Enzyme production is carried out by a method called deep culture fermentation in closed bioreactors (fermentors). In deep culture fermentation, microorganisms multiply in tanks (bioreactor/fermentor) designed to optimize enzyme production and equipped with appropriate equipment to allow control of process conditions, and secrete enzymes into the growth media.

Bioreactors are filled with a liquid called a medium containing the nutrients needed by the microorganisms in order to provide an environment where microorganisms can grow and multiply. Microorganisms grown in small scale bioreactors, called seed cultures, are transferred to large scale bioreactors where the actual production will take place when they show sufficient growth. To be valid for every stage of production, before the transfer of the microorganism desired to be reproduced to the bioreactors, the used bioreactor and media are sterilized and only the desired microorganism is allowed to multiply.

In fermentation, microorganisms multiply under optimal conditions in well-mixed and ventilated bioreactors where parameters such as temperature, pH, dissolved oxygen are tightly controlled and secrete enzymes into the fermentation fluid.