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MICROBIOLOGY

Summary Microbiology is the science responsible for the study of microorganisms, small living things (from "small" mikros, bios, "life" and logos, "study"), also known as microbes. It is the branch of biology dedicated to studying organisms that are only visible through the microscope: prokaryotic organisms and simple eukaryotes. All microscopic living beings are considered microbes, these can be made up of a single cell (unicellular), as well as small cellular aggregates formed by equivalent cells (without cell differentiation); These can be eukaryotes (cells with nuclei) such as fungi and protists, prokaryotes (cells with no defined nucleus) such as bacteria. Although the microbiological knowledge currently available is very extensive, there is still much to be known and new discoveries are constantly being made in this field. So much so that, according to the most common estimates, only 1% of the existing microbes in the biosphere have been studied so far. Therefore, even though more than 300 years have passed since the discovery of microorganisms, the science of microbiology is still in its infancy compared to other biological disciplines such as zoology, botany, or even entomology. When dealing with microbiology, especially microorganisms that are pathogenic to man, it is related to categories of medicine such as pathology, immunology and epidemiology.

History Although the term bacteria, derived from the Greek βακτηριον ("swab"), was not introduced until 1828 by Christian Gottfried Ehrenberg, as early as 1676 Antonie van Leeuwenhoek, who using a single-lens microscope that he himself had built based on the model created by the scholar Robert Hooke in his book "Micrographia" was able to make the first recorded microbiological observation of

"animáculos" as van Leeuwenhoek called and drew them then. Bacteriology (later a subdiscipline of microbiology) is considered founded by the botanist Ferdinand Cohn (1828-1898). Ferdinand Cohn was also the first to formulate a scheme for the taxonomic classification of bacteria. Louis Pasteur (1822-1895) considered the father of Medical Microbiology, and Robert Koch (1843-1910) were contemporaries of Cohn. Perhaps Pasteur's greatest achievement was the refutation by careful experimentation of the then highly respected spontaneous generation theory, which firmly established microbiology within the biological sciences. Pasteur also designed methods for food preservation (pasteurization) and vaccines against various diseases such as anthrax, avian cholera and rabies. Robert Koch is especially known for his contribution to the germ theory of disease, where, by applying Koch's so-called postulates, he managed to demonstrate that specific diseases are caused by specific pathogenic microorganisms. While Louis Pasteur and Robert Koch are often considered the founders of microbiology, their work did not faithfully reflect the true diversity of the microbial world, given their exclusive focus on microorganisms of medical relevance. This diversity was not revealed until later, with the work of Martinus Beijerinck (18511931) and Sergei Winogradsky (1856-1953). Martinus Beijerinck made two great contributions to microbiology: the discovery of viruses and the development of microbiological culture techniques. While his work with the tobacco mosaic virus established the basic principles of virology, it was his development of new cultivation methods that had the greatest immediate impact, as it allowed the cultivation of a wide variety of microbes that had not been previously known. could be isolated. Sergei Winogradsky was the first to develop the concept of chemilithotrophy and thus reveal the essential role that microorganisms play in geochemical processes. He was responsible for the isolation and description for the first time of both nitrifying bacteria and nitrogen-fixing bacteria.

Empiricism and speculation Human knowledge about the effects produced by microorganisms has been present even before being aware of their existence; Due to fermentation processes caused by yeasts, bread, alcoholic beverages and milk products can be made. In ancient times the cause of diseases was attributed to divine punishments, supernatural forces or physical factors (The word malaria means "bad air", it was believed that it was the stale air of the swamps that caused this disease). During this period prior to the discovery of microorganisms, naturalists could only speculate on the origin of diseases. Types of microbiology The field of microbiology can be divided into several sub-disciplines: 

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Microbial physiology: study at the biochemical level of the functioning of microbial cells. Includes the study of microbial growth, metabolism, and structure. Microbial genetics: study of the organization and regulation of microbial genes and how these affect the functioning of cells. It is closely related to molecular biology. Clinical microbiology: studies the morphology of microbes. Medical microbiology: study of the role of microbes in human diseases. It includes the study of microbial pathogenesis and epidemiology and is related to the study of disease pathology and immunology. Veterinary microbiology: study of the role of microbes in veterinary medicine. Environmental microbiology: study of the function and diversity of microbes in their natural environments. It includes microbial ecology, geomicrobiology, microbial diversity, and bioremediation. Evolutionary microbiology: study of the evolution of microbes. Includes bacterial systematics and taxonomy. Industrial microbiology: studies the exploitation of microbes for use in industrial processes. Examples are: industrial fermentation and wastewater treatment. Very close to the biotechnology industry. Aeromicrobiology: study of airborne microorganisms. Food microbiology: study of microorganisms that spoil food. Space Microbiology: Study of the microorganisms present in extraterrestrial space, in space stations, in spacecraft.

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Bacteriology: Study of prokaryotes (bacteria, archaea). Virology: Study of viruses. Mycology: Study of fungi. Parasitology: Study of parasites, especially of animal or protozoan type.

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Protistology: Study of protists. Micropaleontology: Study of microfossils. Palinology: Study of pollen and spores. Phycology: Also called Algology. Study of algae and microalgae. Protozoology: Study of protozoa. Mycobacteriology: Study of the genus Mycobacterium

Microbiology benefits Microorganisms have historically been viewed negatively because of their association with many human diseases. However, pathological microorganisms are a very minority percentage of the total number of microorganisms, most of which play absolutely essential roles and that would not make life on Earth unfeasible. Some examples are the bacteria that fix atmospheric nitrogen (enabling the life of plant organisms), the bacteria of the carbon cycle (essential for reincorporating organic matter into the soil) or the multitude of microorganisms that live symbiotically in our digestive tract, without which digestion would not be viable. Thus, the "higher organisms" (animals, plants ... ) We could not live if it were not for the functions performed by these microscopic beings. In addition, they have wide applications in the industrial field, such as fermentations (for example: for the production of alcoholic beverages or dairy products), the production of antibiotics or that of other products of pharmaceutical or biotechnological interest (hormones, enzymes). Finally, it is also worth highlighting the essential role that microorganisms play in biological research laboratories around the world as tools for gene cloning and protein production. the

production of antibiotics or that of other products of pharmaceutical or biotechnological interest (hormones, enzymes). Finally, it is also worth highlighting the essential role that microorganisms play in biological research laboratories around the world as tools for gene cloning and protein production. the production of antibiotics or that of other products of pharmaceutical or biotechnological interest (hormones, enzymes). Finally, it is also worth highlighting the essential role that microorganisms play in biological research laboratories around the world as tools for gene cloning and protein production. Refutation of the theory of spontaneous generation It is surprising the impact that the idea created by Aristotle on the spontaneous generation caused on the West, although it seems absurd to us today it was taken in the past as the only truth about the origin of life. This idea remained for a thousand years and in that time it underwent great changes, especially those made by the Church, thanks to Saint Thomas Aquinas (whose ideas still remain in force), but it was not until after the creation of the microscope that the idea of the spontaneous generation was completely refuted, the experiments of Francisco Redi, Lazzaro Spallanzani, Luis Pasteur and John Tyndall gave way to the gradual disappearance of the erroneous belief about the origin of life. The process of the extinction of the spontaneous generation begins with Francisco Redi (1626-1698) whose experiments open the door to the long road that a political-religious and intellectual struggle meant. His disagreement with established beliefs led him to test their veracity, so he devised a simple but masterful experiment, with which he was able to test his hypothesis. Redi placed a piece of meat in several jars; sealed half after careful sterilization and left the other half open. After several days he discovered that half of the jars with the piece of meat and that had not been sealed had fly larvae inside sliding on the meat, in contrast to the other jars that despite rotting what they contained inside, did not present any larva. Redi carried out another experiment believing that the air could be to blame for the appearance of the larvae, so doing something similar that, on the last occasion, but with the only detail that this time he did not seal the jars hermetically, but instead placed a gauze that prevented the passage of all organisms (flies) but not air, waited to see what happened, finding days later with the same results as the previous experiment. These simple results laid the foundation stone that marked the beginning of biogenesis. Although Redi's discoveries completely shook all beliefs about the origin of life, the spontaneous generation turned out to be more resistant than

previously thought, thanks to the additions of the English biologist John Needham, who speak about vital forces that animate matter inert. Despite the discoveries of Lazaro Spalanzani, the spontaneous generation was not buried until the arrival of Luis Pasteur and his pasteurization. Pasteur discovered that the air contained invisible organisms that were to blame for the decomposition of food, he used a gooseneck flask (Pasteur flask) with which he ensured a free flow of air into the flask, but not a free flow of the Microorganisms that it transported, being trapped in a filter inside the "u" of the neck, with this method ensured that food lasted for long times without spoiling. Thanks to this and the discoveries of Lazaro Spallanzani, the spontaneous generation remained underground, but it was John Tydall who placed the epitaph. John Tydall studied physics and was very interested in the phenomena of light, with which he was able to study the particles suspended in the air and which were called by bacteria by Ferdinan Cohen long ago. Tyndall discovered that these particles deflected light and realized that the putrefaction process was closely related to the presence of these suspended particles. With this, the trajectory followed by the idea of spontaneous generation from its beginnings to its total disappearance (speaking with hyperbolism, since even today there are still sequels of its passage through our culture) in which they were strongly involved, has been briefly seen. Redi, Spallanzani, Pasteur and Tyndall. I think that although Spallanzani was not spoken of decently in this work, it goes without saying that his investigations, together with Redi's, are the mallet that almost completely destroyed the belief of spontaneous generation. Microbiology today Currently, microbiological knowledge has become so specialized that we find it divided: medical microbiology studies pathogenic microorganisms and the possible cure for the diseases they cause, immunology finds out the causes of the appearance of diseases from an immunological perspective, ecological microbiology studies the niche that corresponds to the microorganisms in the environment, agricultural microbiology the relationships between plants and microorganisms, and biotechnology the possible benefits that the exploitation of microbes can bring to man.

Importance

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Microbiologists have made contributions to biology and medicine, especially in the fields of biochemistry, genetics, and cell biology. Microorganisms have many characteristics that make them ideal "model organisms": They are small, so they do not consume many resources. Some have very short generation times (the time it takes for one bacterial cell to divide in two under optimal conditions is approximately 30 minutes for E. coli and 12 to 24 hours for Mycobacterium tuberculosis). Cells can easily survive separated from other cells.

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The unicellular eukaryotes reproduce by mitotic division and the prokaryotes by binary fission. This allows the spread of genetically equal clone populations.

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They can remain frozen for long periods of time. Even when 90% of cells die in the freezing process, there are millions of cells in every milliliter of body fluid....