chapter 22

• biotechnology


  applying biological organisms or enzymes to the synthesis, breakdown or transformation of materials in the service of people
• most common organisms used in biotechnology:

  • fungi
  • yeasts
  • bacteria
• biotechnology involves using enzymes in a manufacturing process and the most stable and effective form of the enzyme is a whole microorganism
• advantages of using microorganisms for biotechnology

  • no welfare issues to consider, only optimum conditions for growth
  • wide range of chemical synthesis can take place
  • genetic engineering allows artificial manipulation of microorganism e.g to produce human insulin
  • have a short life cycle and rapid growth rate
  • nutrient needs are cheap and simple, raw materials made can be re used by genetic manipulation
  • low temperature needed to grow and low supply of oxygen and food is needed, provide own catalysts in form of enzymes
  • make bioprocesses cheap

  
• microorganisms caan be used to make bread, yogurt and cheese, they have an indirect effect as their action on other foods are important
• microorganisms are involved in baking, brewing, cheese making and yogurt making
• advantages of using microorganisms to produce human food

  • microorganisms reproduce fast and produce protein fast
  • have high protein and little fat
  • can use a wide variety of waste to reduce costs
  • can be genetically modified to produce protein required
  • growth is not dependant on weather or breeding cycles
  • no welfare issues
  • can be made to taste like anything
• disadvantages of using microorganisms to produce human food

  • some can produce toxins if conditions not optimum
  • microorganism has to be separated from nutrient broth
  • need sterile conditions that add to cost
  • involve GM and there are welfare concerns to GM
  • protein has to be purified to contain no toxins
  • people dislike the thought of eating food grown on waste
  • little natural flavour so needs additives
• penicillin needs high oxygen levels and a rich nutrient medium to grow well, it's sensitive to pH and temperature and affects the way it's produced commercially, and it is grown in a semi continuous batch
• in the first stage of penicillin production, the fungus grows and in the second stage it produces penicillin, then the drug is extracted from the medium and purified
• penicillin production


  • relatively small fermenters needed because it is very difficult to maintain high levels of oxygenation in large bioreactors
  • mixture is continuously stirred to keep it oxygenated
  • rich nutrient medium
  • growth medium contains a buffer to maintain pH around 6.5
  • bioreactors are maintained about 25-27 celcius
• reasons why insulin is no longer extracted from animals

  • erratic supply
  • people can have allergies to impure insulin
  • animal insulin takes longer to have an effect than GM so it is more difficult to manage blood sugar levels
  • religious reasons for not using pig products
• bioremedation


  microorganisms being used to break down pollutants and contaminants in the soil or in the water, there are different approaches
• bioremediation - using natural organisms

  many microorganisms naturally break down organic material producing CO2 and H2), soil and water pollutants are often biological e.g sewage and crude oil, if they are supported, they will break down and neutralise contaminants e.g in an oil spill nutrients can be added to the water to increase microbial growth and oil can be dispersed into smaller particles
• bioremediation - GM organisms

  scientists trying to develop GM bacteria which can break down or accumulate contaminants which they would not naturally encounter e.g bacteria that is modified to remove mercury from contaminated water
• bioremediation takes place on the site of contamination, sometimes material is removed for decontamination, in most cases natural microorganisms outperform GM ones, but effectiveness of GM bioremediation is increasing
• during culturing microorganisms, there is always the risk of mutation and a contamination with pathogenic microorganisms from the environment
• nutrient media whilst culturing microorganisms has to be sterile and aseptic techniques must be used, once the agar or nutrient broth is prepared, the bacteria must be added in a process called inoculation
• inoculating broth


  1. make suspension of the bacteria to be grown
  2. mix a known volume with the sterile nutrient broth in the flask
  3. stopper the flask with a cotton wool to prevent air contamination
  4. incubate at a suitable temperature by shaking regularly to aerate the broth, providing oxygen to the growing bacteria
• inoculating agar


  1. sterilize wire inoculation loop by holding it in a bunsen flame until it glows red hot, cannot touch any other surfaces as it cools to avoid contamination
  2. dip the sterilized loop in the bacterial suspension, lid removed of the petri dish and make a zig zag streak across the surface of the agar
  3. avoid the loop digging into the agar by holding it horizontally
  4. replace the lid of the petri dish, held down with tape but not sealed completely so oxygen can get in to prevent growth of anaerobic bacteria
  5. incubate at a suitable temperature