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Physiology of bacteria.pdf pathophysiology
1. Physiology of bacteria. Features of
nutrition, respiration and reproduction
of aerobic and anaerobic prokaryotes.
1
Tyumen state medical university
Department of microbiology
Lecture 3
2. Physiology of bacteria
This physiology studies the following:
• nutrition
• metabolism
• getting energy
• growth and reproduction
• environmental interaction
2
4. Химический состав бактерий
Nutrition is a process of nutrients entering the
cell resulting in the synthesis of structural
components that ensure the growth and
reproduction of bacteria
Nutritional groups
5. Химический состав бактерий
• Water – 70 %
• Dry substrate – 30 %
5
protein – 52 %
carbohydrates (polysaccharides) – 17 %
lipids – 9 %
RNA – 16 %
DNA – 3 %
inorganic compounds – 3 %
Lyophilization is a conservation of bacteria (Drying in the
vacuum from the frozen condition)
Chemical composition of bacteria
6. Пищевые потребности бактерий
6
Macroelements (organogens):
С – 50%, О – 20%, N – 14%, Н – 8%
Microelements: K, Ca, Mg, Na, S, P, Cl
Ultratrace elements: B, W, Fe, Co, Zn, Cu, Mn etc.
Bacterial growth factors: amino acids, lipids,
vitamins, purines, pyrimidines.
Nutritional needs of prokaryotes
7. According to the method of carbon nutrition:
Autotrophs - carbon is obtained from carbon dioxide,
water and inorganic compounds.
Heterotrophs - carbon is obtained from organic
compounds (amino acids, alcohol etc.)
7
Nutritional needs of prokaryotes
Parasites saprophytes
Obligate
(Holoparasites)
Facultative
8. How the organism obtains nitrogen:
Aminoautotrophs – nitrogen is obtained from inorganic
compounds (ammonia salts, nitrates,
nitrites).
Aminoheterotrophs – nitrogen is obtained from organic
compounds (amino acids, purines,
pyrimidines, vitamins)
8
Nutritional needs of prokaryotes
9. Sources of sulfur and phosphors:
• S – sulfates, cysteine, methionine etc.
• Р – phosphoric acid salts
Sources of oxygen:
• О – О2, Н2О, organic compounds
9
Nutritional needs of prokaryotes
10. Classification of microorganism by oxygen using in
metabolism
10
Nutritional needs of prokaryotes
Aerobes Anaerobes
Obligate Obligate
Facultative
Growing on
the air
Microaerophiles Aerotolerant
Strict
obligate
11. Prototrophs are microorganisms which don’t need vitamins, amino acids
and other growth factors because they synthesize them from mineral or organic
compounds.
Prototrophs are microorganisms that do not require ready-made vitamins,
amino acids or other growth factors for their growth; they synthesize them
from mineral or organic compounds.
Auxotrophs are microorganisms that are unable to synthesize a particular
organic compound required for their growth, (they need nutritional compounds).
Auxotrophs are not able to synthesize a certain organic compound which is
necessary for their growth (they need nutrients in a ready-made form).
11
Nutritional needs of prokaryotes
12. Classification by the origin:
1. Natural
2. Artificial
Also there are separated groups: synthetic and
semi-synthetic
12
Culture medium (Growth of medium)
13. Classification by the purpose:
1. Elective
2. Differential
3. Transport
4. Minimal (storage)
13
Culture medium (Growth of medium)
14. Classification by consistence:
1.Liquid
2. Semisolid (1,5 - 4,0 g/l – semisolid GM)
3. Solid (15 - 20 г/л – solid GM)
Agar is polysaccharide made of agarose and
agaropectin.
Agar is a polysaccharide made of agarose and agaropectin.
(Agar is obtained from algae).
14
Culture medium (Growth of medium)
16. • A culture is the microorganisms grown on the
culture medium.
• A colony is a visible accumulation of one
species of microorganisms usually got by the
division from one cell.
• An axenic culture is a culture which include
one species of microbes.
• A strain is an axenic culture of microbes that is
extracted from a certain source in due time.
17. • A culture is the microorganisms grown on a
nutrient medium.
• A colony is a visible accumulation of
individuals of the same species which are
formed as a result of the reproduction of one
cell.
• A pure culture is a culture containing
microbes of the same species.
• A strain is a pure culture of microbes
isolated from a specific source at a specific
time.
19. Aeration
Oxygen is a part of water and many other compounds. We must
note that different microorganisms have different need in oxygen
when we are going to cultivate them.
19
Cultivation conditions
Methods of making anaerobiosis
1. Physical methods
• cultivation in anaerostat
• sowing in agar column by injection
• culture medium boiling before sowing
21. Methods of making anaerobiosis
2. Chemical methods
• addition of reducing compounds
• chemical reactions which consume oxygen
3. Biological methods
Fortner principle
21
Cultivation conditions
22. External space Plasma
membrane
Cytoplasm
1
2 S
3 S
ATP
Cell transport
1. Passive diffusion (transport down the concentration gradient
without transport proteins and energy input)
2. Facilitated diffusion (transport down the concentration gradient
via special transport proteins without energy input)
3. Active transport (transport against the concentration gradient with
transport protein which requires cellular energy)
22
23. • Growth is an increase in the cell size.
• Reproduction is an increase in the amount of cells
by division. Bacteria can grow and divide extremely
rapidly.
23
Growth and reproduction
24. 24
Bacterial reproduction
Bacteria is reproduced by binary division or budding
(rare), they don’t realize mitosis.
Cell division is followed by the production of a
septum to divide the daughter bacteria into two cells.
25. 25
Phases of bacterial growth
Lag-phase
Stationary
phase
Death
phase
Log
(exponential)
phase
N
t, hours
N – amount of cells
26. 1. Lag-phase, 2 - 4 hours.
Bacteria are adapted to cultivation conditions, the
synthesis of inducible enzymes is being done, the
amount of protein increases.
1. Log (exponential) phase, 5 - 12 hours. Maximum
speed of cell division.
26
Phases of bacterial growth
27. Bacteria can divide every 20-40 minutes in
optimal conditions. During the log-phase bacteria
are the most vulnerable because the products of
metabolism are much more sensitive to inhibitors,
drugs and etc.
28. Phases of bacterial growth
3. Stationary phase. This phase can take different
time, it depends on species of bacteria, cultivation
conditions, but it usually takes some hours.
The amount of bacteria is maximum, the amount of
dying bacteria is equal to the amount of born ones.
4. Death phase (from 10 hours and more).
The process of death dominates over the process
of division, because the nutrients decrease, toxic
metabolites accumulate.
28
29. 29
1st stage
Gold sowing (sowing by Gold’s method) of research
material on the growth media
Bacteriological method of diagnosis
30. 30
2nd stage
• Research cultural and morphological properties;
• Re-sowing typical colonies on canted agar for the
accumulation of axenic culture.
3rd stage
Identification (species detection) of culture by
totality of properties:
Morphological, tinctorial, biochemical, antigenic,
toxigenic sensitivity to antibiotics and phages.
Bacteriological method of diagnosis
32. 32
Metabolism is a set of biochemical reactions in the
organism.
Two main types of metabolism
1. Anabolism (constructive)
2. Catabolism (energetic)
Bacterial metabolism
33. All cells require a constant supply of energy to
survive. This energy is derived from the controlled
breakdown of various organic substrates
(carbohydrates, lipids and proteins).
This process of substrate breakdown and
conversion into usable energy is known as
catabolism.
There are some main types of catabolism:
fermentation;
Aerobic respiration;
Mixed.
Catabolism
34. The energy produced in catabolism may be
used in the synthesis of cellular constituents (cell
walls, proteins, fatty acids, nucleic acids), this
process is known as anabolism.
Anabolism
36. 36
• Getting energy
• Breakdown of alien compounds to
monomers
• Synthesis of own polymers from monomers
• Breakdown of old molecules, their
exchanging for new ones
Metabolism function
37. 37
• High speed of reaction by using enzymes.
• Great variety of used substrates.
• Self-regulation of metabolism depending on
environmental conditions.
• Catabolism dominance over anabolism.
• Direction of all the processes on reproduction.
Bacterial metabolism specialties
38. Enzymes are protein catalyst of cell.
Viruses don’t have metabolic enzymes.
Bacteria have all 6 classes of enzymes.
39. Accelerate chemical reactions.
They are saved after reactions.
High specificity to substrates.
They are under the regulation. It is the most
important mechanism of the adaptation to
environment.
Enzyme properties
40. 1. Oxidoreductases are catalyze oxidation/reduction
reactions. They play a great role in getting energy.
2. Transferases are a transfer of a functional
group (e.g. a methyl or phosphate group),
accelerate a reaction in the electron transport
chain and Pentose phosphate pathway.
!!! Adenyl transferases and acetyl transferases determine
the antibiotics resistance of bacteria
40
Enzyme classification by the structure
41. 3. Lyases take part in the reaction of non-hydrolytic cleavage of
bonds with following making double bonds (with possible
connection of different compounds to these bonds)
4. Isomerases are catalyze isomerization (transformation from
one compound to another) changes within a single molecule.
5. Ligases join two molecules with covalent bonds
(biosynthesis reactions).
41
Enzyme classification by the structure
42. 6. Hydrolases catalyze the hydrolysis of various bonds.
Hydrolysis is a chemical reaction in which a molecule of
water ruptures one or more chemical bonds.
42
Enzyme classification by the structure
Enzyme Enzyme aim
Hyaluronidase hyaluronic acid in connective tissue
Neuraminidase neuraminic acid of the mucous
membranes
Collagenase Collagen of muscle fiber
Lecithinase Lecithin of plasma membrane of RBC
and muscle fibers
Proteinase Immunoglobulins
43. ! Other important hydrolases:
beta-lactamases catalyze the cleavage of beta-
lactam ring of penicillin, cephalosporins,
monobactams, carbapenems;
Esterase blocks erythromycin and other similar
structure antibiotics.
44. Endoenzymes
Work inside the cell
Oxidoreductases,
transferases,
lyases, isomerases, ligases
Exoenzymes
Are excreted in
extracellular space
Hydrolases
Classification by
the active location
44
45. 1. Constitutional - enzymes that are being synthesized all the
time of cell living.
2. Inducible – enzymes that are being synthesized only in the
presence of specific (suitable) substrate.
E.g.: lactase (β-galactosidase) are synthesized only in the presence of
lactose.
3. Repressive – synthesis is suppressed by the accumulation of
reaction products.
! All enzymes for every cell is individual and determined genetically.
Biochemical activity of microorganisms is used for
species definition.
45
Enzyme classification by the genetic control:
46. Microorganisms are divided by the source of energy they
get:
1. Photolithotrophs –
Photo – the sun is the source of energy
Litho – inorganic compounds are the source of
electrons
2. Photoorganotrophs–
Photo – the sun is the source of energy
organo - organic compounds are the source of electrons
Catabolism
47. 47
3. Chemolithotrophs –
Chemo – redox reactions are the source of
energy
Litho – inorganic compounds are the source of
electrons
4. Chemoorganotrophs –
Chemo – redox reactions are the source of
energy
organo - organic compounds are the source of
electrons.
Catabolism
49. 49
Catabolism
Respiration
Respiration is a perfect process of getting energy within
redox reactions (glucose oxidation to carbon
dioxide and water).
Properties of respiration:
• high energetic result (we get 36 ATP molecules from 1
molecule of glucose);
• process of phosphorylation occurs in mesosomes;
• oxygen or inorganic compounds are acceptors for
electrons.
50. 50
Catabolism
Respiration
Respiration includes some stages:
1. Glycolysis – 2 ATP molecules are being made from 1
molecule of pyruvate in cytoplasm
2. Citric acid cycle (Krebs cycle) – pyruvate is oxidized to CO2
and H2O in mesosomes. The result is 36 ATP molecules.
3. Electron transport chain (ETC) – electrons are carried on
acceptors in plasma membrane.
Type of respiration depends on the final electrons
acceptor:
Obligate aerobes – oxygen is final acceptor
Microaerophiles need less oxygen concentration
Facultative anaerobes grow in aerobe and anaerobe
conditions.
51. 51
Fermentation occurs without oxygen and the pyruvic acid
produced from glycolysis is converted to various
end products depending on the bacterial
species. These organic molecules are used as
electron acceptors.
Properties of fermentation:
• Low energetic result (from 1 glucose molecule – 2 ATP)
• Process of phosphorylation occurs in cytoplasm
• End products of organic substrate cleavage can be both as
donors as acceptors of hydrogen.
Catabolism
52. 52
There are some types of fermentation depending
on the end product:
1. Alcohol fermentation – yeast of genus
Saccharomyces.
2. Lactic acid fermentation – lactobacilli, bifidobacteria,
streptococci.
3. Propionic acid fermentation – propionic acid bacteria.
4. Butyric acid fermentation – spore forming bacteria.
Catabolism
59. 59
Reactive oxygen species (ROS)
- superoxide (О·
2)
- hydroxyl radical (ОН·)
- hydrogen peroxide (Н2О2) и др.
Mechanisms of protection from ROS (protection from
phagocytosis):
1. Enzymes – catalase, peroxidase, superoxide
dismutase.
2. Cell metabolites – -tocopherol, carotenoids,
chlorophylls
Catabolism
60. Saprophytes are organisms, particularly fungi which obtain
nutrients directly from dead organic matter or wastes.
Saphophytes are prototrophs (they synthesize need of
compounds from glucose and ammonia salts)
Parasites are organisms which obtain nutrients from host
organism.
Parasites are divided by degree of heterotrophy:
а) conditionally pathogenic – E. coli, pseudomonas etc.
б) obligate parasites – salmonella, shigella etc.
Parasites – auxotrophs (they need in nutritional
compounds)
в) obligate intracellular parasites – chlamydia, rickettsia, viruses.
60
Nutrition in prokaryotes
