Biotechnology
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Biotech is the application of biological organisms, systems or processes, to manufacturing and
service industries.
Genetic modification involves the transfer of genes from one organism to an unrelated species.
Both processes involve bacteria as;
1. They can make complex molecules (eg: proteins)
2. They have rapid repro rate (x3 an hour)
3. They can be grown and manipulated without raising ethical concerns.
Bacteria have a genetic code that is the same as all organisms, so plant or animal genes can be
transferred into bacterial DNA.
Bacterial DNA is in the form of a circular strand, or as plasmids (small circular pieces)
Scientists can cut open plasmids and insert sections of DNA from other org.
When the bacteria divides, the DNA in the modified plasmid is copied including the added DNA.
Yeast, other fungi, bact or enzymes from other org are involved in;
1. Bread-making
2. Wine-baking
3. Brewing beer
4. Production of cheese
5. Antibiotic production
6. Production of industrial chemicals (eg: citric acid, lactic acid)
7. Sewage disposal
Fermentation
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This includes a wide range of reactions under the influence of enzymes or microorganisms such as
yeast
Eg: anaeroabic respiration of glucose to ethanol
Microorganisms involved in fermentation use chemical reactions to release energy for their
metabolism
1. Ethanol production
 Ethanol (alcohol is produced from fermented sugar or spare grain by yeast
 Ethanol is used as a renewable energy source for cars in Brazil, Zimbabwe and USA, and produces
less pollution than petrol.
Disadvantages:
1. Not economical as the energy used to grow, fertilize, harvest, and transport sugar cane, then
extract the sugar and convert to ethanol, is more than the energy released by ethanol when it
burns.
2. Env costs – forests are destroyed to plant soy beans/oil palms
 Another biofuel, oil from rapeseed/sunflower seed could replace diesel – less polluting but
expensive to produce.
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Bread production
Flour, water, salt, oil and yeast are mixed to make a dough.
Water activates amylase already present in the flour, which digests some starch into sugar.
With highly refined white flour, adding sugar to the dough helps the process
Yeast ferments the sugar into ethanol and CO2
A protein called gluten gives the dough a sticky, elastic texture, and the CO2 makes bubbles in the
dough to make the bread light in texture.
The dough is kneaded and left for an hour or two at 27°C to allow yeast to respirate.
As the CO2 bubbles build up, the dough rises to about double its volume
The dough is then baked at about 200°C to;
1. Make the bubbles expand more
2. Kill the yeast
3. Evaporate the small quantities of ethanol
Fruit juice production
Pectinases are enzymes extracted from fungi, that are used to separate juice from fruit
They break down pectin, a jelly-like substance that sticks plant cell walls to each other.
During the breakdown process different polysaccharides are released which make the juice cloudy
Pectinases are used to break these down and make the juice more transparent.
The sugars produced also make the juice sweeter.
4. Biological washing powders
 In food and textile industries, proteases and lipases are commercially produced.
 When combined in washing powders, they remove stains in clothes causes by;
1. Proteins – blood or egg
2. Lipids – grease or oil
 Protein and lipid molecules are large and insoluble, but when digested into small, soluble molecules,
they can pass out of cloth.
 Bio washing powers save energy as they can be used to wash clothes at lower temp
 However, if put in hot water, the enzymes denature and the powder becomes ineffective.
Fermenters
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A fermenter is a large, sterile container used to grow microorganisms (bacteria or fungi) on a large
scale, to produce useful products such as insulin, penicillin, mycoprotein.
Production of lactose-free milk
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Lactose is a type of disaccharide sugar found in milk and dairy products.
Lactose intolerance is a digestive problem where the body does not produce enough lactase, so
lactose stays in the gut and is fermented by gut bacteria.
This causes symptoms such as flatulence (wind), diarrhea, stomach pains.
Lactose-free milk is now produced using enzyme lactase, which breaks down lactose sugar into 2
monosaccarides; glucose and galactose – both can be absorbed by the gut.
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Lactase is produced on a large scale by fermenting genetically modified yeast or fungi that carry the
lactase gene.
An alt. large-scale method is to immobilize lactase on the surface of beads, then pass milk over the
beads to remove the lactose.
The advantage is that the enzyme molecules stay on the beads.
Yoghurt production
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Lactase is used in yoghurt production as it speeds up the process and makes yoghurt taste sweeter.
The bacterial culture (2 main species of bact) is added to pasteurized milk at 42°C to ferment the
lactose and produce lactic acid
The acid increases acidity of fermented milk to pH 4.5 and this causes milk to clot and form yoghurt
with a natural sharp taste.
Antibiotic production
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Microorganisms may synthesize antibiotics that destroy other microorganisms, and so they are
grown in fermenters.
Antibiotics attack bacteria is various ways;
1. Upset the production of cell walls
2. Stops reproduction
3. Causes bacteria to burst open
4. Affect protein synthesis and stop bacterial growth.
As animal cells do not have cell walls and have dif cell structures, the antibiotic does not damage
human cells.
However, allergic reactions may occur.
Penicillin is an antibiotic produced by the fungus Penicillium that was discovered by Alexander
Fleming in 1928.
Penicillin can be chemically altered in the lab to make them suitable against many diseases;
ampicillin, methicillin, oxacillin.
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The tank is filled with nutrient solution – sugar, lactose or corn-steep liquor, AA.
Mineral salts added, pH is adjusted between 5 and 6, temp is maintained at about 26°C, and wind is
blown through the liquid and it is stirred.
A culture of the microorganism is added to nutrient liquid and allowed to grow for 24-48 hours.
As the nutrient supply reduces, the microorganism begins to secrete antibiotic.
This nutrient fluid containing the antibiotic is filtered off, and the antibiotic is extracted by
crystallization.
5. Production of insulin
 DNA in bacteria is genetically modified to carry the human insulin gene.
 Bacteria respire aerobically, so air is pumped into the fermenter.
 Conditions such as nutrient levels, temperature, pH and moisture is maintained at optimum levels
for bacteria growth and repro.
 Nutrients are then reduced and bacteria begin to produce insulin.
6. Mycoprotein
 This is a protein-rich meat substitute extracted from fungi, and contains no cholesterol and is lower
in saturated fats than meat.
 Fermented in a similar way to enzymes and antibiotics, using glucose and salts as the feed stock.
 One type of mycoprotein is called Quorn.