Chapter 4 Metabolism,
Biosynthesis and Nutrition
? Microbial Nutrition
? Laboratory Culture of
Microorganisms
? Sterilization,Aseptic
Technique,and Pure Cultures
Microbial Nutrition
Nutrients,Substances in the environment used
by organisms for catabolism and anabolism.
Macronutrients,required in large amounts,
including,C,N,P,S,O,H,K,Mg,Ca,Na,Fe.
Micronutrients,required in small amounts,
including,Co,Zn,Mo,Cu,Mn,Ni,W,Se.
Laboratory Culture of Microorganisms
? C:Organic-Defined media,
glucose,sucrose,acetate,
pyruvate,malate,fatty acids,
alkanes et al,Complex media,
yeast extract,beef extract,
peptone,many other complex
digests,
Inorganic-CO2,HCO3-
? N,Organic-Amino acids,
nitrogenous bases;
Inorganic-NH4Cl,(NH4)2SO4,
KNO3,N2.
? P,KH2PO4,Na2HPO4.
? S,NaSO4,H2S.
? K,KCl,K2HPO4
? Mg,MgCl2,MgSO4
1.5% Agar
Petri Disk Cultivation of a Pure Strain
Microbial
Growth
Conditions
1,Macronutrients
2,Micronutrients
3,Growth factors
4,Environmental factors:
a,temperature
b,pH
c,Oxygen,Aerobes,
Anaerobes,
Facultative aerobes
d,osmotic pressure
The Streak Plate Technique,
to obtain a pure clone
Chapter 9
Growth and Its Control
? In Microbiology,growth is defined
as an increase in the number of
cells.
? Control of Microbial Growth:
–Physical ways,
–Chemical ways.
Cell Growth
Growth rate is the change in cell
number or mass per unit time.
The time interval for the
formation of two cells from one is
called generation time.
The number of cells doubles
during each unit time period,is
referred to as exponential growth.
Relationship between the number
of cells present in a culture
initially (N0) and the number
present after a period of
exponential growth (N):
N=N02n or n=(log(N)-log(N0))/log2
n=the number of generation
3 types of
cell
division:
a.Binary
Fission,
b,Budding,
c,Multiple
Fission
Binary Fission (二分裂 )
Budding (芽殖 )
Multiple Fission
Measuring cell density:
Turbidity vs Cell density
Measurement of cell growth
? Total cell count (direct observation under
microscope)
? Viable count (plate count or colony count)
– Spread plate method
– Pour plate method
– The plates required to have between 30 and 300 colonies.
Viable count,Spread plate method
and Pour plate method
? Three basic steps,
? Dilution,
? Plating
? Incubation
Viable Count,Dilution
Viable Count,Plating
Incubation (and counting)
Spread plate method
Pour plate method
The Growth Cycle of Populations
?Lag phase
?Exponential phase
?Stationary phase
?Death phase
The Growth Cycle of Populations
How to maintain Exponential Growth?
Effect of environmental factors on growth,
T,pH,Water availability and O2
Temperature effect:
1,Psychrophile
(0-20oC)
2,Mesophile
(45-15oC)
3,Thermophile
(40-70oC)
4,Hyperthermophile
(65-95oC)
5,Extrem hyper-
thermophile
(80-120oC)
Thermophile and Biotechnology
? Enzymes from thermophiles are capable of catalyzing
biochemical reactions at high temperature,they are more
stable;
? DNA polymerase,Taq polymerase,has been isolated from
thermophile-Thermus aquaticus,for PCR application;
? DNA polymerase,pfu polymerase,isolated from
hyperthermophile-Pyrocuccus furiosus,is more stable and
useful for PCR application,it also less prone to errors;
? Microbial process carried out at high T also eliminate or
greatly reduce cooling costs.
pH effect on cell growth
? Organisms that live at low pH are called
acidophiles
? Fungi tend to be more acid-tolerant than bacteria
although their interior pH is close to neutrality
? Several bacteria are obligate acidophilic (such as
Thiobacillus,Sulfolobus,Thermoplasma)
? A few organisms are alkaliphilic (pH 10-11),
usually found in highly basic habitates such as
soda lakes and high carbonate soils.
Effect of osmotic pressure on cell growth
? Microorganisms that have a specific
requirement for sodium ion are often called
halophiles
? Organisms able to live in environment high in
sugar are called osmophiles
? Organisms capable of living in very salty
environments are called extreme halophiles
? Organisms able to live in very dry
environments are called xerophiles
Effects of Oxygen on Cell Growth
? Terms used to describe O2 relationships of microorganisms:
? Aerobes:
– Obligate aerobes,oxygen presence necessary
– Facultative aerobes,oxygen not necessary,but better with it
– Microaerophilic aerobes,required O2 at low level than atmospheric
? Anaerobes,
– Aerotolerant,O2 not required,and growth no better if O2 present
– Obligate (strict) anaerobes,Oxygen harmful or lethal
Aerobic,anaerobic
and facultative growth
(a) Obligate aerobes grow
only at the surface
(b) Anaerobes grow away
from the surface
(c) Facultative aerobes
grow throughout the
tube
The above results were obtained
after a reducing agent such as
thioglycolate (巯基醋酸盐 ) was
added to the medium.
Resazurin (刃天青 ),a redox
indicator dye,can be used to
detect oxygen in the medium.
Aerobic,anaerobic,facultative,micro-
aerophilic and aerotolerant anaerobe growth
A small amount of agar has
been added to keep the
liquid from becoming
disturbed and the redox dye,
resazurin,which is pink
when oxidized and colorless
when reduced,is added as a
redox indicator.
A,obligate aerobes
B,Anaerobes
C,Facultative aerobes
D,Microaerophiles
E,Aerotolerant anaerobes
Toxic Forms of Oxygen
?Singlet oxygen
?Superoxide anion (O2-)
? Hydrogen peroxide (H2O2)
? Hydroxyl radical (OH.)
Enzymes that destroy toxic oxygen
(a) H2O2+H2O2 2H2O+O2
(b) H2O2+NADH+H+ 2H2O+NAD+
(c) O2-+O2-+2H+ H2O2 +O2
(d) 4O2-+4H+ 2H2O +3O2
Peroxidase
过氧化氢酶
Catalase
过氧化氢酶
Superoxide dismutase
过氧化氢歧化酶
Catalase+Superoxide dismutase
Microbial Growth Control
? Physical ways
– Heat sterilization (including autoclave
and pasteurization)
– Radiation (microwaves,UV,X-rays,
g-rays and electrons)
– Filtration (depth filter,membrane
filter and nucleation track
(nucleopore) filter)
Microbial Growth Control
? Chemical ways (germicides)
– Agents that kill organisms are often called cidal agents
(bactericidal,fungicidal and viricidal agents)
– Agents that do not kill but only inhibit growth are called
static agents (bacteriostatic,fungistatic,and viristatic
agents)
– Disinfectants are chemicals that kill microorganisms and
are used on inanimate objects
– Antiseptics are chemical agents that kill or inhibit growth
of microorganisms and that are sufficiently nontoxic to be
applied to living tissues.
Measuring antimicrobial activity
Minimum inhibitory concentration (MIC)
Tube dilution techniqueAgar diffusion method
Microbial Growth Control:
Chemotherapeutic agents
? Chemotherapeutic agents,to be used
internally for control of infectious disease,
they must have selective toxicity,these
include:
– Growth factor analog:
? Sulfa drugs (磺胺药 )
? Amino acid analogs
? Vitamin analogs
? DNA base,RNA base analogs
Chemotherapeutic agents,Antibiotics
? Antibiotics are chemical substances produced by certain
microorganisms that inhibit and kill other microorganisms,they are
natural products rather than synthetic chemicals
– Gram-positive bacteria are usually more sensitive to Gram-
negative bacteria
– In bacteria,the important targets of antibiotic action are the cell
wall,the cytoplasmic membrane and the biosynthetic processes
of protein and nucleic acid synthesis
? b-lactam (内酰胺 ) group,which includes the penicillins and
related compounds,has major clinical significance
Range of actions of antibiotics and other agents
Mode of action of major antibiotics
Food Preservation
? Sterlization
? Low temperature (best -20oC or 80oC)
? pH or acidity
? Low water availability
? Canning
? Chemical food preservation
What we have learned so far?
? Macro- and micronutrients? Defined medium and complex medium?
? What are growth factors?
? What environmental factors affect growth of microorganisms?
? How to prepare a medium for cultivation microorganisms?
? How to obtain a pure culture? How to calculate cell growth?
? How cells divide themselves? How to do viable count?
? What is the microbial cell growth cycle?
? How to maintain exponential growth?
? How to name microorganisms that grow best at a temperature?
? How do you you name microorganisms having various O2 tolerance?
? What enzymes are involved in detoxifying toxic active oxygen?
? What are the physical- and chemical ways to halt microbial growth?
? On what sites do antibiotics act on cells?
? How to preserve food?
国庆节愉快
Biosynthesis and Nutrition
? Microbial Nutrition
? Laboratory Culture of
Microorganisms
? Sterilization,Aseptic
Technique,and Pure Cultures
Microbial Nutrition
Nutrients,Substances in the environment used
by organisms for catabolism and anabolism.
Macronutrients,required in large amounts,
including,C,N,P,S,O,H,K,Mg,Ca,Na,Fe.
Micronutrients,required in small amounts,
including,Co,Zn,Mo,Cu,Mn,Ni,W,Se.
Laboratory Culture of Microorganisms
? C:Organic-Defined media,
glucose,sucrose,acetate,
pyruvate,malate,fatty acids,
alkanes et al,Complex media,
yeast extract,beef extract,
peptone,many other complex
digests,
Inorganic-CO2,HCO3-
? N,Organic-Amino acids,
nitrogenous bases;
Inorganic-NH4Cl,(NH4)2SO4,
KNO3,N2.
? P,KH2PO4,Na2HPO4.
? S,NaSO4,H2S.
? K,KCl,K2HPO4
? Mg,MgCl2,MgSO4
1.5% Agar
Petri Disk Cultivation of a Pure Strain
Microbial
Growth
Conditions
1,Macronutrients
2,Micronutrients
3,Growth factors
4,Environmental factors:
a,temperature
b,pH
c,Oxygen,Aerobes,
Anaerobes,
Facultative aerobes
d,osmotic pressure
The Streak Plate Technique,
to obtain a pure clone
Chapter 9
Growth and Its Control
? In Microbiology,growth is defined
as an increase in the number of
cells.
? Control of Microbial Growth:
–Physical ways,
–Chemical ways.
Cell Growth
Growth rate is the change in cell
number or mass per unit time.
The time interval for the
formation of two cells from one is
called generation time.
The number of cells doubles
during each unit time period,is
referred to as exponential growth.
Relationship between the number
of cells present in a culture
initially (N0) and the number
present after a period of
exponential growth (N):
N=N02n or n=(log(N)-log(N0))/log2
n=the number of generation
3 types of
cell
division:
a.Binary
Fission,
b,Budding,
c,Multiple
Fission
Binary Fission (二分裂 )
Budding (芽殖 )
Multiple Fission
Measuring cell density:
Turbidity vs Cell density
Measurement of cell growth
? Total cell count (direct observation under
microscope)
? Viable count (plate count or colony count)
– Spread plate method
– Pour plate method
– The plates required to have between 30 and 300 colonies.
Viable count,Spread plate method
and Pour plate method
? Three basic steps,
? Dilution,
? Plating
? Incubation
Viable Count,Dilution
Viable Count,Plating
Incubation (and counting)
Spread plate method
Pour plate method
The Growth Cycle of Populations
?Lag phase
?Exponential phase
?Stationary phase
?Death phase
The Growth Cycle of Populations
How to maintain Exponential Growth?
Effect of environmental factors on growth,
T,pH,Water availability and O2
Temperature effect:
1,Psychrophile
(0-20oC)
2,Mesophile
(45-15oC)
3,Thermophile
(40-70oC)
4,Hyperthermophile
(65-95oC)
5,Extrem hyper-
thermophile
(80-120oC)
Thermophile and Biotechnology
? Enzymes from thermophiles are capable of catalyzing
biochemical reactions at high temperature,they are more
stable;
? DNA polymerase,Taq polymerase,has been isolated from
thermophile-Thermus aquaticus,for PCR application;
? DNA polymerase,pfu polymerase,isolated from
hyperthermophile-Pyrocuccus furiosus,is more stable and
useful for PCR application,it also less prone to errors;
? Microbial process carried out at high T also eliminate or
greatly reduce cooling costs.
pH effect on cell growth
? Organisms that live at low pH are called
acidophiles
? Fungi tend to be more acid-tolerant than bacteria
although their interior pH is close to neutrality
? Several bacteria are obligate acidophilic (such as
Thiobacillus,Sulfolobus,Thermoplasma)
? A few organisms are alkaliphilic (pH 10-11),
usually found in highly basic habitates such as
soda lakes and high carbonate soils.
Effect of osmotic pressure on cell growth
? Microorganisms that have a specific
requirement for sodium ion are often called
halophiles
? Organisms able to live in environment high in
sugar are called osmophiles
? Organisms capable of living in very salty
environments are called extreme halophiles
? Organisms able to live in very dry
environments are called xerophiles
Effects of Oxygen on Cell Growth
? Terms used to describe O2 relationships of microorganisms:
? Aerobes:
– Obligate aerobes,oxygen presence necessary
– Facultative aerobes,oxygen not necessary,but better with it
– Microaerophilic aerobes,required O2 at low level than atmospheric
? Anaerobes,
– Aerotolerant,O2 not required,and growth no better if O2 present
– Obligate (strict) anaerobes,Oxygen harmful or lethal
Aerobic,anaerobic
and facultative growth
(a) Obligate aerobes grow
only at the surface
(b) Anaerobes grow away
from the surface
(c) Facultative aerobes
grow throughout the
tube
The above results were obtained
after a reducing agent such as
thioglycolate (巯基醋酸盐 ) was
added to the medium.
Resazurin (刃天青 ),a redox
indicator dye,can be used to
detect oxygen in the medium.
Aerobic,anaerobic,facultative,micro-
aerophilic and aerotolerant anaerobe growth
A small amount of agar has
been added to keep the
liquid from becoming
disturbed and the redox dye,
resazurin,which is pink
when oxidized and colorless
when reduced,is added as a
redox indicator.
A,obligate aerobes
B,Anaerobes
C,Facultative aerobes
D,Microaerophiles
E,Aerotolerant anaerobes
Toxic Forms of Oxygen
?Singlet oxygen
?Superoxide anion (O2-)
? Hydrogen peroxide (H2O2)
? Hydroxyl radical (OH.)
Enzymes that destroy toxic oxygen
(a) H2O2+H2O2 2H2O+O2
(b) H2O2+NADH+H+ 2H2O+NAD+
(c) O2-+O2-+2H+ H2O2 +O2
(d) 4O2-+4H+ 2H2O +3O2
Peroxidase
过氧化氢酶
Catalase
过氧化氢酶
Superoxide dismutase
过氧化氢歧化酶
Catalase+Superoxide dismutase
Microbial Growth Control
? Physical ways
– Heat sterilization (including autoclave
and pasteurization)
– Radiation (microwaves,UV,X-rays,
g-rays and electrons)
– Filtration (depth filter,membrane
filter and nucleation track
(nucleopore) filter)
Microbial Growth Control
? Chemical ways (germicides)
– Agents that kill organisms are often called cidal agents
(bactericidal,fungicidal and viricidal agents)
– Agents that do not kill but only inhibit growth are called
static agents (bacteriostatic,fungistatic,and viristatic
agents)
– Disinfectants are chemicals that kill microorganisms and
are used on inanimate objects
– Antiseptics are chemical agents that kill or inhibit growth
of microorganisms and that are sufficiently nontoxic to be
applied to living tissues.
Measuring antimicrobial activity
Minimum inhibitory concentration (MIC)
Tube dilution techniqueAgar diffusion method
Microbial Growth Control:
Chemotherapeutic agents
? Chemotherapeutic agents,to be used
internally for control of infectious disease,
they must have selective toxicity,these
include:
– Growth factor analog:
? Sulfa drugs (磺胺药 )
? Amino acid analogs
? Vitamin analogs
? DNA base,RNA base analogs
Chemotherapeutic agents,Antibiotics
? Antibiotics are chemical substances produced by certain
microorganisms that inhibit and kill other microorganisms,they are
natural products rather than synthetic chemicals
– Gram-positive bacteria are usually more sensitive to Gram-
negative bacteria
– In bacteria,the important targets of antibiotic action are the cell
wall,the cytoplasmic membrane and the biosynthetic processes
of protein and nucleic acid synthesis
? b-lactam (内酰胺 ) group,which includes the penicillins and
related compounds,has major clinical significance
Range of actions of antibiotics and other agents
Mode of action of major antibiotics
Food Preservation
? Sterlization
? Low temperature (best -20oC or 80oC)
? pH or acidity
? Low water availability
? Canning
? Chemical food preservation
What we have learned so far?
? Macro- and micronutrients? Defined medium and complex medium?
? What are growth factors?
? What environmental factors affect growth of microorganisms?
? How to prepare a medium for cultivation microorganisms?
? How to obtain a pure culture? How to calculate cell growth?
? How cells divide themselves? How to do viable count?
? What is the microbial cell growth cycle?
? How to maintain exponential growth?
? How to name microorganisms that grow best at a temperature?
? How do you you name microorganisms having various O2 tolerance?
? What enzymes are involved in detoxifying toxic active oxygen?
? What are the physical- and chemical ways to halt microbial growth?
? On what sites do antibiotics act on cells?
? How to preserve food?
国庆节愉快
