Module 2 Flashcards
A type of culture operation in a closed culture system which contains an initial limited amount of nutrient. As the inoculated culture or inoculum cells grow, it will undergo several phases in the growth curve.
Batch Culture
What are stages of batch fermentation ?
- Shake flask
- Seed fermenter
- Production fermenter
All nutrients are provided at the beginning of the cultivation and products are removed out the end.
Nutrients-Cell-Reagent—–Product
What are the Advantages of Batch culture?
-Short period of time
-Less contamination as the ingredients is added at the beginning
-Separation of batch material for traceability
-East to manage
What are the Disadvantages of Batch culture?
- Products are mixed in with nutrients, reagents, cell debris, and toxin
-Shorter productive time
-Productivity is low
What are the 4 microbial growth phases associated with Batch culture process?
- Lag phase
- Log/Exponential phase
- Stationary phase
- Death phase
On a commercial scale, the lag phase duration should be shortened as much as possible, and it can be resolved by using a ?
Suitable inoculum
Operation of Batch culture is characterized by three periods of time
-Filling period
-Cell growth and Cell production period
- Final emptying period
It is the first major point of microbial growth phase of batch culture process
- It is a period of adapting or adjusting to the cell’s new environment.
Lag phase
Blank transferred from one type of media, with the same environmental conditions, will have the shortest lag period.
Actively growing cells
Blank will have a long lag period, since they must repair themselves before they can engage in reproduction.
Damaged cell
This process could include the repair of macromolecules damage that accumulated during stationary phase and the synthesis of cellular components necessary for growth.
Lag phase
Growth rate of the cells is gradually increasing
- Cell growth rate at a constant, maximum rate
Log/ Exponential phase
The exponential growth of a single celled organism is replicated through?
Binary fission
TRUE OR FALSE
The growth of microorganism and the excretion of product do not depend on the consumption of nutrients dramatically affects the organism’s growth.
False (Depends on the consumption of nutrients)
Cells adjusted to their new environment
Exponential phase
u
cell growth rate
Kd
cell death rate
x
cell concentration
u-Kd can be referred to as?
unet
The 2 type of inhibition causes mathematical
changes in the previously presented Monod
equation for batch kinetics
Substrate inhibition
Product inhibition
In batch fermentation, this can occur after
induction of the recombinant gene
Product inhibition
In batch fermentation, this can occur during the
initial growth phases while substrate
concentrations are high
Substrate inhibition
- It is the third major phase microbial growth in a
batch fermentation process. - The growth rate has declined zero but may still
metabolically active and produce secondary
metabolites.
Stationary phase
Two main methods primarily used to
establish a growth curve
Viable cell count
Optical density
- It is the last major phase of microbial growth in
a batch fermentation process, which is also
known as the decline phase.
Death phase
It can result in depletion of one or more
essential growth nutrients
accumulation of toxin by product.
- Initially higher curve representing the number of cells that are both viable and non-viable
- Determined by taking an optical measurement using a
spectrophotometer
Optical density
- Initially lower curve representing the number of cells that are actually viable
- Determined by plating a sample from the culture
Viable cell count
Measuring the optical density with a
spectrophotometer is a quick and easy way to
develop a ?
growth curve
It is similar to the batch fermentation process
However, there is an extension of the batch
culture by feeding periodically with medium
with no removal from the vessel.
Fed Batch culture
*Kojic acid production is an example of a
secondary metabolite produced by
Aspergillus oryzae
Subsequently, a fed is initiated into the
fermenter when a blank is
attained in which the growth limiting substrate
has exhausted.
‘quasi-steady state
is inhibited by the presence of
readily utilized carbon source or inhibitory
carbon source.
Enzyme synthesis
- In extracellular enzyme production, it is
controlled by ?
catabolite repression
Classification of Fed-Batch Culture.
Fix volume fed batch culture
Variable volume fed batch culture
- In this type of fed-batch, the limiting substrate is
fed without diluting the culture. - The culture volume can also be kept constant by
feeding the growth limiting substrate in undiluted
form, such as a very concentrated liquid.
Fix volume fed batch culture
- Volume changes with fermentation time due to the
substrate feed. - The substrate is provided in a manner that maximizes
the specific growth rate. - The substrate is added exponentially for biomass
production to maintain a constant growth rate in a
culture growing exponentially.
Variable volume fed batch culture
- Fresh fermentation media is continuously added to the
reactor while fermenter broth containing biomass,
products and unused nutrient are continuously removed. - Exponential growth in batch culture may be prolonged by
the addition of fresh medium to the vessel.
Continuous culture
Under this steady state, the µ is controlled by the
?
dilution rate (→ [S])
2 Culture System in Continuous
Process
Chemostat
Turbidostat
Growth of cells is controlled by the
availability of the growth chemical component
of the medium.
Chemostat
Concentration of cells in the
culture is kept constant by controlling the flow
of medium such that the turbidity of the
culture is kept within certain, narrow limits.
Turbidostat
Product is harvested from the
outflow stream
determine the dilution rate
[Substrate]
Application of Continuous Culture
- Biomass production
- Growth associated product or primary
metabolite – ex, ethanol, citric acid - Not suitable for non-growth associated or
secondary metabolite – ex antibiotic
Differentiate Batch Culture, Fed-batch culture, and continuous culture
A batch culture is a closed culture system that begins with a limited amount of nutrients, and no additional nutrients are introduced during the process. Fed-batch culture extends this by periodically adding fresh medium without removing any content from the vessel. In continuous culture, fresh medium is continuously added while the broth containing biomass, products, and unused nutrients is simultaneously removed.
Explain the lag phase, exponential phase, stationary phase and death phase
- The lag phase is an adaptation period, where the bacteria are adjusting to their new conditions. while the Exponential phase the cells are dividing at a constant rate resulting in an exponential increase in the number of cells present. The Stationary phase It occurs when the number of cells dividing and dying is in an equilibrium state. Lastly, the Death phase is where the rate of cells dying is greater than the rate
of cells dividing.
