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  • Question
  • The lowest biomass yield in a culture of Escherichia coli will be in


  • Options
  • A. an aerated batch culture containing a initial high concentration of glucose
  • B. an aerated batch reactor containing an initial low concentration of glucose
  • C. an aerated fed-batch reactor having a low glucose concentration
  • D. an aerated continuous reactor having a low glucose concentration

  • Correct Answer
  • an aerated batch culture containing a initial high concentration of glucose 


  • Fermentation Reactors problems


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    • 1. 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 from a medium containing 10 g.l-1 of peptone, then the rate of protogon synthesis would be

    • Options
    • A. 0 g.l-1h-1
    • B. 0.5 g.l-1h-1
    • C. 1 g.l-1h-1
    • D. 2 g.l-1h-1
    • Discuss
    • 2. Unsteady state mass balance for dynamic model of continuous stirred tank reactor (CSTR) is

    • Options
    • A. time rate of total amount in rector = rate of addition to reactor -rate of removal + rate of formation
    • B. total amount in rector = rate of addition to reactor - rate of removal + rate of formation
    • C. rate of total amount in rector = rate of addition to reactor - rate of removal + rate of formation
    • D. none of the above
    • Discuss
    • 3. 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

    • Options
    • A. decrease abruptly
    • B. increase
    • C. increase drastically
    • D. be zero
    • Discuss
    • 4. A chemostat has a liquid volume of 2 litres and is being fed at a rate of 4 litres per hour. Dilution rate for this reactor will be

    • Options
    • A. 2 litres
    • B. 2 litres per hour
    • C. 2 h-1
    • D. 4 litres per hour
    • Discuss
    • 5. In a fluidized bed reactor, the function of the disengagement zone is to

    • Options
    • A. reduce loss of particles from the reactor
    • B. reduce the velocity of the particles near the surface of the reactor
    • C. reduce foaming problems
    • D. all of the above
    • Discuss
    • 6. The main reason for production of antibiotics in fed batch reactors is

    • Options
    • A. the presence of precursors is often toxic to the cells
    • B. higher yields when cells enter the stationary phase
    • C. higher yields when cell growth slows
    • D. all of the above
    • Discuss
    • 7. When a culture of fermenting yeast becomes metabolically uncoupled, ethanol

    • Options
    • A. becomes a secondary metabolite
    • B. production becomes growth associated
    • C. production becomes non-growth associated
    • D. becomes a growth nutrient
    • Discuss
    • 8. For organisms growing in a chemostat, the specific growth rate

    • Options
    • A. cannot be determined
    • B. can be determined from the dilution rate
    • C. equals to the maximum specific growth rate of the culture
    • D. none of the above
    • Discuss
    • 9. Mixing profiles closest to plug flow are observed in

    • Options
    • A. continuous packed bed reactor
    • B. stirred tank reactor with biomass recycles
    • C. continuous fluidized bed bioreactor
    • D. all of these
    • Discuss
    • 10. Toxins accumulated in a reactor can lead to low biomass yields probably due to which of the following?

    • Options
    • A. NAD+ is diverted away from homeostasis to anabolism
    • B. ATP is diverted away from homeostasis to anabolism
    • C. NAD+ is diverted away from anabolism to homeostasis
    • D. ATP is diverted away from anabolism to homeostasis
    • Discuss


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