Bacteria can be grown in large numbers in the laboratory. This is called culturing. Your teacher will supply you with some sterile nutrient agar media in Petri dishes. These dishes should be sterile or free of all microorganisms. Nutrient agar contains all the nutrients bacteria require in order to grow.
1. You will attempt to culture bacteria from five separate sources: soil, air, water, skin and hair. It is very important that you follow your teacher’s instructions, as culturing bacteria in large numbers can create a risk of infection.
2. Monitor the growth of bacteria by taking pictures of sealed, unopened plates every 24 hours.
z The Importance of Bacteria
Bacteria play a very important role in cycling matter through the Earth: z z
Some bacteria can photosynthesise. This means that they take in carbon dioxide from the air, which helps reduce global warming.
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The majority of bacteria are decomposers. By breaking down dead organisms, bacteria release the nutrients back into the environment for other organisms to use.
Learn more about the cycling of matter in Earth and Space 22.2
The following table outlines other benefits of bacteria. Use
Example Food Vitamins Antibiotics Biotechnology Natural gas
Bacteria can be used to make yoghurt and cheese from milk. Probiotics contain living cultures of bacteria that help keep the gut healthy
Bacteria in the large intestine produce vitamins B and K
Bacteria produce antibiotics that can be used to treat certain diseases
E. coli has been genetically engineered to produce insulin, which is used to treat diabetes
Bacteria can be used in piggeries to break down waste organic matter, reducing the amount of waste and producing natural gas as a fuel
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Learn more about global warming in Earth and Space 25.2
