12.The Golden age of microbiology. The discoveries of Pasteur and Koch. Their significance for microbiology, biotechnology and medicine.

Pasteur showed microbial fermentation and the nature of many human diseases, was one of the founders of microbiology and immunology.

. By 1861 Pasteur showed that the formation of alcohol, glycerol and succinic acid fermentation can occur only in the presence of microorganisms is often specific.

Louis Pasteur proved that fermentation is a process that is closely associated with the life of yeast fungi that feed and reproduce through the fermenting liquid .Pasteur demonstrated that fermentation is caused by the growth of micro-organisms, and the emergent growth of bacteria in nutrient broths is due not to spontaneous generation, but rather to biogenesis  Pasteur's research also showed that the growth of micro-organisms was responsible for spoiling beverages, such as beer, wine and milk. With this established, he invented a process in which liquids such as milk were heated to kill most bacteria and moulds already present within them.

Pasteur's later work on diseases included work on chicken cholera. During this work, a culture of the responsible bacteria had spoiled and failed to induce the disease in some chickens he was infecting with the disease. Upon reusing these healthy chickens, Pasteur discovered he could not infect them, even with fresh bacteria; the weakened bacteria had caused the chickens to become immune to the disease, though they had caused only mild symptoms. In the 1870s, he applied this immunization method to anthrax, which affected cattle, and aroused interest in combating other diseases. This discovery revolutionized work in infectious diseases, Pasteur produced the first vaccine for rabies by growing the virus in rabbits, and then weakening it by drying the affected nerve tissue.

1876: Robert Koch (1843-1910). German bacteriologist was the first to cultivate anthrax bacteria outside the body using blood serum at body temperature. By making a series of careful, methodical experiments, he finds that the only cause of the disease is the bacterium Bacillus anthracis, and exploring its biological cycle of development. Sets the epidemiological features of the disease, shows that one coli bacteria can form a of many millions colony. These studies are the first to prove the origin of the bacterial disease. Building on pasteur's "germ theory", he subsequently published "Koch's postulates" (1884), the critical test for the involvement of a microorganism in a disease:

1)The agent must be present in every case of the disease.

2)The agent must be isolated and cultured in vitro.

3)The disease must be reproduced when a pure culture of the agent is inoculated into a susceptible host.

4)The agent must be recoverable from the experimentally-infected host.

In 1881, Koch published the work, "Methods for studying pathogens», which describes a method for growing bacteria on solid media. This method was important to isolate and study pure bacterial cultures.

13.Ecological and physiological approach to microbiology. Microecological principle in the study of microorganisms. Chemolythotrophic microorganisms. Nitrogen-fixing bacteria. Research and discovery of Sergei Winogradsky, Victor Omelyansky and Martin Beijerinck.

Winogradsky is best known for discovering chemoautotrophy, which soon became popularly known as chemosynthesis, the process by which organisms derive energy from a number of different inorganic compounds and obtain carbon in the form ofcarbon dioxide. With the discovery of organisms that oxidized inorganic compounds such as hydrogen sulfide and ammonium as energy sources, autotrophs could be divided into two groups: photoautotrophs and chemoautotrophs.Chemolithotrophy is found only in prokaryotes and is widely distributed among Bacteria and Archaea. The spectrum of inorganic compounds that can be used as electron donors by chemolithotrophs is rather broad (H₂S, S⁰, S₂O ₃ ²⁻ , H₂, Fe²⁺, NO₂ ⁻or NH₃).

chemolithoautotrophs obtain energy from the oxidation of inorganic compounds and carbon from the fixation of carbon dioxide. Examples: Nitrifying bacteria, Sulfur-oxidizing bacteria, Iron-oxidizing bacteria, Knallgas-bacteria. Nitrifying Bacteria,  any of a small group of aerobic bacteria (family Nitrobacteraceae) that use inorganic chemicals as an energy source. They are microorganisms that are important in the nitrogen cycle as converters of soil ammonia to nitrates, compounds usable by plants. The nitrification process requires the mediation of two distinct groups: bacteria that convert ammonia to nitrites (Nitrosomonas, Nitrosospira, Nitrosococcus, and Nitrosolobus) and bacteria that convert nitrites (toxic to plants) to nitrates (Nitrobacter, Nitrospina, and Nitrococcus). In agriculture, irrigation with dilute solutions of ammonia results in an increase in soil nitrates through the action of nitrifying bacteria. Omelyansky proposed methods of isolation and culture of nitrifying bacteria by examining their morphology and physiology. In this way he was the first to highlight the culture and anaerobic spore-forming bacteria fermenting fiber with the formation of organic acids and hydrogen. By studying the aerobic nitrogen-fixing bacteria of the genus Azotobacter, proved the existence of bacteria that produce methane from ethanol, and found that the amount of available nitrogen in proportion to the absorption of organic matter. In addition, the first to indicate the possibility of using microorganisms as chemical tracers.

Martin Beijerinck is considered one of the founders of virology. In 1898, he published results on the filtration experiments demonstrating that tobacco mosaic disease is caused by an infectious agent smaller than a bacterium.His results were in accordance with the similar observation made byDmitri Ivanovsky in 1892. Beijerinck could not culture the filterable infectious agent, however he concluded that the agent can replicate and multiply in living plants. He named the new pathogen virus to indicate its non-bacterial nature. Beijerinck asserted that the virus was somewhat liquid in nature, calling it "contagium vivum fluidum" (contagious living fluid). It was not until the first crystals of the tobacco mosaic virus. Beijerinck also discovered nitrogen fixation,^[8] the process by which diatomic nitrogen gas is converted to ammonium ions and becomes available to plants. Bacteria perform nitrogen fixation, dwelling inside root nodules of certain plants (legumes). In addition to having discovered a biochemial reaction vital to soil fertility and agriculture, Beijerinck revealed this archetypical example of symbiosis between plants and bacteria.

Beijerinck discovered the phenomenon of bacterial sulfate reduction, a form of anaerobic respiration. He learned bacteria could use sulfate as a terminal electron acceptor, instead of oxygen. This discovery has had an important impact on our current understanding of biogeochemical cycles.Spirillum desulfuricans, the first known sulfate-reducing bacterium, was isolated and described by Beijerinck.

Beijerinck invented the enrichment culture, a fundamental method of studying microbes from the environment.

14.Immunological period of microbiology . Notable contribution to the antiseptic treatment for the prevention and cure of wound infections. Phagocytic and humoral theory of immunity. Era of chemotherapy and antibiotics.

The first theoretical premise in the field, backed by experiment, were cellular (phagocytic) theory of AI. Mechnikov (1883) and humoral immunity theory of Paul Ehrlich (1890). Ehrlich assumed that on the surface of cells that produce antibodies that have a variety of chemical groups that perform the function of receptors. Antigen with their complementary groups blocking these receptors and stimulates simultaneously similar receptors in higher amounts. Some of the latter with the cell membrane breaks down, and is included as the specific antibodies in the blood circulation. Thus, the antigen would indicate a cess which it synthesize antibodies. Mechnikov studied the behavior of the various agents in leukocytes (protective blood cells) human and apes. Numerous experiments were the basis for the theory of phagocytosis, the scientists suggested.

According to theory, all human cells, which are involved in phagocytosis by macrophages may be divided and macrophages.

To macrophages are granular leukocytes (basophils, neutrophils) is red blood cells. Macrophages - is movable leukocytes (spleen cells, lymph cells, monocytes) and fixed (epithelial cells lining the inside wall of the vessel, the pulp of spleen cells).

The basis of the phagocytic theory

The basis of the phagocytic theory Metchnikoff put three basic properties of phagocytes.

Phagocytes are able to protect and clean the toxins from infections of the decay products of tissues.

Phagocytes are (a) antigens on the cell membrane.

Phagocytes have the ability to secrete enzymes and biologically active substances.

Especially the rapid development of microbiology and immunology were 50 and 60 years of this century. This was facilitated by the following reasons:

. the most important discoveries in the field of molecular biology, genetics, bioorganic chemistry;

  the emergence of new sciences such as genetic engineering, biotechnology, computer science;

. the creation of new,'s methods and scientific instruments that allow to penetrate deeper into the mysteries of nature.

Thus, from the 50's in the development of Microbiology and Immunology, Molecular Genetics and began a period that is characterized by several fundamentally important scientific advances and discoveries. They are:

- Deciphering the molecular structure and molecular organization of the biological many viruses and bacteria, the opening of the simplest forms of life. "Infectious protein" prion;

- Interpretation of the structure of antibodies, immunoglobulins [EdelmanD., R. Porter, 1959];

- Development of a method of cultures animal and plant cells and growing them on an industrial scale to produce viral antigens;

- The production of recombinant viruses and recombinant bacteria. - Preparation of vaccines (hepatitis B vaccine, malaria, HIV antigens, and other antigens)

- The development of synthetic vaccines based on natural or synthetic antigens and their fragments, as well as artificial media. adjuvant (assistant). immune system stimulant;