Bacteria belong to the realm of moneras. These are tiny unicellular organisms, that is, they are formed by a single cell, they do not contain the hereditary material enclosed in a nucleus, like other cells; nor do they possess the structures that are common in other cells; for this reason it is considered that moneras or bacteria, have little relation with the other kingdoms.
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Bacteria, like any other organism, are classified into two categories, according to the way they get their energy, and in this we refer to the terms: Autotrophs and Heterotrophs.
Autotroph organisms are those that have the ability to obtain energy by manufacturing their own food. While organisms that can not produce their food are called Heterotrophs. To understand these two words, let's see their meanings below: Auto- is a prefix that means "by itself" and the root -trofo means "food" and the second prefix hetero-means "other". Heterotrophic organisms can feed on autotrophs or other heterotrophs, but all ultimately depend on autotrophic organisms for their feeding.
Before the term "bacterium" was used to refer to certain types of moneras, others of them were known as blue-green algae, but now they are called cyanobacteria or blue-green bacteria; Nowadays all moneras are considered bacteria, so that both terms are used interchangeably. Since bacteria are a better known term than moneras, from now on we will use the word bacteria to continue referring to these important organisms.
Many scientists have claimed that bacteria were the first life forms on Earth, which appeared about 3,500 million years ago, being the only living beings for 2 billion years; bacteria are the most numerous organisms on Earth, scientists calculate that in an ounce of soil there are an average of 2.500 million bacteria.
The bacteria can have different shapes and sizes, many of them can be seen in the microscope with elongated capsule-shaped, spherical, like a marble, curled like springs, round or have no shape. In addition, the range of colors of the bacteria ranges from red and yellow to blue and violet. Some of them live as separate cells and others in groups of cells linked together.
One of the most notable characteristics of a bacterium is the cell wall, as we can see in the image:
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The cell wall is a rigid and rigid structure that surrounds, holds, shapes and protects the cell; almost all bacteria have a cell wall; They also have a protective layer, this layer is called capsule. Now, how does the capsule protect the bacteria? The cell wall is internally covered by the cell membrane, which will control substances entering and leaving the cell, inside this membrane is the cytoplasm, which is a gelatinous mixture of substances that forms almost the entire cell .
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Unlike almost all cells, the hereditary material of the bacteria is not enclosed in the nucleus, since the moneras or bacteria do not have any membrane that separates the hereditary material from the rest of the cell. Many bacteria can not move on their own, move from one place to another in air and water currents, in clothing and other objects. While there are others with structures that allow them to move in liquid media, called flagella. Flagella are species of long, thin whips that propel the bacteria.
Vital functions of bacteria
Bacteria have more means of obtaining the energy they need to live than all the combined organisms of the other kingdoms. Like most other organisms, many bacteria need oxygen to obtain energy from food. others can live without oxygen and there are others that die with the presence of oxygen.
As we pointed out earlier, many bacteria are heterotrophic, we said at the beginning that this kind of bacteria is not capable of making its own food, therefore it has to eat, usually other organisms, to obtain energy. Some bacteria feed on living organisms, acting as parasites. This type of bacteria causes infections in humans, animals and plants. Other bacteria feed on dead beings, decomposing these organisms until they become simpler substances. In this process, materials that will serve as nutrients are returned to the soil. Other bacteria are autotrophic, as we also said at the beginning, that this type of bacteria are those that make their own food, some of them use the energy of sunlight to make food; the nauseating smell of sulfur from some sludge or decomposing food is due to the action of this type of bacteria.
Changes produced by bacteria in the environment
The bacteria continue to modify the environment favoring other organisms, for example. bacteria are the first organisms that grow in the living rock created by the volcanic action, as they grow, decompose the rock and help to form earth and soon plants begin to grow, which in turn, these bacteria and new plants will serve as food to animals, fungi and protists; originating in this way, other changes to the environment and the survival of larger organisms; what was an inert rock, became a fertile place.
Relationship of symbiosis between bacteria and other organisms
Some bacteria help other organisms form a society, or symbiosis, this is a relationship in which an organism lives on, near or within another in which both benefit; Let's see an example, certain bacteria that live in the intestines of animals, such as cows, termites, horses and humans.
Bacteria and humans
Bacteria are useful for humans, as they are involved in the production of food, fuel, medicines and other products. Some are used in industrial processes; and others to break down the pollutants that pollute the environment. Yes we speak that the majority of the bacteria are useful and harmless, some of them also cause us problems, when they damage our food or poison the sources of water; others cause diseases in human beings, domestic animals, livestock and crops
Foods
Many food products, especially dairy products, are made with the help of bacteria, they are also used in the preparation of cheeses, curds, yogurt, sour cream, pickles, soy sauce, vinegar and corn syrup. The bacteria that fix nitrogen provide substances needed for crops; In flooded crops such as rice fields, blue-green bacteria are a natural fertilizer.
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ome bacteria break down food and make other tasty or useful products, for example a type of bacteria breaks down milk and forms yogurt. In many cases we want to preserve food and for this we use mechanisms to avoid or delay the decomposition of food by heat, drying, salting, refrigerating, or proceeding to smoke them; All these processes prevent or delay the growth of bacteria, for example, milk when heated at certain temperatures for pasteurization, thus eliminating most of the bacteria that damage it. Bacterial growth can also be prevented by heating and then canning vegetables, fruits, meat and fish; but if they do not heat up enough they can grow bacteria inside the can and produce poisonous toxins that generate a gas that inflates the can, for this reason they should not be consumed, because it can cause serious problems for our health.
Water contamination by bacteria
Harmful bacteria damage water sources, when environmental conditions change, environmental pollution or other causes, blue-green bacteria and other bacteria, multiply rapidly in the water, forming an unpleasant foam with a bad smell, which It can cause health problems, if this contaminated water is ingested by people or by animals.
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Fuels and bacteria
Certain bacteria decompose wastes, such as fruit shells, leaves and trunks of fallen trees, animal manure, sewage in the process of which methane is generated; This is a natural gas that can even be used to cook and heat the house. It must be remembered that for millions of years, the heat and pressure of the interior of the Earth modified the remains of ancient blue-green bacteria and other organisms, and formed an oily mixture of chemicals; This mixture is called what we all know as oil, which under a process of refining many useful substances are obtained as: Gasoline, kerosene, gas oil and other products that serve as raw material in textile and plastic factories.
Bacteria clean the environment
Bacteria are used to clean the environment, some are used to treat sewage, and to decompose waste; some to decompose oil spilled in the sea and others to decompose complex chemicals such as pesticides and plastics.
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"Science magazine has just published the discovery of a non-classified bacterium that quickly degrades the oil released into the sea without significant oxygen depletion, the result of research by microbial ecologist Terry Hazen in collaboration with scientists of the Lawrence Berkeley National Laboratory (Berkeley Lab), following the explosion of the BP oil platform in the Gulf of Mexico." Source
Bacteria, health and medicine
Some bacteria are good for health, and in this case we refer to those who live in our intestines, these provide us with benefits, so they help digest food, they also make vitamins that the body can not elaborate and at the same time . They help us to avoid diseases by displacing harmful bacteria in the digestive tract.
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Certain bacteria produce substances that fight diseases, some of them are processed to obtain chemical products, which destroy or weaken other harmful bacteria in our body, these products are what are called antibiotics. Before continuing, we must ask ourselves this question: How are bacteria transformed into antibiotics? Recently scientists have found a way to modify the hereditary material of bacteria, with these data or information, scientists have been able to make bacteria produce medicines and other useful substances. There are bacteria that produce a wide range of antibiotics, such as certain strains of the genus Streptomyces (Streptomycin, tetracycline, erythromycin) among others.
Tetracycline made with bacteria
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Among the human diseases caused by bacteria we have laryngitis, some types of pneumonia, diphtheria, cholera, tetanus, tuberculosis, bubonic plague and Lyme disease. Other bacteria cause mouth problems such as tooth decay and pyorrhea. Some diseases can be avoided with good hygiene and vaccination and others can be treated with antibiotics.
Bacteria in the industry
Bacteria have been used for leather tanning for a long time. They have also been used for the extraction of copper, gold and other valuable metals from rocks. There are some types of rocks rich in metals that could have been the result of the action of the bacteria that lived millions of years ago. On the other hand, scientists have tried to find an economic means to use to make plastics and other complex compounds.
Although the time has not yet come for bacterial plastics, there are other substances that are commercially manufactured by bacteria for different purposes: coloring food, processing paper and cloth, and modifying chemical products, to name a few.
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