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Course: Class 12 Biology (India) > Unit 10
Lesson 4: Applications of BiotechnologyBioreactors and downstream processing
Large-scale production and purification of recombinant proteins using bioreactors.
Key terms
| Term | Meaning |
|---|---|
| recombinant protein | protein expressed by organism that is carrying modified genetic information |
| bioreactor | apparatus that allows production of biological products on an industrial scale |
| stirred-tank bioreactor | bioreactor that uses either mechanical or gaseous means to stir contents |
| downstream processing | purification and processing of products after synthesis |
What is a bioreactor?
If you were asked to close your eyes and imagine a factory, what is the first thing that comes to your mind? Cars? Steel? Maybe some chemicals? How about ... living organisms?
It may seem strange at first - why would we need to mass produce organisms? You might have already learnt that some microorganisms like bacteria or yeast can be be made to take up foreign DNA. Genes of interest within this DNA express recombinant proteins . In fact, these microorganisms can be thought of as tiny protein factories - each cell produces a certain amount of the desired product.
Scientists in labs can grow small amounts of these cells in beakers and flasks, but what if we wanted really large amounts? For example, a lot of pharmaceutical drugs are made up of recombinant proteins - for which we would need hundreds of litres of cell culture.
The solution is to make a factory that encourages the growth of the smaller factories! A bioreactor is simply an instrument that allows large scale growth of the recombinant cells, and therefore produces huge amounts of recombinant proteins.
Types of bioreactors
Essentially, a bioreactor is a system that provides an ideal environment for the production of biomolecules. Most bioreactors can be thought of as vessels with control units that help regulate cell growth conditions such as temperature, pH, oxygen/carbon dioxide levels, etc.
Stirred-tank bioreactors are very commonly used for the industrial production of biological products like enzymes, antibodies, vaccines, etc. The constant stirring of the vessel's contents ensures that all the necessary nutrients get uniformly distributed, and that conditions are homogenous throughout. The image below is a schematic of a stirred-tank bioreactor system, which uses a propellor to mix contents.
Another variant is known as a sparged stirred-tank bioreactor, in which gas is bubbled through the chamber to mix the contents (instead of mechanical stirring). The image below depicts the bubbled gas molecules as circles and the cells or other solid material as stars.
Downstream processing
Once the necessary product has been manufactured, it needs to be purified and tested for quality. This is especially important for pharmaceutical products such as drugs and vaccines. Downstream processing refers to this process, along with the recycling and disposal of by products and waste.