Bacterial Growth Stages,
Microbial Metabolism and
Classifications Based on
Metabolism
Bacterial Growth Stages
What is the growth curve and its importance?
When bacterial inoculum is added to broth media, bacterial increase in
population follows a pattern. The distinct curve is known as the bacterial
growth curve.
Displays logarithm of number of bacteria per millilitre over time
Important when:
inoculating known amount of bacteria to identify the bacterial growth by
the responding bacterial variable
bacterial kinetics, bacterial numbers as well as growth kinetics in culture
is important to know.
ex. if studying if bacterial can metabolize oil spill, slope and shape of
growth curve can determine if bacteria can metabolize the
Bacterial Growth Stages, Microbial Metabolism and Classifications Based on Metabolism 1
, substance and if the bacteria can find potential energy sources in
the waste.
Draw a bacterial growth curve graph and state and describe the different phases
1. Lag phase
Adaptation phase, time between inoculation and start of multiplication
Multiplication doesn’t start directly after inoculation
Characteristics:
bacteria acclimatize to new environment, switch on enzymes
increase in size not in number
when centrifuged or under previously stressed conditions such
as pressure, get squashed
when inoculated in culture media return to normal
metabolically active
Duration depends on many variable (species, culture media,
temperature, etc),
1 hour - days
2. Log phase
rapid exponential growth, maximum growth rate.
bacterial population doubles every generation
Characteristics:
cells are uniformly stained (all alive)
still sensitive to adverse conditions (anitimicrobial agents etc)
brief, unless constantly supplied with nutrients or constant removal
of metabolic waste products
steep slope
3. Stationary phase
growth almost stops:
lack nutrients
lack water oxygen
Bacterial Growth Stages, Microbial Metabolism and Classifications Based on Metabolism 2
Microbial Metabolism and
Classifications Based on
Metabolism
Bacterial Growth Stages
What is the growth curve and its importance?
When bacterial inoculum is added to broth media, bacterial increase in
population follows a pattern. The distinct curve is known as the bacterial
growth curve.
Displays logarithm of number of bacteria per millilitre over time
Important when:
inoculating known amount of bacteria to identify the bacterial growth by
the responding bacterial variable
bacterial kinetics, bacterial numbers as well as growth kinetics in culture
is important to know.
ex. if studying if bacterial can metabolize oil spill, slope and shape of
growth curve can determine if bacteria can metabolize the
Bacterial Growth Stages, Microbial Metabolism and Classifications Based on Metabolism 1
, substance and if the bacteria can find potential energy sources in
the waste.
Draw a bacterial growth curve graph and state and describe the different phases
1. Lag phase
Adaptation phase, time between inoculation and start of multiplication
Multiplication doesn’t start directly after inoculation
Characteristics:
bacteria acclimatize to new environment, switch on enzymes
increase in size not in number
when centrifuged or under previously stressed conditions such
as pressure, get squashed
when inoculated in culture media return to normal
metabolically active
Duration depends on many variable (species, culture media,
temperature, etc),
1 hour - days
2. Log phase
rapid exponential growth, maximum growth rate.
bacterial population doubles every generation
Characteristics:
cells are uniformly stained (all alive)
still sensitive to adverse conditions (anitimicrobial agents etc)
brief, unless constantly supplied with nutrients or constant removal
of metabolic waste products
steep slope
3. Stationary phase
growth almost stops:
lack nutrients
lack water oxygen
Bacterial Growth Stages, Microbial Metabolism and Classifications Based on Metabolism 2
