Question

The function of the part labelled X in the given diagram is to

• A. evenly mix the culture broth and sterilise it
• B. evenly mix the culture broth and provide uniform aeration throughout the culture
• C. evenly mix the culture broth and maintain uniform pH
• D. All of these

Answer 1

The correct option is B evenly mix the culture broth and provide uniform aeration throughout the culture

Bioreactors are large vessels that are used for large scale culturing of cells (plant, animal or microbial) to obtain specific gene products for commercial use.

Simple stirred-tank bioreactors are one of the most commonly used bioreactors. These are large, closed cylindrical vessels, usually made of steel.

Its components include central shaft, flat bladed impellers, oxygen delivery system, foam control machine, temperature and pH control systems, cooling jacket, sampling ports etc.

The part labelled X in the diagram are the flat bladed impellers which remain coupled to the shaft in the centre. With the help of a motor, the shaft and the impellers keep rotating. This helps in thorough mixing of the culture media and ensures oxygen availability throughout the bioreactor. Hence, they ensure uniform aeration throughout the culture.

Maintenance of pH, usually between 6-8, is crucial for cell growth which is done by addition of buffers etc.

Bioreactors also have inlets to allow the entry of steam into the culture media which helps to kill the microbes and sterilise the medium prior to inoculation.