I/GCSE Biology - Microbiology

• Microorganisms can be grown in an agar culture medium with a carbohydrate energy source and various minerals, vitamins and proteins
• You need to take careful safety measures and use sterilized equipment to grow uncontaminated cultures of microorganisms and to avoid the growth of harmful pathogens

• Yeast is a single celled organism which can respire aerobically producing CO₂ and water. This reaction is used in bread making to make dough rise
• Yeast can also respire Anaerobically, producing Ethanol and CO₂ in a process called Fermentation
• The fermentation reaction of yeast is used to produce ethanol in the production of Beer and Wine

• Bacteria are used in making yoghurt and cheese
• In the production of yoghurt a starter culture acts on warm milk. In I/GCSE Biology, lactose is converted to lactic acid in a process called Lactic Fermentation. This changes the texture and taste of the milk to make yoghurt
• In cheese making a different starter culture is added to warm milk giving a lactic fermentation which results in solid Curds and liquid Whey.
• The curds are often mixed with other bacteria or moulds before they are left to ripen into cheese.

• In I/GCSE Biology, microorganisms can be grown on a large scale in vessels known as Fermenters to make useful products such as antibiotics and Mycoprotein food (Quorn)
• Industrial Fermenters usually have a range of features to make sure the fermentation takes place in the best possible conditions for the maximum yield of product
• The fungus Fusarium is grown on sugar syrup in aerobic conditions to produce Mycoprotein foods

Diagram: The chemical structure of penicillin

• The antibiotic penicillin was discovered by Alexander Fleming; the method of mass production was the work of Howards Florey and Ernst Chain
• Penicillin is made by growing the mould Penicillium In a Fermenters
• The medium contains sugars, and other nutrients and has a good supply of Oxygen
• The mould only starts to grow penicillin when the nutrients have been used up

• In I/GCSE Biology, biogas is mainly methane and can be produced by anaerobic fermentation of a wide range of plant products and waste materials that contain carbohydrates
• Many different organisms are involved in the breakdown of material in biogas production

• Ethanol based fuels can be produced by the anaerobic fermentation of sugar cane juices and from glucose derived from maize starch by the action of the enzyme Carbohydrase
• Ethanol is distilled from the fermentation products and can be used as a fuel in motor vehicles on its own or mixed with petrol to produce Gasohol

That's the end of the topic!

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