Batch Culture

• Organism in housed in a enclosed vessel
  • Cannot grow exponentially
• Nutrient concentration affects both growth rate and growth yield
  • Low concentrations- Growth rate is submaximal since nutrients cannot be transport into the cell fast enough to satisfy metabolic demand
  • High concentrations- maximal growth rate may be obtained, but the cell density can continue to increase in proportion to the concentration of nutrients in the medium
• Growth Curve describes the growth cycle
  • Lag Phase
  • Exponential phase
  • Stationary Phase
  • Death Phase
• Lag Phase
  • Brief or extended time frame
  • Inoculum taken from old culture
    • Lag is present due to cells being deprived of key nutrients
  • Lag present if inoculum is low of viability(few live cells)
  • Lag is present if cells are damaged but not killed by stressor(Temperature, radiation, toxic chemicals)
  • Lag is observed when microbial culture is transferred from a rich to poor culture
• Exponential Phase
  • Cell population doubles at regular intervals for a brief or extended period
    • Depends on available resources and other factors
  • Cells are in their healthiest state
  • Rate of exponential growth is influenced by environmental conditions( temperature, composition of culture medium) and genetic characteristics
  • Prokaryotes grow faster than eukaryotes
  • Small eukaryotes grow faster than larger ones
• Stationary Phase
  • No net increase or decrease in cell number and thus the growth rate of the population is zero.
  • Energy metabolism and biosynthetic processes may continue at reduced rate
• Death Phase
  • Rate of cell death is slower than rate of exponential growth and viable cells remain in culture for months or years
  • Cryptic Growth- Exponential and Death phases balance each other out