Controlling in-vitro Growth Flashcards
physcial methods of controlling microbial growth
heat
filtration
dessication
radiation
chemical methods of controlling microbial growth
inanimate objects
animate objects
what is sterilization
destruction of all life forms
commercial sterilization
autoclaving- 1210 C at 15-17 psi
chemical- ethylene oxide
glutaraldehyde
what is disinfection
destruction of pathogen
pasteurization
what is a disinfectant
disinfection of inanimate objects
what is antiseptic
disinfection of animate objects
what is sanitization
reduction to safe levels
what is degerming
mechanical
what is stasis
static- prevent growth
what is cidal
to kill
what is death rate
cumulative time to kill 90% of organisms
measured as D value
effectiveness of procedure
what are parameters affecting microbial death
quantity of microorganisms present
presence of organic matter
length of exposure
microbial characteristica
what are the mechanisms of microbial agents
plasma mebrane leakage
protein denaturing
nucleic acids mutation (radiation)
what are some physical antimicrobial methods
heat
denaturing for moist heat and pasteurization
oxidation for dry heat and flaming
what is dessication
dehydrators
organisms need water
organisms cannot grow but can remain viable for years
what is filtration
physically remove
membrane filters < 1 micrometer
HEPA- removes microorganisms larger than 0.3 micrometers
reverse osmosis filtered with pressure
ultrafilttration
what is radiation
mutates DNA
not always harmful
ionizing- short wavelengths- x-rays and gamma
non-ionizing- UV and air and water sterilization
effective t controlling growth
what effect does freezing have on organisms
static effect
slows down growth
what are examples of osmotic pressure
pcikling and curing
considerations for chemical methods of controlling growth in-vitro
some for inanimate objects only
rough surfaces harder than smooth surfaces to control- skin considered a rough surface
chemical methods for controlling growth in-vitro
phenols and phenolics
Lister
denatures proteins
disrupts membranes
ex. lysol
very good/toxic
alcohol for controlling growth in-vitro
not very effective against spores and viruses
denatures proteins
disrupts membranes
70% IPA
what is a halogen
strong oxidizer-denatures proteins
ex. chlorine and iodine
what is an oxidizing agent
strong oxidizer denatures proteins
ex. hydrogen peroxide and ozone
what are surfactants
do not denature proteins
cationic surfactants- decrease surface tension and disrupts cell membranes
colorless, tasteless, and relatively harmless
food preservatives
ex. benzalkonium chloride
what are aldehydes
denatures proteins
ex formaldehyde
