3rd Flashcards
The function of the disengagement zone in an
airlift fermenter is to
- prevent CO2 rich bubbles from entering the downcomer
- reduce the velocity of the bubbles
- reduce liquid loss as aerosols
Stationary phase is described as
no further increase in the cell population
after a maximum value
In the accelerated phase, cell starts to
increase and the division rate increases to
reach a maximum
The Monod model predicts that the specific
growth rate
will increase with the concentration of the growth limiting substrate until it reaches a maximum value
A mixed fermentation is one, which produces
both acid and alcohol
The function of a mechanical seal is to
- prevent contaminants entering the reactor
- prevent cells from leaving the reactor
The phenomenon in which substrates are used in a sequential manner is known as
diauxie
The dilution rate, D is defined as (where F = volumetric flow rate, VR= total volume of culture in the reactor and μ specific growth rate)
F/VR
Diauxie is
the stagewise uptake of nutrients
An open system in which the growth rate is maintained by adding a nutrient (present in
limiting quantities) at the same rate as that medium containing micro-organism is removed is called
Chemostat
In the death phase
nutrients available for the cells are depleted
and begin to die
The maximum specific growth rate of an
organism depends on
medium composition
temperature
pH
Which of the following is not correct for the Monod model and the Michaelis Menten Model
a. The Michaelis Menten Model was derived from a curve fitting exercise
b. The Michaelis Menten model was derived from an analysis of the mechanism of microbial growth
c. The Monod model was derived from an analysis of the mechanism of microbial growth
Bubble column reactor has
large height to diameter ratio
Why a T-flask used in small-scale cell culture is incubated in a horizontal position
- To save space
- To increase the surface area of the liquid-air
interface
An open system in which the growth rate is maintained by the removal and addition of media at such a rate as to maintain a constant cell density is called a
Turbidostat
Wash out in steady state fermentation occurs
when
dilution rate is higher than the maximum
specific growth rate
Fermenter should be filled with medium upto
75-80%
Bacterial growth curve is obtained by plotting
log of number of cells versus time
When intracellular enzymes of whole cells are to be used in a bio-conversion process, it is often necessary to____________the cells.
Permeabilize
Heat transfer rates (per unit volume) will be
lowest in
Continuous packed bed reactor
The function(s) of the draft tube in an airlift
bioreactor is
- to reduce bubble coalescence
- to improve circulation
- to even out shear conditions throughout the reactor
The Monod Model relates
specific growth rate to the substrate
availability
The height to diameter ratio (H/D) for the
column fermenters is
> 3
The high oxygen transfer efficiencies of airlift
bioreactors is due to
- the large aspect ratio of the reactor, which leads to a high gas hold-up
- the large aspect ratio of the reactor, which leads to a high oxygen solubility at the base of the reactor
- the draft tube, which reduces bubble
coalescence in the reactor
The maximum specific growth rate (μm) of an organism in batch culture is equal to slope of a plot of
In [biomass] against time for exponential
phase data only
The region of an airlift bioreactor in which the liquid travels in a downward direction is called the
Downcomer
Population doubling time, td can be expressed as (where μ is the specific growth rate.)
ln2/μ
A higher Ks value of Monod’s equation means
greater affinities to substrate
The increased air flow rate in bubble column fermenter can cause excessive foaming and
high retention of air bubbles in the column which
decreases the productivity of the fermenter
Which of the following is correct for the prediction of time requirement in a batch fermenter?
- Carrying out experiments
- Mathematical modelling of the
fermentation process
In an airlift bioreactor, the spent gases released from the liquid are called
disengagement zone
The contents in jet loop reactor are mixed
through
external pumping
The specific growth rate (μ) is defined as
the rate of individual cells division or increase in their biomass
The number of baffles in a standard stirred tank
bioreactor is
4
In the stationary phase
growth rate is equal to death rate
Which of the following is an example of a
mathematical model?
- Volume of cuboid = length x breadth x height
- The Monod Model
- The Michaelis Menten Equation
Biomass concentrations during fermentation is
- diluting the samples to optical density less than 0.3
- monitored by controlling the changes in biomass concentrations
- considering that optical density is
proportional to the surface area of the biomass in the sample
Chemostats work on the principle of
maintaining uniform nutrients
concentration
During the exponential phase the maximum specific growth rate equals specific growth rate as
concentration of growth limiting substrate is much greater than the Monod constant
