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Microbiology

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Title: Microbiology


1
Chair of Medical Biology, Microbiology, Virology,
and Immunology
THE PHYSIOLOGY OF MICROORGANISMS.
Lecturer As. Prof. O. Pokryshko
2
Lecture schedule
  1. Growth of bacteria.
  2. Reproduction of bacteria.
  3. Respiration of bacteria.

3
Nutritional Types
  • Carbon sources
  • Heterotroph must obtain carbon in an organic
    form made by other living organisms such as
    proteins, carbohydrates, lipids and nucleic acids
  • Autotroph - an organism that uses CO2, an
    inorganic gas as its carbon source
  • not nutritionally dependent on other living things

3
4
  • Nitrogen Sources
  • Main reservoir is nitrogen gas (N2) 79 of
    earths atmosphere is N2.
  • Nitrogen is part of the structure of proteins,
    DNA, RNA ATP these are the primary source of
    N for heterotrophs.

4
5
  • Nitrogen Sources
  • Some bacteria algae use inorganic N nutrients
    (NO3-, NO2-, or NH3).
  • Some bacteria can fix N2.
  • Regardless of how N enters the cell, it must be
    converted to NH3, the only form that can be
    combined with carbon to synthesis amino acids,
    etc.

5
6
Nutritional Types
  • Energy source
  • chemotroph gain energy from chemical compounds
  • phototrophs gain energy through photosynthesis

6
7
Transport Movement of Chemicals Across the Cell
Membrane
  • Passive transport does not require energy
    substances exist in a gradient and move from
    areas of higher concentration towards areas of
    lower concentration
  • diffusion
  • osmosis diffusion of water
  • facilitated diffusion requires a carrier

7
8
Transport Movement of Chemicals Across the Cell
Membrane
  • Active transport requires energy and carrier
    proteins gradient independent
  • active transport
  • group translocation transported molecule
    chemically altered

8
9
9
10
10
11
Gas Requirements
  • Oxygen
  • As oxygen is utilized it is transformed into
    several toxic products
  • singlet oxygen (O2), superoxide ion (O2-),
    peroxide (H2O2), and hydroxyl radicals (OH-)
  • Most cells have developed enzymes that neutralize
    these chemicals
  • superoxide dismutase, catalase
  • If a microbe is not capable of dealing with toxic
    oxygen, it is forced to live in oxygen free
    habitats.

11
12
Categories of Oxygen Requirement
  • Aerobe utilizes oxygen and can detoxify it
  • obligate aerobe - cannot grow without oxygen
  • facultative anaerobe utilizes oxygen but can
    also grow in its absence
  • microaerophylic requires only a small amount of
    oxygen

12
13
Categories of Oxygen Requirement
  • Anaerobe does not utilize oxygen
  • obligate anaerobe - lacks the enzymes to
    detoxify oxygen so cannot survive in an oxygen
    environment
  • aerotolerance anaerobes do no utilize oxygen
    but can survive and grow in its presence

13
14
Carbon Dioxide Requirement
  • All microbes require some carbon dioxide in their
    metabolism.
  • capneic grows best at higher CO2 tensions than
    normally present in the atmosphere

14
15
Oxygen requirements
1.
1.
1.
2.
2.
2.
3.
4.
3.
4.
3.
4.
Aerobic culture
Anaerobic culture
Microaerobic culture
1. Obligate anaerobe 2. Facultative anaerobe 3.
Microaerophile 4. Obligate aerobe
1.
2.
3.
4.
16
Growth requirements
  • Temperature
  • Pyschrophiles 4-20C
  • Mesophiles 15-48C
  • Thermophiles 42-68C
  • Extreme thermophiles gt68C

17
17
18
Effects of pH
  • Majority of microorganisms grow at a pH between 6
    and 8
  • Obligate acidophiles grow at extreme acid pH
  • Alkalinophiles grow at extreme alkaline pH

18
19
The Population Growth Curve
In laboratory studies, populations typically
display a predictable pattern over time growth
curve.
20
The Population Growth Curve
  • Stages in the normal growth curve
  • ______phase flat period of adjustment,
    enlargement little growth
  • _____________________ phase a period of maximum
    growth will continue as long as cells have
    adequate nutrients and a favorable environment

20
21
The Population Growth Curve
  • Stages in the normal growth curve
  • _________ phase rate of cell growth equals rate
    of cell death caused by depleted nutrients and
    O2, excretion of organic acids and pollutants
  • _________ phase as limiting factors intensify,
    cells die exponentially in their own wastes

21
22
Nutrient media
  • Ordinary (simple) media
  • Special media (serum agar, serum broth,
    coagulated serum, potatoes, blood agar, blood
    broth, etc.).
  • Elective media
  • Enriched media

23
Nutrient media
  • Differential diagnostic media (1) proteolytic
    action
  • (2) fermentation of carbohydrates (Hiss media)
  • (3) haemolytic activity (blood agar)
  • (4) reductive activity of micro-organisms
  • (5) media containing substances assimilated only
    by certain microbes.

24
Biochemical properties
25
Colonies
26
Colonies
27
Colonies
28
Pure Cultures Isolation
29
Isolated colonies obtaining
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