Which of the following should be chosen for best yield if one were to produce a recombinant protein in large amounts?

Concept:

• In recombinant DNA (rDNA) technology, the aim is to produce a desirable protein product.
• In order to obtain the protein, the rDNA needs to be expressed.
• The host cells must be induced to express the foreign gene by providing appropriate conditions.
• This would provide us with the recombinant protein, produced by a heterologous host.
• Heterologous host refers to the host cell that produces the protein in a cell line where it is not supposed to be.
• The recombinant proteins can be extracted and purified using various separation techniques in the laboratory.
• But this kind of laboratory set-up would only give a small-scale production.
• Large scale production is carried out in bioreactors that use a continuous culture system.

Explanation:

• A continuous culture system is where used medium is removed from one side while fresh medium is added from other side.
• This necessitates the presence of in-lets and out-lets.
• This system helps in maintaining the cells in the exponential phase of growth.
• This gives us a higher yield of the desired protein due to the larger biomass produced.
• In a typical bioreactor with a continuous culture system, 100-1000L of cultures can be processed.

Hence, the correct answer is option (3).

Additional InformationStirred-type Bioreactors - 

• It may be of 2 types:
  • A simple stirred-tank bioreactor that comes with a stirrer to mix the contents evenly and facilitate oxygen availability throughout the reactor.
  • A sparged stirred-tank bioreactor that uses sterile air bubbles to increase the surface area for oxygen transfer.
• They also consist of in-lets and out-lets for maintaining a continuous culture system.