The properties of microorganisms
Microorganisms (like bacteria and fungi) are useful for making products on an industrial scale because..
- They reproduce rapidly under the right conditions, so products can be made quickly.
- They have plasmids- these can be genetically modified so you can make the microorganism produce the product you need.
- Their biochemistry is quite simple- for example, fewer reactions happen in microorganisms than in humans. This means that the microorganism can be made to produce things that they normally wouldn't without causing them major problems.
- They can make complex molecules that are difficult to produce artificially.
- There are no ethical concerns with using microorganisms- they can be discarded.
The industrial use of microorganisms
Large amounts of micoorganisms are grown in containers called fermenters. The conditions inside fermenters are kept at the optimum for growth to get the highest yield of desirable product. Some of these products include:
- ANTIBIOTICS- Some types of bacteria and fungi can be used to produce medicines on a large scale. E.g. penicillin is an antibiotic made by growing Penicillium mould (a type of fungus) in a fermenter.
- FOOD FROM FUNGI- A type of single-celled-protein made by fungi is used to make meat substitutes for vegetarian meals, e.g. Quorn.
- ENZYMES FOR MAKING FOOD- Enzymes are needed to make some types of food e.g. cheese. Traditionally cheese is made using a mix of enzymes called rennet from the lining of a calf's stomach. Now chymosin (the important enzyme in rennet) can be produced by genetically modified microorganisms in large quantities-it's used as a vegetarian substitute for rennet.
- ENZYMES FOR WASHING POWDER- Enzymes produced by bacteria can be used to make biological washing powders because they help to break down stains. For example, amylase enzymes can remove carbohyrate stins (e.g. jam and chocolate) and lipases can get rid of fat stains (e.g, butter and oil).
- BIOFUELS- microorganisms can be used to make fuel, for example: Yeast can be used to produce ethanol, a waste product of anaerobic respiration. In some countries e.g. Brazil, cars are adapted to run on a mixture of ethanol and petrol- this is known as gasohol. Microorganisms can be used to produce biogas- a fuel that's used for things like heating, cooking and lighting. It's made by fermentation of plant and animal waste containing carbohyrates.
GENETIC MODIFICATION is where a gene from on organism is transferred to another.
The organisms with the transferred gene will the produce a protein using instructions in that gene. The protein can be made even though the gene came from another organism because all orgainsms have the same genetic code.
The important stages of genetic modification:
- First the gene that's responsible for producing the desirable protein is isolated- its position on the source DNA is identified.
- The useful gene is then rreplicated to create lots of copies.
- Each gene is joined to a vector- a carrier for the gene with makes it easier to insert into the new cell. Plasmids and viruses are often used as vectors.
- Vectors containing the useful gene are transferred into new cells, e.g. bacterial cells.
- Not all of the new cells will be modified, e.g. the vector might not have been transferred properly.
- Theindividuals that have been successfully modified are then selected.