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Biotechnology means using microbes to make useful products. Microbes include bacteria and yeast- a...

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  • Biotechnology means using microbes to make useful products.

    Microbes include bacteria and yeast- a fungus.

    Useful products include bread, beer, wine, human antibiotics, insulin, biological detergents.

    Biotechnology is a major growth industry in Biology.

  • YeastYeast is a single-celled fungus.

    It uses sugar as a food supply

    Yeast reproduces new cells in a process called budding

    Word equation

    nucleuscytoplasmcell wallbudsSugar carbon dioxide + alcohol + energy

  • Respiration in YeastYeast respires glucose to obtain energy. If oxygen is present it will carry out aerobic respiration, which releases most of the energy from the glucose. If oxygen is not available it will continue to respire anaerobically, but in doing so receives much less energy.Aerobic respirationglucose+oxygenlots of energy+carbon dioxide+waterAnaerobic respiration (fermentation)glucosea littleenergy+carbon dioxide+ Alcohol (ethanol)CREDIT

  • Fermentation Experimentthermometerlayer of oilvacuum flaskbicarbonate indicatorYeast in boiled and cooled glucose solutionBoiling removes dissolved oxygen and kills all microbes. Cooling prevents yeast being killed when added.Oil keeps oxygen out of yeast and sugar mixture.Shows release of heat.Prevents heat loss.Detects release of carbon dioxide.Control the same as shown but use dead yeastCREDIT

  • ResultsAfter 2 days;CREDIT

    Experimental flaskControl flaskThermometer readingRises from 20oC to 23oCNo changeBicarbonate indicator colour changeOrange to yellowNo changeDistillation of liquid in flask at 80oCEthanol collectedNo ethanol

  • Yeast is used in the baking and brewing industries.Uses of YeastRespiration in yeast releases bubbles of carbon dioxide which spread through the dough, making it rise. Yeast Ferments the sugars in fruit and grains to produce alcohol.

  • Alcoholic fermentationBrewers Yeast releases energy from sugar in the absence of oxygen (anaerobically) to produce alcoholBrewingThe sugars required are obtained from barley grains during a process called malting.MaltingBarley grains are soaked in water for 2 days.

    The seeds germinate and the enzyme amylase changes starch into sugar.Endosperm (starch store)CREDIT

  • Maltings BuildingCREDIT

  • Effect of germination on barley grainsdry barley grains contain starch but not simple sugarbarley grains that have been allowed to germinate for a few days contain simple sugar but only a little starchgerminating seeds need;

    wateroxygen warmth ConclusionStarch is broken down to simple sugar during germinationCREDIT

  • starchsimple sugaramylasethis degradation process is brought about by an enzyme - amylase normally in seed germination the sugar is used to provide food for the developing plantin brewing the sugar is used to provide food for yeast for fermentationCREDIT

  • After malting;

    The germinated barley grains are ground up with hot water to make a mash.This is sprayed with hot water to retrieve the sugars.The sugary liquid is boiled with hops in a wort kettle to give flavour and remove all unwanted microbes.The resulting mixture (called wort) is cooled, yeast are then added and grown under ideal conditions in a fermenter.The resulting beer is allowed to mature in casks.CREDIT

  • growing condition required by yeastway in which growing condition is providedfood supplystarch converted to sugar for yeast by germinating barley grains on floor of malting housesuitable temperaturetemperature of fermenter vessel controlled by thermostatlack of competitionall other micro-organisms killed by boiling in wort kettle before yeast is addedCREDIT

  • FermentersA fermenter is a vessel which can be used to manufacture a range of products in the presence or absence of oxygen.They can be small and simple . or large and complex needing to be monitored by computer.CREDIT

  • Brewing -- Commercial Batch Processing


  • Batch Processing This is the technique used by commercial brewers to provide the best conditions for fermentation.

    The common feature of all batch processes is that they involve closed systems.

    After the addition of the raw materials, nutrients and yeast culture, the system is left untouched, although controlled, until fermentation ends.The beer then has to be drawn off and separated from the yeast, and the fermenter system needs to be cleaned and sterilised before being re-used. This wastes time and money.Fermentation ends because nutrients run out or waste materials build up.CREDIT

  • In brewing, the fermenter is a large copper tank into which are placed the nutrients and yeast Sensors monitor the pH, temperature and oxygen concentration to provide ideal growing conditions for the yeast.( about 10oC 18oC and a pH of about 7)(Respiration produces heat)CREDIT

  • ImmobilisationImmobilisation involves attaching a cell or enzyme to another substance so that it cant move freely.Whole cells such as yeast can be trapped inside gel beads.Enzymes can be attached to glass beads.enzymesenzymes attached to glass beadCREDIT

  • Free YeastImmobilised Yeast

  • Many industries use immobilised cells or enzymes because;

    Products are separated easily and cheaply from cells or enzymes

    Products are easily purified.

    Less waste as cells / enzymes can be re-used

    Can be used in continuous flow processingCREDIT

  • Commercial Continuous Flow ProcessCREDIT

  • Continuous flow processingRaw materials continuously fed inProduct continuously removedEnzyme (or cell) immobilised to glass / gel bead Glass / gel beadFermenter vesselCREDIT

  • Continuous Flow Process;Can be expensive to develop and set up, but;

    Raw materials are continuously added to the fermenter, so the cells / enzymes receives a steady stream of raw materials.

    Product does not have to be separated from cells / enzymes, so money saved.

    Cells / enzymes can be used again, so money saved.

    Valuable time not lost in cleaning out and re-setting fermenter as in batch processing.

    Less waste and pollution as cells / enzymes not discarded.


  • Fresh milk from a cow contains many bacteria The bacteria multiply and make the milk go sour. Lactose sugar in milk is broken down by bacteria to lactic acid Milk is pasteurised before we can drink it to remove harmful bacteria. Putting the milk in the fridge slows down the growth of any remaining bacteria.The souring of milk by producing lactic acid is a Fermentation process BacteriaLactose sugar Lactic AcidMilk Fermentation by BacteriaCREDIT

  • Making yogurtYogurt relies on the souring of milk by bacteria.The milk is sterilised by heatingBacteria are addedThe bacteria feed on the milk sugar (lactose) and convert it to lactic acid , this makes the milk curdle and go lumpy and gives yoghurt its sour tasteFlavourings and colourings are added to give the final product.

  • How Cheese is MadeBacteria are added to the milk to make it go sour.

    Next an enzyme called rennin is added.

    This breaks down the proteins in milk and causes the milk to separate into solids (curds) and a liquid (whey).

  • The liquid whey is then drained off.The curd is finally allowed to ripen and mature to form cheese.Some cheeses are then flavoured by adding different microbes.Blue stilton

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