General microbiology, historical periods of microbiology, bacteria, structure of bacterial cell

1. GENERAL
MICROBIOLOGY AND
VIROLOGY.
The morphology of bacteria
and viruses.
Lecture number 1.

2. The subject of microbiology is the special
world of living beings invisible by naked
eye which sizes are within the range from
1-10 nm up to 0.1-1 mm.

3. Microbiology
Microbiology (Greek micros - small,
Latin bios - life) is a complex of
biological sciences that study
morphology, systematics, physiology,
genetics, ecology of microorganisms,
relationships with other organisms
inhabiting our planet.

4. Microorganisms are the most ancient form of
organizing life on Earth, they appeared long
before the appearance of plants and animals -
about 3-4 billion years ago. At present,
microorganisms represent the most significant
and most diverse part of organisms inhabiting
the biosphere of the Earth. This served as the
basis for the separation of all microorganisms
into 4 large kingdoms: bacteria, fungi, protozoa
and viruses. Each of them is an object of study
of separate sections of microbiology,
independent disciplines - bacteriology, virology,
mycology, protozoology

5. The tasks of microbiology
and immunology:
• to give an idea of the classification
and biological properties of
pathogenic and conditionally
pathogenic microorganisms;
• to acquaint with modern methods of
microbiological diagnosis of common
infectious and non-infectious diseases
of microbial etiology and to give an
idea of the structure of the immune.

6. Taking into account the tremendous role the
microorganisms play in nature, the problems of
microbiology are rather diverse. Microbiology steadily
differentiates into various scientific parts and
disciplines.
Modern microbiology includes general microbiology
(investigates common principles of structural
organization and general functions of microorganisms),
special microbiology (performs the detailed study of
certain microbial agents and groups); industrial
microbiology that is the major part of modern
biotechnology; agricultural microbiology; space
microbiology; sanitary microbiology; veterinary
microbiology; and medical microbiology.

7. The main goals of medical
microbiology:
 1. Laboratory diagnosis of diseases caused by
microorganisms by means of versatile microbiological
methods; the detection of pathogenic microbial agents in
living organisms and external environment.
 2. Sanitary control of microbial pollution of water, air, soil,
house, foodstuffs, drugs, etc.
 3. The development of biological products for medicine
(antibiotics, vaccines, immune sera, polyclonal and
monoclonal antibodies, cytokines and others) that are used
for prophylaxis and treatment of bacterial, viral, fungal and
protozoan diseases; autoimmune and inflammatory
disorders.

8. HISTORY OF MICROBIOLOGY:
DESCRIPTIVE PERIOD
The end of XVII – middle of
XIX century:
• Discovery of the world of
microorganisms, description
of microorganisms.
• Anthony van Leeuwenhoek
– discoverer of first
microorganisms

9. Middle of XIX – beginning of ХХ
century:
 Study of living activity of microbial cell,
discovery of infectious (causing disease)
bacteria, beginning of scientific microbiology.
Louis Pasteur
Robert Koch
PHYSIOLOGICAL (PASTEUR’S)
PERIOD

10. Louis Pasteur Robert Koch

11. • Discovery of pathogenic microorganisms
– Staphylococcus
– Pneumococcus
– Clostridium
• Development of active (live weakened) vaccines
- chicken cholera
– anthrax
– rabies
• Other discoveries
– microbial nature of fermentation
– microbial nature of “disease” of wine and beer
– impossibility of spontaneous self-origin of microorganisms
– methods of dry heat sterilization and pasteurization
SCIENTIFIC CONTRIBUTION OF
PASTEUR

12. SCIENTIFIC CONTRIBUTION OF
KOCH
• Discovery of pathogenic microorganisms
– anthrax rod
– cholera vibrio (Koch’s comma)
– tuberculosis rod (Koch’s rod)
• Development of basic principals of identification of
pathogenic microbes causing disease
– Henle-Koch postulates:
1. Microbe has to be isolated from individuals suffering from the disease
2. The etiological agent (microbe) must be cultivated in pure culture
3. Pure culture of the pathogen when introduce into susceptible host
(experimental animal) has to produce the symptoms characteristic for the
disease
• Other discoveries
– solid agar media for cultivation of microorganisms
– aniline dyes
– immersion objective for light microscopy
– microphotography
– sterilization by steam

13. IMMUNOLOGICAL PERIOD
Beginning – middle of ХХ century
• Discovery of immune response
Metchnikoff
Ehrlich

14.  Metchnikoff – developer of cellular theory of immunity

15. Ehrlich
– founder of humoral
theory of immunity
– developer of
chemotherapy of
infectious diseases

16. MODERN PERIOD
Middle of XX century
Molecular biological methods of
research

17. Principles of Microbial
Classification
Classification
• distribution of
microorganisms
into groups with
similar
characteristics
Nomenclature
• name of
microorganisms in
accordance with
international
requirements
Identification
• comparison of
unknown
microorganisms
with already
classified.
The science that studies classification is called
taxonomy. It includes three interrelated areas:

18. By the decision of the International Code
for Bacteria the following taxonomic
categories are recommended: class,
department, order, family, genus, species.
The name of the species corresponds to a
binary nomenclature, i.e. consists of two
words.
For example, the causative agent of
typhoid fever is written as Salmonella
ryphi.

19. According to the classification D.
Burgey are divided into 4
departments
Gracilicutes - bacteria with a thin cell wall,
gram-negative;
Firmicutes - bacteria with a thick cell wall,
Gram-positive;
Tenericutes - bacteria "soft", "tender" without a
rigid cell wall, including mycoplasmas;
Mendosicutes - the so-called arhebacteria,
characterized by a defective cell wall.

20. Morphology of Bacteria
Bacteria (Gk. bakterion – small stick) are
predominantly unicellular organisms. The size of
bacteria varies from 0.1 to 20 mm or more. Most
of pathogenic bacteria are within the range 0.2 to
10 mm.
The shapes and sizes of microbes are not strictly
stable. They get adaptation to the surroundings and
environmental conditions. But in constant
situations bacteria maintain their sizes and shapes
that are specific characteristics for certain
microbial groups.

21. Spherical
Meningococci Pneumococci
Gonococci Staphylococci
Veylonella Streptococci

22. Rounded sticks
Sticks with
thickened ends
Chopped-off
sticks
Rod-shaped

23. Spiral
Vibrios Spirilla
Campylo-
bacteria
spirochetes
TreponemasB
orreliae
Leptospirae

24. The structure of bacteria is well studied by
electron microscopy of whole cells and their
ultra-thin sections.
A bacterial cell consists of a cell wall, a
cytoplasmic membrane, a cytoplasm with
inclusions, and a nucleus called a nucleoid.
There are additional structures: capsule,
microcapsule, mucus, flagella, saw, some
bacteria under adverse conditions are able to
form spores.
The composition of bacteria, like other
microbes, includes water, proteins, nucleic acids,
carbohydrates, lipids, mineral substances.

30. Bacterial cells can be classified
into Gram-positive or
Gram-negative based on the
structural differences between
Gram-positive and Gram-
negative cell walls. The cell
walls of
the Gram-positive bacteria have
simpler chemical structures
compared to Gram-negative
bacteria.

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