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20 Cards in this Set

  • Front
  • Back
destruction of all forms of microbes: cells, endospores, viruses
killing, inhibition, or removal of pathogens from INANIMATE objects
Destruction of pathogens on LIVING TISSUE
via chemicals
reduction of microbial populations to levels safe according to public health standards
What is Death of a microbe?
When it can't grow anymore
Mechanisms of death (3) water no life
2. alteration of membrane permeability
3. damage to proteins and nucleic acids (disrupts replication and metabolism)
dry heat is required for:
powders and oils
Hot air oven kills at what temp? how long? and how?
160 C; 2 hours, oxidation reactions (alter proteins) and removal of water, for powders oils and glassware
does not erode or corrode
Boiling water
100 C, doesn't sterilize, kills by denaturing proteins
121.5 C, sterilizes, 15-30 to kill, Fractional sterilization (Tyndallization - repeated 3x)
not sterilization, used for food, increase shelf life, spores not affected
destroys Mycobacterium tuberculosis and Coxiella burnetii (Q fever)
LTLT (30', 62.9C), HTST (flash- 15s, 71.6C)
Ultrapasteurization (3s, 82C)
Hot oil
160C, used by dentists, sterilizes, does not corrode or erode metal, bad b/c gotta wipe off oil and may reintroduce microbes
membrane: cellulose acetate, nylon, nitrocellulose, polycarbonate
UV light
thymine dimers, random mutation, surface sterilization, gram positive less susceptible
Ionizing Radiation
Gamma and xrays, force e- out of shells, destroy nucleic acids and proteins
for heat sensitive materials (pharmaceuticals, plastics)
Cobalt 60:
FDA used to kill Trichinella spirilis(roundworm)
Exception: deinococcus radiodurans
move water molecules
heat and dessication
no other specific activity again microbes
Light Amplification by Stimulated Emission of Radiation
concentrated light kills instantly
coverage is problem
Ultrasonic vibrations
Cavitation: formation and implosion of bubbles
Known as 'cold boiling'
use of cavitrons
requires liquid
Preservation Methods (3)
1. Dessication (no water no life)
2. Sugars and salts (osmotic pressure, water diffuses out) molds can tolerate high sugar though
3. Low temp- lowers metabolic rate and growth rate