5.2.2

5.2.2: Biotechnology

(a) state that biotechnology is the industrial use of living organisms (or parts of living organisms) to produce food, drugs or other products (HSW6a);

Biotechnology is the industrial use of living organisms (or parts of living organisms) to produce food, drugs or other products. They can be used to produce food such as cheese or yogurt and also drugs such as Penicillin.

(b) explain why microorganisms are often used in biotechnological processes;

Microorganisms are used because they...

• Grow rapidly in favorable conditions
• Grow at low temperatures
• Are not climate dependent
• Can grow anywhere in the world
• Often produce other products which are released into the environment and can be harvested
• Can be engineered to produce specific products
• Often grow products which are more pure than those generated by chemical processes

(c) describe, with the aid of diagrams, and explain the standard growth curve of a microorganism in a closed culture;

Source

This is the standard growth curve which occurs for almost all microorganisms over the period of their growth. The lag phase occurs when the microorganisms are adjusting to their environment, this could involve taking up water for example. The exponential growth happens next when the nutrients are in a high concentration and waste products are low. Each generation doubles in size in this phase. The stationary phase is where the death rate and the reproductivity rate is equal. There is nutrient exhaustion and waste products begin to rise. Finally is the decline (death) phase, this is where the death rate increases above the reproductivity rate and eventually all microorganisms die. This is due to the increase in toxic waste and decrease in nutrients available.

(d) describe how enzymes can be immobilised;

Enzymes can be immobilised in many ways:

• Covalent bonding and adsorption both involve the bonding of the enzyme to the immobilising mixture. These bonds however are not strong and the mixture can become detached, leaving the enzymes immobilised
• Entrapment and membrane separation involves the immobilising mixture not being attached to the enzymes however it being passed over the enzymes, still immobilising them

(e) explain why immobilised enzymes are used in large-scale production;

Immobilised enzymes are used because they are...

• Not present in the products and therefore do not need to be removed from the products, this reduces purification costs
• More stable because the immobilising matrix stabilises the enzyme
• Immediately available for re-use, this is particularly useful in continuous processes

(f) compare and contrast the processes of continuous culture and batch culture;

Continuous culture is where the nutrients are added at regular time intervals and the products are removed at regular time intervals, this is how Insulin is made. Batch culture is where a known amount of nutrients are added at the start of the process, the process is given time to continue and the products are then removed from the fermentation vessel at the end when the fermentation vessel is emptied, Peniciliin is made in this way.

(g) describe the differences between primary and secondary metabolites;

Primary metabolites are products made by the microorganisms as part of their normal growth. These metabolites follow the growth curve. Secondary metabolites are products not made by the microorganisms normal growth. They usually begin to grow after the main growth period of the microorganism.

(h) explain the importance of manipulating the growing conditions in a fermentation vessel in order to maximise the yield of product required;

Growing conditions in the fermentation vessel can be manipulated to maximise the yield of the product. Manipulations can include changes in:

• pH
• Concentration of oxygen
• Nutrient time intervals and type of nutrient

(i) explain the importance of asepsis in the manipulation of microorganisms;

Asepsis is the absence of unwanted microorganisms. This is very important as unwanted microorganisms will compete for space and nutrients, may produce toxic chemicals, can cause spoilage and can destroy the desired products. This overall causes a decrease in the yield of wanted microorganisms.