Biochem - Fermentation Reactors [S1] Flashcards
1
Q
- Yield coefficient represents
A
- Conversion efficiency of a substrate into product
2
Q
- The lowest biomass yield in a culture of Escherichia coli will be in
A
- An aerated batch culture containing an initial high concentration of glucose
3
Q
- When two populations compete for a single growth limiting substrate in a continuous fermenter, which organism would not be washed out?
A
- Organism maintaining the lowest substrate concentration
4
Q
- The continuous cultures are not widely used in industry because
A
- All of the above
5
Q
- The lowest yield of ATP is in
A
- Fermentation
6
Q
- Mixing in an anaerobic sludge blanket reactor is due to
A
- Release of gases by the microbial populations
7
Q
- In batch culture, protogon is produced from peptone during the stationary phase with a yield of 0.4 protogon mg per g of peptone. If it is to be produced in a chemostat at a dilution rate of 0.5 h−1−1from a medium containing 10 g/L of peptone, then the rate of protogon synthesis would be
A
- 2 g/L-h
8
Q
- Formation of end product by Lactococcus lactis will become non-growth associated as lactic acid accumulates because
A
- Cells will redirect ATP to the active transport of lactic acid and H+ out of the cells
9
Q
- Which of the following would not be subjected to the “glucose effect”?
A
- Aspergillus fumigatus
10
Q
- Immobilized cell reactors for wastewater treatment have the advantage of having/being
A
- All of the above
11
Q
- Which of the statement is true for continuous reactor at steady state?
A
- Biomass, substrate, and product concentrations do not change with time
12
Q
- A continuous bioreactor in which only the flow rate is used to control the rate of cell or product productivity is called
A
- Chemostat
13
Q
- for organisms growing in a chemostat, the specific growth rate
A
- Can be determined from the dilution rate
14
Q
- Saccharomyces cerevisiae is being grown in a chemostat converts glucose to biomass, ethanol, glycerol, and carbon dioxide. At steady state, the concentration of glucose, biomass, ethanol, and glycerol will
A
- Be constant
15
Q
- In aerobic yeast fermentation for production of citric acid from alkanes using a fed-batch culture, why alkanes are slowly fed to the yeast?
A
- Fast addition of alkanes will inhibit the cells and reduce oxygen transfer rates
16
Q
- A continuous reactor has a dilution rate of 0.5/h. Its residence time would be
A
- 2 h
17
Q
- Which of the following is used to calculate mass of substrate in the reactor?
A
- Volume of reactor x substrate concentration in reactor
18
Q
- If biomass yields are constant, then the biomass productivity of a culture growth in continuous reactor will
A
- Increase with dilution rate until washout
19
Q
- Low dissolved oxygen concentrations leads to
A
- Low biomass yields
20
Q
- In a continuous reactor, the medium contains 40 g/L of maltose and the medium flow rate is 10 liters per hour and the effluent contains 20 g/L of lactate. What is the productivity of lactate production from this reactor?
A
- 200 g-lactate/L
21
Q
- A fed-batch reactor containing 1 g/L of substrate in 2 liter of medium. It is fed with 1 g/L of substrate at the rate of 1 liter per hour. After 10 hours, the concentration of substrate in the reactor was 0.5 g/L. the mass of substrate that was used by the culture in the reactor was
A
- 6g
22
Q
- Toxins accumulated in a reactor can lead to low biomass yields probably due to which of the following?
A
- ATP is diverted away from anabolism to homeostasis
23
Q
- The cellular productivity in a continuous stirred tank fermenter (CSTF) increases with an increase in the dilution rate and reaches a maximum value. If the dilution rate is increased beyond the maximum point, the productivity will
A
- Decrease abruptly
24
Q
- Fluidized bed bioreactors provide higher mass transfer rates than packed bed bioreactors because
A
- All of the above
25
Q
- In fed-batch fermentation, mass of substrate utilized is calculated using the relationship
A
- Initial mass of substrate in the reactor - final mass of substrate in the reactor + flow rate x [substrate in the feed]
26
Q
- A chemostat has a liquid volume of 2 liters and is being fed at a rate of 4 liters per hour. Dilution rate for this reactor will be
A
- 2 h-1
27
Q
- Mixing per unit volume is observed to be poorest in
A
- Continuous packed bed reactor
28
Q
- The growth of an organism on glucose is described by the following Monod model parameters:μm=0.5 h−1μm=0.5h−1andKs=0.1 g⋅L−1Ks=0.1g⋅L−1, if the concentration of glucose in the feed is 10 g/L and the dilution rate is set to 0.4/h, then the steady state concentration of glucose in the effluent will be
A
- 1.0 g/L
29
Q
- A continuous reactor at steady state contains 0.04 g/L of biomass and 0.02 g/L of phenol. The feed contained 0.1 g/L of phenol. The biomass yield would be
A
- 0.5 g/g
30
Q
- A culture system with constant environmental conditions maintained through continual provision of nutrient and removal of wastes is called culture system.
A
- Continuous
31
Q
- The main reason for production of antibiotics in fed batch reactors is
A
- All of the above
32
Q
- Fed batch reactors is used to produce vinegar because
A
- All of the above
33
Q
- When a culture of fermenting yeast becomes metabolically uncoupled, ethanol
A
- Production becomes non-growth associated
34
Q
- Mixing profiles closest to plug flow are observed in
A
- Continuous packed bed reactor
35
Q
- On a glucose medium, the growth of an organism is characterized by the following Monod model and stoichiometric parameters
A
- 0.5 g/L
36
Q
- Unsteady state mass balance for dynamic model of continuous stirred tank reactor (CSTR) is
A
- Time rate of total amount in reactor = rate of addition to reactor - rate of removal + rate of formation
37
Q
- A fed-batch reactor initially contains 2 liter of medium. If it was fed at 1 liter per hour, then after 10 hours, the volume of the reactor will be
A
- 13 liter
38
Q
- A Bacillus sp. Produces an antibiotic only during the stationary phase when grown in a batch culture. If grown in a 5 liter continuous culture, the steady state productivity of the antibiotic
A
- Will be zero
39
Q
- In a fluidized bed reactor, the function of the disengagement zone is to
A
- All of the above
40
Q
- Saccharomyces cerevisiae produces high biomass yields at low glucose concentrations and high dissolved oxygen concentrations. Which of the following should be followed for maximizing its biomass productivity?
A
- All of the above
