growing microorganisms on an industrial scale

• what are the two ways that microorganisms can be grown on an industrial scale?

  • batch fermentation
  • continuous fermentation
• what are primary and secondary metabolites?

  • primary metabolites- needed for essential growth, used in the initial active growth period of bacteria
  • secondary metabolites- not necessary for essential growth, but are still used by cells. Utilised in the stationary period of bacterial growth once the cell mass has reached its maximum

  
• what is batch fermentation?

  • industrial fermentation that runs for a set time
  • process stopped before the death phase and the products are sterilised. The bioreactor is cleared, sterilised and a new batch culture replaces the old one
• what is continuous fermentation?

  • industrial fermentation that occurs when culture broth is removed continuously and more nutrient medium is added
  • medium, waste products, microorganisms and the product continuously removed, keeping the culture volume in the bioreactor constant
  • nutrients, pH and metabolic products kept constant
• state the conditions that can be manipulated to maximise yield in industrial fermentation

  • temperature- heating/cooling systems linked to temperature sensors (temp too high- enzymes denature, too low, bacteria won't reproduce fast enough)
  • nutrients and oxygen- oxygen and nutrient medium added in controlled amounts
  • mixing- liquid in bioreactor viscous- diffusion not sufficient for bac absorbing oxygen/nutrients or for constant temp. stirred continuously with mixing mechanism
  • asepsis- bioreactors are sealed and aseptic, because if microorganisms from the air contaminate it, yield is affected
• describe what a bioreactor looks like

  bioreactor- where fermentation takes place

  A) steam

  B) motor

  C) cold water inlet

  D) compressed air