Question

Which of the following set-up should be chosen for best yield if one were to produce a recombinant protein in large quantities for commercial purposes?

• A. A liquid culture in a laboratory flask of the largest capacity
• B. A stirred-tank bioreactor with inlets and outlets
• C. Any of the above
• D. A stirred-tank bioreactor without inlets and outlets

Answer 1

The correct option is B A stirred-tank bioreactor with inlets and outlets

The process of obtaining the desired foreign gene product from a genetically engineered organism is known as bioprocessing. It consists of two stages- upstream processing and downstream processing.

The biosynthetic phase of growing the genetically modified cells in bioreactors at a large scale is known as upstream processing. The type of upstream processing where recombinant cells are grown in culture conditions maintained at a steady state is known as continuous culture.

It is characterised by draining out of used culture medium from one side through outlets of the culture vessel/ bioreactor and simultaneous addition of fresh medium from the other side through inlets.

Such a culture method ensures continuous supply of nutrients to the cells. Thus, the cells are able to undergo exponential growth in the culture. As the number of cells in the culture media increases exponentially, the amount of desired protein expressed by them also increases. This helps to obtain higher yields of desired proteins. Without an inlet and outlet, continuous cultures cannot be maintained.

Liquid cultures grown in laboratory flasks are not fit for large scale production at industrial levels.