control of microbial growth

sepsis

bacterial contamination in the body

antisepsis

destroying harmful microorganisms from living tissues

asepsis

absence of significant contamination

sterilization

removing and destroying all microbial life

disinfection

control directed at destroying harmful microorganisms

sanitization

lowering microbial counts to safe levels

degerming

mechanical removal of microbes from a limited area

biocide/germicide

treatments that kill microbes

bacteriostatic

inhibiting, not killing, microbes

heat

denatures enzymes

thermal death point

lowest temperature at which all cells in a liquid culture are killed in 10 min

thermal death time

minimal time for all bacteria in a liquid culture to be killed at a particular temperature

autoclave

steam under pressure, 121 C at 15 psi for 15 min, kills at organisms and endospores

pasteurization

reduces spoilage organisms and pathogens

high temp short time

72 C for 15 sec

thermoduric organisms

survive pasteurization but wont cause food spoilage

protein denaturation

caused by moist heat, protein denaturation, low temp, extreme pH, and high pressure

filtration

for heat sensitive liquids, pore size traps microorganisms on membrane filter

cold

bacteriostatic effect, many microbes survive but do not grow

osmotic pressure

plasmolysis, results in loss of water from microbial cells

radiation

emission of energy as electromagnetic waves, destroys or damages DNA

ionizing radiation

x rays, gamma rays, electron beams, damages DNA by causing mutations

nonionizing radiation

UV light, damages DNA by creating thymine dimers, microwaves

phenols

disrupts plasma membrane, denatures enzymes, rarely used, irritating

terpenes

disruption of plasma membrane, plant essential oils, in foods and disinfectants

alcohol

protein denaturation and lipid dissolution, not effective against endospores or nonenveloped viruses, needs water for denaturation

soap and detergent

mechanical removal of microbes through scrubbing, skin degerming

organic acids

metabolic inhibition, affects molds, foods and cosmetics

nitrates/nitrites

inhibits iron containing enzymes of anaerobes, meat products

peroxygen

oxidation, contaminated water and surfaces, effective against oxygen sensitive anaerobes in deep wounds

bacteriocins

proteins produces by one bacterium that inhibits another

pimaricin

prevents spoilage of cheese

aldehydes

inactivate proteins by cross linking with functional groups, preserves specimens

use-dilution test

metal cylinder dipped in test bacteria, then disinfectant, then transferred to culture media to see if bacteria survived

disk diffusion method

filter paper disks soaked in chemical or antibiotic and placed on culture