Title: Microbiology
1Chair of Medical Biology, Microbiology, Virology,
and Immunology
THE PHYSIOLOGY OF MICROORGANISMS.
Lecturer As. Prof. O. Pokryshko
2Lecture schedule
- Growth of bacteria.
- Reproduction of bacteria.
- Respiration of bacteria.
3Nutritional 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
6Nutritional Types
- Energy source
- chemotroph gain energy from chemical compounds
- phototrophs gain energy through photosynthesis
6
7Transport 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
8Transport Movement of Chemicals Across the Cell
Membrane
- Active transport requires energy and carrier
proteins gradient independent - active transport
- group translocation transported molecule
chemically altered
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1010
11Gas 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
12Categories 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
13Categories 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
14Carbon Dioxide Requirement
- All microbes require some carbon dioxide in their
metabolism. - capneic grows best at higher CO2 tensions than
normally present in the atmosphere
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15Oxygen requirements
1.
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2.
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3.
4.
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4.
3.
4.
Aerobic culture
Anaerobic culture
Microaerobic culture
1. Obligate anaerobe 2. Facultative anaerobe 3.
Microaerophile 4. Obligate aerobe
1.
2.
3.
4.
16Growth requirements
- Temperature
- Pyschrophiles 4-20C
- Mesophiles 15-48C
- Thermophiles 42-68C
- Extreme thermophiles gt68C
1717
18Effects 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
19The Population Growth Curve
In laboratory studies, populations typically
display a predictable pattern over time growth
curve.
20The 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
21The 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
22Nutrient media
- Ordinary (simple) media
- Special media (serum agar, serum broth,
coagulated serum, potatoes, blood agar, blood
broth, etc.). - Elective media
- Enriched media
23Nutrient 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.
24Biochemical properties
25Colonies
26Colonies
27Colonies
28Pure Cultures Isolation
29Isolated colonies obtaining