Lesson 10 of 11 · 6 min
Bioreactors and downstream processing
NCERT §9.3.5, §9.3.6
On her last week Kavya is taken to the pilot plant, where a steel tank taller than her hums quietly, and a technician draws a small sample from a valve near its base.
The lesson in notes
In short
Small cultures cannot give appreciable amounts of product, so bioreactors were developed to process large volumes of culture, 100-1000 litres.
A bioreactor is a vessel in which raw materials are converted biologically into specific products or enzymes, using microbial, plant, animal or human cells.
It keeps the conditions right for making the product: temperature, pH, substrate, salts, vitamins and oxygen.
The most common type is the stirred-tank bioreactor: usually cylindrical or with a curved base to help mixing. The stirrer mixes the contents evenly and spreads oxygen through them.
In a sparged stirred-tank bioreactor, sterile air bubbles are sparged (bubbled) through the culture.
A bioreactor has an agitator system, an oxygen delivery system, a foam control system, a temperature control system, a pH control system, and sampling ports for drawing off small volumes of culture from time to time.
After the biosynthetic stage, the product goes through separation and purification, together called downstream processing.
It is then formulated with suitable preservatives. Drugs must pass thorough clinical trials, and every product needs strict quality control testing. Both downstream processing and quality control vary from product to product.