Factors Affecting the Growth of Penicillium
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 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
- The process works as follows:
- A starter culture of the fungus Penicillium is added to the fermenter
- The culture is added to a liquid nutrient medium
- The conditions are controlled to maintain an optimum growth environment
- temperature
- pH
- oxygen supply
- nutrient supply
- After a period of time, an antibiotic is secreted from the fungus
- The culture medium is incubated and then filtered to remove the fungus. The antibiotic is then extracted
A fermenter diagram
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 |
