Chapter 7 Flashcards
_______: removing and destroying all microbial life
Sterilization
____ _______: Killing Clostridium botulinum endospores from canned goods
Commercial sterilization
_______: destroying harmful microorganisms
Disinfection
______: destroying harmful microorganisms from living tissue (antiseptic)
Antisepsis
What is degerming?
The mechanical removal of microbes from a limited area
What is sanitization?
lowering microbial counts on eating utensils to safe levels
Biocide (germicide) is what?
Treatments that kill microbes
Name two germicides
Fungicide and virucide
What does Virucide do?
Inactivates viruses
What does bacteriostasis do?
Inhibits growth and multiplication of microbes
What is a problem with bacteriostasis?
Once a bacteriostatic agent is removed, growth might resume
What are the three main ways various agents kill or inhibit microbes?
Alteration of membrane permeability, damage to proteins, and damage to nucleic acids
One way agents kill or inhibit microbes is through altering the membrane permeability. What does this cause?
Lysis or death
One way agents kill or inhibit microbes is by damaging the proteins. How does this happen?
Proteins are denatured by heat and chemicals.
One way agents kill or inhibit microbes is by damaging the nucleic acids. How does this work?
Damage is caused by heat, chemicals, and UV. Microbes then cannot replicate or make protein
Bacteria usually die at a ______ rate
constant
Which four factors affect the death rate of microbes?
- Number of microbes
- Environmental influences
- Time of exposure
- Characteristics of microbe
The more microbes present, the longer it takes to kill them. True or False
True
What are the four environmental factors that affect the death rate?
- Presence of organic matter
- Biofilms
- Nature of suspending medium (heat tx)
- Temperature
Chemical antimicrobials require what?
Extended time (affects death rate)
What are the main four environmental factors that affect the growth of microorganisms
- Heat
- Filtration
- Radiation
- osmotic pressure
Thermal death point?
lowest temperature at which all microbes in a particular liquid suspension will be killed in 10 minutes
Thermal death time?
Minimal length of time for all microbes in a liquid culture to be killed in a given temperature
Decimal reduction time
____ heat kills by oxidation effects
Dry
What does direct flaming do?
Sterilizes inoculating loops
What is hot air sterilization?
- Items placed in oven.
2. 170 celsius maintained for two hours ensures sterilization
What temperature does hot air sterilization require
170 celsius
Free flowing steam sterilization is also called
autoclaving
Boiling, a type of moist heat sterilization is also considered _______
pasteurization
Moist heat sterilization does what?
Coagulates and denatures proteins
What are the requirements for autoclaving
121 celsius at 15 psi for 15 minutes
Using an _______ kills all organisms and endospores
autoclave
Does pasteurization use extreme or mild heat to kill microbes?
Mild
Why does pasteurization use mild heating to kill microbes?
To not damage the taste of the product
The ______ test is used to see if a product has been pasteurized correctly. The thing they’re testing will be inactive
Phosphatase
If Phosphatase is present in a gallon of milk, was it pasteurized correctly?
No
Milk is pasteurized at ___ celsius for 15 minutes
75
______ is the passage of substance through a screen like material
Filtration
HEPA stands for
High-efficiency particulate air filters
_____ filters remove microbes > 0.22 um and .45 um
Membrane
_____ filters remove microbes that are > .3 um in diameter
HEPA
Which filter can you purchase if you want filter out viruses and large proteins at .01um
Membrane filters
Which bacteria and mycoplasma can still pass through filters?
Flexible bacteria like spirochetes and wall-less mycoplasma
What is the difference between slow and fast freezing when considering killing bacteria
Fast freezing is not as harmful; the microbe will go dormant. Slow freezing is more harmful due to ice crystals disrupting cellular and molecular structure
