Bacteria surround us everywhere, moreover, they live inside the human body, and in large numbers. Due to their small size, it is impossible to see them with the naked eye, however, they can bring both tangible harm and benefit. In general, the role of bacteria in nature is huge.
Classification of living things
For a long time there was no coherent system at all that distinguished organisms. However, the famous Karl Linney laid the foundation for the modern binomial classification, highlighting the 3 main, in his opinion, groups: animals, plants and minerals. He proposed the term "kingdom."
In the future, as technology developed and new knowledge gained, the classification improved, prokaryotes and eukaryotes were identified , the main difference between which was the absence and presence of a nucleus in the cells. Today there are 8 kingdoms that have significant differences: viruses, archaea, protists, chromists, plants, fungi, animals and bacteria. As for the latter, we all know about their existence and constantly encounter them, although we do not see them. It may even seem strange that they were singled out in a separate kingdom of nature.
Bacteria
These simplest representatives of wildlife for a long time "hid" from human eyes. Nevertheless, the results of their activities were obvious already in antiquity: sour milk, rotting of fallen leaves, fermentation of sugar and much more. So the importance of bacteria in nature, even long before their direct discovery, is difficult to overestimate.
This group of organisms is one of the oldest on the planet - they exist for more than 3.5 billion years, and about a third of this period they were the only living creatures on Earth. Despite the fact that evolution affected them in one way or another, the structure of bacteria remains rather primitive, because they do not even have a nucleus. And those representatives of this kingdom who are able to survive in the most extreme conditions, can even be attributed to the simplest. Moreover, they are the largest group of organisms of all existing on Earth.
Discovery and study
For quite a long time, scientists did not even suspect the existence of organisms that were not visible to them. Of course, the pioneer of bacteria in the XVII century was the man who invented the microscope - a native of Holland Anthony van Levenguk. His instruments gave an increase of up to 160 times, so the scientist noticed strange creatures in drops of water, mud, plaque and many other environments - he called them animalcalculi. In the course of research, he came across both different and similar organisms, and he carefully sketched them. So the foundations of microbiology were laid. The very name "bacteria" was proposed by Christian Ehrenberg in 1828.
The connection of these organisms with various diseases was first announced at the end of the 18th century by a military doctor D. S. Samoilovich. Using a microscope, he tried to find the causative agent of the plague that he had to face during an epidemic in Moscow. Despite the fact that he did not succeed, he proved that infection occurs only through direct contact with the patient or his things. Then the idea of vaccinations by means of weakened or killed microorganisms was proposed. It was later implemented in England when the doctor Eduard Jenner noticed the immunity of patients to smallpox after a history of cow.
Further, for several decades, microbiology was mainly engaged in the collection and systematization of information, revealed the role of bacteria in nature and various life processes. Then there was a distinction between them and viruses due to serious differences in structure. But the positive value of bacteria in the life of nature was not immediately appreciated.
Features
Due to the need to adapt for survival in a variety of conditions, bacteria have to not only have the ability to quickly reproduce, but also differ in some diversity, which will be discussed later.
All organisms belonging to this kingdom, of course, have common features. For example, they are all prokaryotes, that is, they do not have a separate nucleus and some other cellular organelles. Meanwhile, they are usually larger in size than eukaryotes and reach approximately 0.005 millimeters. The largest bacterium known to science does not exceed 0.75 mm across, and it can even be seen with the naked eye.
First of all, representatives of this kingdom have a cell wall that gives the cell a shape, as well as a special mucous capsule that protects the body from drying out and contributes to its sliding movement. Sometimes the thickness of this layer may be greater than that of the rest of the bacterium. The cytoplasm, in comparison with the cells of other microorganisms, is more dense and structured. All nutrients are located right in it, since there are no vacuoles. Another organ that helps the cell move can be represented by villi on its surface. But they may be absent.
Varieties
Living bacteria differ primarily in the shape of the cell, which is why they are divided into groups according to how they look. The main species are called so:
- cocci;
- bacilli;
- vibrios;
- spirochetes;
- Spirillas
- streptococci;
- staphylococci.
In addition, there is a distinction according to the type of conditions suitable for life. We give an example. Those organisms that can exist in the absence of oxygen are called anaerobic. In addition, microbiologists distinguish between gram-negative and gram-positive bacteria. Here we are only talking about the reaction to a special dye, which depends on the structure of the cell membrane. Gram-negative bacteria have a thicker protective shell.
Spread
They live everywhere, and therefore are forced to take such mutable forms. The vents of volcanoes and icy deserts, sea depths and mountains, poor in oxygen - bacteria can be found everywhere. This is only possible due to their amazing vitality and rapid reproduction: simple division can occur approximately every 20 minutes.
By the way, in conditions that are completely unsuitable for the continuation of life, wildlife bacteria can form so-called spores, that is, go into a form suitable for transfer by wind or water. When the environment again becomes quite favorable, microorganisms again take on a vegetative form and give rise to a new colony. Thus, the spread of bacteria in nature is preserved and continues.
Meaning and role
The importance of what these tiny organisms do is hard to overestimate. The role of bacteria in nature is truly enormous. First of all, it is to them we owe the existence of complex life forms in their current form. After all, blue-green algae, as cyanobacteria are often called, have actually created the atmosphere and maintain the oxygen level at the required level. Until now, these microorganisms living in the thickness of the oceans generate more than half of O 2 .
Perhaps the second most important value of bacteria in nature is their participation in the disposal of organics. Without this, it is also difficult to imagine the modern world. There is a whole class of saprophyte organisms (which includes bacteria). They are directly involved in the cycle of substances in nature, decomposing the remains of organic tissues to minerals necessary for plant nutrition. So these "crumbs" are an integral part of any ecosystem.
Another important role of bacteria in nature is the conversion of some substances to others, although this is not always desirable. Yeast allows you to get dough and alcohol, and lactic acid bacteria - kefir, cottage cheese, yogurt and other similar products. But that is not all. Think of the bacteria that make up the intestinal microflora in mammals. It is they that allow the digestive system to absorb nutrients so efficiently that enter the body along with food.
Protection
However, the role of bacteria in nature is not limited to certain positive aspects. So, there are pathogens that cause serious illnesses, so often there is a need to get rid of unwanted "guests". For this, there is not only basic hygiene, that is, washing hands and body with soap, but also disinfection, as well as sterilization of various objects and surfaces. Measures to protect against bacteria may include boiling and prolonged exposure to hot steam, treatment with alcohol solutions or chlorine compounds, as well as ultraviolet light. If everything is done correctly, most of the pathogenic cells die.
As for food, they also undergo various processing methods: pasteurization, preservation, boiling, frying, stewing, baking, etc. This allows you to extend their shelf life and make them safe to eat. But comprehensive protection against bacteria can have a flip side: due to the lack of the need to always be ready, the immune system can weaken. So too much zeal in the war against bacteria is not worth it.