Control of Microorganisms

  1. Heat
    • fast, reliable, inexpensive,
    • no chemical contamination.
    • Above maximum growth temperatures biological changes in organic molecules leads to cell death. Fatal dehydration
  2. Direct Flame
    simple incineration
  3. Hot Air Oven
    • radiating dry heat
    • Useful for dry powders, oily material, glassware
  4. Boiling Water
    • moist heat penetrates better than dry heat thus, lower temp and shorter exposure time can be used
    • Denatures protein
    • Not sterilization for viruses and spores
  5. Autoclave
    • moist heat inform of pressurized steam
    • Most dependable forsterilization
    • Higher gas pressure =higher gas temp
    • Heat is sterilizing agent NOT pressured. Requirements: 15 pounds per square inch, 121.5 degrees C,15 minutes
  6. Pasteurization
    • not sterilization
    • Reduces bacterial population of a liquid
    • Spores not affected
  7. Inorganic Filters
    porcelain or ground glass
  8. Organic Filters
    organic material in filter attracts organic material of organism
  9. Membrane filter
    • cellulose acetate or polycarbonate control pore size
    • Example: Hepa filters remove microbes from air
  10. UV Light (radiation)
    • Exposed cell’s DNA absorbs energy
    • Adjacent Thymine bases link (thymine dimmers), can’t replicate past it
    • Chromosome replication impaired
    • Maintenance proteins not produced
  11. Xrays and Gamma Rays
    • Pass through microbial molecules via loss of electrons
    • Creates ions (ionizing radiation)
    • Combine with proteins and nucleic acids
  12. Chemical Control
    • Rarely achieve sterilization
    • Goal: destroy pathogen on or in an object (disinfection)
  13. Disinfectant
    agent used on lifeless object
  14. Antiseptic
    • agent used on living object
    • Usually bacteriocidal: kills microorganisms
  15. bacteriostatic
    temporarily prevents multiplication
  16. Sepsis
    contamination of an object or tissue by microorganisms
  17. Aseptic
    object or tissue free of contaminating microorganisms
  18. Sanitize
    reduce microbe population to “safe” level
  19. Degerm
    remove microorganisms from surface (ie: wash hands)
Card Set
Control of Microorganisms
Control of Microorganisms