Ch 6 Microbial Growth

  1. microbial growth
    the numbers to cells not to the changes in the size of the cells
  2. colonies
    accumulations of the cells large enough to be visible without a microscop
  3. requirements for growth
    • physical - temperature, pH, osmotic pressure
    • chemical - carbon, oxygen, sulfur, nitrogen
  4. chemically defined media
    media infused with certain chemicals to accommodate certain bacteria
  5. fastidious
    many growth factors required
  6. complex media
    used to grow most heterotrophic microbes
  7. anaerobic growth media
    often has thio (sulfur) chemicals
  8. selective media
    suppresses growth of unwanted bacteria
  9. differential media
    distinguish between types of bacteria
  10. lyophilization
    dehydrated / freeze dried bacteria
  11. generation time
    time needed to undergo binary fission
  12. lag phase
    phase where bacteria is gathering materials; preparing for division; some division
  13. log phase
    phase where there is rapid division
  14. stationary phase
    phase where rate of reproduction = rate of death
  15. death / decline
    rapid death of the bacteria
  16. direct counts
    • count colonies
    • quebec colony counter
    • serial dilutions
    • direct microscopic counts
  17. count colonies
    assume that 1 bacteria formed the colony (CFU = colony forming unit)
  18. quebec colony counter
    count typical amount of colonies in the appropriate size box and multiply by the number of boxes that fit the plate
  19. serial dilutions
    • decrease concentration to be able to do direct count
    • must multiply colonies by dilution number
  20. direct microscopic counts
    put colonies in liquid on a microscope slide
  21. indirect counts
    • spectrophotometer
    • metabolic products
    • dry weight
  22. spectrophotometer
    • measures absorbency or transmission (turbidity)
    • turbidity is caused by bacteria
  23. metabolic products
    determine how much bacteria by knowing how much of a product is produced by 1 bacteria
  24. dry weight
    dry bacteria up and weigh
  25. psychrophile
    cold loving
  26. mesophile
    middle temperature loving
  27. thermophile
    heating loving bacteria
  28. plasmolysis
    cell shrivels
  29. cytolysis
    cell explodes
Card Set
Ch 6 Microbial Growth
bacteria growth requirements, counts, & media