Monday, 10 June 2013

A2 Biology: Biotechnology

Biotechnology involved the exploitation of living organisms or biological processes to improve agriculture, animal husbandry, food science, medicine and industry

Food production

  • Yoghurts and cheese
    • produced by bacterial growth in milk
    • this chnages the texture and flavour
    • the bacteria prevent the growth of those bacteria that caue spoilage
    • this helps preserve ood
  • 'Qourn'
    • produced by the growth of a fungus 'Fusarium'
  • The fungal mass (mycelium) is processed and shaped into food
  • Soy Sauce
    • Roasted soya beans are fermented with yeast of fungus such as Aspergillus.
Drugs and pharmaceuticals
  • Penicillin
    • this is a product of the growth of a fungus called Penicillium.
    • It is a by-product of the organisms metabolism
    • this is isolated from the growth medium and is used as an antibiotic
  • Insulin
    • Bacteria such a E.coli are genetically modified to carry human insulin gene
    • they secrete insulin as they grow
Bioremediation of waste products
  • a variety of bacteria and fungi use organic waste in the water as nutrients and make wast harmless
  • e.g. Fusarium grown on corn steep liquor, a waste product of the corn milling industry.
Why use bacteria and Fungi?
  • grows rapidly in favourable conditions
  • can produce chemicals or proteins that are released into the surrounding medium and ce be harvested
  • can be genetically modified to produce specific products
  • grow well at relatively low temperatures
  • can be grown anywhere in the world - not climate dependant
  • generated products that are in a pure form than those generated via chemical processes
  • can often be grown using nutrient materials that would otherwise useless or even toxic to humans
GROWTH CURVE

What is a culture?
  • it's a growth of micro-organisms
  • it may be pure culture (single species) or mixed culture (mix of species)
  • they can be cultured in liquid broth or solid nutrient agar gel.
Lag phase - organisms adjusting to conditions, cells active but not reproducing. Population is fairly constant
Log phase - population size doubles each generation. plenty of space and nutrients to reproduce.
Stationery phase - nutrients level decrease, waste products builds up. Death rate = production rate
Death phase - nutrients exhaustion, increased level of toxic waste products. Death rate > reproduction rate.

FERMENTATION

  • Fermentation refers to the culturing of micoorganisms
  • they could grow both aerobically and anaerobically in tanks called fermenters
Fermenters
  • growth of an microorganism on an enormous scale
  • begins with a 'start culture' a small pure culture from whicl all microorganis will grown
  • conditions
    • temperature
    • type and tie of addition of nutrients
    • O2 concentration
    • pH

  • Batch culture
    • microorganisms mixed with specific quantity of nutrients then grown for a fixed period, no further nutrients added
    • advantages and disadvantages
      • growth rate slower
      • easy to set up and maintain
      • if contaminated, one batch is lost
      • lless efficient - not operating all the time
      • useful for producing secondary metabolites
  • Continuous culture
    • microorganisms mixed with nutrients and nutrients are added continuously  with products removed continuously throughout the process
    • advantages and disadvantages
      • growth rate higher
      • difficult to set up and maintain
      • if contaminated, huge volumes lost.
      • ore efficient, operated continuously
      • useful fro primary metabolites.
  • Aseptic technique - asepsis
    • unwanted micro-organisms can contaminate the fermentation process
    • to avoid this, aseptic technique ensures contamination of the culture does not occur
    • contamination may result in products being unsafe
    • unwanted micro-organisms
      • compete with culture micro-organisms for nutrients and space
      • reduce the yield of the product
      • may cause spoilage, produce toxic chemicals or destroy the culture micro-organisms

    Metabolism and metabolites

    • Metabolites include:
      • chemicals such as hormones and enzymes
      • waste products e.g. CO2, urea and O2
      • these can be nutrients required by other organisms
    • primary metbolites
      • these are produced by organisms as part of its normal growth
        • amino acids
        • proteins
        • enzymes
        • ethanol
        • lactate
    • secondary metabolites
      • these are produced by the organism and are not part of its normal growth
        • antibiotic chemicals
        • produced y a small number of microorganisms
    Industrial enzymes
    • Commercial use of enzymes
      • Pectinase can be used in fruit juice extraction
      • Metabolic enzymes in the bacteria A. niger produce citric acid used in detergents
    • Downstreaming
      • isolated enzymes can be produced in large quantities through biotechnology
      • their extraction from the fermentation medium is known as downstream processing
      • this is their separation and purification
    • Immoilising enzymes
      • when using enzymes in industry they need to be removed after they have served their purpose
      • this can be a costly process
      • it is possible to immobilise enzymes and prevent them from mixing
      • immbolisation
        • this is a technique were enzyme molecules are held, separated from the reaction mixture
        • substrate molecules can bind to the enzymes and the products are formed go back into the reaction leaving the enzymes in place
        • methods
          • adsorption
          • covalent bonding
          • entrapment
          • membrane separation 

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