Types of Bioreactors: A Comprehensive Guide for Biotechnology Students

Question 1

What is a key advantage of using an airlift bioreactor compared to a stirred-tank bioreactor?

Accepted Answer

Enhanced oxygen transfer due to continuous aeration and circulation

Accepted Answer

Reduced risk of cell damage due to lower shear forces

Answer

Increased cell density

Question 2

What is the primary operating mode of a chemostat bioreactor?

Accepted Answer

Continuous

Answer

Batch

Answer

Fed-batch

Answer

Sequencing batch

Question 3

What is the primary reason for incorporating baffles into stirred-tank bioreactors?

Accepted Answer

Enhancement of mixing efficiency

Answer

Reduction of excessive shear forces

Answer

Increase in oxygen transfer rate

Answer

Precise control of temperature

Question 4

Which type of bioreactor is most suitable for fermentation processes involving highly viscous fluids?

Accepted Answer

Airlift bioreactor

Answer

Stirred-tank bioreactor

Answer

Hollow-fiber bioreactor

Answer

Perfusion bioreactor

Question 5

Which type of bioreactor is commonly utilized for large-scale production of antibiotics and secondary metabolites?

Accepted Answer

Fed-batch bioreactor

Answer

Airlift bioreactor

Answer

Batch bioreactor

Answer

Perfusion bioreactor

Question 6

Which bioreactor configuration operates in a closed environment, preventing contamination?

Accepted Answer

Batch

Answer

Continuous

Answer

Semi-continuous

Answer

Open

Question 7

What is the primary function of a sparger in a bioreactor system?

Accepted Answer

Introduce gas into the culture medium

Answer

Generate agitation

Answer

Maintain temperature

Answer

Monitor pH levels

Question 8

In the design of a bioreactor for large-scale manufacturing, which factor is of paramount importance?

Accepted Answer

Oxygen mass transfer rate

Answer

Cost of raw materials

Answer

Shear sensitivity of cells

Answer

Heat transfer efficiency

Question 9

Which type of bioreactor employs an external membrane to separate the culture broth, allowing for constant perfusion of nutrients?

Accepted Answer

Hollow-fiber bioreactor

Answer

Packed-bed bioreactor

Answer

Fluidized-bed bioreactor

Answer

Bubble column bioreactor

Question 10

Which mixing method is commonly employed in stirred-tank bioreactors to ensure thorough mixing and prevent stagnant zones?

Accepted Answer

Mechanical agitation

Answer

Pneumatic agitation

Answer

Electromagnetic agitation

Answer

Sonication

Question 11

What is a potential challenge associated with using a hollow-fiber bioreactor?

Accepted Answer

Membrane fouling

Answer

High operating expenses

Answer

Low mass transfer rates

Answer

Difficulty in scaling up

Question 12

Which type of bioreactor is commonly used for producing monoclonal antibodies and other high-value proteins?

Accepted Answer

Perfusion bioreactor

Answer

Batch bioreactor

Answer

Continuous bioreactor

Answer

Fed-batch bioreactor

Question 13

Which bioreactor type is best suited for large-scale recombinant protein production using suspension mammalian cells?

Accepted Answer

Stirred-tank bioreactor due to its efficient mixing and oxygen transfer capabilities.

Answer

Packed-bed bioreactor is designed for immobilized enzymes or microbial cells, not ideal for suspension mammalian cells.

Answer

Wave bioreactor, a gentler option for shear-sensitive cells, may not offer sufficient scale-up capacity.

Answer

Airlift bioreactor, while providing low shear stress, may be limited in scalability for large-scale production.

Question 14

What is a key advantage of utilizing an airlift bioreactor over a stirred-tank bioreactor for aerobic fermentation?

Accepted Answer

Reduced shear stress on sensitive cells, as airlift bioreactors rely on air bubbles for mixing instead of mechanical agitation.

Answer

Lower operational costs may not be a significant advantage compared to stirred-tank bioreactors.

Answer

Easier sterilization process is not a defining advantage of airlift bioreactors compared to stirred-tank bioreactors.

Answer

Higher oxygen transfer rates may be achieved in both stirred-tank and airlift bioreactors, depending on the specific design and operating conditions.

Question 15

Which bioreactor configuration is best suited for carrying out immobilized enzyme reactions?

Accepted Answer

Packed-bed bioreactor, as it provides a fixed support for enzyme immobilization, ensuring prolonged enzyme activity and reusability.

Answer

Photobioreactor is designed for cultivating photosynthetic organisms, not enzyme reactions.

Answer

Bubble column bioreactor is suitable for gas-liquid reactions, not specifically designed for enzyme immobilization.

Answer

Fluidized bed bioreactor is more applicable for cell cultures or microbial processes, not typically used for enzyme immobilization.

Question 16

What is a major drawback associated with employing a continuous stirred-tank reactor (CSTR) in bioprocessing?

Accepted Answer

Potential for cell washout due to continuous inflow and outflow of culture broth, which can result in loss of cells from the bioreactor.

Answer

Limited scalability for large-scale production is more applicable to other bioreactor types, not CSTRs.

Answer

High energy consumption for mixing may be an operational consideration but not a critical drawback.

Answer

Difficulty in maintaining sterility is not a specific challenge associated with CSTRs.

Question 17

Which type of bioreactor utilizes light energy to cultivate photosynthetic organisms?

Accepted Answer

Photobioreactor, specially designed to provide optimal conditions for the growth and cultivation of photosynthetic microorganisms or algae.

Answer

Membrane bioreactor is primarily used for wastewater treatment or bioremediation, not photosynthesis.

Answer

Fixed-film bioreactor is characterized by cells immobilized on a solid support, not light utilization.

Answer

Solid-state bioreactor is used for solid-substrate fermentation processes, not photosynthetic cultivation.

Question 18

In a perfusion bioreactor, what is the primary purpose of the cell retention device?

Accepted Answer

To retain cells within the bioreactor while allowing the removal of spent media and nutrients, facilitating continuous operation and cell growth.

Answer

To facilitate cell harvesting is not the primary function of the cell retention device in a perfusion bioreactor.

Answer

To prevent foam formation is not a specific function of the cell retention device in a perfusion bioreactor.

Answer

To enhance oxygen transfer rates is not a primary function of the cell retention device, although oxygenation is important in bioreactors.

Question 19

Which bioreactor design provides the highest level of control over environmental parameters such as pH, temperature, and dissolved oxygen?

Accepted Answer

Stirred-tank bioreactor, due to its efficient mixing and precise monitoring systems, allowing for optimal control and maintenance of critical growth conditions.

Answer

Wave bioreactor, while providing gentler mixing, may have limitations in precise control of environmental parameters.

Answer

Packed-bed bioreactor, designed for enzyme immobilization, may not prioritize precise control of environmental parameters.

Answer

Airlift bioreactor, although suitable for shear-sensitive cells, may have limitations in precise environmental control compared to stirred-tank bioreactors.

Question 20

What is a major advantage of employing disposable bioreactors in pharmaceutical production?

Accepted Answer

Reduced risk of cross-contamination, as disposable bioreactors eliminate the need for cleaning and sterilization between batches, minimizing the risk of contamination carryover.

Answer

Increased process flexibility may be an advantage but is not specific to disposable bioreactors.

Answer

Lower capital investment costs may be true for some cases but is not a universal advantage of disposable bioreactors.

Answer

Enhanced scalability for larger volumes is not a defining advantage of disposable bioreactors.

Question 21

Which bioreactor type is particularly well-suited for cultivating cells that are vulnerable to shear forces?

Accepted Answer

Wave bioreactor, as it provides a gentle mixing action through rocking or wave-like motion, minimizing shear stress on delicate cells.

Answer

Stirred-tank bioreactor, while a common type, may not be ideal for shear-sensitive cells due to its mechanical agitation.

Answer

Bubble column bioreactor, characterized by rising air bubbles, may not be suitable for shear-sensitive cells.

Answer

Fluidized bed bioreactor, designed for cell-particle interactions, may not be suitable for shear-sensitive cells.

Question 22

A key feature of a fixed-film bioreactor is:

Accepted Answer

Immobilization of microorganisms on a solid support, allowing for high cell density and continuous operation, often used in wastewater treatment.

Answer

Continuous mixing is not a defining feature of fixed-film bioreactors.

Answer

Oxygen transfer may be limited in some fixed-film bioreactors due to mass transfer limitations.

Answer

Fixed-film bioreactors are not primarily designed for suspension cell cultures.