill them completely. They will be inactive for some time. Bacteria have been discovered in frozen salt deposits that are hundreds of millions of years old. These bacteria came to life when they were studied.
6. BACTERIA IN SPACE
Scientists have long suspected that something evil was going on on starships and space stations - astronauts were getting sick too often. 15 of the 29 astronauts fell victim to bacterial or viral infections during their flight. Scientists' suspicions intensified even more when it turned out that on the Mir space stations and the ISS, seemingly harmless bacteria happily began to chew all kinds of structural materials, which led to accelerated corrosion.
All this prompted biologists to seriously study the behavior of microorganisms in space. In 2006, a group of Salmonella went into space on the Atlantis shuttle in a securely insulated container. The 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 to the control group, increased three (!) times.
For a whole year, astrobiologists tried to understand what caused the increase in the aggressiveness of salmonella. And here are the first results!
In space, Salmonella activated a section of DNA that controls the functioning of 160 genes. In addition, salmonella began to unite, forming a thin layer - a biofilm, which makes any microorganisms extremely dangerous. Interestingly, such behavior was not typical for salmonella on Earth before.”
Some experts consider weightlessness to be the cause of the mutation, others - cosmic radiation.
Over the many years of operation, the Mir space station has become a real testing ground for many technical solutions. It was on Mir that we managed to study small space free riders and learn how to fight 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. When microbes come into contact with a variety of materials, they quickly settle in and start eating. As a result, the materials favored by the voracious invisibles change color and their strength, sealing properties, dielectric and other characteristics decrease.
Over twenty years of research, scientists have discovered 250 species of microorganisms that live inside manned spacecraft.
All samples of microorganisms grown in space are stored at the Institute of Medical and Biological Problems in sealed ampoules - scientists do not know how they will behave in the terrestrial environment. There is another reason for keeping space mutants in a secure location. According to experts, if you take a microorganism grown in space that used metal as part of its environment, and continue to cultivate it, increasing the metal content in its environment, you can potentially obtain a biological weapon that can literally devour a tank or a helicopter.
Particularly interesting is the situation related to the navigation window of the Soyuz spacecraft, which spent six months in orbit. Crew members noted a deterioration in the visibility of the window. After the ship returned to Earth, research was carried out. The presence of mold mycelium 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 lines of mycelium growth, the glass was, as it were, etched.
7. AMAZING ABILITIES OF MICROBES
Specialists from the University of Massachusetts have distinguished themselves with a real breakthrough in science: the Geobacter microbe, which is capable of producing electricity from dirt and waste water. This is a great way to cleanse our Planet of dirt and wastewater.
Currently, scientists are looking for alternative fuels, replacing oil, gas, and coal with safer ones - biological, more environmentally friendly. Scientists at the University of Texas have created a new type of microbe that produces cellulose, which in turn can be converted into ethanol and other types of biofuels. With the help of salt water, blue-green algae, along with cellulose, also produce glucose and sucrose, which is used to produce biofuel - ethanol.
However, bacteria can participate in technological progress. After all, their ability to destroy almost any material can be used for the benefit of humans. Microorganisms may well be used in waste processing. 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, in the near future, malicious bacteria may turn into the most useful guardians of the environment.
8. BACTERIA – HEALTH FIGHTERS!
Houseplants can improve people's health. In a 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. A liter of air in a poorly ventilated living room contains about 500 thousand dust particles. During the day, a person inhales about 10 thousand liters of air containing dangerous and non-dangerous microbes.
The cleaner the air in public places, around human habitation and in rooms, the less people get sick. It is estimated that if you run a vacuum cleaner brush over the surface of an object four times, 50% of germs are removed. By maintaining good hygiene, brushing your teeth, washing your hands with soap and food, and food, the likelihood of getting sick is reduced many times over.
Forests and parks are of great importance in the fight for clean air. Green spaces deposit and absorb dust and release phytoncides that kill microbes.
CONCLUSION
So let's summarize. What have we found out? Humans 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. In order for bacteria to be our friends and not enemies, we need to: wash our hands with soap, wash our faces, brush our teeth, wash vegetables and fruits, plant a lot of trees. Take care of our planet, keep clean, breathe fresh air.
LIST OF REFERENCES USED:
1. S.A. Pavlovich ''Microbiology with microbiological research''. Study guide. Minsk: Higher school, 2009.-502 p.
2.L.V.Rechits ''Sanitary biology''. Educational edition. Gomel. Higher school, 2009.-320s.
3. School notebook on biology. 1991.
4. Encyclopedias: TSB., Around the World.
5. Magazine ''New Technologies''. 2009.
6. A. Zheleznyak encyclopedia ‘Cosmonautics’. 2007.
7. Scientific and journalistic magazine ‘’Cosmonautics News’’,
8. S.N. Plernikov, A.B. Korzyak ''The Amazing is Nearby''. Educational encyclopedia. 2005.
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Bacteria - friends and enemies of humans
Interesting facts The French scientist Louis Pasteur was one of the first to prove that bacteria do not originate in substances on their own. To destroy bacteria, he boiled the broth in glass flasks, which he then sealed. The broth did not spoil as long as the flasks were closed. Pasteur's work formed the basis of pasteurization - preserving food from spoilage by heating it to a temperature not exceeding 100 degrees Celsius. The number of bacteria in the human body exceeds the number of native cells by 10 times, and their total weight is about 2.5 kg.
Plants and animals are made up of tiny cells. Some of the cells can live independently, alone. Are there organisms smaller than cells? It turns out yes! These are bacteria. The kingdom of bacteria is comparable to the kingdoms of animals and plants. Bacteria are much smaller than cells. Most of them are less than one thousandth of a millimeter in size. It is no coincidence that bacteria are sometimes called microbes (from the Greek mikros - small and bios - life).
Bacteria reproduce simply by dividing in half. This happens in just a few minutes! Within a day, from one bacterium that finds itself in suitable conditions, tens of billions of exactly the same bacteria can form. A collection of bacteria that results from the division of one original bacterium is called a colony. Such colonies are clearly visible to the naked eye. They look like colored specks. You've probably seen similar spots on a piece of stale sausage or cheese. Food spoils thanks to the work of bacteria!
Bacteria need energy to live. Many of them get it by destroying nutrients created by other organisms. Some bacteria are capable of multiplying in the human body. They can be very dangerous, causing diseases: plague, tuberculosis, dysentery, cholera, gangrene and many others. Festering pimples, inflamed wounds are the consequences of the body’s fight against bacteria that have penetrated inside.
So bacteria are the enemy? Not really. Many of them live off the nutrients of dead organisms. Such bacteria are called saprophytes (from the Greek sapros - rotten). Saprophytic bacteria destroy fallen leaves and wilted grass. As a result, plant residues turn into humus, that is, into the fertile part of the soil. Soil would not have appeared on our planet if saprophytic bacteria had not destroyed plant and animal remains!
Saprophytic bacteria are involved in pickling cucumbers, mushrooms, and sauerkraut. And there are bacteria that live in the human body and are his helpers. We are talking about beneficial E. coli - bacteria that live in the intestines. They help digest food. Organisms of different species that help each other are called symbionts (from the Greek sym, syn - together and bios - life). We can say that E. coli is a human symbiont. Every healthy person has billions of these E. coli!
Cell Membrane Imagine a building that has heightened security measures in place so that no one or anything that could cause harm can get inside. In our body, such protection is provided to cells by their membrane. It contains “doors” - entrances and exits from the cell, as well as receptors that allow the cell to perceive the environment. They are located on the walls of the shell and subject to strict control everything that enters and exits the cell, because if it takes any harmful substance inside, the cell will die. The cell membrane consists of two layers of lipids, that is, fats, and protein molecules run across it.
“Moidodyr” by K.I. Chukovsky is one of my favorite books. And I always wondered why the crocodile, Moidodyr, washcloths, and soap were angry at the dirty one. This boy was just funny. And my mother told me that when adults say that you need to wash your hands before eating, after a walk, brush your teeth, wash your face - this is not just a requirement. It turns out that we are surrounded by a whole world of invisible creatures that arose on the planet many billions of years ago and 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 can be both beneficial and harmful to humans and animals. In order to get an idea of what we were dealing with, my mother suggested that I conduct several experiments.
From various sources we know that people who do not follow simple rules of personal hygiene often get sick and even end up in the hospital, and the reason for this is bacteria. But it is also known that beneficial microorganisms can protect humans from the harmful effects of environmental factors. Microorganisms have existed for millions of years and therefore have learned to live in the most difficult conditions, and it is very important for a person to be able to use the beneficial properties of microorganisms and know how to protect himself from their harm.
Bacteria are microscopically small organisms. Bacteria - (from the Greek word bacterium - rod) are truly omnipresent. The first inhabitants of the Earth were bacteria. For almost two billion years they remained its only inhabitants. Over time, they invented photosynthesis, that is, they learned to convert sunlight into energy-rich carbohydrates. We began to inhale oxygen. They populated any niche suitable for life. There are thousands, or even millions, of bacteria in the air and water, in any lump of soil and in every living organism. They can live in the harshest conditions that other organisms cannot withstand. They can be detected in the upper layers of the atmosphere at an altitude of several tens of kilometers and in deep underground wells; in boiling volcanic springs and in the thickness of Antarctic glaciers. Bacteria have been found even in water cooling a nuclear reactor, i.e. where the radiation level is many times higher than the lethal dose for humans. The myriads of bacteria inhabiting the Earth carry out gigantic geochemical activities that support the cycle of life. Together with fungi, bacteria destroy dead organic matter and convert it into carbon dioxide and water, regulate the composition of the atmosphere, and help maintain soil fertility.
About the microscope.
Bacteria can only be seen with a strong microscope. Dreaming of discovering new worlds, people made risky expeditions to uncharted shores. However, until the 17th century, no one suspected that wonderful creatures of nature existed nearby. The man who discovered the world of microorganisms was Anthony Van Leeuwenhoek. He was born in Holland into a poor family. I worked a lot since childhood. He had one hobby. He loved to grind optical glasses and achieved great success in this matter; at that time, the most powerful lenses could magnify the image by 20 times, and Lievenhoek created lenses that magnified by 150 and even 300 times. These lenses turned out to be a window to a new world. One day, while examining a drop of water under the lens, Livenhug saw a miracle - the smallest living creatures. So in 1673 man first became acquainted with bacteria. He reported his discovery to the Royal Society of London, and while scientists were deciding whether to believe or not this discovery, Lievenhoek looked at everything he could through the lenses. This is how he learned that muscles consist of fibers, microbes live in human saliva, and red balls float in the blood. Over 50 years of work, the scientist discovered more than 200 microorganisms. Many famous people came to the scientist, including Peter the Great. Everyone wanted to look into the mysterious world.
Even the most powerful light microscope cannot see the smallest parts of bacteria. A real revolution in science occurred with the creation of the electron microscope. It magnifies the image thousands of times. And in the mid-90s of the last century, a laser microscope was created. To catch the smallest cell and monitor it, scientists study not a single microbe, but a cluster - bacterial cultures. If all the cells are the same, then it is a pure culture. Such a homogeneous mass can grow in a test tube or flask with a special nutrient medium. If the nutrients in the test tube run out, the bacteria may die. To do this, a pure culture of bacteria is constantly reseeded into a new medium. Various substances are added to these media, such as gelatin, agar-agar (a substance from brown seaweed). After this, the nutrient medium is poured into special, flat dishes and a bacterial culture is introduced into a thin loop. From each cell a new colony grows. This is how the “hunt” for the microbe goes on.
My mother and I came to the Department of Microbiology at the Medical Academy and were shown special dishes (Petri dishes), test tubes, flasks and ovens in which bacteria grow. We were asked to do several experiments.
We placed a finger in a cup with a special substance, and made the same imprint in another cup, but after we washed our hands. The cups were placed in a special cabinet.
Using a cotton swab, they took a scraping from the teeth and placed it in another cup and also placed it in the cabinet.
The laboratory doctor told us that he would take photographs of these dishes at certain intervals so that we could evaluate how the bacteria were growing. We will have to evaluate the experience after 3 days.
And now 3 days have passed. We were shown what had grown in our cups. Where we applied unwashed hands, almost the entire cup was covered with droplets of different colors and shapes, which adhered tightly to the nutrient medium. Where we sowed with clean hands, there were much fewer of these droplets. In the cups with scrapings from the mouth there were many different white, grayish colonies.
These colonies were applied to glass using a thin loop, painted with a special paint, and looked at through a microscope. Under the microscope we saw small balls, long threads, thick rods. There were six different microbes in total. And in the mouth wash - eight.
But a light microscope cannot see the structure of bacteria; an electron microscope can show this.
Most often they consist of one cell and are shaped like balls or sticks.
The cell that makes up the body of most bacteria, like any other, contains protoplasm and is surrounded by a cytoplasmic membrane. Protoplasm contains DNA - a computer that stores the development program. We can say that a bacterial cell is a bag filled with various substances.
A bacterial cell has a strong wall; sometimes a dense cover of mucus (capsule) forms around the cell, which protects the cell from drying out.
Structure of bacteria
Diagram of the structure of a bacterial cell: 1 - cell wall, 2 - outer cytoplasmic membrane, 3 - circular DNA molecule, 4 - ribosomes, 5 - inclusions, 6 - mesosome (membrane reserve)
There are many motile bacteria. Some can crawl like caterpillars on a hard surface. In a liquid environment, bacterial cells swim with the help of flagella - thin outgrowths that are not found anywhere else in nature. At the junction of the flagellum and the cell, it is as if a powerful motor is working. Under its action, the flagellum rotates around its axis, which gives the cell a helical movement. With the help of flagella, bacteria can move to where there are more nutrients or leave areas with unfavorable conditions. Cylindrical bacteria are called rods, and spherical bacteria are called cocci. All bacteria reproduce by simple division, sometimes bacteria have the shape of a comma (vibrios), rods twisted into spirals, turning into fancy threads.
The laboratory doctor said that not all bacteria are harmful and most importantly, for them to cause disease, their quantity is very important. It turns out that many bacteria have adapted and live in certain conditions. Similar colonies, called “biofilms,” began to be found everywhere: on rocks and reefs, on plants and monuments, on the walls of water pipes and pieces of contact lenses. It is also known that each of us has a certain composition of beneficial bacteria, but for another person they can be harmful. Therefore, it is necessary for everyone to have their own toothbrush, comb, and cannot bite one apple or candy. So, bacteria live in colonies. But that means they need to somehow communicate with each other. How? The answer was found only in the 1990s. It turned out that bacteria use a chemical communication system to count their relatives, releasing special signal substances - ferromones. They measure their concentration using a specific receptor. While there are few pheromones, this means there are few microbes, and it is not profitable for them to act together. But news flies after news, confirming: “We are together!” And now there is no trace of the former harmlessness. As soon as the number of bacteria reaches a certain amount, the entire colony unanimously releases a toxin, which makes a person feel sick. Since we learned that it is not the microbes themselves that are dangerous, but their number, it has become clear that we can fight them differently. It is necessary not to destroy bacteria, but to prevent them from communicating with each other. Let the microbes, even having formed a large colony, still believe that they are separated. Let them not realize that it is high time for them to go on the attack. This means that we need to find those special substances that suppress the chemical signals of microbes.
Escherichia coli
This is the most famous bacterium that lives in the body of humans and animals without causing them much harm. Its cells live in the intestines. This bacterium is necessary for the normal functioning of the body, it produces useful vitamins, destroys harmful microbes, but in some cases it becomes aggressive and causes acute disorders, and it can be infected through dirty hands. This bacterium grows very quickly. On a nutrient medium, it begins to actively multiply within 3 hours and can be seen under a microscope. We concluded that hands should be washed every 3-4 hours. American scientists conducted experiments. They took samples from supermarket carts, coins, toys in children's rooms of various stores and cultured them on nutrient media. And it turned out that the largest number of germs is on cart handles and money, even more than on dirty fruit. Therefore, be sure to wash your hands with soap not only before eating and after visiting the toilet, but also after going to the store and being in any public places. A large amount of E. coli in soil or water is a clear indicator of contamination. In any modern city there is a special sanitary service that monitors the condition of drinking water and the condition of the soil, regularly measuring the amount of E. coli in them. Recently, the bacterium has begun to develop new professions; scientists have learned to transplant genes of other bacteria and even animals into it, this makes it possible to artificially create substances useful to humans, for example, using E. coli, to obtain insulin and other medicines.
In the cup where we sowed the plaque from the teeth, there were even more different microbes. These microbes looked like balls, bunches of grapes, sticks. It turned out that the growth of these bacteria was slower. The fact is that special substances are produced in the mouth that inhibit the growth of bacteria. And if a person brushes his teeth twice a day, regularly treats his teeth, then more of these substances are produced, and they prevent microbes from multiplying.
The invisible world of bacteria is not safe. Vibriobacilli exist in nature. They are able to penetrate the cell and begin to actively multiply there, which leads to cell death. Some bacteria are able to form a special capsule that protects them from harmful environmental influences; such a capsule is called a spore. The spores look completely lifeless and can remain without food for a long time, be exposed to the harmful effects of radiation, boiling, and are not affected by many toxic substances. But as soon as they find favorable conditions, they come to life and begin to actively grow. There are bacteria that have long caused people a lot of trouble, for example, the causative agent of anthrax, this disease can affect both herbivores and people, and a very large number of animals could die in a matter of days. This bacillus will persist in the soil for decades, and then infect other animals. This disease was defeated after the German scientist Robert Koch discovered the pathogen, and an animal vaccination was created. But there are also bacilli that help humans. They cause disease not in humans, but in the larvae of some insects. Once in the intestines of an insect, these bacilli quickly cause its death. Since these bacilli are completely harmless to animals and plants, they are used to protect gardens, vineyards, and vegetable plantations. These drugs are widely used to combat caterpillars of the cabbage cutworm, Siberian silkworm, and Colorado potato beetle larvae. Bacterial control agents are more effective and cause less environmental pollution.
In 1861 Louis Pasteur, the great French scientist, discovered living organisms that can grow in the complete absence of oxygen. These bacteria are called clostridia. They obtain the energy necessary for life through fermentation, and outwardly look like drumsticks. During the fermentation process, clostridia produce alcohol, acetic acid, and acetone. When acetone was needed to make explosives during the war, it was produced using clostridia. People have long used clostridium to produce flax. The stem of this plant contains a special substance - pectin, which is difficult to separate. But if the stems are soaked in water, bacteria begin to multiply on them and destroy this substance. However, some clostridia can cause very serious illness in humans. For example, when clostridia get into a wound, they begin to multiply and cause tetanus, which can kill a person. Therefore, when a person gets injured (steps on a rusty nail or is bitten by a dog), he must be vaccinated against tetanus. In addition, clostridia multiply in low-quality canned food and sausages, impregnating the products with toxic substances. When consuming such products, you can get botulism, a very dangerous form of poisoning.
Lactic acid bacteria.
Many traditional drinks and products, such as kefir, yogurt, kumiss, sour cream, cottage cheese, cheese, would not exist without the activity of special lactic acid bacteria. These bacteria, once in milk, begin to ferment and convert milk sugar into lactic acid. It not only adds flavor to drinks, but also 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 when plant tissues die. These bacteria are found in various foods prepared by fermentation, for example in sauerkraut, pickled cucumbers, and pickled olives. Lactic acid bacteria are used in agriculture to preserve feed. Juicy tops of beets or other fodder plants are placed in special pits and compressed. This process is called ensiling. After ensiling, many lactic acid bacteria develop in the compressed mass, and lactic acid reliably protects the silage from decomposition, and the feed only becomes better, since the bacteria enrich it with various beneficial substances.
There are some other very interesting bacteria in nature. They are called actinomycetes. In appearance, they are a system of long branching threads on which spores are formed. This structure resembles a mycelium. Actinomycetes are found in huge quantities in the soil, and if the thread of one bacterium located in one gram of soil is pulled into one thread, then the length of this thread will be several hundred meters. It is these bacteria that give the soil its unique smell. Many soil actinomycetes can feed on substances that are inaccessible to other bacteria. These substances include chitin, which makes up the shells of insects. Streptomycetes are widely used in medicine. They produce valuable antibiotics that have a detrimental effect on pathogenic bacteria. The discovery of these substances made a real revolution in medicine.
Nodule bacteria.
If legumes (clover, peas, or alfalfa) are sown on a field depleted from long use, the soil fertility is restored. Farmers of past centuries knew about this property of legumes. Only in 1866 The famous botanist and soil scientist Mikhail Stepanovich Voronin, using a microscope, saw tiny bodies in the swellings on the roots of legumes. The scientist suggested that special bacteria develop in the nodules. 20 years later, the Dutch microbiologist Martin Willem Beijerinck confirmed this guess: he isolated bacteria from pea nodules that were called nodule bacteria, or rhizobia.
Now nodule bacteria have been very well studied. It turned out that they have an amazing ability: they absorb nitrogen directly from the air. Only bacteria can do this. This is very important for science, because it is nitrogen that is lacking in soils that have become infertile.
Louis Pasteur
“a benefactor of humanity” - this is what they said about Louis Pasteur. Pasteur was born in France and received his doctorate at the age of 25. He studied chemistry, biology, veterinary medicine, medicine, and in each area of his work they solved some important problem. While working in the center of French winemaking, Pasteur discovered the cause of alcoholic fermentation. It turned out that it is caused by the smallest living creatures - alcohol yeast. He discovered that microbes are killed if the product is heated too much. Now this is called pasteurization. It was Louis Pasteur who discovered that microbes are the cause of all infectious diseases in the human body. The emergence of a new science, microbiology, is associated with his name. His laboratory created substances that can protect people from diseases. He worked for about 5 years to create a vaccine against rabies, a terrible disease transmitted through the bite of a sick animal. To test the vaccine, he wanted to infect himself with rabies, but a sick boy was brought to him, bitten by a dog. The child was doomed and Louis Pasteur took the risk of vaccinating him. The boy recovered. This news spread throughout the world, and special laboratories for vaccine production began to be created in different parts of the world. In Russia, Pasteur's teachings were taken up by the great Russian scientist Ilya Ilyich Mechnikov. He is the founder of immunology - the science of the body's defenses. There is innate and acquired immunity. Innate immunity is inherited, and acquired immunity occurs due to vaccinations. This is how a person protects himself from many diseases. It is especially important to get vaccinated when we travel to hot countries or plan to spend a lot of time in the forest. It is very important, in order not to get sick, to keep the apartment clean, not to leave dirty dishes, not to throw garbage anywhere, and to wash your hands more often.
Survey results
Considering that it is very important to know what kind of world surrounds us, we decided to conduct a survey in our class and find out what students know about bacteria. The following questions were proposed:
1. Microorganisms are:
The smallest organisms
The largest organisms
All of the schoolchildren surveyed answered that these are the smallest organisms.
2. Do you know what a microscope is for?
Out of 23 schoolchildren, 21 know that the microscope is intended for studying microorganisms, 2 people did not know about it.
When answering this question, many children ticked several answer options, which means that in our class, most students wash their hands not only when they become dirty, but also before eating, after using the toilet, and in other cases.
The answers to the question about how often schoolchildren brush their teeth were as follows:
From the answers to the fourth question of the questionnaire, it became clear that the majority of schoolchildren take proper care of their teeth, and those children who do not yet do this will definitely brush their teeth twice a day.
The fifth question we asked: - Why can’t you eat dirty fruits and vegetables? And here are the answers we received.
Almost all students know that unwashed vegetables and fruits contain a large number of microbes that can cause various diseases.
1. We are surrounded by a huge world of microorganisms that are found everywhere in living and inanimate nature, the human and animal bodies.
2. Microbes can only be seen with a microscope.
3. In nature, there are both harmful and beneficial microorganisms. Harmful microbes include those that cause diseases in humans and animals (Koch's bacillus, salmonella, vibrio cholerae and others). Beneficial ones include lactic acid bacteria, nodule bacteria, etc.). The number of microorganisms is of great importance for the development of diseases.
4. In order to be healthy, you must carefully observe the rules of hygiene.
the oldest group of organisms currently existing on Earth. The first bacteria probably appeared more than 3.5 billion years ago and for almost a billion years they were the only living creatures on our planet. Since these were the first representatives of living nature, their body had a primitive structure. Over time, their structure became more complex, but to this day bacteria are considered the most primitive single-celled organisms. It is interesting that some bacteria still retain the primitive features of their ancient ancestors. This is observed in bacteria living in hot sulfur springs and anoxic mud at the bottom of reservoirs. The discoverer of the world of bacteria was Anthony Leeuwenhoek, a Dutch naturalist of the 17th century. Bacteria are classified as prokaryotes and are classified into a separate kingdom - Bacteria. Due to their simplicity of organization and unpretentiousness, bacteria are widespread in nature. Bacteria are found everywhere: in a drop of even the purest spring water, in grains of soil, in the air, on rocks, in polar snow, desert sands, on the ocean floor, in oil extracted from great depths, and even in the water of hot springs with a temperature of about 80? WITH. They live on plants, fruits, various animals and in humans in the intestines, oral cavity, limbs, and on the surface of the body.
