Why microorganisms are useful
Biotechnology uses living organisms, especially bacteria and fungi, to make useful products. Microorganisms are ideal because they reproduce very rapidly, need only simple, cheap nutrients, have no ethical concerns compared with animals, and can be grown in large fermenters in any climate.
Key idea
In a fermenter, conditions are controlled: temperature (a water jacket cools the reaction), pH, oxygen supply (for aerobic microbes) and nutrient concentration are all monitored to give the best yield.
Yeast, bread and alcohol
Yeast is a fungus that respires anaerobically, turning sugar into ethanol and carbon dioxide.
Worked example
glucose → ethanol + carbon dioxide (+ energy). In brewing the ethanol is the useful product; in bread-making the carbon dioxide is useful because the gas bubbles make the dough rise.
Useful enzymes
Remember
- Biological washing powders contain proteases and lipases that digest protein and fat stains at low temperatures.
- Lactase converts lactose to make lactose-free milk.
- Pectinase increases the yield and clarity of fruit juice.
- Penicillin (an antibiotic) is made by growing the fungus Penicillium in fermenters.
Using enzymes in industry saves energy (they work at lower temperatures) and gives fast, specific reactions. To keep the microorganisms working well, everything added to the fermenter is first sterilised to kill unwanted microbes, a paddle stirs the mixture so nutrients and oxygen reach every cell, and sensors continuously check the pH and temperature. Because microorganisms grow so quickly and can use waste materials as food, biotechnology gives a cheap, reliable and continuous supply of foods, fuels and medicines.