What are bioreactors? Describe a stirred-tank bioreactor with a diagram, and explain downstream processing.
How to lay out the answer. Follow the frame, then write it in your own words.
1 · Define a bioreactor. A vessel in which raw materials are biologically converted into specific products using microbial, plant, animal or human cells.
2 · State what it provides. Large volumes (100 to 1000 litres) and optimum temperature, pH, substrate, salts, vitamins and oxygen.
3 · Describe the stirred-tank type. Cylindrical or with a curved base; a stirrer mixes the culture and spreads oxygen; in the sparged type, sterile air is bubbled in.
4 · List its systems.
Agitator
Oxygen delivery
Foam control
Temperature control
pH control
Sampling ports
5 · Draw it. [Diagram: motor, shaft, flat bladed impeller, culture broth, foam breaker, sterile air inlet, acid/base for pH control, steam for sterilisation]
6 · Explain downstream processing. Separation and purification, formulation with preservatives, clinical trials for drugs and strict quality control.
7 · Link to real life. This is how recombinant insulin reaches a chemist's shelf pure and safe.
8 · Close in one line. So the bioreactor makes the product in bulk and downstream processing makes it fit for use.
Scoring tip: List all six systems and label the motor, impeller, foam breaker and sterile air inlet on the diagram.
