Continuous Culture

• Open system
• Growth vessel of known fresh medium is added at constant rate while equal volume of spent culture medium is removed at same rate
• Chemostat
  • Device in which growth rate and cell density are controlled independently
    • Dilution rate- rate at which fresh medium is pumped in and spent medium is removed
    • Concentration of a limiting nutrient(Carbon or nitrogen) are present in sterile medium entering chemostat vessel
    • Growth rate controlled by dilution rate
    • Cell yield(density) controlled by concentration of limiting nutrient
  • At high dilution rates
    • Organisms cannot grow fast enough to compete with its dilution and is washed out of chemostat
  • At low dilution rates
    • Cells may die from starvation because the limiting nutrient is not being added fast enough to support minimal cell metabolism
  • Cell population can be maintained in exponential phase for long periods of time
  • Chemostats can used for enrichment and isolation of bacteria from nature