Industrial fermenters
Fermenters are containers used to grow bacteria and fungi in large amounts. For example:
transgenic bacteria
Penicillium mould for producing penicillin (an antibiotic)
Fusarium mould for producing mycoprotein (a fungus-based meat substitute)
Stainless steel with water jacket and paddles. Steam and nutrients enter at top. Cooling water and air at bottom. Exhaust at top right. Cooling water leaves near top. Outlet for the product at base.
Diagram of a fermenter
Fermenters are usually made from a metal that will not corrode, such as stainless steel. They may hold thousands of litres. The table describes the main features of a fermenter and their function.
Feature Function Reason
Steam inlet Hot steam sterilises the inside of the fermenter An aseptic precaution to prevent contamination by unwanted microorganisms
Nutrient inlet Allows sterile nutrients to enter the fermenter Microorganisms need nutrients so that they can grow and reproduce
Water jacket with cooling water Keeps the temperature inside constant Microorganisms grow best at an optimum temperature
Air inlet Provides a source of oxygen Microorganisms need oxygen for aerobic respiration
Filter on air inlet Stops microorganisms getting inside the fermenter An aseptic precaution to prevent contamination by unwanted microorganisms
Stirring paddles Keeps the mixture inside the fermenter agitated (stirred) Mixes the microorganisms with the nutrients and keeps the temperature even
The pH inside the fermenter is monitored to check it is at the optimum value for the particular microorganism being grown. The pH can be adjusted, if necessary, using acids or alkalis.