Biotechnology

Biotechnology

• state that biotechnology is the industrial use of living organisms (or parts of living organisms) to produce food, drugs or other products

Biotechnology – the industrial use of living organisms (or parts of living organisms) to produce food, drugs or other products.

• explain why microorganisms are often used in biotechnological processes

Many biotechnological processes make use of microorganisms (bacteria and fungi) as they have many advantages:

• Rapid growth in favourable conditions.
• Proteins and chemicals produced can be harvested.
• Can be genetically engineered to produce specific products.
• Grows well at low temperatures – lower than those chemical processes.
• Can be grown anywhere – not climate-dependent.
• Purer products than those produced in chemical processes.
• Can be grown using nutrient materials that are useless or toxic to humans.

  

• describe, with the aid of diagrams, and explain the standard growth curve of a microorganism in a closed culture

A culture is a growth of microorganisms. A pure culture contains one microorganism and a mixed culture contains multiple species.

1. Lag phase – organisms are adjusting to surroundings (taking in water, cell expansion, activating specific genes, synthesising specific enzymes. Cells are active but not reproductive = population remains fairly constant.
2. Log (exponential) phase – population size doubles each generation as every individual has enough space and nutrients to reproduce.
3. Stationary phase – nutrient levels decrease and waste products and other metabolites build up. Rate of death is equal to rate of reproduction.
4. Decline/death phase – nutrient exhaustion and increased levels of waste products and metabolites lead to death rate exceeding reproduction rate. Eventually, all organisms will die in a closed system.

• describe how enzymes can be immobilised

Immobilisation of enzymes – where enzymes are held, separated from the reaction mixture. Substrate molecules can bind to the enzyme molecules and the products formed go back into the reaction mixture leaving the enzyme molecules in place.

Methods for immobilising enzymes depend on ease of preparation, cost, relative importance of enzyme ‘leakage’ and efficiency of the particular enzyme that is immobilised.

• explain why immobilised enzymes are used in large-scale production

In many areas of clinical research and diagnosis and in some industrial processes, the product of a single chemical reaction is required. It is often more efficient to use isolated enzymes to carry out the reaction rather than growing the whole organism or using an inorganic catalyst. Isolated enzymes can be produced in large quantities in commercial biotechnological processes.

Downstream processing – the extraction of enzyme from the fermentation mixture, involving separation and purification of any product of large-scale fermentations.

• compare and contrast the processes of continuous culture and batch culture

Industrial-scale fermentations can be operated in two ways:

• Batch:
• The microorganism is mixed with a specific quantity of nutrient solution.
• It is left to grow for a fixed period with no further nutrient added.
• At the end of the period, the products are removed and the fermentation tank is emptied.
• For example, pencillin.
• Continuous:
• Nutrients are added to the fermentation tank.
• Products are removed from the fermentation tank at regular intervals/continuously.
• For example, insulin.

  

• describe the differences between primary and secondary metabolites

  

Metabolites – the products of metabolism (the sum of all of the chemical reactions in an organism), e.g. new cells and cellular components, chemicals such as hormones and enzymes, waste products such as carbon dioxide, oxygen, urea, ammonia, nitrates.

Primary metabolites – substances produced by an organism as part of its normal growth, e.g. amino acids, proteins, enzymes, nucleic acids, ethanol, lactate. The production of primary metabolites matches the growth in population of the organism.

Secondary metabolites – substances produced by an organism that are not part of its normal growth, e.g. antibiotic chemicals. The production of secondary metabolites usually begins after the main growth period of the organisms – does not match the growth in population of the organism.

• explain the importance of manipulating the growing conditions in a fermentation vessel in order to maximise the yield of product required

Commercial applications of biotechnology often require the growth of a particular organism on an enormous scale. An industrial-scale fermenter is essentially a huge tank, which may have capacity of tens of thousands of litres. The growing conditions in it can be manipulated and controlled in order to ensure the best possible yield of the product.

The conditions that affect the microorganisms being cultured include:

• explain the importance of asepsis in the manipulation of microorganisms

Asepsis – the absence of unwanted microorganisms.

Aseptic technique – refers to the measures to ensure that unwanted microorganisms do not contaminate the culture that is being grown or the products that are extracted.

The nutrient medium in which the microorganisms grow could also support the growth of many unwanted microorganisms. Any unwanted microorganism is called a contaminant. Unwanted microorganisms:

• Compete with the culture microorganisms for nutrients and space.
• Reduce the yield of useful products from the culture microorganisms.
• May cause spoilage of the product.
• May produce toxic chemicals.
• May destroy the culture microorganism and their