Microbiology: Module 12

Sanitization

is reduction of microbial count to safe levels on eating utensils

Thermal death time

the lowest temperature at which all microbes in a liquid will be killed in 10 mins

autoclave

provides steam at high pressure and is used to sterilize items and culture media

True

A .22 micrometer filter can be used to remove almost all types of bacteria from a liquid

Sterilization

destruction of all forms of microbial life

Iodine

name an example of a halogen that can be used as an antimicrobial

Microbial Death

The permanent loss of a microorganism's ability to grow and reproduce

Exponential Death

Microorganisms die at a constant percentage over time, not all at once.

Physical Methods

Methods that use physical agents to kill or inhibit microorganisms.

• Heat (boiling, autoclaving)

• UV radiation

• Ionizing radiation

• Cold

• Drying (desiccation)

examples of physical methods of microbial control

• Damage DNA

• Denature proteins

• Destroy cell structures

How do physical methods of microbial control work?

Chemical Methods

Methods that use chemicals to kill or inhibit microorganisms.

• Damage cell membranes

• Denature proteins

• Damage DNA or other cell components

How do chemical methods of microbial control work?

• Alcohols

• Bleach (chlorine)

• Iodine

• Hydrogen peroxide

• Phenolics

examples of chemical methods of microbial control

Mechanical Methods

Methods that physically remove microorganisms.

• Filtration

• Handwashing

• Scrubbing surfaces

examples of Mechanical methods of microbial control

Remove microorganisms instead of killing them.

How do mechanical methods of microbial control work?

Kill microorganisms or prevent their growth.

How do biological methods of microbial control work?

• Antibiotics

• Bacteriophages

• Probiotics

examples of Biological methods of microbial control

Biological Methods

Methods that use living organisms or their products to control microorganisms.

False

In complex growth medium, we know exactly how much of each nutrient is present

false

When using method of microbial control, death is instantaneous

Filtering with a 0.22 micron filter

an example of physical control of microbial growth