Aerobic Fermentation - The main feature of aerobic fermentation is the provision for adequate aeration; in some cases, the amount of air needed per hour is about 60-times the medium volume. Therefore, bioreactors used for aerobic fermentation have a provision for adequate supply of sterile air, which is generally sparged into the medium.
In addition, these fermenters may have a mechanism for stirring and mixing of the medium and cells. Aerobic fermenters may be either of the

(i) stirred tank type in which mechanical motor driven stirrers are provided or
(ii) of air lift type in which no mechanical stirrers are used and the agitation is achieved by the air bubbles generated by the air supply.

Generally, these bioreactors are of closed or batch type, but continuous flow reactors are also used such reactors provide a continuous source of cells and are also suitable for product generation when the product is released into the medium.