Bioreactors are considered as vessels in which raw materials are biologically converted into specific products by microbes, plant and animal cells and/or their enzymes.
Small volume cultures cannot yield appreciable quantities of products.
To produce in large quantities, the development of bioreactors, where large volumes (100-1000 liters) of culture can be processed, was required.
A bioreactor provides the optimal conditions for achieving the desired product by providing optimum growth conditions (temperature, pH, substrate, salts, vitamins, oxygen)
The most commonly used bioreactors are of stirring type.
Stirring type bioreactors are:
Simple stirred-tank bioreactor
Sparged stirred-tank bioreactor
A stirred-tank reactor is usually cylindrical or with a curved base to facilitate the mixing of the reactor contents.
The stirrer facilitates even mixing and oxygen availability throughout the bioreactor.
Alternatively, air can be bubbled through the reactor.
The bioreactor has an agitator system, an oxygen delivery system and a foam control system, a temperature control system, pH control system and sampling ports so that small volume of the culture can be withdrawn periodically.