Cambridge O Level5090

Biotechnology

Biology 5090 Chapter Notes

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BiotechnologyGenetic modification
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Biotechnology notes

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In this chapter

  1. 1Introduction to Biotechnology and Fermenters
  2. 2Yeast in Food and Fuel Production
  3. 3Industrial Enzymes as Biological Tools
  4. 4Penicillin: The Mould That Saves Lives
  5. 5Mycoprotein: Growing Food in a Fermenter

1. Introduction to Biotechnology and Fermenters

Biotechnology is the use of living organisms or their products for industrial purposes. We've used it for centuries in baking and brewing. Modern biotechnology often uses microorganisms like bacteria and fungi because they grow rapidly, have simple nutritional needs, and can produce a huge range of useful substances. To grow these microbes on a large scale, we use a piece of equipment called a fermenter. A fermenter is a large, sterile container designed to provide the perfect conditions for microbial growth, allowing us to harvest either the microbes themselves or the products they make.

Key term

Biotechnology: The application of biological organisms, systems, or processes to manufacturing and service industries.

Examiner insight

Examiners expect you to be able to list the key conditions maintained in a fermenter and explain why each one is important for optimal microbial growth.

Common pitfall

Confusing 'fermentation' as used in biotechnology (any process in a fermenter) with the specific biological process of anaerobic respiration.

Worked example 14 marks

The diagram shows an industrial fermenter. Explain the function of the water jacket and the air inlet.

  1. 1

    Step 1: Identify the function of the water jacket. The metabolic reactions of the microorganisms release heat, which could raise the temperature and kill them. The water jacket allows cold water to circulate around the outside of the fermenter to absorb this heat and maintain a constant, optimal temperature.

  2. 2

    Step 2: Identify the function of the air inlet. The air inlet is used to supply oxygen to the microorganisms for aerobic respiration. The air is filtered before it enters to ensure it is sterile and does not introduce contaminating microbes.

Recap

  • Biotechnology uses living organisms to create useful products.
  • Microorganisms like bacteria and fungi are often used due to their rapid growth rate.
  • A fermenter is a vessel used to cultivate microorganisms on a large scale.
  • Key conditions controlled in a fermenter include temperature, pH, nutrient levels, oxygen, and sterility.
  • Sterility, or aseptic conditions, is crucial to prevent contamination by unwanted microbes.

Quick check

  1. State two reasons why microorganisms are ideal for many biotechnological processes.2 marks
  2. What is the purpose of the paddles (impellers) inside a fermenter?1 mark

2. Yeast in Food and Fuel Production

Yeast, a single-celled fungus, is a workhorse of biotechnology. It carries out anaerobic respiration in the absence of oxygen. In this process, it breaks down sugar (glucose) into ethanol and carbon dioxide, releasing a small amount of energy. This simple reaction is fundamental to two major industries: baking and biofuel production. In bread-making, the carbon dioxide gas produced gets trapped in the dough, causing it to rise. In brewing and biofuel production, the target product is ethanol.

Glucose → Ethanol + Carbon Dioxide

C6H12O6 → 2C2H5OH + 2CO2

Key term

Anaerobic Respiration: Respiration that does not require oxygen, breaking down glucose to release a relatively small amount of energy.

Common pitfall

Forgetting that it's the carbon dioxide that makes bread rise. The ethanol is also a product but it evaporates away during baking.

Fun fact

The carbon dioxide produced during industrial ethanol fermentation is often captured and sold to the food industry to put the fizz in carbonated drinks.

Worked example 14 marks

Explain the role of yeast in bread-making.

  1. 1

    Step 1: Yeast is mixed with flour and water to make dough. The yeast uses the carbohydrates in the flour as a source of sugar.

  2. 2

    Step 2: The yeast begins to respire anaerobically, breaking down the sugar.

  3. 3

    Step 3: This process produces carbon dioxide gas and ethanol. The bubbles of carbon dioxide gas get trapped within the dough.

  4. 4

    Step 4: The trapped gas causes the dough to expand and rise. During baking, the high temperature kills the yeast and evaporates the ethanol.

Worked example 24 marks

Ethanol produced by yeast is used as a biofuel. Describe how it is produced on a large scale.

  1. 1

    Step 1: Yeast is grown with a source of sugar, such as sugar cane juice or corn starch, in a large fermenter.

  2. 2

    Step 2: Oxygen is initially supplied for the yeast to reproduce quickly (aerobic respiration). Then, conditions are made anaerobic to maximise ethanol production.

  3. 3

    Step 3: The yeast anaerobically respires the sugar to produce ethanol and carbon dioxide.

  4. 4

    Step 4: Once the ethanol concentration reaches a certain level (which would kill the yeast), the mixture is removed. The ethanol is then separated and purified from the mixture by fractional distillation.

Recap

  • Yeast performs anaerobic respiration in the absence of oxygen.
  • The products of anaerobic respiration in yeast are ethanol and carbon dioxide.
  • In bread-making, the carbon dioxide makes the dough rise.
  • In brewing and biofuel production, the ethanol is the desired product.
  • The word equation for this process is Glucose → Ethanol + Carbon Dioxide.

Quick check

  1. What is the name of the single-celled fungus used in baking and brewing?1 mark
  2. What happens to the ethanol produced during the baking of bread?1 mark

3. Industrial Enzymes as Biological Tools

Enzymes are biological catalysts that can be extracted from microorganisms and used in industrial processes. They are highly specific and efficient, often allowing reactions to occur at lower temperatures and pressures, saving energy. For example, pectinase is used in fruit juice production. It breaks down pectin, a substance in plant cell walls, which helps to release more juice from the fruit and makes the juice clearer. In biological washing powders, proteases and lipases are included to break down protein-based stains (like blood) and fat-based stains (like grease) into smaller, soluble substances that can be washed away easily. This works effectively at lower wash temperatures, saving electricity.

Pectin (+ Pectinase) → Soluble sugars

Protein (+ Protease) → Amino acids

Fat (+ Lipase) → Fatty acids + Glycerol

Key term

Immobilised Enzymes: Enzymes that are physically attached to an insoluble material, allowing them to be easily separated from the products and reused.

Examiner insight

Students score well when they can clearly link a specific named enzyme (e.g., pectinase) to its specific industrial application (e.g., increasing fruit juice yield) and its substrate (pectin).

Worked example 13 marks

A company produces lactose-free milk.(a) Name the enzyme used.(b) Name the sugar it breaks down.(c) Name the products of this reaction.

  1. 1

    Step 1 (a): The enzyme used to break down lactose is lactase.

  2. 2

    Step 2 (b): The sugar it breaks down is lactose, the main sugar in milk.

  3. 3

    Step 3 (c): Lactase breaks down lactose into two simpler sugars: glucose and galactose.

Worked example 22 marks

Explain one advantage and one disadvantage of using biological washing powders.

  1. 1

    Step 1 (Advantage): They are effective at lower temperatures (e.g., 30-40°C), which saves energy and reduces electricity bills. This is because the enzymes provide an alternative reaction pathway with a lower activation energy.

  2. 2

    Step 2 (Disadvantage): The enzymes can be denatured if the wash temperature is too high. Also, some people can have allergic reactions to the enzymes if they come into contact with their skin.

Recap

  • Industrial enzymes are catalysts extracted from microorganisms.
  • Pectinase breaks down pectin to increase fruit juice yield.
  • Proteases and lipases in biological washing powders remove protein and fat stains.
  • Using enzymes allows industrial processes to run at lower temperatures, saving energy.
  • Lactase is used to break down lactose in milk to produce lactose-free dairy products.

Quick check

  1. Why does adding pectinase to fruit pulp increase the volume of juice extracted?2 marks
  2. Why should you not use a very hot water wash with a biological washing powder?1 mark

4. Penicillin: The Mould That Saves Lives

Penicillin is a famous antibiotic, a drug that kills bacteria. It was discovered by Alexander Fleming and is produced by the mould (a type of fungus) called *Penicillium*. For industrial production, the fungus is grown in a large fermenter under very specific conditions. Unlike yeast for ethanol, *Penicillium* needs a constant supply of oxygen for aerobic respiration to produce the penicillin. The fermenter is filled with a nutrient broth, and the culture is constantly stirred to keep the fungus in suspension and ensure even distribution of oxygen and nutrients. The temperature and pH are carefully controlled for maximum yield. Crucially, the entire process must be aseptic (sterile) to prevent contamination by bacteria, which could either destroy the penicillin or compete for nutrients.

Key term

Antibiotic: A chemical substance, produced by a microorganism, that kills or prevents the growth of bacteria.

Examiner insight

Marks are often awarded for explaining *why* sterile conditions are so crucial in penicillin production: to prevent contamination by other microbes that might compete for nutrients or even break down the penicillin being produced.

Common pitfall

Stating that antibiotics, like penicillin, can be used to treat viral infections like the flu or a cold. They are only effective against bacteria.

Worked example 15 marks

Describe the conditions required inside an industrial fermenter for the production of penicillin, and explain why each condition is necessary.

  1. 1

    Step 1 (Nutrients): A nutrient medium containing sugars and amino acids is provided for the fungus to grow and synthesise the antibiotic.

  2. 2

    Step 2 (Oxygen): A continuous supply of sterile air is bubbled through the medium because the fungus produces penicillin by aerobic respiration.

  3. 3

    Step 3 (Temperature): The temperature is maintained at an optimum (around 25-30°C) using a water jacket. This ensures the fungal enzymes work efficiently without denaturing.

  4. 4

    Step 4 (pH): The pH of the medium is monitored and kept at an optimum level. This prevents enzymes from denaturing.

  5. 5

    Step 5 (Asepsis): All inputs (nutrients, air) are sterilised, and the fermenter itself is sterilised before use (e.g., with high-pressure steam). This prevents contamination by other microorganisms that would compete for resources or spoil the product.

Recap

  • Penicillin is an antibiotic produced by the fungus *Penicillium*.
  • Antibiotics are drugs that kill bacteria, but they do not affect viruses.
  • Penicillin is produced in large fermenters under aerobic conditions.
  • Strict aseptic (sterile) conditions are essential to prevent bacterial contamination.
  • Temperature, pH, nutrient supply, and oxygen levels must be carefully controlled.

Quick check

  1. Name the microorganism that produces penicillin.1 mark
  2. Is the production of penicillin an aerobic or anaerobic process?1 mark

5. Mycoprotein: Growing Food in a Fermenter

Mycoprotein is a food product where the microorganism itself is the main ingredient. It is a protein-rich meat substitute sold under brand names like Quorn™. It is made from the mycelium (the thread-like body) of the fungus *Fusarium*. The fungus is grown in a large fermenter in a process that is continuous, unlike the batch process for penicillin. A sterile glucose syrup and minerals are fed into the fermenter, along with a supply of oxygen, as the fungus respires aerobically. The temperature and pH are carefully controlled. As the fungus grows, it is continuously harvested. The fungal biomass is then heat-treated to reduce the nucleic acid content, and pressed to give it a meat-like texture before being formed into products like burgers and sausages.

Key term

Mycoprotein: A food protein derived from the processed fungal mycelium (hyphae) of a microorganism like *Fusarium*, used as a meat substitute.

Fun fact

The fungus used for Quorn™, *Fusarium venenatum*, was originally discovered in a soil sample from a garden in Buckinghamshire, UK, in 1967 during a search for new sources of food protein.

Worked example 13 marks

State three advantages of producing protein in the form of mycoprotein compared to producing protein from beef cattle.

  1. 1

    Step 1 (Speed/Efficiency): Mycoprotein production is much faster. The biomass of the fungus can double in a few hours, whereas cattle take years to mature. It is also more efficient at converting its food source into protein.

  2. 2

    Step 2 (Land Use): Mycoprotein is produced in fermenters, which take up very little land space compared to the vast areas of land required for grazing cattle and growing their feed.

  3. 3

    Step 3 (Health/Welfare): Mycoprotein is low in fat and cholesterol-free, making it a healthier option. There are no animal welfare issues involved in its production.

Recap

  • Mycoprotein is a protein-rich food made from the fungus *Fusarium*.
  • In this process, the biomass of the microorganism itself is the product.
  • The fungus is grown in a fermenter under aerobic conditions on a glucose syrup.
  • Mycoprotein is a sustainable and healthy meat alternative that is low in fat.
  • Production is much faster and requires less land than traditional livestock farming.

Quick check

  1. What is the name of the fungus used to make Quorn™?1 mark
  2. What is the main carbohydrate source for the fungus when producing mycoprotein?1 mark

End-of-chapter exercise

Test yourself on the whole chapter. Work through these before moving on.

  1. State two reasons why microorganisms like bacteria and yeast are useful in biotechnology.2 marks
  2. Yeast is used in bread-making. (a) Name the gas that makes the dough rise. (b) Name the process that produces this gas. (c) What happens to the ethanol produced during this process?3 marks
  3. Describe how the enzyme lactase is used to produce lactose-free milk and explain why this product is important for some people.4 marks
  4. A fermenter is used for producing penicillin. Explain the purpose of the (a) water jacket, (b) air supply, and (c) sterile nutrient inlet.5 marks
  5. Biological washing powders contain enzymes like proteases. Explain how these enzymes work to remove stains and state one advantage of using them compared to non-biological powders.3 marks
  6. Describe the production of mycoprotein for use as a human food. Include the name of the microorganism, the conditions in the fermenter, and how the final product is made.6 marks
  7. Explain why aseptic precautions are essential when culturing microorganisms in a fermenter. Describe two specific aseptic precautions that would be taken.4 marks
  8. Compare and contrast the use of yeast in the production of bread and the production of ethanol for biofuel. Refer to the key process, useful products, and waste products in your answer.6 marks
  9. Define the term 'biotechnology'.2 marks
  10. Discuss two advantages and one disadvantage of producing protein as mycoprotein compared with producing protein by rearing cattle.3 marks

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