Most people associate the word “bacteria” with something unpleasant and a threat to health. IN best case scenario Fermented milk products come to mind. At worst - dysbacteriosis, plague, dysentery and other troubles. But bacteria are everywhere, they are good and bad. What can microorganisms hide?
What are bacteria
Man and bacteria
The appearance of bacteria in the body
Beneficial bacteria are: lactic acid bacteria, bifidobacteria, E. coli, streptomycents, mycorrhizae, cyanobacteria.
They all play an important role in human life. Some of them prevent infections, others are used in production medicines, still others maintain balance in the ecosystem of our planet.
Types of harmful bacteria
Harmful bacteria can cause a number of serious illnesses in humans. For example, diphtheria, anthrax, sore throat, plague and many others. They are easily transmitted from an infected person through air, food, or touch. It is the harmful bacteria, the names of which will be given below, that spoil food. From them appears bad smell, rotting and decomposition occurs, they cause diseases.
Bacteria can be gram-positive, gram-negative, rod-shaped.
Names of harmful bacteria
Table. Harmful bacteria for humans. Titles| Titles | Habitat | Harm |
| Mycobacteria | food, water | tuberculosis, leprosy, ulcer |
| Tetanus bacillus | soil, skin, digestive tract | tetanus, muscle spasms, respiratory failure |
|
Plague stick (considered by experts as a biological weapon) |
only in humans, rodents and mammals | bubonic plague, pneumonia, skin infections |
| Helicobacter pylori | human gastric mucosa | gastritis, peptic ulcer, produces cytoxins, ammonia |
| Anthrax bacillus | soil | anthrax |
| Botulism stick | food, contaminated dishes | poisoning |
Harmful bacteria can for a long time reside in the body and absorb useful substances from it. However, they can cause an infectious disease.
The most dangerous bacteria
One of the most resistant bacteria is methicillin. It is better known as Staphylococcus aureus (Staphylococcus aureus). This microorganism can cause not one, but several infectious diseases. Some types of these bacteria are resistant to powerful antibiotics and antiseptics. Strains of this bacterium can live in upper sections respiratory tract, in open wounds and urinary canals of every third inhabitant of the Earth. For a person with a strong immune system, this does not pose a danger. 
Harmful bacteria to humans are also pathogens called Salmonella typhi. They are the causative agents of acute intestinal infections and typhoid fever. These types of bacteria, harmful to humans, are dangerous because they produce toxic substances that are extremely dangerous to life. As the disease progresses, the body becomes intoxicated, there is a very strong fever, rashes on the body, and the liver and spleen become enlarged. The bacterium is very resistant to various external influences. Lives well in water, on vegetables, fruits and reproduces well in milk products.
Clostridium tetan is also one of the most dangerous bacteria. It produces a poison called tetanus exotoxin. People who become infected with this pathogen experience terrible pain, seizures and die very hard. The disease is called tetanus. Despite the fact that the vaccine was created back in 1890, 60 thousand people die from it every year on Earth.
And another bacterium that can lead to human death is Mycobacterium tuberculosis. It causes tuberculosis, which is drug-resistant. If you do not seek help in a timely manner, a person may die.
Measures to prevent the spread of infections
Harmful bacteria and the names of microorganisms are studied by doctors of all disciplines from their student days. Healthcare annually seeks new methods to prevent the spread of life-threatening infections. If you follow preventive measures, you will not have to waste energy on finding new ways to combat such diseases.
To do this, it is necessary to timely identify the source of the infection, determine the circle of sick people and possible victims. It is imperative to isolate those who are infected and disinfect the source of infection.
The second stage is the destruction of pathways through which harmful bacteria can be transmitted. For this purpose, appropriate propaganda is carried out among the population.
Food facilities, reservoirs, and food storage warehouses are taken under control.
Every person can resist harmful bacteria by strengthening their immunity in every possible way. A healthy lifestyle, observing basic hygiene rules, protecting yourself during sexual intercourse, using sterile disposable medical instruments and equipment, a complete restriction from communication with people in quarantine. If you enter an epidemiological area or a source of infection, you must strictly comply with all the requirements of sanitary and epidemiological services. A number of infections are equated in their effects to bacteriological weapons.
What types of bacteria are there: names and types
The most ancient living organism on our planet. Not only have its members survived for billions of years, but they are also powerful enough to wipe out every other species on Earth. In this article we will look at what types of bacteria there are.
Let's talk about their structure, functions, and also name some useful and harmful types.
Discovery of bacteria
Types of bacteria in urine
Structure
Metabolism
Reproduction
Place in the world
Previously, we figured out what bacteria are. Now it’s worth talking about what role they play in nature.
Researchers say that bacteria are the first living organisms to appear on our planet. There are both aerobic and anaerobic varieties. Therefore, single-celled creatures are able to survive various disasters that occur on the Earth.
The undoubted benefit of bacteria lies in the assimilation of atmospheric nitrogen. They are involved in the formation of soil fertility and the destruction of the remains of dead representatives of flora and fauna. In addition, microorganisms participate in the creation of minerals and are responsible for maintaining oxygen and carbon dioxide reserves in the atmosphere of our planet.
The total biomass of prokaryotes is about five hundred billion tons. It stores more than eighty percent of phosphorus, nitrogen and carbon.
However, on Earth there are not only useful, but also pathogenic species bacteria. They cause many deadly diseases. For example, among these are tuberculosis, leprosy, plague, syphilis, anthrax and many others. But even those that are conditionally safe for human life can become a threat if the level of immunity decreases.
There are also bacteria that infect animals, birds, fish and plants. Thus, microorganisms are not only in symbiosis with more developed beings. Next we will talk about what pathogenic bacteria there are, as well as about beneficial representatives of this type of microorganism.
Bacteria and humans
Even at school they teach what bacteria are. Grade 3 knows all kinds of cyanobacteria and other single-celled organisms, their structure and reproduction. Now we'll talk about practical side question.
Half a century ago, no one even thought about such an issue as the state of microflora in the intestines. Everything was fine. Eating more natural and healthier, less hormones and antibiotics, less chemical emissions into the environment.
Today, in conditions of poor nutrition, stress, and an overabundance of antibiotics, dysbiosis and related problems are taking leading positions. How do doctors propose to deal with this?
One of the main answers is the use of probiotics. This is a special complex that repopulates the human intestines with beneficial bacteria.
Such an intervention can help with such unpleasant issues as food allergies, lactose intolerance, disorders gastrointestinal tract and other ailments.
Let's now touch on what beneficial bacteria there are, and also learn about their effect on health.
Three types of microorganisms have been studied in the most detail and are widely used to have a positive effect on the human body: acidophilus, Bulgarian bacillus and bifidobacteria.
The first two are designed to stimulate the immune system, as well as reduce the growth of some harmful microorganisms such as yeast, E. coli, and so on. Bifidobacteria are responsible for digesting lactose, producing certain vitamins and lowering cholesterol.
Harmful bacteria
Earlier we talked about what types of bacteria there are. The types and names of the most common beneficial microorganisms were announced above. Next we will talk about the “single-cell enemies” of humans.
There are some that are harmful only to humans, while others are deadly for animals or plants. People have learned to use the latter, in particular, to destroy weeds and annoying insects.
Before delving into what harmful bacteria are, it’s worth determining how they spread. And there are a lot of them. There are microorganisms that are transmitted through contaminated and unwashed food, by airborne droplets and contact, through water, soil or through insect bites.
The worst thing is that just one cell, once in the favorable environment of the human body, is capable of multiplying to several million bacteria within just a few hours.
If we talk about what types of bacteria there are, the names of pathogenic and beneficial ones are difficult for a layman to distinguish. In science, Latin terms are used to refer to microorganisms. In common parlance, abstruse words are replaced by concepts - “Escherichia coli”, “pathogens” of cholera, whooping cough, tuberculosis and others.
Preventive measures to prevent the disease are of three types. These are vaccinations and vaccinations, interruption of transmission routes (gauze bandages, gloves) and quarantine.
Where do bacteria in urine come from?
Which bacteria are beneficial?
Bacteria are everywhere - we have heard a similar slogan since infancy. We are trying with all our might to resist these microorganisms by sterilizing the environment. Is it necessary to do this?
There are bacteria that are protectors and helpers of both humans and the environment. These living microorganisms cover humans and nature with millions of colonies. They are active participants in all processes occurring on the planet and directly in the body of any living creature. Their goal is to be responsible for the correct flow of life processes and to be everywhere where one cannot do without them.
The vast world of bacteria
According to studies conducted regularly by scientists, the human body contains more than two and a half kilograms of various bacteria.
All bacteria are involved in life processes. For example, some help in the digestion of food, others are active assistants in the production of vitamins, and others act as protectors against harmful viruses and microorganisms.
One of the very useful living creatures present in the external environment is a nitrogen-fixing bacterium, which is found in the root nodules of plants that release nitrogen into the atmosphere necessary for human respiration.
There is another group of microorganisms that are associated with the digestion of waste organic compounds, helping to maintain soil fertility at the proper level. This includes nitrogen-fixing microbes.
Medicinal and food bacteria
Other microorganisms accept active participation in the process of obtaining antibiotics - these are streptomycin and tetracycline. These bacteria are called Streptomyces and are soil bacteria that are used in the manufacture of not only antibiotics, but also industrial and food products.
For these food industries, the bacterium Lactobacillis is widely used, which is involved in fermentation processes. Therefore, it is in demand in the production of yogurt, beer, cheese, and wine.
All these representatives of microorganisms-helpers live in their own way. strict rules. Violation of their balance leads to the most negative phenomena. First of all, dysbacteriosis is caused in the human body, the consequences of which are sometimes irreversible.
Secondly, all human restorative functions associated with internal or external organs, in case of imbalance beneficial bacteria are much more difficult. The same applies to the group that is involved in food production.
Bacteria are single-celled organisms lacking chlorophyll.
Bacteria are found everywhere, inhabiting all habitats. The largest number of them is found in the soil at a depth of up to 3 km (up to 3 billion in one gram of soil). There are many of them in the air (at an altitude of up to 12 km), in the bodies of animals and plants (both living and dead), and the human body is no exception.
Among bacteria there are immobile and mobile forms. Bacteria move with the help of one or more flagella, which are located on the entire surface of the body or in a certain area.
Bacterial cells vary in shape:
- spherical - cocci,
- rod-shaped - bacilli,
- comma-shaped - vibrios,
- twisted - spirilla.
Cocci:
Monococci: these are separately located cells.
Diplococci: These are paired cocci; after division they can form pairs.
Gonococcus Neisser: the causative agent of gonorrhea
Pneumococci: the causative agent of lobar pneumonia
Meningococci: the causative agent of meningitis (acute inflammation of the meninges)
Streptococci: These are round-shaped cells that, after dividing, form chains.
α - viridans streptococci
β - hemolytic streptococci, the causative agents of scarlet fever, sore throat, pharyngitis...
γ - non-hemolytic streptococci
Staphylococcus: This is a group of microorganisms that do not disperse after division, forming huge, disorderly clusters.
Causative agent: pustular diseases, sepsis, boils, abscesses, phlegmon, mastitis, pyodermatitis and pneumonia in newborns.
Sarcin: This is an accumulation of cocci in groups in the form of bags of 8 or more cocci.
Rod-shaped:
These are bacteria cylindrical, similar to rods measuring 1-5×0.5-1 microns, often located singly .
The actual bacteria: These are rod-shaped bacteria that do not form spores.
Bacilli: These are rod-shaped bacteria that form spores.
(Koch's bacillus, Escherichia coli, anthrax causative agent, Pseudomonas aeruginosa, plague causative agent, whooping cough causative agent, chancroid causative agent, tetanus causative agent, botulism causative agent, pathogen...)
Vibrios:
These are slightly curved cells, shaped like commas, 1-3 microns in size.
Vibrio cholerae: the causative agent of cholera. Lives in water through which infection occurs.
Spirilla:
These are convoluted microorganisms in the form of a spiral, with one, two or more spiral rings.
Harmless bacteria living in wastewater and dammed reservoirs.
Spirochetes:
These are thin, long, ax-shaped bacteria, represented by three species: Treponema, Borrelia, Lertospira. Treponema pallidum is pathogenic for humans - the causative agent of syphilis is sexually transmitted.
Structure of a bacterial cell:
Bacterial cell structure well studied using electron microscopy. A bacterial cell consists of a membrane outer layer which is called the cell wall, and the inner one is the cytoplasmic membrane, as well as cytoplasm with inclusions and nucleotides. There are additional structures: capsule, microcapsule, mucus, flagella, pili, plasmids;
Cell wall - a strong, elastic structure that gives the bacterium a certain shape and “restrains” the high osmotic pressure in the bacterial cell. It protects the cell from the action harmful factors external environment.
Outer membrane represented by lipopolysaccharides, phospholipids and proteins. On its outer side there is lipo-polysaccharide.
Between the cell wall and the cytoplasmic membrane is the periplasmic space, or periplasm, containing enzymes.
Cytoplasmic membrane adjacent to the inner surface of the bacterial cell wall and surrounds the outer part of the bacterial cytoplasm. It consists of a double layer of lipids, as well as integral proteins that penetrate it through.
Cytoplasm occupies the bulk of the bacterial cell and consists of soluble proteins, ribonucleic acids, inclusions and numerous small granules - ribosomes, responsible for protein synthesis. The cytoplasm contains various inclusions in the form of glycogen granules, polysaccharides, fatty acids and polyphosphates.
Nucleotide - equivalent to the nucleus in bacteria. It is located in the cytoplasm of bacteria in the form of double-stranded DNA, closed in a ring and tightly packed like a ball. Typically, a bacterial cell contains one chromosome, represented by a DNA molecule closed in a ring.
In addition to the nucleotide, the bacterial cell may contain extrachromosomal factors of heredity - plasmids, representing covalently closed DNA rings and capable of replication regardless of the bacterial chromosome.
Capsule - a mucous structure firmly associated with the cell wall of bacteria and having clearly defined external boundaries. Usually the capsule consists of polysaccharides, sometimes of poly-peptides,
Many bacteria contain microcapsule - mucous formation, detected only by electron microscopy.
Flagella bacteria determine cell motility. Flagella are thin filaments originating from the cytoplasmic membrane, they are attached to the cytoplasmic membrane and the cell wall by special disks, they are long, they consist of a protein - flagellin, twisted in the form of a spiral. Flagella are detected using an electron microscope.
Controversy - a peculiar form of resting gram-positive bacteria formed in the external environment under unfavorable conditions for the existence of bacteria (drying, nutrient deficiency, etc.).
L-form bacteria.
In many bacteria, with partial or complete destruction of cell walls, L-forms are formed. For some they occur spontaneously. The formation of L-forms occurs under the influence of penicillin, which disrupts the synthesis of cell wall mucopeptides. According to L-shape morphology different types bacteria are similar to each other. They are spherical, formations of various sizes: from 1-8 microns to 250 nm, they are capable, like viruses, of passing through the pores of porcelain filters. However, unlike viruses, L-forms can be grown on artificial nutrient media by adding penicillin, sugar, and horse serum. When penicillin is removed from the nutrient medium, the L-forms again turn into original forms bacteria.
Currently, L-forms of Proteus, Escherichia coli, Vibrio cholerae, Brucella, causative agents of gas gangrene and tetanus and other microorganisms have been obtained.
Gram-positive microorganisms (gr + m/o).
These include: Staphylococcus aureus and Staphylococcus epidermidis and Streptococcus...
Habitat: upper respiratory tract and skin.
Reservoir: skin, air, care items, furniture, bedding, clothing.
They do not die when dried.
Reproduction: they do not reproduce outside humans, but are capable of reproduction in food products if not properly stored.
Gram-negative microorganisms (gr - m/o).
These include: Escherichia coli, Klebsiella, Citrobacter, Proteus, Pseudomonas aeruginosa...
Habitat: intestines, mucous membranes of the urinary and respiratory tract...
Reservoir: wet rags, brushes for washing dishes, breathing equipment, wet surfaces, medicinal and weak disinfectants. solutions.
They die when dried out.
Reproduction: accumulate in the external environment, in disinfectants. solutions with low concentrations.
Transmitted: by airborne droplets and household contact.
At this very moment, man, when you read these lines, you are benefiting from the work of bacteria. From the oxygen we breathe in to the nutrients our stomachs extract from our food, we have bacteria to thank for thriving on this planet. In our body there are about ten times more microorganisms, including bacteria, than our own cells. Essentially, we are more microbes than people.
It's only recently that we've begun to understand a little about microscopic organisms and their impact on our planet and health, but history shows that centuries ago our ancestors were already harnessing the power of bacteria to ferment foods and drinks (whoever heard of bread and beer?).
In the 17th century, we began to study bacteria directly in our bodies in close connection with us - in the mouth. Antoni van Leeuwenhoek's curiosity led to the discovery of bacteria when he examined a plaque between his with your own teeth. Van Leeuwenhoek waxed poetic about the bacteria, describing the bacterial colony on his teeth as “a little white substance, like hardened dough.” Placing the sample under a microscope, van Leeuwenhoek saw that the microorganisms were moving. So they are alive!
You should know that bacteria played a vital role for the Earth, becoming key point in creating breathable air and biological richness for the planet we call home.
In this article, we will provide you with an overview of these tiny but very influential microorganisms. We'll look at the good, the bad, and the downright bizarre ways bacteria have shaped human history and environment. First, let's look at how bacteria differ from other types of life.
Bacteria Basics
Well, if bacteria are invisible to the naked eye, how can we know so much about them?
Scientists have developed powerful microscopes to look at bacteria - which range in size from one to a few microns (millionths of a meter) - and figure out how they relate to other life forms, plants, animals, viruses and fungi.
As you may know, cells are the building blocks of life, from the tissues of our body to the tree that grows outside our window. Humans, animals and plants have cells with genetic information contained in a membrane called the nucleus. These types of cells, called eukaryotic cells, have specialized organelles, each of which has a unique job to help the cell function.
Bacteria, however, do not have a nucleus, and their genetic material (DNA) floats freely inside the cell. These microscopic cells have no organelles and have other methods of reproduction and transfer of genetic material. Bacteria are considered prokaryotic cells.
Do bacteria survive in an environment with or without oxygen?
Their shape: rods (bacillus), circles (cocci) or spirals (spirillum)
Are the bacteria gram-negative or gram-positive, that is, do they have an outer protective membrane that prevents staining of the cell interior?
How bacteria move and explore their environment (many bacteria have flagella, tiny whip-like structures that allow them to move around in their environment)
Microbiology - the study of all types of microbes, including bacteria, archaea, fungi, viruses and protozoa - distinguishes bacteria from their microbial cousins.
Bacteria-like prokaryotes, now classified as archaea, were once together with bacteria, but as scientists learned more about them, they gave bacteria and archaea their own categories.
Microbial nutrition (and miasma)
Like people, animals and plants, bacteria need food to survive.
Some bacteria - autotrophs - use basic resources such as sunlight, water and chemicals from the environment to create food (think of cyanobacteria, which have been converting sunlight into oxygen for 2.5 million years). Other bacteria are called heterotrophs by scientists because they get their energy from existing organic matter as food (for example, dead leaves on forest floors).
The truth is that what may be tasty to bacteria will be disgusting to us. They have evolved to absorb all types of products, from oil spills and nuclear byproducts to human waste and decomposition products.
But the tendency of bacteria to specific source nutrition can benefit society. For example, art experts from Italy turned to bacteria that can eat excess layers of salt and glue, reducing the durability of priceless works of art. Ability to recycle bacteria organic matter also very beneficial to the Earth, both in soil and water.
From daily experience, you're well aware of the odor caused by bacteria as they consume the contents of your trash can, digesting leftover food and emitting their own gaseous byproducts. However, this is not all. You can also blame bacteria for causing those awkward moments when you pass gas yourself.
One big family
Bacteria grow and form colonies when given the chance. If food and environmental conditions are favorable, they multiply and form sticky clumps, called biofilms, to survive on a variety of surfaces - from rocks to the teeth of your mouth.
Biofilms have their pros and cons. On the one hand, they are mutually beneficial to natural objects (mutualism). On the other hand, they can be a serious threat. For example, doctors who treat patients with medical implants and devices have serious concerns about biofilms because they provide real estate for bacteria. Once colonized, biofilms can produce byproducts that are toxic—and sometimes fatal—to humans.
Like people in cities, cells in a biofilm communicate with each other, exchanging information about food and potential dangers. But instead of calling neighbors on the phone, bacteria send notes using chemicals.
Also, bacteria are not afraid to live on their own. Some species have developed interesting ways to survive in harsh conditions. When there is no more food and conditions become unbearable, bacteria preserve themselves by creating a hard shell, an endospore, which puts the cell into a state of dormancy and preserves the genetic material of the bacterium.
Scientists find bacteria in such time capsules that were stored for 100 and even 250 million years. This suggests that the bacteria can self-storage for a long time.
Now that we know what opportunities colonies provide to bacteria, let's figure out how they get there - through division and reproduction.
Bacteria reproduction
How do bacteria create colonies? Like other life forms on Earth, bacteria need to replicate themselves in order to survive. Other organisms do this through sexual reproduction, but not bacteria. But first, let's discuss why diversity is good.
Life undergoes natural selection, or the selective forces of a certain environment allow one type to flourish and reproduce more than another. You may remember that genes are the machinery that instructs a cell what to do and determines what color your hair and eyes will be. You get genes from your parents. Sexual reproduction results in mutations, or random changes in DNA, which creates diversity. The more genetic diversity there is, the greater the chance that an organism will be able to adapt to environmental constraints.
For bacteria, reproduction does not depend on meeting the right microbe; they simply copy their own DNA and divide into two identical cells. This process, called binary fission, occurs when one bacterium splits into two, copying DNA and passing it on to both parts of the divided cell.
Since the resulting cell will ultimately be identical to the one from which it was born, this method of propagation is not the best for creating a diverse gene pool. How do bacteria acquire new genes?
It turns out that bacteria use a clever trick: horizontal gene transfer, or the exchange of genetic material without reproducing. There are several ways that bacteria use to do this. One method involves collecting genetic material from the environment outside the cell - from other microbes and bacteria (through molecules called plasmids). Another way is viruses, which use bacteria as a home. When viruses infect a new bacterium, they leave the genetic material of the previous bacterium in the new one.
The exchange of genetic material gives bacteria the flexibility to adapt, and they adapt if they sense stressful changes in the environment, such as food shortages or chemical changes.
Understanding how bacteria adapt is extremely important for fighting them and creating antibiotics for medicine. Bacteria can exchange genetic material so frequently that sometimes treatments that worked before no longer work.
No high mountains, no great depths
If you ask the question “where are the bacteria?”, it is easier to ask “where are there no bacteria?”
Bacteria are found almost everywhere on Earth. It is impossible to imagine the number of bacteria on the planet at any one time, but some estimates put their number (bacteria and archaea together) at 5 octillion - a number with 27 zeros.
Classifying bacterial species is extremely difficult for obvious reasons. There are now approximately 30,000 officially identified species, but the knowledge base is constantly growing, and there are opinions that we are just the tip of the iceberg of all types of bacteria.
The truth is that bacteria have been around for a very long time. They produced some of the oldest fossils, dating back 3.5 billion years. Results scientific research suggest that cyanobacteria began creating oxygen approximately 2.3-2.5 billion years ago in the world's oceans, saturating the Earth's atmosphere with the oxygen we breathe to this day.
Bacteria can survive in the air, water, soil, ice, heat, on plants, in the intestines, on the skin - everywhere.
Some bacteria are extremophiles, meaning they can withstand extreme conditions that are either very hot or cold, or lack the nutrients and chemicals we typically associate with life. Researchers found such bacteria in the Mariana Trench, the deepest point on Earth at the bottom of the Pacific Ocean, near hydrothermal vents in water and ice. There are also bacteria that like high temperatures, such as those that color the opalescent pool in Yellowstone National Park.
Bad (for us)
While bacteria make important contributions to human and planetary health, they also have a dark side. Some bacteria can be pathogenic, meaning they cause illness and disease.
Over the course of human history, some bacteria (it’s clear why) received bad reputation, causing panic and hysteria. Take the plague, for example. The bacterium that causes the plague, Yersinia pestis, not only killed more than 100 million people, but may have contributed to the collapse of the Roman Empire. Before the advent of antibiotics, drugs that help fight bacterial infections, they were very difficult to stop.
Even today, these pathogenic bacteria seriously scare us. Thanks to the development of resistance to antibiotics, bacteria that cause anthrax, pneumonia, meningitis, cholera, salmonellosis, tonsillitis and other diseases that still remain close to us always pose a danger to us.
This is especially true for Staphylococcus aureus, the bacterium responsible for staph infections. This “superbug” causes numerous problems in clinics, since patients very often contract this infection when implanting medical implants and catheters.
We've already talked about natural selection and how some bacteria produce a variety of genes that help them cope with environmental conditions. If you have an infection and some of the bacteria in your body are different from others, antibiotics may affect most of the bacterial population. But those bacteria that survive will develop resistance to the drug and remain, waiting for the next chance. Therefore, doctors recommend completing the course of antibiotics to the end, and in general using them as rarely as possible, only as a last resort.
Biological weapons are another frightening aspect of this conversation. Bacteria can be used as a weapon in some cases, in particular anthrax was used at one time. In addition, not only people suffer from bacteria. A separate species, Halomonas titanicae, has shown an appetite for the sunken ocean liner Titanic, eating away at the metal of the historic ship.
Of course, bacteria can cause more than just harm.
Heroic bacteria
Let's explore good side bacteria. After all, these microbes gave us such delicious products, like cheese, beer, sourdough and other fermented elements. They also improve human health and are used in medicine.
Individual bacteria can be thanked for the formation human evolution. Science is collecting more and more data about microflora - microorganisms that live in our bodies, especially in the digestive system and intestines. Research shows that bacteria, new genetic materials, and the diversity they bring into our bodies allow humans to adapt to new food sources that have not been exploited before.
Let's look at it this way: by lining the surface of your stomach and intestines, bacteria “work” for you. When you eat, bacteria and other microbes help you break down and extract nutrients from your food, especially carbohydrates. The more diverse the bacteria we consume, the more diversity our bodies gain.
Although our knowledge of our own microbes is very limited, there is reason to believe that the absence of certain microbes and bacteria in the body may be associated with human health, metabolism and susceptibility to allergens. Preliminary studies in mice have shown that metabolic diseases like obesity are associated with a diverse and healthy microbiota, rather than our prevailing “calories in, calories out” mentality.
The possibilities of introducing certain microbes and bacteria into the human body, which can provide certain benefits, are now being actively explored, but at the time of writing general recommendations on their use have not yet been established.
In addition, bacteria played an important role in the development of scientific thought and human medicine. Bacteria played a leading role in the development of Koch's 1884 postulates, which led to the general understanding that disease is caused by a specific type of microbe.
Researchers studying bacteria accidentally discovered penicillin, an antibiotic that saved many lives. Also, quite recently, in connection with this, it was opened easy way edit the genome of organisms, which could revolutionize medicine.
In fact, we are just beginning to understand how to benefit from our cohabitation with these little friends. In addition, it is not clear who is the true owner of the Earth: people or microbes.
At this very moment, man, when you read these lines, you are benefiting from the work of bacteria. From the oxygen we breathe in to the nutrients our stomachs extract from our food, we have bacteria to thank for thriving on this planet. In our body there are about ten times more microorganisms, including bacteria, than our own cells. Essentially, we are more microbes than people.
It's only recently that we've begun to understand a little about microscopic organisms and their impact on our planet and health, but history shows that centuries ago our ancestors were already harnessing the power of bacteria to ferment foods and drinks (whoever heard of bread and beer?).
In the 17th century, we began to study bacteria directly in our bodies in close connection with us - in the mouth. Antoni van Leeuwenhoek's curiosity led to the discovery of bacteria when he examined a plaque between his own teeth. Van Leeuwenhoek waxed poetic about the bacteria, describing the bacterial colony on his teeth as “a little white substance, like hardened dough.” Placing the sample under a microscope, van Leeuwenhoek saw that the microorganisms were moving. So they are alive!
You should know that bacteria have played a critical role on Earth, being key to the creation of breathable air and the biological richness of the planet we call home.
In this article, we will provide you with an overview of these tiny but very influential microorganisms. We'll look at the good, the bad, and the downright bizarre ways that bacteria shape human and environmental history. First, let's look at how bacteria differ from other types of life.
Bacteria Basics
Well, if bacteria are invisible to the naked eye, how can we know so much about them?
Scientists have developed powerful microscopes to look at bacteria - which range in size from one to a few microns (millionths of a meter) - and figure out how they relate to other life forms, plants, animals, viruses and fungi.
As you may know, cells are the building blocks of life, from the tissues of our body to the tree that grows outside our window. Humans, animals and plants have cells with genetic information contained in a membrane called the nucleus. These types of cells, called eukaryotic cells, have specialized organelles, each of which has a unique job to help the cell function.
Bacteria, however, do not have a nucleus, and their genetic material (DNA) floats freely inside the cell. These microscopic cells have no organelles and have other methods of reproduction and transfer of genetic material. Bacteria are considered prokaryotic cells.
- Do bacteria survive in an environment with or without oxygen?
- Their shape: rods (bacillus), circles (cocci) or spirals (spirillum)
- Are the bacteria gram-negative or gram-positive, that is, do they have an outer protective membrane that prevents staining of the cell interior?
- How bacteria move and explore their environment (many bacteria have flagella, tiny whip-like structures that allow them to move around in their environment)
Microbiology- the science of all types of microbes, including bacteria, archaea, fungi, viruses and protozoa - distinguishes bacteria from their microbial cousins.
Bacteria-like prokaryotes, now classified as archaea, were once together with bacteria, but as scientists learned more about them, they gave bacteria and archaea their own categories.
Microbial nutrition (and miasma)
Like people, animals and plants, bacteria need food to survive.
Some bacteria—autotrophs—use basic resources like sunlight, water, and environmental chemicals to create food (think of cyanobacteria, which have been converting sunlight into oxygen for 2.5 million years). Other bacteria are called heterotrophs by scientists because they get their energy from existing organic matter as food (for example, dead leaves on forest floors).
The truth is that what may be tasty to bacteria will be disgusting to us. They have evolved to absorb all types of products, from oil spills and nuclear byproducts to human waste and decomposition products.
But a bacteria's affinity for a particular food source could benefit society. For example, art experts in Italy turned to bacteria that can eat excess layers of salt and glue, reducing the durability of priceless works of art. The ability of bacteria to process organic matter is also very beneficial for the Earth, both in soil and in water.
From daily experience, you're well aware of the odor caused by bacteria as they consume the contents of your trash can, digesting leftover food and emitting their own gaseous byproducts. However, this is not all. You can also blame bacteria for causing those awkward moments when you pass gas yourself.
One big family
Bacteria grow and form colonies when given the chance. If food and environmental conditions are favorable, they reproduce and form sticky clumps called biofilms to survive on surfaces ranging from rocks to the teeth of your mouth.
Biofilms have their pros and cons. On the one hand, they are mutually beneficial to natural objects (mutualism). On the other hand, they can be a serious threat. For example, doctors who treat patients with medical implants and devices have serious concerns about biofilms because they provide real estate for bacteria. Once colonized, biofilms can produce byproducts that are toxic—and sometimes fatal—to humans.
Like people in cities, cells in a biofilm communicate with each other, exchanging information about food and potential dangers. But instead of calling neighbors on the phone, bacteria send notes using chemicals.
Also, bacteria are not afraid to live on their own. Some species have developed interesting ways to survive in harsh environments. When there is no more food and conditions become unbearable, bacteria preserve themselves by creating a hard shell, an endospore, which puts the cell into a state of dormancy and preserves the genetic material of the bacterium.
Scientists find bacteria in such time capsules that were stored for 100 and even 250 million years. This suggests that the bacteria can self-storage for a long time.
Now that we know what opportunities colonies provide to bacteria, let's figure out how they get there - through division and reproduction.
Bacteria reproduction
How do bacteria create colonies? Like other life forms on Earth, bacteria need to replicate themselves in order to survive. Other organisms do this through sexual reproduction, but not bacteria. But first, let's discuss why diversity is good.
Life undergoes natural selection, or the selective forces of a certain environment allow one type to flourish and reproduce more than another. You may remember that genes are the machinery that instructs a cell what to do and determines what color your hair and eyes will be. You get genes from your parents. Sexual reproduction results in mutations, or random changes in DNA, which creates diversity. The more genetic diversity there is, the greater the chance that an organism will be able to adapt to environmental constraints.
For bacteria, reproduction does not depend on meeting the right microbe; they simply copy their own DNA and divide into two identical cells. This process, called binary fission, occurs when one bacterium splits into two, copying DNA and passing it on to both parts of the divided cell.
Since the resulting cell will ultimately be identical to the one from which it was born, this method of propagation is not the best for creating a diverse gene pool. How do bacteria acquire new genes?
It turns out that bacteria use a clever trick: horizontal gene transfer, or the exchange of genetic material without reproducing. There are several ways that bacteria use to do this. One method involves collecting genetic material from the environment outside the cell - from other microbes and bacteria (through molecules called plasmids). Another way is viruses, which use bacteria as a home. When viruses infect a new bacterium, they leave the genetic material of the previous bacterium in the new one.
The exchange of genetic material gives bacteria the flexibility to adapt, and they adapt if they sense stressful changes in the environment, such as food shortages or chemical changes.
Understanding how bacteria adapt is extremely important for combating them and creating antibiotics for medicine. Bacteria can exchange genetic material so frequently that sometimes treatments that worked before no longer work.
No high mountains, no great depths
If you ask the question “where are the bacteria?”, it is easier to ask “where are there no bacteria?”
Bacteria are found almost everywhere on Earth. It is impossible to imagine the number of bacteria on the planet at any one time, but some estimates put their number (bacteria and archaea together) at 5 octillion - a number with 27 zeros.
Classifying bacterial species is extremely difficult for obvious reasons. There are now approximately 30,000 officially identified species, but the knowledge base is constantly growing, and there are opinions that we are just the tip of the iceberg of all types of bacteria.
The truth is that bacteria have been around for a very long time. They produced some of the oldest fossils, dating back 3.5 billion years. Scientific research suggests that cyanobacteria began creating oxygen approximately 2.3-2.5 billion years ago in the world's oceans, saturating the Earth's atmosphere with the oxygen we breathe to this day.
Bacteria can survive in the air, water, soil, ice, heat, on plants, in the intestines, on the skin - everywhere.
Some bacteria are extremophiles, meaning they can withstand extreme conditions that are either very hot or cold, or lack the nutrients and chemicals we typically associate with life. Researchers found such bacteria in the Mariana Trench, the deepest point on Earth at the bottom of the Pacific Ocean, near hydrothermal vents in water and ice. There are also bacteria that like high temperatures, such as those that color the opalescent pool in Yellowstone National Park.
Bad (for us)
While bacteria make important contributions to human and planetary health, they also have a dark side. Some bacteria can be pathogenic, meaning they cause illness and disease.
Throughout human history, certain bacteria have (understandably) gotten a bad rap, causing panic and hysteria. Take the plague, for example. The bacterium that causes the plague, Yersinia pestis, not only killed more than 100 million people, but may have contributed to the collapse of the Roman Empire. Before the advent of antibiotics, drugs that help fight bacterial infections, they were very difficult to stop.
Even today, these pathogenic bacteria seriously scare us. Thanks to the development of resistance to antibiotics, bacteria that cause anthrax, pneumonia, meningitis, cholera, salmonellosis, tonsillitis and other diseases that still remain close to us always pose a danger to us.
This is especially true for Staphylococcus aureus, the bacterium responsible for staph infections. This “superbug” causes numerous problems in clinics, since patients very often contract this infection when implanting medical implants and catheters.
We've already talked about natural selection and how some bacteria produce a variety of genes that help them cope with environmental conditions. If you have an infection and some of the bacteria in your body are different from others, antibiotics may affect most of the bacterial population. But those bacteria that survive will develop resistance to the drug and remain, waiting for the next chance. Therefore, doctors recommend completing the course of antibiotics to the end, and in general using them as rarely as possible, only as a last resort.
Biological weapons are another frightening aspect of this conversation. Bacteria can be used as a weapon in some cases, in particular anthrax was used at one time. In addition, not only people suffer from bacteria. A separate species, Halomonas titanicae, has shown an appetite for the sunken ocean liner Titanic, eating away at the metal of the historic ship.
Of course, bacteria can cause more than just harm.
Heroic bacteria
Let's explore the good side of bacteria. After all, these microbes gave us delicious foods like cheese, beer, sourdough and other fermented elements. They also improve human health and are used in medicine.
Individual bacteria can be thanked for shaping human evolution. Science is collecting more and more data about microflora - microorganisms that live in our bodies, especially in the digestive system and intestines. Research shows that bacteria, new genetic materials, and the diversity they bring into our bodies allow humans to adapt to new food sources that have not been exploited before.
Let's look at it this way: by lining the surface of your stomach and intestines, bacteria “work” for you. When you eat, bacteria and other microbes help you break down and extract nutrients from your food, especially carbohydrates. The more diverse the bacteria we consume, the more diversity our bodies gain.
Although our knowledge of our own microbes is very limited, there is reason to believe that the absence of certain microbes and bacteria in the body may be associated with human health, metabolism and susceptibility to allergens. Preliminary studies in mice have shown that metabolic diseases like obesity are associated with a diverse and healthy microbiota, rather than our prevailing “calories in, calories out” mentality.
The possibility of introducing certain microbes and bacteria into the human body that may provide certain benefits is currently being actively explored, but at the time of writing, general recommendations for their use have not yet been established.
In addition, bacteria played an important role in the development of scientific thought and human medicine. Bacteria played a leading role in the development of Koch's 1884 postulates, which led to the general understanding that disease is caused by a specific type of microbe.
Researchers studying bacteria accidentally discovered penicillin, an antibiotic that saved many lives. Also, quite recently, in connection with this, an easy way to edit the genome of organisms was discovered, which could revolutionize medicine.
In fact, we are just beginning to understand how to benefit from our cohabitation with these little friends. In addition, it is not clear who is the true owner of the Earth: people or microbes.
Jul 22, 2017 Gennady
Reproduction of bacteria by fission is the most common method of increasing the size of a microbial population. After division, bacteria grow to their original size, which requires certain substances(growth factors).
The methods of reproduction of bacteria are different, but most of their species have a form of asexual reproduction by fission. Bacteria rarely reproduce by budding. Sexual reproduction of bacteria is present in a primitive form.
Rice. 1. In the photo bacterial cell in the stage of division.
Genetic apparatus of bacteria
The genetic apparatus of bacteria is represented by a single DNA - chromosome. The DNA is closed in a circle. The chromosome is localized in a nucleotide that does not have a membrane. A bacterial cell contains plasmids.
Nucleoid
A nucleoid is an analogue of a nucleus. It is located in the center of the cell. It contains DNA, the carrier of hereditary information in a folded form. Unwound DNA reaches a length of 1 mm. The nuclear substance of a bacterial cell does not have a membrane, a nucleolus or a set of chromosomes, and does not divide by mitosis. Before dividing, the nucleotide is doubled. During division, the number of nucleotides increases to 4.
Rice. 2. The photo shows a bacterial cell in a section. A nucleotide is visible in the central part.
Plasmids
Plasmids are autonomous molecules folded into a ring of double-stranded DNA. Their mass is significantly less than the mass of a nucleotide. Despite the fact that hereditary information is encoded in the DNA of plasmids, they are not vital and necessary for the bacterial cell.
Rice. 3. The photo shows a bacterial plasmid.
Stages of division
After reaching a certain size characteristic of an adult cell, division mechanisms are launched.
DNA replication
DNA replication precedes cell division. Mesosomes (folds of the cytoplasmic membrane) hold DNA until the division (replication) process is completed.
DNA replication is carried out with the help of enzymes DNA polymerases. During replication, the hydrogen bonds in double-stranded DNA are broken, resulting in the formation of two single-stranded daughter DNAs from one DNA. Subsequently, when the daughter DNAs have taken their place in the separated daughter cells, they are restored.
As soon as DNA replication is complete, a constriction appears as a result of synthesis, dividing the cell in half. First, the nucleotide undergoes division, then the cytoplasm. Cell wall synthesis completes division.
Rice. 4. Scheme of bacterial cell division.
Exchange of DNA sections
In Bacillus subtilis, the process of DNA replication ends with the exchange of sections of 2 DNA.
After cell division, a bridge is formed through which the DNA of one cell passes into another. Next, both DNAs are intertwined. Some sections of both DNA stick together. At the sites of adhesion, DNA segments are exchanged. One of the DNA goes along the jumper back into the first cell.
Rice. 5. Variant of DNA exchange in Bacillus subtilis.
Types of bacterial cell divisions
If cell division is ahead of the separation process, then multicellular rods and cocci are formed.
With synchronous cell division, two full-fledged daughter cells are formed.
If the nucleotide divides faster than the cell itself, then multinucleotide bacteria are formed.
Methods for separating bacteria
Division by breaking
Division by breaking is characteristic of anthrax bacilli. As a result of this division, the cells break at the junction points, breaking the cytoplasmic bridges. Then they repel each other, forming chains.
Sliding division
With sliding separation, after division the cell becomes detached and, as it were, slides along the surface of another cell. This method of separation is typical for some forms of Escherichia.
Split split
With secant division, one of the divided cells with its free end describes an arc of a circle, the center of which is the point of its contact with another cell, forming a Roman quinque or cuneiform (Corynebacterium diphtheria, Listeria).
Rice. 6. The photo shows rod-shaped bacteria forming chains (anthrax bacilli).
Rice. 7. The photo shows a sliding method for separating E. coli.
Rice. 8. The splitting method of separating corynebacteria.
Type of bacterial clusters after division
Clusters of dividing cells have a variety of shapes, which depend on the direction of the division plane.
Globular bacteria arranged one by one, two by two (diplococci), in packets, in chains, or like bunches of grapes. Rod-shaped bacteria - in chains.
Spiral shaped bacteria- chaotic.
Rice. 9. The photo shows micrococci. They are round, smooth, and white, yellow and red in color. In nature, micrococci are ubiquitous. They live in different cavities of the human body.
Rice. 10. In the photo there are diplococcus bacteria - Streptococcus pneumoniae.
Rice. 11. The photo shows Sarcina bacteria. Coccoid bacteria cluster together in packets.
Rice. 12. The photo shows the bacteria streptococci (from the Greek “streptos” - chain). Arranged in chains. They are causative agents of a number of diseases.
Rice. 13. In the photo, the bacteria are “golden” staphylococci. Arranged like “bunches of grapes”. The clusters are golden in color. They are causative agents of a number of diseases.
Rice. 14. In the photo, the coiled Leptospira bacteria are the causative agents of many diseases.
Rice. 15. The photo shows rod-shaped bacteria of the genus Vibrio.
Bacterial division rate
The rate of bacterial division is extremely high. On average, one bacterial cell divides every 20 minutes. Within just one day, one cell forms 72 generations of offspring. Mycobacterium tuberculosis divides slowly. The entire division process takes them about 14 hours.
Rice. 16. The photo shows the process of streptococcus cell division.
Sexual reproduction of bacteria
In 1946, scientists discovered sexual reproduction in a primitive form. In this case, gametes (male and female reproductive cells) are not formed, but some cells exchange genetic material ( genetic recombination).
Gene transfer occurs as a result conjugation- unidirectional transfer of part of the genetic information in the form plasmids upon contact of bacterial cells.
Plasmids are DNA molecules small size. They are not associated with the chromosome genome and are capable of doubling autonomously. Plasmids contain genes that increase the resistance of bacterial cells to unfavorable conditions external environment. Bacteria often pass these genes on to each other. Transfer of genetic information to bacteria of another species is also noted.
In the absence of a true sexual process, it is conjugation that plays a huge role in the exchange of useful characteristics. This is how the ability of bacteria to exhibit drug resistance is transmitted. The transfer of antibiotic resistance between disease-causing populations is particularly dangerous for humanity.
Rice. 17. The photo shows the moment of conjugation of two E. coli.
Phases of bacterial population development
When inoculated on a nutrient medium, the development of the bacterial population goes through several phases.
Initial phase
The initial phase is the period from the moment of sowing to their growth. On average, the initial phase lasts 1 - 2 hours.
Breeding delay phase
This is the phase of intensive bacterial growth. Its duration is about 2 hours. It depends on the age of the crop, the period of adaptation, the quality of the nutrient medium, etc.
Logarithmic phase
During this phase, there is a peak in the rate of reproduction and increase in the bacterial population. Its duration is 5 - 6 hours.
Negative acceleration phase
During this phase, there is a decline in the reproduction rate, the number of dividing bacteria decreases, and the number of dead bacteria increases. The reason for the negative acceleration is the depletion of the nutrient medium. Its duration is about 2 hours.
Stationary maximum phase
During the stationary phase, an equal number of dead and newly formed individuals is noted. Its duration is about 2 hours.
Death Acceleration Phase
During this phase, the number of dead cells progressively increases. Its duration is about 3 hours.
Logarithmic death phase
During this phase, bacterial cells die at a constant rate. Its duration is about 5 hours.
Decrease rate phase
During this phase, the remaining living bacterial cells enter a dormant state.
Rice. 18. The figure shows the growth curve of a bacterial population.
Rice. 19. In the photo, a colony of Pseudomonas aeruginosa is blue-green, a colony of micrococci yellow, Bacterium prodigiosum colonies are blood red in color and Bacteroides niger colonies are black in color.
Rice. 20. The photo shows a colony of bacteria. Each colony is the offspring of a single cell. In a colony, the number of cells is in the millions. The colony grows in 1 - 3 days.
Division of magnetically sensitive bacteria
In the 1970s, bacteria living in the seas were discovered that had a sense of magnetism. Magnetism allows these amazing creatures to navigate along lines magnetic field Earth and find sulfur, oxygen and other substances it needs so much. Their “compass” is represented by magnetosomes, which consist of a magnet. When dividing, magnetically sensitive bacteria divide their compass. In this case, the constriction during division becomes clearly insufficient, so the bacterial cell bends and makes a sharp fracture.
Rice. 21. The photo shows the moment of division of a magnetically sensitive bacterium.
Bacterial growth
When a bacterial cell begins to divide, two DNA molecules move to opposite ends of the cell. Next, the cell is divided into two equal parts, which are separated from each other and increase to their original size. The division speed of many bacteria averages 20 - 30 minutes. Within just one day, one cell forms 72 generations of offspring.
During the process of growth and development, a mass of cells quickly absorbs nutrients from the environment. This is facilitated by favorable environmental factors - temperature regime, sufficient quantity nutrients, the required pH of the environment. Aerobic cells require oxygen. It is dangerous for anaerobes. However, unlimited proliferation of bacteria does not occur in nature. Sunlight, dry air, lack of food, high temperature environmental and other factors have a detrimental effect on the bacterial cell.
Rice. 22. The photo shows the moment of cell division.
Growth factors
For the growth of bacteria, certain substances (growth factors) are necessary, some of which are synthesized by the cell itself, some of which come from the environment. The need for growth factors is different for all bacteria.
The need for growth factors is a constant feature, which makes it possible to use it for identifying bacteria, preparing nutrient media, and using it in biotechnology.
Bacterial growth factors (bacterial vitamins) - chemical elements, most of which are water-soluble B vitamins. This group also includes hemin, choline, purine and pyrimidine bases and other amino acids. In the absence of growth factors, bacteriostasis occurs.
Bacteria use growth factors to minimum quantities and unchanged. A number of chemicals in this group are part of cellular enzymes.
Rice. 23. The photo shows the moment of division of a rod-shaped bacterium.
The most important bacterial growth factors
- Vitamin B1 (thiamine). Takes part in carbohydrate metabolism.
- Vitamin B2" (riboflavin). Takes part in redox reactions.
- Pantothenic acid is an integral part of coenzyme A.
- Vitamin B6 (pyridoxine). Takes part in amino acid metabolism.
- Vitamins B12(cobalamins are substances containing cobalt). They take an active part in the synthesis of nucleotides.
- Folic acid. Some of its derivatives are part of enzymes that catalyze the synthesis of purine and pyrimidine bases, as well as some amino acids.
- Biotin. Participates in nitrogen metabolism and also catalyzes the synthesis of unsaturated fatty acids.
- Vitamin PP(nicotinic acid). Participates in redox reactions, the formation of enzymes and the metabolism of lipids and carbohydrates.
- Vitamin H(para-aminobenzoic acid). It is a growth factor for many bacteria, including those inhabiting the human intestines. Folic acid is synthesized from para-aminobenzoic acid.
- Gemin. It is a component of some enzymes that take part in oxidation reactions.
- Kholin. Takes part in the reactions of cell wall lipid synthesis. It is a supplier of methyl group in the synthesis of amino acids.
- Purine and pyrimidine bases(adenine, guanine, xanthine, hypoxanthine, cytosine, thymine and uracil). The substances are needed mainly as components of nucleic acids.
- Amino acids. These substances are components of cell proteins.
Requirement for growth factors of certain bacteria
Auxotrophs To ensure life, they require the supply of chemicals from the outside. For example, clostridia are not able to synthesize lecithin and tyrosine. Staphylococci require the supply of lecithin and arginine. Streptococci require the supply of fatty acids - components of phospholipids. Corynebacteria and Shigella require nicotinic acid. Staphylococcus aureus, pneumococci and Brucella require vitamin B1. Streptococci and tetanus bacilli - in pantothenic acid.
Prototrophs independently synthesize the necessary substances.
Rice. 24. Different conditions environmental conditions have different effects on the growth of bacterial colonies. On the left is steady growth in the form of a slowly expanding circle. Right - rapid growth in the form of "escapes".
Studying the need of bacteria for growth factors allows scientists to obtain a large microbial mass, so necessary in the manufacture of antimicrobial drugs, serums and vaccines.
Read more about bacteria in the articles:
Bacterial proliferation is a mechanism for increasing the number of microbial populations. Bacterial division is the main method of reproduction. After dividing, the bacteria must reach adult size. Bacteria grow by quickly absorbing nutrients from their environment. Growth requires certain substances (growth factors), some of which are synthesized by the bacterial cell itself, and some of which come from the environment.
