Fermentation Reactors problems
- 1. Two continuous bioreactors containing the same organisms, fed with the same feed at the same dilution rate were compared. Reactor 1 started with an initial concentration of glucose of 10 g.l-1, while reactor 2 contained 0.1 g.l-1 of glucose at the start of the process then at steady state
Options- A. the concentration of glucose in reactor 1 would be greater than that in reactor 2
- B. the concentration of glucose in reactor 1 would be equal to reactor 2
- C. the concentration of glucose in reactor 1 would always be zero.
- D. the concentration of glucose in reactor 1 would be less than that in reactor 2 Discuss
Correct Answer: the concentration of glucose in reactor 1 would be equal to reactor 2
- 2. In a glucose-yeast extract medium, Lactococcus lactis has a maximum specific growth rate (um) of 1.23 h-1. What would be the specific growth rate of this organism at steady state in a 4 litre reactor being fed at 2 litres per hour?
Options- A. 0.5 h-1
- B. 1.2 h-1
- C. 2.4 h-1
- D. 4 h-1 Discuss
Correct Answer: 0.5 h-1
- 3. The toxicity of organic acids to cells
Options- A. enhances as the pH falls
- B. reduces as the pH falls
- C. is not affected by pH
- D. is highest at pH 7.0 Discuss
Correct Answer: enhances as the pH falls
- 4. A microorganism which is subjected to the Crabtree effect is most likely to
Options- A. ferment in the presence of low concentrations of sugar and dissolved oxygen
- B. respire in the presence of low sugar and high dissolved oxygen concentrations
- C. ferment in the presence of high concentrations of sugar and dissolved oxygen
- D. respire in the presence of high sugar and low dissolved oxygen concentrations Discuss
Correct Answer: ferment in the presence of high concentrations of sugar and dissolved oxygen
- 5. Production of organic acids in batch culture is generally growth associated phase followed by non-growth associated production. The probable reason for this is that
Options- A. organic acids uncouple catabolism from anabolism
- B. biomass yields increase as the fermentation proceeds
- C. organic acids are secondary metabolites
- D. high concentrations of organic acid promote the growth of the microbial population Discuss
Correct Answer: organic acids uncouple catabolism from anabolism
- 6. In an activated sludge process, the biomass is recycled to
Options- A. increase the efficiency of the process
- B. reduce sludge volumes
- C. increase the concentration of cells
- D. all of the above Discuss
Correct Answer: all of the above
- 7. Continuous culture has an advantage over to a batch cultures as
Options- A. continuous reactors do not need to be shut down and cleaned as regularly as a batch reactor
- B. most downstream and upstream processes are continuous in nature and thus the operation of continuous bioreactor can be better integrated into the overall manufacturing process
- C. cells can be maintained at a constant physiological state simply by setting the dilution rate
- D. all of the above Discuss
Correct Answer: all of the above
- 8. Yeast is typically produced in fed batch reactors because
Options- A. yeast cells produce ethanol at low glucose concentrations
- B. yeast cells ferment at low glucose concentrations
- C. yeast cells respire at low glucose concentrations
- D. all of the above Discuss
Correct Answer: yeast cells respire at low glucose concentrations
- 9. Monoclonal antibodies are typically produced in fed batch reactors because
Options- A. hybridoma cells ferment at high maltose concentrations
- B. hybridoma cells yield higher lactate at high glucose concentrations
- C. hybridoma cells respire at high glucose concentrations
- D. none of the above Discuss
Correct Answer: hybridoma cells yield higher lactate at high glucose concentrations
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