Agricultural microbiology. Microbiology of plants. Work program of the discipline
Infectious ram epididymitis (lat. - Epididymitis infectiosa arietum; English - Infectious ram epididymitis; sheep epididymitis) - a special form of sheep brucellosis - an acute and chronic infectious disease, manifested by proliferative inflammatory processes in the testes and their appendages, their atrophy, decreased reproductive function in rams, and in ewes - abortions, the birth of unviable lambs and infertility.
Historical information, distribution, degree of danger and damage. The disease was established in New Zealand and Australia in 1942. The causative agent was identified by Simmons, Hall, Buddle and Boyes (1953). In 1956, by morphological similarity with Brucella, it was identified as a new independent species of Brucella and named B. ovis. The disease has been registered in more than 100 countries around the world.
The causative agent of the disease. The causative agent of epididymitis, Brucella ovis, is cocco-shaped or slightly elongated, small gram-negative bacteria, immobile, do not form spores, they perceive aniline dyes well, they are stained red according to the Kozlovsky or Shulyak-Shin method. Some strains form a capsule.
For the cultivation of the pathogen, enriched nutrient media are used, on which Brucella of this species, when isolated, grows for a long time (10 ... 30 days) under conditions of high CO2 content (10 ... 15%).
A feature of the microorganism is that during the initial isolation and testing in a sample with trypanflavin, the culture is characterized as a stable R-form that does not have A- and M-antigens of smooth brucella (S-form). The causative agent is not lysed by brucellosis Tb-phage. It also lacks the surface envelope S-antigen typical of other Brucella, but its O-antigen is immunologically related to the O-antigens of other Brucella species. Cross-reacts with B. canis and with rough variants of other Brucella species.
The stability of the pathogen is low. At 60 "C, it dies after 30 minutes, at 70 "C - in 5 ... 10 minutes, at 100 ° C - instantly. In the surface layers of the soil, brucella survive up to 40 days, at a depth of 5 ... 8 cm - up to 60, in water - up to 150 days. In milk, bacteria persist for up to 4...7 days, in frozen meat - 320, in wool of sheep - 14...19 days. Ultraviolet rays kill Brucella in 5...10 days, direct sunlight - from a few minutes to 3...4 hours.
Of the disinfectants, 1 ... 2% solutions of formaldehyde, bleach and creolin, 5% freshly slaked lime (calcium hydroxide), sodium hydroxide solution, etc. are used.
Epizootology. Sheep, ewes and lambs are susceptible to the disease. Under natural conditions, mass re-infection and the spread of the disease occur during the periods of breeding campaign and lambing.
Transmission of the pathogen is carried out mainly through sexual contact. Infection of ewes is possible both during natural mating with sick rams, and during artificial insemination. The main factors in the transmission of the pathogen are the semen and urine of a sick ram. Some ewes inseminated with such sperm have abortions, and in such a case, the pathogen is released into the external environment with aborted fetuses, stillborn lambs, fetal membranes and outflows from the genital tract. Normally lambing sheep can also excrete the pathogen with the placenta.
Healthy rams become infected by mating with ewes previously covered with diseased rams. Re-infection of rams is also possible as a result of long-term joint keeping of sick and healthy animals. In herds of adult rams, up to 78% of the livestock get sick.
Lambs up to 5-6 months of age usually do not get sick. Isolated cases of infection were noted among 10-15-month-old rams, but the symptoms of the disease in young animals are usually absent. Most often, rams are affected at the age of 2 ... 7 years, that is, during the period of increased functional activity. The incidence of ewes is the same as that of rams.
Pathogenesis. The causative agent, having entered the body of a ram or ewe, multiplies in the places of penetration and in the nearest regional lymph nodes. In the future (after 7 days or more), it penetrates into the parenchymal organs and spreads with the blood throughout the body (generalization phase). After a short time, the pathogen disappears from the bloodstream and is localized, as a rule, in the epithelium of the seminiferous tubules of the testes and their appendages in rams or in the pregnant uterus of a sheep and multiplies there. As a result, rams first develop an acute and then a chronic inflammatory process (epididymitis and testiculitis), and abortions occur in pregnant sheep due to malnutrition of the fetus.
In pregnant ewes, due to the development of a necrotic process in the birth membranes, the nutrition of the fetus is disrupted, which leads to abortion or the birth of non-viable offspring. Sheep are aborted if they are pregnant for no more than 2 months. When they are infected in a later period of pregnancy, the pathological process does not have time to develop and the fetus is born, but more often it is not viable.
Course and clinical manifestation. In sheep, the disease is acute and chronic.
In an acute course in sheep, a deterioration in the general condition, deterioration or lack of appetite, an increase in body temperature to 41 ... 42 ° C, exudative inflammation of the testes and their appendages are noted. The testicles can be enlarged 3-5 times. The scrotum is inflamed and also enlarged several times due to the accumulation of a large amount of exudate in it. The skin of the scrotum is tense, hot, reddened, painful. Often there is inflammation of one testis with a pronounced asymmetry. Register one- or two-sided increase in the appendages of the testes to the size of a chicken egg. Their consistency is dense, bumpy, fluctuation is noted. The mobility of the testicles is reduced, or they are motionless, their atrophy is possible. They become hard, the border between the appendage and the testis is poorly palpable. Sheep are reluctant to move, lag behind the herd, stand in one place with their hind limbs apart.
In most rams, sperm production is impaired, ejaculate volume, sperm mobility and density are reduced; its color becomes yellow-gray or yellow-green. Violations of spermiogenesis can be the reason for the low fertility of females.
After 2-3 weeks, these signs gradually disappear, body temperature drops to normal, swelling of the scrotum decreases, but it remains sac-like, and the disease becomes chronic.
Ewes have abortions or give birth to weak, non-viable lambs. Often, after lambing, the afterbirth is delayed and endometritis develops.
pathological signs. In rams, the changes are localized mainly in the appendages of the testicles. The common vaginal membrane fuses with the testis and appendage. At the head of the appendage, connective tissue grows in the form of thin strands. When cut in the affected appendage, fibrous growths and necrotic sequesters of various sizes are found, filled with a serous, purulent, cheesy or creamy odorless liquid. The tissue of the testicles is compacted, petrified in places.
Characteristic histological changes are hyperplasia and metaplasia of the epithelium surrounding the epididymis, especially in the tail of the epididymis, which leads to the appearance of tuberosity on the affected epididymis, and then cysts. Inside the latter, neutrophils accumulate. With blockage of the spermatic tract, chronic fibrosis occurs, changes are observed in the excretory tubules in the form of epithelial hyperplasia and an increase in the folding of their walls.
In ewes, the surface of the amniotic membrane and chorioallantois contains a yellowish, sticky, pus-like mass. In more severe cases, the chorioallantoic membrane is fused with the amnion, thickened up to 2-3 cm, necrotic, sometimes with the capture of blood vessels and cathelidons.
Diagnosis and differential diagnosis. The diagnosis is made on the basis of typical clinical signs, the results of bacteriological, serological and allergic studies of animals, taking into account epizootological data and pathological changes.
Sampling of the biomaterial and its examination by laboratory methods is carried out in accordance with the approved Manual for the Diagnosis of an Infectious Disease of Sheep Caused by Brucella Ovis (Infectious Epididymitis of Sheep). For serological diagnostics, kits of specific components for setting up RA with a colored oat antigen, RSK, RDSK, ELISA, RNGA and RNAt are produced. In the complex of diagnostic tests for allergic diagnosis of infectious epididymitis of sheep, brucellovin is used. However, they are not decisive in making a diagnosis.
The only reliable method that gives unambiguous results is bacteriological, which involves the isolation and identification of the microorganism.
Pathological material for this can be the pus-like contents of the sequesters of the affected appendages, altered areas of the testes, sperm of rams; from sheep - discharge from the genital tract (in the first days after the abortion), cavity contents and altered necrotic areas of the uterine horns, ovaries and deep pelvic lymph nodes, aborted fetuses and placentas. Sometimes in sick sheep it is possible to detect brucella in other organs (lungs, udder, etc.). The resulting primary cultures are subjected to serological identification using RDSC.
The diagnosis of infectious epididymitis is considered established, and the flock is considered unfavorable upon receipt of positive results of a bacteriological or serological study (isolation of B. ovis culture, positive RDSC, ELISA, RHAt). In flocks that are unfavorable for infectious epididymitis (on farms, farms, settlements), animals that react to this disease during the study, as well as having clinical signs of the disease, are recognized as sick.
In differential diagnosis in sheep, contagious and non-contagious diseases that cause similar lesions of the testes and their appendages (brucellosis, pseudotuberculosis, diplococcal infection), injuries, and poisoning should be excluded. Infertility and abortion in sheep can be the result of campylobacteriosis, salmonellosis, listeriosis, chlamydia, etc.
Immunity, specific prophylaxis. During the period of illness, antibodies appear in the blood of animals and an allergic restructuring of the body occurs, which indicates the formation of immunity. It was noted that shortly after mating with infected rams, the number of ewes responding positively to RDSC gradually increases.
In our country and abroad, work is being carried out to find immunogenic vaccines; at present, sheep are not vaccinated in Russia.
Prevention. In order to prevent the introduction of an infectious agent from abroad, Veterinary requirements when importing breeding and use sheep and goats into the Russian Federation, as well as sheep semen, only healthy breeding sheep and goats born and raised in the exporting country, non-pregnant, not vaccinated against brucellosis and originating from farms and administrative territories free from infectious epididymitis for 12 months.
To control the well-being of herds within the country, at least once a year, before the start of a breeding campaign, clinical, allergic and serological studies of all sires in breeding farms, breeding plants, farms, stations and enterprises for artificial insemination of animals are carried out. Pedigree rams selected for sale are also subject to verification.
Treatment. Sick animals are not treated.
Control measures. When a disease of rams with infectious epididymitis is established, a breeding sheep farm (breeding farm, station, breeding enterprise) is declared unfavorable and restrictions are introduced. The withdrawal of animals from such a flock (farm) to other flocks or farms for breeding and production purposes is prohibited.
Sheep with clinical signs of the disease (epididymitis, orchitis) are handed over for slaughter, and the rest of the animals of the dysfunctional flock (group) are examined monthly clinically (with mandatory palpation of the testicles and their appendages) and every 20 ... 30 days - serologically in order to identify new patients . Identified sick and reacting animals are sent for slaughter.
After receiving two negative results of a serological study in a row and in the absence of signs of the disease, the group (flock) of rams being healed is put on a 6-month control, during which they are examined 2 times, and upon receipt of negative results, the flock (group) is recognized as recovered from epididymitis.
Sheep and ewes, born from sheep of a dysfunctional flock, are kept in an isolated group, examined by clinical and serological methods from the age of 12 months, and rams - starting from 5 ... 6 months. Reacting (sick) animals are handed over for slaughter. The withdrawal of young animals of a disadvantaged group for breeding purposes is not allowed.
The rest of the sheep are examined serologically twice 1 and 2 months after lambing, as well as once 2-4 weeks before the start of the breeding season and artificial insemination. Those who react positively are recognized as sick and handed over for slaughter.
Non-reacting ewes are artificially inseminated with semen from healthy sires and examined monthly. Such a flock is recognized as healthy if the sheep have not had abortions caused by B. ovis for 2 years, and negative results have been obtained in the study of blood serum.
When slaughtering sick animals and using meat, meat and other products, they are guided, as in case of animal brucellosis, by the Rules for the veterinary and sanitary examination of slaughtered animals and the veterinary and sanitary examination of meat and meat products, and when processing and using skins, skins (smushkovyh), wool - Instructions for the disinfection of raw materials of animal origin and enterprises for its procurement, storage and processing.
It is necessary to maintain cleanliness and strictly follow the rules for keeping animals and caring for them, carry out current, and before lifting restrictions - final disinfection of premises, pens, walking areas, equipment, inventory and other objects, as well as disinfestation, deratization, sanitary repair of livestock buildings and other veterinary and sanitary measures in accordance with applicable rules.
Control questions and tasks. 1. Describe the etiology and clinical manifestations of inspection epididymitis in sheep. 2. How does this disease differ from classic sheep brucellosis? 3. When is the diagnosis of the disease considered established? 4. What measures should be taken to prevent the introduction of the infectious agent from abroad and the spread of the disease within the country? 5. List the general and specific measures for the elimination of infectious epididymitis of sheep in the sheep farm.
Belova Alena, group 12
Independent work 1
Microbiology subject
Microbiology is a science, the subject of which is microscopic creatures called microorganisms, their biological characteristics, systematics, ecology, relationships with other organisms.
Microorganisms are the most ancient form of life organization on Earth. In terms of quantity, they represent the most significant and most diverse part of the organisms inhabiting the biosphere.
Microorganisms include:
1) bacteria;
2) viruses;
4) protozoa;
5) microalgae.
A common feature of microorganisms is microscopic dimensions; they differ in structure, origin, physiology.
Bacteria are unicellular microorganisms of plant origin, devoid of chlorophyll and without a nucleus.
Mushrooms are unicellular and multicellular microorganisms of plant origin, devoid of chlorophyll, but having features of an animal cell, eukaryotes.
Viruses are unique microorganisms that do not have a cellular structural organization.
The main sections of microbiology: general, technical, agricultural, veterinary, medical, sanitary.
General microbiology studies the most general patterns inherent in each group of the listed microorganisms: structure, metabolism, genetics, ecology, etc.
The main task of technical microbiology is the development of biotechnology for the synthesis of biologically active substances by microorganisms: proteins, enzymes, vitamins, alcohols, organic substances, antibiotics, etc.
Agricultural microbiology deals with the study of microorganisms that participate in the cycle of substances, are used to prepare fertilizers, cause plant diseases, etc.
Veterinary microbiology studies the pathogens of animal diseases, develops methods for their biological diagnosis, specific prophylaxis and etiotropic treatment aimed at the destruction of pathogenic microbes in the body of a sick animal.
The subject of study of medical microbiology is pathogenic (pathogenic) and conditionally pathogenic microorganisms for humans, as well as the development of methods for microbiological diagnostics, specific prevention and etiotropic treatment of infectious diseases caused by them.
A branch of medical microbiology is immunology, which studies the specific mechanisms of protection of human and animal organisms from pathogens.
The subject of study of sanitary microbiology is the sanitary and microbiological state of environmental objects and food products, the development of sanitary standards.
Independent work 2.
History of development of microbiology
Microbiology (from the Greek micros - small, bios - life, logos - doctrine, i.e. the doctrine of small forms of life) - a science that studies organisms that are indistinguishable (invisible) with the naked eye of any kind of optics, which, for their microscopic size, are called microorganisms (microbes).
The subject of study of microbiology is their morphology, physiology, genetics, taxonomy, ecology and relationships with other life forms.
Taxonomically, microorganisms are very diverse. They include prions, viruses, bacteria, algae, fungi, protozoa, and even microscopic metazoans.
According to the presence and structure of cells, all living nature can be divided into prokaryotes (having no true nucleus), eukaryotes (having a nucleus) and life forms without a cellular structure. The latter need cells for their existence, i.e. are intracellular life forms (Fig. 1).
According to the level of organization of genomes, the presence and composition of protein-synthesizing systems and the cell wall, all living things are divided into 4 kingdoms of life: eukaryotes, eubacteria, archaebacteria, viruses and plasmodia.
Prokaryotes that combine eubacteria and archaebacteria include bacteria, lower (blue-green) algae, spirochetes, actinomycetes, archaebacteria, rickettsiae, chlamydia, mycoplasmas. Protozoa, yeasts and filamentous eukaryotic fungi.
Microorganisms are invisible to the naked eye representatives of all kingdoms of life. They occupy the lowest (most ancient) stages of evolution, but they play an important role in the economy, the circulation of substances in nature, in the normal existence and pathology of plants, animals, and humans.
Microorganisms populated the Earth 3-4 billion years ago, long before the appearance of higher plants and animals. Microbes represent the most numerous and diverse group of living beings. Microorganisms are extremely widespread in nature and are the only forms of living matter that inhabit any, the most diverse substrates (habitats), including more highly organized organisms of the animal and plant world.
We can say that without microorganisms, life in its modern forms would be simply impossible.
Microorganisms created the atmosphere, carry out the circulation of substances and energy in nature, the breakdown of organic compounds and protein synthesis, contribute to soil fertility, the formation of oil and coal, the weathering of rocks, and many other natural phenomena.
With the help of microorganisms, important production processes are carried out - baking, winemaking and brewing, the production of organic acids, enzymes, food proteins, hormones, antibiotics and other drugs.
Microorganisms, like no other form of life, are affected by a variety of natural and anthropic (related to human activity) factors, which, given their short lifespan and high reproduction rate, contributes to their rapid evolution.
The most notorious are pathogenic microorganisms (microbes-pathogens) - the causative agents of diseases of humans, animals, plants, insects. Microorganisms that acquire pathogenicity for humans (the ability to cause diseases) in the process of evolution cause epidemics that claim millions of lives. Until now, infectious diseases caused by microorganisms remain one of the main causes of death and cause significant damage to the economy.
The variability of pathogenic microorganisms is the main driving force in the development and improvement of systems for protecting higher animals and humans from everything alien (alien genetic information). Moreover, until recently, microorganisms were an important factor in natural selection in the human population (an example is the plague and the modern spread of blood groups). Currently, the human immunodeficiency virus (HIV) has encroached on the holy of holies of man - his immune system.
The main stages in the development of microbiology, virology and immunology
These include the following:
1 Empirical knowledge (before the invention of microscopes and their application to study the microworld).
J. Fracastoro (1546) suggested the living nature of agents of infectious diseases - contagium vivum.
2 The morphological period took about two hundred years.
Anthony van Leeuwenhoek in 1675 first described protozoa, in 1683 - the main forms of bacteria. The imperfection of instruments (the maximum magnification of X300 microscopes) and methods for studying the microworld did not contribute to the rapid accumulation of scientific knowledge about microorganisms.
3. Physiological period (since 1875) - the era of L. Pasteur and R. Koch.
L. Pasteur - the study of the microbiological foundations of the processes of fermentation and putrefaction, the development of industrial microbiology, the elucidation of the role of microorganisms in the circulation of substances in nature, the discovery of anaerobic microorganisms, the development of the principles of asepsis, methods of sterilization, weakening (attenuation) of virulence and obtaining vaccines (vaccine strains).
R. Koch - a method for isolating pure cultures on solid nutrient media, methods for staining bacteria with aniline dyes, the discovery of pathogens of anthrax, cholera (Koch's comma), tuberculosis (Koch's sticks), improvement of microscopy techniques. Experimental substantiation of the Henle criteria, known as the postulates (triad) of Henle-Koch.
4 Immunological period.
I.I. Mechnikov is a "poet of microbiology" according to the figurative definition of Emile Roux. He created a new era in microbiology - the doctrine of immunity (immunity), having developed the theory of phagocytosis and substantiating the cellular theory of immunity.
At the same time, data were accumulating on the production of antibodies against bacteria and their toxins in the body, which allowed P. Ehrlich to develop a humoral theory of immunity. In the subsequent long-term and fruitful discussion between supporters of phagocytic and humoral theories, many mechanisms of immunity were revealed, and the science of immunology was born.
Later it was found that hereditary and acquired immunity depends on the coordinated activity of five main systems: macrophages, complement, T- and B-lymphocytes, interferons, the main histocompatibility system, providing various forms of immune response. I.I. Mechnikov and P. Erlich in 1908. was awarded the Nobel Prize.
February 12, 1892 at a meeting of the Russian Academy of Sciences, D.I. Ivanovsky reported that the causative agent of tobacco mosaic disease is a filterable virus. This date can be considered the birthday of virology, and D.I. Ivanovsky - its founder. Subsequently, it turned out that viruses cause diseases not only in plants, but also in humans, animals, and even bacteria. However, only after establishing the nature of the gene and the genetic code, the viruses were classified as wildlife.
5. The next important step in the development of microbiology was the discovery of antibiotics. In 1929 A. Fleming discovered penicillin, and the era of antibiotic therapy began, which led to the revolutionary progress of medicine. Later it turned out that microbes adapt to antibiotics, and the study of the mechanisms of drug resistance led to the discovery of a second - outside the chromosomal (plasmid) bacterial genome.
The study of plasmids showed that they are even simpler organisms than viruses, and, unlike bacteriophages, do not harm bacteria, but endow them with additional biological properties. The discovery of plasmids significantly supplemented the ideas about the forms of existence of life and possible ways of its evolution.
6. The modern molecular genetic stage in the development of microbiology, virology and immunology began in the second half of the 20th century in connection with the achievements of genetics and molecular biology, the creation of the electron microscope.
In experiments on bacteria, the role of DNA in the transmission of hereditary traits was proven. The use of bacteria, viruses, and later plasmids as objects of molecular biological and genetic research led to a deeper understanding of the fundamental processes underlying life. Elucidation of the principles of encoding genetic information in the DNA of bacteria and the establishment of the universality of the genetic code made it possible to better understand the molecular genetic patterns inherent in more highly organized organisms.
The deciphering of the Escherichia coli genome has made it possible to construct and transplant genes. To date, genetic engineering has created new areas of biotechnology.
The molecular genetic organization of many viruses and the mechanisms of their interaction with cells have been deciphered, the ability of viral DNA to integrate into the genome of a sensitive cell and the main mechanisms of viral carcinogenesis have been established.
Immunology has undergone a real revolution, going far beyond infectious immunology and becoming one of the most important fundamental biomedical disciplines. To date, immunology is a science that studies not only protection against infections. In the modern sense, immunology is a science that studies the mechanisms of self-defense of the body from everything genetically alien, maintaining the structural and functional integrity of the body.
Immunology currently includes a number of specialized areas, among which, along with infectious immunology, the most significant include immunogenetics, immunomorphology, transplantation immunology, immunopathology, immunohematology, oncoimmunology, ontogeny immunology, vaccinology and applied immunodiagnostics.
Microbiology and virology as fundamental biological sciences also include a number of independent scientific disciplines with their own goals and objectives: general, technical (industrial), agricultural, veterinary, and medical microbiology and virology, which is of the greatest importance for mankind.
Medical microbiology and virology studies pathogens of human infectious diseases (their morphology, physiology, ecology, biological and genetic characteristics), develops methods for their cultivation and identification, specific methods for their diagnosis, treatment and prevention.
7. Prospects for development.
On the threshold of the 21st century, microbiology, virology and immunology represent one of the leading areas of biology and medicine, intensively developing and expanding the boundaries of human knowledge.
Immunology has come close to regulating the body's self-defense mechanisms, correcting immunodeficiencies, solving the problem of AIDS, and fighting cancer.
New genetically engineered vaccines are being created, new data are emerging on the discovery of infectious agents that cause “somatic” diseases (gastric ulcer, gastritis, hepatitis, myocardial infarction, sclerosis, certain forms of bronchial asthma, schizophrenia, etc.).
The concept of emerging and reemerging infections has emerged. Examples of the restoration of old pathogens are mycobacterium tuberculosis, rickettsia of the tick-borne spotted fever group and a number of other pathogens of natural focal infections. New pathogens include human immunodeficiency virus (HIV), Legionella, Bartonella, Ehrlichia, Helicobacter pylori, and Chlamydia pneumoniae. Finally, viroids and prions, new classes of infectious agents, have been discovered.
Viroids are infectious agents that cause lesions in plants similar to viral ones, however, these pathogens differ from viruses in a number of ways: the absence of a protein shell (naked infectious RNA), antigenic properties, a single-stranded circular structure of RNA (of viruses, only hepatitis D virus), small RNA.
Prions (proteinaceous infectious particle - a protein-like infectious particle) are protein structures devoid of RNA that are the causative agents of some slow infections in humans and animals, characterized by lethal lesions of the central nervous system such as spongiform encephalopathy, kuru, Creutzfeldt-Jakob disease, Gerstmann-Straussler-Scheinker syndrome , amniotrophic leukospongiosis, bovine spongiform encephalopathy (bovine “rabies”), scrapie in sheep, mink encephalopathy, chronic wasting disease of deer and elk. It is assumed that prions may play a role in the etiology of schizophrenia and myopathies. Significant differences from viruses, primarily the absence of their own genome, do not yet allow us to consider prions as representatives of wildlife.
3. Tasks of medical microbiology.
These include the following:
Establishment of the etiological (causal) role of microorganisms in normal and pathological conditions.
Development of diagnostic methods, specific prevention and treatment of infectious diseases, indication (detection) and identification (determination) of pathogens.
Bacteriological and virological control of the environment, food, compliance with the sterilization regimen and surveillance of sources of infection in medical and child care institutions.
Monitoring the sensitivity of microorganisms to antibiotics and other medicinal preparations, the state of microbiocenoses (microflora) of surfaces and cavities of the human body.
4. Methods of microbiological diagnostics.
Methods for laboratory diagnosis of infectious agents are numerous, the main ones include the following.
Microscopic - using instruments for microscopy. Determine the shape, size, relative position of microorganisms, their structure, the ability to stain with certain dyes.
The main methods of microscopy include light microscopy (with varieties - immersion, dark-field, phase-contrast, luminescent, etc.) and electron microscopy. These methods can also include autoradiography (isotope detection method).
Microbiological (bacteriological and virological) - isolation of a pure culture and its identification.
Biological - infection of laboratory animals with the reproduction of the infectious process on sensitive models (bioassay).
Immunological (options - serological, allergological) - is used to detect the antigens of the pathogen or antibodies to them.
Molecular genetic - DNA and RNA probes, polymerase chain reaction (PCR) and many others.
Concluding the material presented, it is necessary to note the theoretical significance of modern microbiology, virology and immunology. The achievements of these sciences made it possible to study the fundamental processes of life at the molecular genetic level. They determine the modern understanding of the essence of the mechanisms of development of many diseases and the direction of their more effective prevention and treatment.
Microbiology (from the Greek. micros - small, bios - life, teaching) - the science of the smallest organisms not visible to the naked eye, called microorganisms or microbes. Bacteria and some microscopic fungi are the subject of microbiology. Microbiology studies the structure, physiology, biochemistry, genetics and ecology of microorganisms, their role and importance in the life of humans, animals and the productivity of the biosphere.
Microbiology owes its successful development primarily to the achievements of physics and chemistry, which enriched microbiology with original research methods that made it possible to decipher some of the features of metabolism. The use of electron microscopy made it possible to study the fine structure of a bacterial cell, chemistry provided many new analytical methods of research, which made it necessary to reconsider the ways and essence of energy metabolism, the chemistry of the biosynthesis of a number of substances. In turn, microbiology has made a valuable contribution to genetics, biochemistry, and molecular biology. The use of microorganisms as objects of genetic and biochemical research opened a new era in natural science. The achievement of microbiology is associated with the solution of many theoretical problems in general biology and medicine, as well as the widespread use of microbiology in the national economy. For the first time, the role of DNA in the transmission of hereditary information was established on microorganisms, the complex structure of the gene and the dependence of mutation processes on changes in the structure of DNA were proved. The study of the biosynthetic activity of microorganisms has shown their ability (and high activity) to synthesize very valuable compounds of great national economic importance.
In the process of enrichment and development of microbiology, new scientific disciplines - mycology and virology - with their own tasks and objects of research, spun off. Subsequently, depending on the ecology of microorganisms and the practical needs of a person in microbiology, directions were distinguished that differed in research tasks - general microbiology, industrial, geological, agricultural, medical, veterinary, etc.
General microbiology studies the structure and vital activity of microorganisms, their distribution in nature, genetics, questions of systematics and classification. This section is the base for all other branch sections of microbiology.
Industrial (technical) microbiology studies microorganisms used in various industries to obtain food products, alcohol, enzymes, amino acids, vitamins, antibiotics, feed protein and other biologically active substances, and also develops methods for protecting products and raw materials from spoilage by microorganisms.
Geological microbiology studies the role of microorganisms in the formation and decomposition of ores, in the production of metals from these ores, in the formation of minerals, and in the circulation of the most important biogenic elements.
Agricultural microbiology studies microorganisms that play a role in the formation of soil structures, increasing soil fertility, creating bacterial fertilizers, as well as microorganisms that cause crop diseases (phytopathogenic) and develops measures to combat them.
Medical microbiology studies microorganisms that cause human diseases and develops methods for diagnosing, preventing and treating these diseases. It also studies the conditions for the preservation of pathogenic microbes in the external environment, the ways and mechanisms of their spread.
Veterinary microbiology studies microorganisms that cause infectious diseases in farm animals, game and wild animals, fish, bees, as well as pathogens common to animals and humans (zooanthroponoses). Veterinary microbiology also studies microorganisms that are important in animal husbandry (microflora of feed, gastrointestinal tract) and food technology of animal origin.
Veterinary microbiology consists of three parts:
general microbiology - studies the morphology, physiology, distribution and preservation of pathogenic microbes in the external environment, the genetics of microorganisms, pathogenicity and virulence, the role of microbes in the infectious process, their distribution and localization in the animal body, etc .;
immunology - studies the patterns of manifestation, mechanisms and methods of controlling immunity, antigens and antibodies, immunological tolerance, issues of allergies, specific diagnostics, etc .;
private (special) microbiology - studies the properties of pathogens of infectious animal diseases, issues of pathogenesis, laboratory diagnostics, specific prevention and therapy.
There are a large number of research institutes in our country (the All-Union Institute of Experimental Veterinary Medicine, the All-Union Institute of Veterinary Virology and Microbiology, the All-Union Research Institute of Veterinary Sanitation, the All-Union State Scientific and Control Institute of Veterinary Preparations), a number of special research institutes and problem laboratories , a network of republican, regional, inter-district and district veterinary laboratories in which microbiologists work. Microbiological problems in veterinary medicine are also studied at the departments of microbiology in veterinary universities and veterinary faculties of agricultural universities in the country. Microbiological research at the university uses a number of related disciplines: epizootology, veterinary medical examination, obstetrics, surgery, pharmacology, etc. Such a wide application of microbiological knowledge and methods determines their exceptional importance in the formation of professional thinking of a general veterinarian.
The main problems of modern microbiology are the in-depth study of the molecular organization and metabolism of microorganisms, the microbiological synthesis of new valuable products, the influence of environmental factors on the vital activity of microorganisms; the search for specific means of combating infectious diseases of humans, animals and plants.
Questions for the exam
by discipline "Agricultural Microbiology"
for engineering students
specialties 1-74 02 01 Agronomy
1. Microbiology as a biological science. Subject and methods of research.
2. History of the development of microbiology. Morphological, physiological, biochemical, ecological and genetic period of development.
3. The main tasks and directions of development of microbiology at the present stage.
4. Distribution and role of microorganisms in nature.
5. Prokaryotic and eukaryotic microorganisms, their cellular organization and main differences.
6. The main forms of bacteria and their sizes.
7. General scheme of the structure of a bacterial cell.
8. External structures of a bacterial cell (capsule, outgrowths). movement of bacteria.
9. Structure, chemical composition and functions of the bacterial shell. Gram-positive and gram-negative bacteria, L-forms.
10. Structure and functions of the cytoplasmic membrane. Mesosomes.
11. Cytoplasm and its structures (nucleoid, ribosomes, inclusions).
12. Endospores: formation, structure and properties. Other resting forms.
13. Location of spores in the cell. Germination of spores.
14. Methods of reproduction of prokaryotes. Growth of cell mass of microorganisms on nutrient media.
15. Principles of taxonomy and nomenclature of microorganisms, taxonomic categories. The concept of strain and clone.
16. Systematics according to D. Bergi. Classification criteria.
17. General characteristics of department 1 - Gracilicutes. Bacteria, bacteria with anoxic and oxygen type of photosynthesis.
18. General characteristics of department 2 - Firmicutes. Firmibacteria and tallobacteria.
19. General characteristics of department 3 - Tenericutes. Mycoplasmas.
20. General characteristics of department 4 - Mendosicutes. Archaebacteria.
21. Actinomycetes, their systematic position, structure and reproduction. The value of actinomycetes in the soil-forming process.
22. Microscopic fungi: mucor, penicillium, aspergillus. Yeast.
23. Practical use of molds and yeasts.
24. Viruses: structure, properties, classification. Viroids and prions.
25. Structure and reproduction of bacteriophages. Virulent and temperate phages.
26. Hereditary factors of bacteria. Nucleoid and plasmids.
27. Mutational and recombinative variability in prokaryotes.
28. Transformation, conjugation and transduction as sources of hereditary variability.
29. Practical use of genetic engineering in microbiology.
30. Methods of nutrition and supply of nutrients to the cell.
31. Chemical composition and nutritional needs of microorganisms.
32. The main types of nutrition of microorganisms in relation to energy sources, hydrogen donor, carbon source.
33. Sources of nitrogen and vitamins in microorganisms. Assimilation of ash elements.
34. Nutrient media for growing microorganisms. Classification by consistency, by purpose, by origin.
35. The concept of metabolism: anabolism and catabolism.
36. The main ways of obtaining energy by microorganisms: aerobic respiration, incomplete oxidation, anaerobic respiration, fermentation.
37. Influence on microorganisms of humidity and concentration of solutions. Osmophilic and halophilic organisms.
38. The ratio of microorganisms to temperature. Thermal sterilization methods.
39. Impact on organisms of light, radiation, pressure, ultrasound, electricity, mechanical shocks.
40. The ratio of microorganisms to oxygen.
41. The influence of the acidity of the environment on the development of microbes.
42. The action of chemically toxic substances on microorganisms. Disinfection and antiseptics.
44. Antibiotics of microbial and animal origin, phytoncides.
45. Theoretical foundations of methods of storage, processing and conservation of food products.
46. Carbon cycle in nature and the role of microorganisms.
47. Alcoholic and glycerin fermentation. Pathogens, conditions, chemistry and meaning.
48. Lactic acid fermentation: homofermentative and heterofermentative.
49. Pathogens, conditions, chemistry and significance.
50. Propionic acid fermentation. Pathogens, conditions, chemistry and meaning.
51. Butyric and acetone-butyl fermentation. Pathogens, conditions, chemistry and meaning.
52. Decomposition of pectin substances. Pathogens, conditions, chemistry and meaning. Rosy lobe of flax.
53. Decomposition of starch. Pathogens, conditions, chemistry and meaning.
54. Obtaining acetic and citric acids. Pathogens, conditions, chemistry and meaning.
55. Oxidation of fats by microorganisms. Pathogens, conditions, chemistry and meaning.
56. General scheme of the nitrogen cycle in nature.
57. Ammonification of proteins. Pathogens, conditions, chemistry and meaning.
58. Immobilization of nitrogen in the soil. The influence of this process on the nitrogen nutrition of plants.
59. Nitrification. Pathogens, conditions, chemistry and meaning.
60. Denitrification: direct and indirect. Pathogens, conditions, chemistry and meaning.
61. Biological fixation of molecular nitrogen. Its essence and chemistry.
62. Free-living nitrogen-fixing microorganisms: Clostridiumpasteurianum,Azotobacter,Beijerinskia ,Derxia,Azomonas, cyanobacteria.
63. Symbiotic nitrogen fixation in legumes and non-legumes. Characteristics of the genus Rhizobium and Frankia. Optimal conditions for nitrogen fixation. bacterial preparations.
64. Associative nitrogen fixation in the rhizosphere and phyllosphere. Characteristic azospirillum,pseudomonas,Klebsiella,Flavobacterium and their use.
65. Cycle of sulfur in nature: mineralization, sulfification and desulfurization. Pathogens, conditions, chemistry and meaning.
66. Cycle of phosphorus in nature. Mineralization of organic phosphorus and mobilization of phosphates.
67. The cycle of iron in nature. Pathogens, conditions, chemistry and meaning.
68. Soil as a habitat for microorganisms.
69. Participation of microorganisms in the soil-forming process.
70. Methods for determining the composition and activity of soil microorganisms. The method of breeding and sowing on dense nutrient media, the method of direct counting.
71. Microflora of various types of soils. Microorganisms-indicators.
72. Influence of tillage, fertilizers and pesticides on the activity and species composition of soil microflora.
73. The use of microbial preparations in the control of pests and diseases of agricultural crops.
74. Microflora of rhizoplane and rhizosphere. Mycorrhiza. role in plant life.
75. Microflora of the phyllosphere, its composition and role in plant life. Grain microflora and its changes under different storage conditions.
76. Microbiological processes during hay drying and silage.
77. Feed ensiling. Vigorous plants. Silo quality indicators.
78. Spread of microorganisms in water. Water treatment methods and the use of microorganisms.
79. Quantitative and qualitative composition of air microflora.
80. Spread of infectious diseases through water and air.
81. Application of bioconversion methods in agriculture.
Compiled by:
Associate Professor of the Department, Ph.D.S. Freezing