(a) Bioreactors are chambers in which microorganisms are cultured in a liquid medium. A larger biomass or large volume of culture can be processed leading to higher yields of desired specific products (proteins/enzymes), under controlled conditions. Hence, the development of bioreactors greatly helped in producing the desired products on a large scale.(b) Stirring type of bioreactor is most commonly used. Working: The structure of a stirred bioreactor is cylindrical. It facilitates even mixing of medium and the raw materials throughout the tank. It also ensures a continuous supply of oxygen. The reactor is provided with a baffle and a rotating stirrer that offers excellent mixing. The tank also possesses inlets/sampling ports that allows the person to alter the volumes of the culture. The tank has multiple controlling systems such as pH, temperature, foam, oxygen delivery and agitator system.