phisiology of bacteria [Автосохраненный].ppt

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1. Chemical composition of bacterial
cell
Water: coupled,
free
Solids:
mineral content
organic matter

2. Bacterial cell water
Coupled water - it is a structural element
of the cytoplasm, the amount is constant,
can not be solvent.
Free water is a solvent of crystalline
substances, is a source of ions, the
amount of free water varies depending on
the metabolic activity of the bacterial cell.

3. Вода в бактериальной
клетке
Role of water:
Medium for biochemical reactions
Source of hydrogen and hydroxyl ions
The environment in which the colloids are
located
Bacterial cell water

4. Solids
Mineral content:
C -50%
O2 -30%
N2-8-15%
P2 -3%
Na-1%
Ca, Mn, Zn-in total-0,3% ("trace" minerals)

5. The role of minerals in the
bacterial cell
Involved in the activation of enzymes
Participate in the regulation of osmotic
pressure
Participate in the regulation of pH
Participate in the regulation of redox potential

6. Organic substance
Proteins
Lipids
Carbohydrates

7. Features of bacterial proteins
Proteins make up 30-50% of the dry residue
Contain more acid and neutral aminoacids
and less alkaline amino acids
Contain diaminopimelic acid
The proteins include nucleoproteins (DNA - 5-
oxymethyl)

8. Functions of bacterial
proteins
Constructing
Enzymatic
Regulatory

9. BACTERIAL PROTEIN TOXINS
Bacterial protein toxins are the most powerful
human poisons known and retain high activity
at very high dilutions.
 
Exotoxins are usually secreted by living
bacteria.
The production of the toxin is generally
specific to a particular bacterial species that
produces the disease associated with the
toxin (e.g. only
 
Clostridium tetani 
produces
tetanus toxin; only
 
Corynebacterium
diphtheriae 
produces the diphtheria toxin). 

10. The lipids of the bacterial
cell
Lipids: free fats, neutral fats, waxes,
phospholipids
Functions: participate in energy
metabolism and are a stock of nutrients
The amount of lipids varies greatly: from 5
to 35% (Mycobacteria)

11. The carbohydrates of the
bacterial cell
Monosaccharides (nutrients)
Polysaccharides (nitrogen-free-are part of
the capsule; containing nitrogen-
acetylmuramic acid, N-acetylglucosamine)
Functions: participate in energy
metabolism and are a stock of nutrients,
constructing function.

13. Enzymes of the bacterial cell
Classifications:
By mechanism of action
On genetic control of synthesis
By substrate

14. Bacterial enzymes by
mechanism of action
Oxidoreductases
Lyase's
Ligase's
Hydrolases
Isomerases
Transferases

15. The enzymes on the substrate
Saccharolytic
Proteolytic
Hemolytic
Antioxidant

16. Classification of enzymes by
genetic synthesis method
Constitutive - are
 produced constitutively by the cell 
under
 all physiological conditions. 
Inducible 
-are stimulated by a specific substrate, the
inducer,
 which is the substrate of the enzyme or a compo
und
 structurally related to it.
Repressible
 enzyme
 
- an enzyme whose synthesis (rate
of production) is inhibited (repressed) when the product
that it synthesizes is present in high concentrations.
Repressible enzymes are usually the enzymes involved in
biosynthetic or anabolic pathways.

17. Classification by a set of enzymes
Prototrophs - have a complete set of
enzymes
Auxotrophs- do not have a complete set
of enzymes and depend on the
composition of the medium (auxotrophs
for arginine, B6, etc.)

21. Bacterial nutrition processes
Nutrients are supplied by 3 mechanisms:
1. Passive diffusion-concentration gradient,
no energy consumption
2.Facilitated diffusion-by concentration
gradient, permease transporter proteins, no
energy consumption consumption
3.Active transport - against concentration
gradient, energy consumption occurs

22. The processes of
respiration of bacteria

23. 3 types depending on the
involvement of oxygen
1) Oxygen respiration-oxygen oxidation of air
(ATP, ADP, AMP)
1 molecule of glucose—688,5 kcal
2) Fermentation -a set of redox processes of the
breakdown of organic substances under
anaerobic conditions
3) Putrefaction as a respiration process in
bacteria - multistage anaerobic and aerobic
cleavage of proteins and other nitrogen-
containing compounds

24. Reminder

25. Classification of bacteria on the
basis of gaseous requirement
1
Obligate (strict) aerobes:
Those bacteria that require oxygen and
cannot grow without O
2.
These bacteria carry out only oxidative type of
metabolism.
Examples: Neisseria, Vibrio.

26. Obligate anaerobes:
2
Those bacteria that can grow only in absence
of Oxygen.
Oxygen is harmful to obligate anaerobes
These bacteria have only fermentative type of
metabolism
Examples: Peptococcus, Peptostreptococcus,
Clostridium.

27. Toxic effects of oxygen to
anaerobic bacteria
Pasteur effect-inhibits anaerobic processes in
the presence of oxygen
There are no antioxidant enzymes
(catalase, SOD)
Oxygen is toxic

28. The causative agent of
tetanus – Clostridium tetani

29. Causative agents of
gas gangrene (Closrtidium
perfringens et al.

30. Botulism (Clostridium
botulinum)

31. Facultative anaerobes:
3
Those bacteria that do not require O2 but can
use it if available.
Growth of these bacteria become better in
presence of O2
These bacteria carryout both oxidative and
fermentative type of metabolism
Examples:
  E.
coli, Klebsiella, Salmonella

32. Aerotolerant anaerobes
4
Those bacteria do not require O2 for growth
but can tolerate the presence of O2 (9-11%).
Growth of these bacteria is not affected by
the presence of O2.
These bacteria have only fermentative type
of metabolism.
Example:
 
Brucella (some speices)

33. Microaerophiles:
5
Those bacteria that do not require O2 for
growth but can tolerate low concentration of O2
(1-3%).
These bacteria only have fermentative type of
metabolism
Example: 
Clostridium perfringens

34. Capnophiles:
6
Those bacteria that require carbondioxide for
growth.
They are CO
2 loving organism
Most of the microaerophiles are capnophilic in
nature.
Example:
 
Campylobacter, Helicobacter pylori,
Brucella abortus

35. Growth and reproduction of
bacteria
Growth-weight gain (microbial mass)
Reproduction-increasing the number of
individuals per unit volume (number \ ml3)

36. Bacterial growth and
reproduction

37. Determination of the number
of bacteria
Direct methods-
(cell counting)
Goryaev's camera
Coulter counter
Indirect methods:
by turbidity standards
on colonies (through 24h)

38. E.g. Direct methods

39. E.g. Indirect methods:
by turbidity standards
on colonies (through 24h)

40. Determination of microbial mass
Direct measurement-m \ ml3 or m\mm3
Protein content, C, N, AMC
By optical density

41. Methods of cultivation
Periodic (curve of cultivation in liquid NM,
characteristic of stages)

43. Continuous culture
technique
Continuous culture technique is also called as
open system of cultivation.
In this technique fresh sterile medium is
added continuously and used up media with
bacterial culture is removed continuously at
the same rate. So the volume and bacterial
density remain same in the cultivation vessel.
In this technique, bacteria grow continuously
in their log phase.

44.   Synchronous cultures
Synchronous cultures are composed of
populations of cells that are at the same
stage of their life cycle.