Chapter 6

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Chapter 6
2010-05-13 19:57:22
Microbial Growth

quiz 5
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  1. Mircobial Growth
    increase in # of cells, not cell size.
  2. Physical requirements for cell growth
    • Temp
    • pH
    • Osmotic Pressure
  3. Chemical requirements
    • C, N, S, P,
    • trace elements
    • Oxygen
    • Organic Growth Factors.
  4. Cold loving microbes
    • Psychrophiles - minimum grow at 0 C, optimum at 15 C
    • Psychrotrophs - Grow at 0C, optimally at 20-30 C
  5. Moderate temp loving microbes
    • Mesophiles - optimum growth at 25-40 C
    • Most common tyme of microbes.Spoilage and disease organisms.
  6. Heat loving microbes
    • Thermophiles - grow optimally 50-60 C
    • Hyperthermophiles - grow optimally at 80C or greater
  7. What is the name of bacteria that grow in acidic envirnoment?
    • Acidophiles - pH 0-3
    • Most bacteria grow between pH6.5-7.5 (neutral)
  8. Osmotic Pressure
    • In hypertonic solution - water leaves the cells causing plasmolysis - shkrinkage of cytoplasm
    • In Hypotonic solution - water moves into the cell causing lyses of the cell.
  9. Salt loving micrboes
    • Extreme and obligate halophiles - require high sal concentration in order to grow
    • Facultative halophiles - do not require high salt, but can grwo in 2% salt concentration.
  10. Chemical requirements
    • Carbon
    • Nitrogen
    • Sulfur
    • phosphorus
    • Trace elements
    • Oxygen
    • Organic Growth factors
  11. Carbon
    • most abondant in the cell
    • Used to make structural organic molecules and energy rich molecules
  12. Nitrogen
    • 14 % of dry weight
    • Found in amino acids, proteins, DNA, RNA, ATP
    • Most bacteria dicmpose prtoein to get N
  13. Sulfur
    • 2%
    • Found in R group of amino acids and the vitamins
    • Also necessary for synthesis fo DNA and RNA
  14. Phosphorous
    • 2 %
    • Found in DNA, RNa, ATP, and phospolipid membrane
  15. Trace elements
    • Inorganic element required in small amounts
    • Usually needed to serve as enzyme cofactors
  16. Obligate aerobes
    require oxygen to live. O2 fianl electron acceptor
  17. Microaerophiles
    are aerobic, btu grown only when oxygen concetreates are lower than that found in air.
  18. Facultative anaerobes
    use oxygen when present, but are able two grow via fermentation when oxygen not present.
  19. Obligate anaerobes
    • unable to grow when oxygen present
    • use oxygen atomsalready present in cellular molecules.
  20. Aerotolerant anaerobes
    cannot use oxygen for metabolism, but tolerate it fairly well.
  21. Toxic forms of oxygen
    • Singlet Oxygen
    • Superoxide free radicals
    • Peroxide anion
    • Hydroxyl radical
  22. Signlet oxygen
    • O2 boosted to higher energy state than normal
    • Estremely ractive. Presten in phagocytic white blood cells.
  23. Superoxide free radicals
    • O2.- =O2 with unpaired electron, steals electron from neighboring molecules and turn them into free radicals.
    • Neutralized by superoxide dismutase to produce H2O2 and O2
  24. Peroxide anion
    O22- combine with 2 protone to form O2 and H2O2 is than neutralized by catalse peroxidase to form water
  25. Hydroxyl Radical
    • OH.
    • Ionizing radiation form hydorxyl radicals react with DNA and damages cells.
  26. Organic growth factors
    • cells cannot make tham, need to get from outside.
    • ex. vitamins
  27. Chemically definde media
    • exact chemical compasition is known ( Energy, C, N, S, P, growth factors
    • Fastidious oragnisms grow on this type of media mainly autotrophic bacteria - CO2 carbon source
  28. Complex Media
    • don't know exactly what's in it
    • Used to grown heterotrophic bacteria and fungi (organic carbon source)
    • Peptons- brokendown proteins
  29. Reducing media
    anaerobic grwoth media heated to drive off O2
  30. Selective Media
    • Inhibits the growth of paricular microbes
    • ex. 7% NaCl
  31. Differential Media
    visual differences between groups of microbs.
  32. EMB
    selective agains G+ bacteria, and differential on the basis of lactose fermentation.
  33. Enrichment Media
    Encourages growth of desired microbes but not others, so it is also selective.
  34. A colony
    called a colony-forming unit (CFU)
  35. Short term storage
  36. Long term storage
    • Deep freezing in a suspending liquid (cryopreserving agent is added)
    • preserves for several years
  37. Lyophilization
    freez drying, added cryoprotectant - preserved for many years
  38. Generation time
    time required for a cell to divide
  39. Lag phase of growth
    • Inoculate bacteria, prepare for growth
    • cells metabolicly active but do not divide.
  40. Log phase
    bacteria growth at absolute max it can grow
  41. Stationary Phase
    bacteria slow down due to toxic by product, number of new cells grwoing is eqqual to number fo cells dying off.
  42. Death pahse
    More death, than division.