Microbiology & Biotechnology

Biotechnology Applications

5th Year · 6th Year (Leaving Cert)

✓By the end of this lesson students will be able to define biotechnology and give examples of its applications.
✓By the end of this lesson students will be able to describe the role of microorganisms in fermentation processes for yoghurt, beer, and bread production.
✓By the end of this lesson students will be able to explain the production of antibiotics and the concept of immobilised enzymes, including their advantages.
✓By the end of this lesson students will be able to outline the function of key components in a bioreactor and discuss its advantages for industrial processes (HL).

Key concepts

Biotechnology

Biotechnology is the use of living organisms, or their products, to make or modify products or processes for specific use. It involves applying biological organisms, systems, or processes to technological and industrial uses.

Fermentation

Fermentation is a metabolic process that produces chemical changes in organic substrates through the action of enzymes. In the context of biotechnology, it typically refers to anaerobic respiration carried out by microorganisms to produce useful products like alcohol, acids, or gases.

Yoghurt Production

Yoghurt is produced by the fermentation of milk by specific bacteria, primarily Lactobacillus bulgaricus and Streptococcus thermophilus. These bacteria convert lactose (milk sugar) into lactic acid. The lactic acid causes the milk proteins (casein) to coagulate, thickening the milk and giving yoghurt its characteristic texture and tangy flavour. The process occurs at warm temperatures (approx. 40-45°C).

Beer Production

Beer is produced by the fermentation of malted barley (or other grains) by yeast, typically Saccharomyces cerevisiae. The yeast ferments sugars (derived from the malt) into ethanol (alcohol) and carbon dioxide. The process involves malting, mashing, boiling (with hops), fermentation, and maturation. Fermentation usually occurs at controlled temperatures (e.g., 18-25°C for ales, 8-12°C for lagers) in large vats.

Bread Production

Bread production involves the fermentation of sugars in dough by yeast, Saccharomyces cerevisiae. The yeast respires anaerobically, producing carbon dioxide and ethanol. The carbon dioxide gas gets trapped in the dough, causing it to rise and giving bread its light, airy texture. The ethanol evaporates during baking. The process requires warmth for optimal yeast activity.

Antibiotics Production

Antibiotics are chemical substances produced by microorganisms (e.g., fungi, bacteria) that kill or inhibit the growth of other microorganisms. Penicillin, a widely used antibiotic, is produced by the fungus Penicillium chrysogenum. Industrial production involves growing the fungus in large bioreactors under carefully controlled conditions, often using a batch culture method where the fungus is grown, the antibiotic is extracted, and the bioreactor is then cleaned and refilled.

Immobilised Enzymes

Immobilised enzymes are enzymes that are fixed, or bound, to an inert, insoluble material, such as alginate beads, cellulose, or glass. This prevents them from mixing freely with the substrate and product. Advantages include: enzymes can be reused, the product is not contaminated with enzyme, increased enzyme stability (less denaturation), and continuous processes are possible.

Bioreactors (HL)

A bioreactor is a vessel designed to maintain optimal conditions for biological processes, such as the growth of microorganisms or cells, or the activity of enzymes. They are used for large-scale industrial production of products like antibiotics, enzymes, and vaccines. Key components include: a stirrer (for mixing and aeration), an inlet for nutrients, an outlet for products, probes for monitoring pH and temperature, an air inlet (for aerobic processes), and a cooling jacket (to remove heat generated by metabolic activity).

Key facts to remember

1Biotechnology uses living organisms or their products for specific applications.
2Fermentation is an anaerobic process carried out by microorganisms, producing substances like lactic acid (yoghurt) or ethanol and carbon dioxide (beer, bread).
3Lactobacillus and Streptococcus bacteria ferment lactose to lactic acid in yoghurt production.
4Saccharomyces cerevisiae (yeast) ferments sugars to ethanol and carbon dioxide in beer and bread making.
5Antibiotics, such as penicillin, are produced by microorganisms like Penicillium chrysogenum.
6Immobilised enzymes are fixed to an inert support, offering advantages like reusability and increased stability.
7Bioreactors (HL) are large vessels designed to maintain optimal conditions (pH, temperature, aeration, nutrients) for large-scale biological processes.
8Key components of a bioreactor include a stirrer, probes for pH and temperature, nutrient inlets, and a cooling jacket.

Worked examples

Example 1

Outline the process of making yoghurt, identifying the key microorganisms involved and their role.

IMilk is heated to about 80-90°C to kill unwanted microorganisms and denature milk proteins, which helps with thickening.

IIThe milk is then cooled to an optimal fermentation temperature, typically 40-45°C.

IIIA starter culture containing specific bacteria, primarily Lactobacillus bulgaricus and Streptococcus thermophilus, is added to the milk.

IVThese bacteria ferment the lactose (milk sugar) into lactic acid.

VThe lactic acid causes the milk proteins (casein) to coagulate, leading to the thickening of the milk and giving yoghurt its characteristic texture and tangy flavour.

VIThe fermentation continues until the desired acidity and consistency are reached, after which the yoghurt is cooled to slow down bacterial activity.

Answer

Yoghurt production involves heating milk, cooling it, and then adding a starter culture of Lactobacillus bulgaricus and Streptococcus thermophilus. These bacteria ferment lactose into lactic acid, which coagulates milk proteins, resulting in the thick, tangy product. The process is stopped by cooling.

Remember to name the specific bacteria and the product of their fermentation (lactic acid).

Example 2

Explain three advantages of using immobilised enzymes in industrial processes.

I**Enzyme Reusability:** Immobilised enzymes can be easily separated from the product and reused multiple times, reducing production costs.

II**Product Purity:** Since the enzymes are fixed, they do not contaminate the final product, simplifying downstream purification processes.

III**Increased Stability:** Immobilisation often provides a more stable environment for the enzyme, protecting it from denaturation by heat or pH changes, thus extending its lifespan and activity.

IV**Continuous Processing:** Immobilised enzymes allow for continuous flow systems, where substrate can be continuously passed over the enzyme, and product collected, leading to more efficient large-scale production.

Answer

Three advantages of using immobilised enzymes in industrial processes are: they can be easily reused, leading to cost savings; the final product is not contaminated by the enzyme, simplifying purification; and the enzymes often exhibit increased stability, allowing for a wider range of operating conditions and longer operational life. Additionally, they facilitate continuous processing.

Focus on the practical benefits for industry, such as cost, efficiency, and product quality.

Example 3

(HL) Describe the function of any three labelled components of a typical bioreactor.

I**Stirrer/Impeller:** The stirrer ensures thorough mixing of the culture medium, nutrients, and microorganisms. It also helps to distribute heat evenly and, in aerobic processes, ensures adequate aeration (oxygen supply) throughout the culture.

II**pH Probe and Controller:** The pH probe continuously monitors the pH of the culture medium. The controller automatically adds acid or alkali to maintain the optimal pH range for the microorganisms or enzyme activity, preventing denaturation or inhibition.

III**Temperature Probe and Cooling Jacket/Heating Coil:** The temperature probe monitors the temperature inside the bioreactor. The cooling jacket (or heating coil) circulates water or other fluids to remove excess heat generated by metabolic activity (or to add heat if needed), maintaining the optimal temperature for the biological process.

IV**Air Inlet/Sparger:** For aerobic processes, the air inlet introduces sterile air (or oxygen) into the bioreactor, providing the necessary oxygen for microbial respiration. The sparger disperses the air into fine bubbles for efficient oxygen transfer.

Answer

Three components of a bioreactor and their functions are: a stirrer, which mixes the culture and ensures even distribution of nutrients and oxygen; a pH probe and controller, which monitor and maintain the optimal pH by adding acid or alkali; and a temperature probe with a cooling jacket, which monitors and regulates the temperature to prevent denaturation or inhibition of biological activity.

For HL, it's crucial to understand *why* each component is necessary for optimal conditions.

Common mistakes

✗Confusing aerobic respiration with anaerobic fermentation; fermentation specifically refers to anaerobic processes.
✗Not naming the specific microorganisms involved in each fermentation process (e.g., just 'bacteria' instead of 'Lactobacillus bulgaricus').
✗Forgetting the specific products of fermentation (e.g., lactic acid for yoghurt, ethanol and CO2 for beer/bread).
✗Listing advantages of immobilised enzymes without sufficient explanation of *why* they are advantages (e.g., 'reusable' instead of 'reusable, reducing costs').
✗Forgetting that bioreactors require sterile conditions to prevent contamination by unwanted microorganisms.

Exam tips

★Learn specific examples for each application: microorganism, substrate, and product. This is a common exam question.
★Be able to clearly state and explain the advantages of immobilised enzymes and bioreactors (HL).
★For bioreactors (HL), practice drawing and labelling a diagram, and be able to explain the function of each labelled part.
★Understand the underlying biological principles, such as anaerobic respiration, that drive these biotechnological processes.

Ready to practise?

Try a problem on this topic

Snap a photo or type a question — get step-by-step working instantly.

Solve a problem →← Biology curriculum