Fermenters (Cambridge O Level Biology)

Penicillin Production

• Penicillin was the first antibiotic, discovered in 1928 by Alexander Fleming
• He noticed that some bacteria he had left in a Petri dish had been killed by the naturally occurring Penicillium mould
• The penicillium mould produces a chemical to prevent it from being infected by certain types of bacteria

The Action of Penicillin

Penicillin produced by the fungus Penicillium inhibits bacterial growth

• The chemical was isolated and named penicillin
• Since the discovery of penicillin, methods have been developed to produce it on a large scale, using an industrial fermenter

A Fermenter

A diagram of an industrial fermenter used to produce large quantities of microorganisms.

• Fermenters are containers used to grow (‘culture’) microorganisms like bacteria and fungi in large amounts
• These can then be used for many biotechnological processes like producing genetically modified bacteria and the penicillium mould that produces penicillin
• The advantage of using a fermenter is that conditions can be carefully controlled to produce large quantities of exactly the right type of microorganism

Conditions in a Fermenter Table

Condition	Why and how it is controlled
Aseptic precautions	Fermenter is cleaned by steam to kill microorganisms and prevent chemical contamination, which ensures only the desired microorganisms can grow
Nutrients	Nutrients are needed for use in respiration to release energy for growth and reproduction of the microorganisms
Optimum temperature	Temperature is monitored using probes and maintained using a water jacket. This ensures an optimum environment for enzymes to increase enzyme activity and prevent denaturation
Optimum pH	pH is monitored using a probe to check it is at the optimum value for the microorganism being grown. The pH can be adjusted using acids and alkalis
Oxygenation	Oxygen is required for aerobic respiration to take place
Agitation	Stirring paddles are used to ensure temperature, pH, nutrients, and oxygen are all distributed evenly throughout the fermenter
Waste	The contents are filtered to remove waste created by the microorganisms

Mycoprotein – the process of creating food from a fungus

• The fungus Fusarium is cultured (grown) on an industrial scale in fermenters
• These fermenters are large vats that can be kept at the optimum pH and temperature for Fusarium to grow
• The fungus is grown in aerobic conditions (it is provided with oxygen) and provided with glucose syrup as a food source (to allow the fungus to respire)
• The fungus grows and multiplies within the fermenter
• The fungal biomass is then harvested and purified to produce mycoprotein
• Mycoprotein is a protein-rich food suitable for vegetarians eg. it is used in Quorn^TM products 

Production of Insulin

• Genetic modification is changing the genetic material of an organism by removing or altering genes within that organism, or by inserting genes from another organism
• The organism receiving the genetic material is said to be ‘genetically modified’, or is described as a ‘transgenic organism’
• The DNA of the organism that now contains DNA from another organism as well is known as ‘recombinant DNA’
• The gene for human insulin has been inserted into bacteria which then produce human insulin which can be collected and purified for medical use to treat people with diabetes