Small volume cultures cannot yield appreciable quantities of products. To produce in large quantities, the development of bioreactors, where large volumes (1001000 litres) of culture can be processed, was required. Thus, bioreactors are large vessels in which raw materials are biologically converted into specific products, individual enzymes, etc., using microbial plant, animal or human cells.

A bioreactor provides the optimal conditions for achieving the desired products by providing optimum growth conditions (temperature, , substrate, salts, vitamins. oxygen).