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...Industrial use of living organisms or parts of living organisms to produce food, drugs etc...

  • Extracellular - secreted out of the cell by exocytosis (produced inside)
  • Intracellular - produced in the cell - more expensive as the bacterial membrane has to be broken and the contents purified


  • work at moderate temperatures and pressures
  • biodegrable
  • specific - Act on one substrate


  • Sensitive to environmental change (denature)
  • Unstable when purified and expensive to purify

Biosensors - used for analysing biologically active compounds in solution. Enzymes are used because they are specific and sensitive. These can generate a colour change or a small electrical charge proportional to the substrate present

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Batch Cultures

  • Closed Culture - no nutrients added and no waste products removed
  • Product harvested once at the stationary phase
  • low product yield
  • Not expensive if contaminated
  • Secondary Metabolites - Molecules used to help microorganisms to survive, produced during the stationary phase

Continuous Cultures

  • Open culture - constant supply of nutrients and removal of waste products at exponential phase
  • High Yield
  • Expensive if contaminated
  • Primary Metabolites - molecules used for growth by microorganisms produced during the exponential growth phase
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Culture Medium

  • Sulfur - for the disulphide bonds needed in the territory level of structure
  • Carbon Source - corn syrup - for the carbohydrates needed in respiration
  • Nitrogen Source - for the production of amino acids in proteins in binary fission reproduction
  • Amino Acids - for proteins needed to produce enzyme

Downstream Processing - Growth of microbes followed by the production of enzymes you need. This is followed by extracting and purifying the enzyme from these microbes

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Immobilised Enzymes

Gel Entrapment - the enzyme is mixed with gel-forming ingredients and when the gel forms, the enzyme remains trapped in the gel matrix, the pores are large enough to let the substrate in, but not the enzyme
Chemical - covalent attachment of the enzyme to a supporting material
Adsorption - to various surfaces. however, as the attachment is not permanent, the method is usually only used for scientific studies or disposable enzymes
Encapsulation - enzymes are  in a compartment behind a semi-permeable (porous) membrane Advantages

  • No losses due to flushing away enzymes
  • No purification/Immediate reuse
  • more stable
  • enzymes can be altered


  • High initial investment
  • may lower catalytic activity/loss of activty when making beads
  • diffusion of substrates/products may be hampered by immobilisation layer
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