enviromental control of metabolism

• what are micro organisms

  archea, bacteria and some species of eukaryotes
• why are micro organims used

  due to their adaptability, ease of cultivation and speed of growth
• what do they use for metabolism

  a wide variety of substrates
• what do micro organisms produce from their metabolic pathways

  a range of products
• what do many micro organisms produce? - give an example

  complex molecules required for biosynthesis, for example, amino acids, vitamins and fatty acids
• many micro organisms produce the complex molecules for biosynthesis, but others may require these to be supplied in...?

  the growth media
• when culturing micro organisms, what does their growth media require?

  raw materials for biosynthesis and and energy source
• where is an energy sourced derived from to culture micro organisms

  chemical substrates or light in photosynthetic micro organisms
• list some culture conditions

  sterility, control of temperature, oxygen levels and pH
• what do sterile conditions in fermenters reduce

  competiton with desired micro organisms for nutrients and to reduce the risk of spoilage of the product
• explain the lag phase

  enzymes are induced to metabolise substrates
• explain the log/exponential phase

  contains the most rapid growth of micro organisms due to plentiful nutrients
• explain the stationary phase

  it occurs due to nutrients in the culture media becoming depleted and the production of toxic metabolites. secondary metabolites are also produced such as antibiotics. in the wild these metabolites confer an ecological advantage by allowing the micro organisms which produce them to outcompete other micro organisms
• explain the death phase

  occurs due to the toxic accumulation of metabolites or the lack of nutrients in the culture
• what scales are used in producing or interpreting growth curves of micro orgainisms?

  semi logarithmic scales
• what is the viable cell count

  counting only the living micro organisms
• what is the total cell count

  counting all viable and dead cells
• what do only viable cell counts show?

  a death phase where cell numbers are decreasing