Module 2

Question 1

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.

Answer 1

Batch Culture

Question 2

What are stages of batch fermentation ?

Answer 2

• Shake flask
• Seed fermenter
• Production fermenter

Question 3

All nutrients are provided at the beginning of the cultivation and products are removed out the end.

Answer 3

Nutrients-Cell-Reagent—–Product

Question 4

What are the Advantages of Batch culture?

Answer 4

-Short period of time
-Less contamination as the ingredients is added at the beginning
-Separation of batch material for traceability
-East to manage

Question 5

What are the Disadvantages of Batch culture?

Answer 5

• Products are mixed in with nutrients, reagents, cell debris, and toxin
  -Shorter productive time
  -Productivity is low

Question 6

What are the 4 microbial growth phases associated with Batch culture process?

Answer 6

• Lag phase
• Log/Exponential phase
• Stationary phase
• Death phase

Question 7

On a commercial scale, the lag phase duration should be shortened as much as possible, and it can be resolved by using a ?

Answer 7

Suitable inoculum

Question 8

Operation of Batch culture is characterized by three periods of time

Answer 8

-Filling period
-Cell growth and Cell production period
- Final emptying period

Question 9

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.

Answer 9

Lag phase

Question 10

Blank transferred from one type of media, with the same environmental conditions, will have the shortest lag period.

Answer 10

Actively growing cells

Question 11

Blank will have a long lag period, since they must repair themselves before they can engage in reproduction.

Answer 11

Damaged cell

Question 12

This process could include the repair of macromolecules damage that accumulated during stationary phase and the synthesis of cellular components necessary for growth.

Answer 12

Lag phase

Question 13

Growth rate of the cells is gradually increasing
- Cell growth rate at a constant, maximum rate

Answer 13

Log/ Exponential phase

Question 14

The exponential growth of a single celled organism is replicated through?

Answer 14

Binary fission

Question 15

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.

Answer 15

False (Depends on the consumption of nutrients)

Question 16

Cells adjusted to their new environment

Answer 16

Exponential phase

Question 17

u

Answer 17

cell growth rate

Question 18

Kd

Answer 18

cell death rate

Question 19

x

Answer 19

cell concentration

Question 20

u-Kd can be referred to as?

Answer 20

unet

Question 21

The 2 type of inhibition causes mathematical
changes in the previously presented Monod
equation for batch kinetics

Answer 21

Substrate inhibition
Product inhibition

Question 22

In batch fermentation, this can occur after
induction of the recombinant gene

Answer 22

Product inhibition

Question 23

In batch fermentation, this can occur during the
initial growth phases while substrate
concentrations are high

Answer 23

Substrate inhibition

Question 24

• 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.

Answer 24

Stationary phase

Question 25

Two main methods primarily used to
establish a growth curve

Answer 25

Viable cell count
Optical density

Question 26

• It is the last major phase of microbial growth in
  a batch fermentation process, which is also
  known as the decline phase.

Answer 26

Death phase

Question 26

It can result in depletion of one or more
essential growth nutrients

Answer 26

accumulation of toxin by product.

Question 27

• Initially higher curve representing the number of cells that are both viable and non-viable
• Determined by taking an optical measurement using a
  spectrophotometer

Answer 27

Optical density

Question 28

• Initially lower curve representing the number of cells that are actually viable
• Determined by plating a sample from the culture

Answer 28

Viable cell count

Question 29

Measuring the optical density with a
spectrophotometer is a quick and easy way to
develop a ?

Answer 29

growth curve

Question 30

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.

Answer 30

Fed Batch culture

Question 31

*Kojic acid production is an example of a
secondary metabolite produced by

Answer 31

Aspergillus oryzae

Question 32

Subsequently, a fed is initiated into the
fermenter when a blank is
attained in which the growth limiting substrate
has exhausted.

Answer 32

‘quasi-steady state

Question 33

is inhibited by the presence of
readily utilized carbon source or inhibitory
carbon source.

Answer 33

Enzyme synthesis

Question 34

• In extracellular enzyme production, it is
  controlled by ?

Answer 34

catabolite repression

Question 35

Classification of Fed-Batch Culture.

Answer 35

Fix volume fed batch culture
Variable volume fed batch culture

Question 36

• 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.

Answer 36

Fix volume fed batch culture

Question 37

• 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.

Answer 37

Variable volume fed batch culture

Question 38

• 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.

Answer 38

Continuous culture

Question 39

Under this steady state, the µ is controlled by the
?

Answer 39

dilution rate (→ [S])

Question 40

2 Culture System in Continuous
Process

Answer 40

Chemostat
Turbidostat

Question 41

Growth of cells is controlled by the
availability of the growth chemical component
of the medium.

Answer 41

Chemostat

Question 42

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.

Answer 42

Turbidostat

Question 43

Product is harvested from the

Answer 43

outflow stream

Question 44

determine the dilution rate

Answer 44

[Substrate]

Question 45

Application of Continuous Culture

Answer 45

• Biomass production
• Growth associated product or primary
  metabolite – ex, ethanol, citric acid
• Not suitable for non-growth associated or
  secondary metabolite – ex antibiotic

Question 46

Differentiate Batch Culture, Fed-batch culture, and continuous culture

Answer 46

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.

Question 47

Explain the lag phase, exponential phase, stationary phase and death phase

Answer 47

• 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.