(e) the use of microorganisms in biotechnological processes

The idea

Microorganisms are used in biotechnology because they grow rapidly, have simple growth requirements and can be genetically modified. In this section you learn how bacteria and fungi are exploited in processes such as fermentation, the production of enzymes, antibiotics, insulin and other proteins, and in food production such as cheese and yoghurt making. You should be able to link each process to the microorganism involved, the conditions it needs (for example a controlled temperature, a suitable substrate and aseptic technique) and the product formed. You should also recognise why microorganisms are chosen: fast reproduction, large surface area to volume ratio, ability to use waste materials as substrates and ease of genetic engineering. A multiple-choice question may ask you to identify a product, a suitable microorganism or a reason for using microbes rather than plants or animals.

What earns the marks

• Identifies that microorganisms reproduce rapidly and can be cultured on a large scale in fermenters.
• Recognises that bacteria and fungi can be genetically modified to produce human proteins such as insulin.
• States that microorganisms can use a range of substrates, including waste materials, to produce useful products.
• Links a named process, such as fermentation in cheese or yoghurt production, to the microorganism responsible and the product formed.
• Explains that aseptic technique and controlled conditions (temperature, pH, oxygen) are needed to optimise product yield.

Common mistakes and how to put them right

• Thinking all biotechnological processes use bacteria.

  Put it right: Fungi such as yeast are also widely used, for example in fermentation.

• Assuming microorganisms are always harmful.

  Put it right: Many are exploited beneficially in food production and medicine.

• Believing genetic modification is unnecessary.

  Put it right: Genetic engineering allows microbes to make products they would not naturally produce, such as human insulin.

Exam tips

• Read the question carefully to identify whether it asks for a product, a microorganism or a reason for using microbes.
• Eliminate options that confuse the role of bacteria and fungi in named processes.
• Recall that controlled conditions and aseptic technique are central to successful biotechnological use of microorganisms.