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Why are bacteria, yeasts and fungi the favourite living tools of the biotechnology industry?

Describe the main groups of microorganisms used in biotechnology and explain why they are suitable as biological tools

A focused answer to the O-Level outcome on microorganisms as tools. The main groups (bacteria, yeasts, fungi), why they are so useful, and the products they help make.

Generated by Claude Opus 4.88 min answer

Reviewed by: AI editorial process; not yet individually human-reviewed

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  1. What this dot point is asking
  2. The answer
  3. Examples in context
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What this dot point is asking

This outcome asks you to describe the main groups of microorganisms used in biotechnology and to explain why they make such good biological tools. The key insight is that microorganisms are, in effect, tiny self-replicating factories: fast, cheap to feed, and easy to grow and modify.

The answer

The main groups

Three groups of microorganisms do most of the work in biotechnology:

  • Bacteria. Single-celled prokaryotes such as those used to ferment milk into yoghurt or, when engineered, to make human insulin. Their plasmids make them easy to engineer.
  • Yeasts. Single-celled fungi such as baker's and brewer's yeast, used to ferment sugars into ethanol and carbon dioxide in brewing and bread-making.
  • Fungi (moulds). Multicellular fungi such as the mould that produces the antibiotic penicillin, and others used to make enzymes and foods.

Why microorganisms are so useful

Microorganisms are favoured because almost everything about them suits large-scale production:

  • Rapid reproduction. Many bacteria divide every twenty minutes or so, so huge numbers build up quickly.
  • Small size, large numbers. Billions can be grown in a single bioreactor, so a small space gives a large output.
  • Cheap, simple food. They grow on inexpensive nutrient sources, keeping costs down.
  • Useful chemistry. Their natural reactions, such as fermentation, make valuable products.
  • Easy to engineer. Bacteria especially can be given new genes, so they make products they would never make naturally.

What they produce

Between them, these microorganisms make foods (bread, yoghurt, cheese, soy sauce), drinks (beer, wine), medicines (insulin, antibiotics), and industrial products (enzymes, ethanol fuel).

Examples in context

Example 1. Penicillin from a mould. The antibiotic penicillin is produced naturally by a Penicillium mould grown in large fermenters. It shows how a microorganism's own chemistry can be harnessed at scale to make a life-saving product, with no genetic engineering needed.

Example 2. Engineered bacteria for insulin. Bacteria do not normally make human insulin, but because they are easy to engineer they can be given the human gene and then produce it in bulk. This contrasts with penicillin and shows the two routes: using a microorganism's natural ability, or giving it a new one.

Try this

Q1. Name the three main groups of microorganisms used in biotechnology. [3 marks]

  • Cue. Bacteria, yeasts and fungi (moulds).

Q2. Give two reasons why microorganisms are well suited to large-scale production. [2 marks]

  • Cue. They reproduce very quickly and can be grown in huge numbers in a small space on cheap nutrient sources.

Q3. State the microorganism used to make bread rise and explain how it does so. [2 marks]

  • Cue. Yeast, which ferments the sugars in the dough and releases carbon dioxide gas that makes the dough rise.

Exam-style practice questions

Practice questions written in the style of SEAB exam questions on this dot point, with worked answer explainers. The year tag is the paper they imitate, not the source.

Original5 marksExplain why microorganisms such as bacteria and yeast are widely used in biotechnology.
Show worked answer →

Examiners want several reasons that all point to microorganisms being easy and cheap to use as factories.

Microorganisms are suitable because they reproduce very quickly, so large numbers build up in a short time. They are small and can be grown in huge numbers in a relatively small space, such as a bioreactor. They have simple nutritional needs and can grow on cheap food sources, keeping costs low.

They carry out useful chemical reactions, for example fermentation, and can be genetically engineered to make products they would not make naturally, such as human insulin. Bacteria in particular have plasmids that make them easy to engineer.

What markers reward: at least three valid reasons, such as rapid reproduction, growth in large numbers in a small space, cheap simple nutrient needs, useful metabolism, and ease of genetic engineering.

Original4 marksName one bacterium, one yeast and one fungus used in biotechnology, and state a product or process associated with each.
Show worked answer →

The answer should give a named example from each group with a correct use. Generic group names with a clear product are acceptable at this level.

A bacterium such as Lactobacillus is used to ferment milk into yoghurt. A yeast such as Saccharomyces (baker's or brewer's yeast) is used to ferment sugars into ethanol and carbon dioxide in brewing and bread-making. A fungus such as Penicillium is used to produce the antibiotic penicillin.

What markers reward: a correct example from each of the three groups, each paired with a valid product or process.

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