FACTORS AFFECTING GROWTH (L2)

FACTORS AFFECTING GROWTH (L2)

1. CULTURE MEDIA

   • Media ingredients
     • A Carbon source
       • Glucose
         • for bacterial growth
     • Water
     • various salts
       • For bacterial growth
     • A source of amino acid/ nitrogen
       • E.g. beef, yeast extract

2. BATCH CULTURE

   • contains extra ingredients needed for growth
   • e.g. universal bottles, flasks, fermenters of liquid medium

3. GROWTH CURVES

   • LAG
     • organisms adjust to new environment
       • intense preparation for growth
         • No increase in population
     • Little/no cell division
     • Intence metabolic activity, cells grow in size.
     • Variable time from 1 minute to several days
     • length of lag phase depends on
       • status of transferred cells
         • exponential/ stationary phase
       • how its measured
   • EXPONENTIAL
     • Cells dividing
     • period of most rapid growth
     • biomass increasing logarithmically
     • increase in cell numbers (No. of cells produces>cells dying)
     • increase in cell size
     • cells at highest metabolic activity
     • most susceptible to environmental factors
     • growth rate is at maximum
       • determined by prevailing conditions
         • Carbon and energy sources
         • presence/absence of nutrients
         • Temp
         • Aeration
         • pH
   • STATIONARY
     • decrease in metabolic activity
     • decrease in cell viability (cell walls leak)
     • cells become smaller
   • DEATH
     • cells growth stops
     • cells begin to die due to unfavourable conditions
     • death is fast and constant

4. CALCULATIONS

5. CONTINUOUS CULTURE

   • maintains cells in exponential growth for long periods
   • fresh media is added at a content rate
     • while equal volume of spent media is removed at the same rate

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