Ch. 11: physical and chemical control of microbes Flashcards
(87 cards)
Sterilization
-process that completely removes/destroys all viable microorganisms, including viruses from object/habitat
~kills all life, destroys all viral particles; no trace left
~mostly done thru heat, but also some chemicals can do
fungicide
a chemical that can kill fungal spores, hyphae, and yeast
bacteriostatic
any process or agent that inhibits bacterial growth
disinfection/disinfectants
destruction of vegetative/pathogenic nonsporulating microbes or their toxins, usually on inanimate surfaces,
disinfectant=chemical used for this purpose
killing many microbes; minimize/reduce# of microbes
Sepsis
*presence of pathogenic organisms or their toxins in blood
[when microbes are in the bloodstream]
Asepsis
killing many microbes; minimize/reduce# of microbes
Sanitizer
physically removes microbes; does not necessarily kill them
Mode of action
How does it work to kill microbes?
Surfactants
an agent that reduces surface tension and forms a water-soluble interface
-derives from -surface-active agent
ex) detergent, soap, wetting agents, dispersing agents
Autoclave
a sterilization chamber that allows use of steam under pressure to sterilize materials
most common autoclave temperature/pressure combination is 121 C and 15 PSI.
Pasteurize
heat treatment of perishable fluids like milk, juice, or wine to destroy heat-sensitive vegetative cells, followed by rapid chilling to inhibit growth of survivors and germination of spores
-prevents infection & spoilage
desiccation
to dry thoroughly/ preserve by drying
lyophilization
freeze-drying; separation of a dissolved liquid from solvent by freezing solution and evacuating solvent under vacuum
-means of preserving viability of cultures
ionizing radiation
electromagnetic waves (x-ray or gamma) or high-speed electrons that cause dislodgement of electrons on target molecules, which creates ions; can break covalent bonds;
MOA=lot of energy= can slice thru DNA = large scale DNA mutations [foods like raspberries can be treated with radiation]
~if DNA bonds broken, can kill / greatly impact cell
-can penetrate liquids
-used by food industry, requires labeling
non-ionizing radiation
A type of low-energy radiation that does not have enough energy to remove an electron (negative particle) from an atom or molecule.
– creating new, unusual covalent bonds between thymines and cytosines & produces deletion mutations on DNA
~visible, infrared, and ultraviolet light; microwaves; radio waves; and radiofrequency energy from cell phones.
halogens
[common examples, MOA]
a group of related chemicals with antimicrobial applications
-most common halogens used in disinfectants/antiseptics = chlorine & iodine
[chemical group] anything in group 7 [[or group 17 depending on the table]] of the periodic table; of these, mostly use chloride and iodine (others are rare/dangerous/harmful)
Found in ⅓ of all disinfectants today
MOA= they break disulfide bonds in proteins; proteins fold over on themselves and a covalent bond can form between 2 sulfur atoms in amino acid cysteine
cross-linking
formation of covalent bonds which hold portions of several polymer chains together
what would happen to microbial contaminants in the food you store in your freezer?
they remain dormant, or may grow at a slow rate
when you lay out in the sun, what happens to your cells?
they gain small point mutations because of the thymine dimers
The process that destroys or removes all microorganisms and microbial forms including bacterial endospores is
sterilization.
The use of a physical or chemical process to destroy most vegetative pathogens on inanimate objects is
disinfection.
true or false: A microorganism that loses its ability to be motile could be considered dead.
false
Microbiological contaminants are best described as
unwanted microbes present on or in a substance.
The process of using a cleansing technique to mechanically remove and reduce microorganisms and debris to safe levels is
sanitization.
