Lecture Seven - Controlling Microbes

sterilization

destruction or removal of all viable organisms (more extreme conditions than disinfection, effective against endospores)

disinfection

killing, inhibition, or removal of disease causing (pathogenic) organisms but NOT endospores

disinfectants

agents (chemical) used for disinfection

sanitization

reduction of microbial population to levels deemed safe (based on public health standards)

antisepsis

prevention of infection of living tissue by microorganisms

antiseptic

chemical agents that kill or inhibit growth of microorganisms when applied to tissue

-cide

suffix indicating that agent kills (germicide - kills pathogens and many non pathogens but no necessarily endospores)

-static

suffice indicating that agent inhibits growth

d value - controlling microbial growth

time to kill 90% of cells (antimicrobial agnates decrease value)

2 d values - controlling microbial growth

time to kill 99% of cells

change in temperature

growth rate will increase with temperature but proteins could denature if the temperature is too high

response to temperature

heat shock response (occurs at high end of temperature range, emergency proteins are produced and help keep proteins from denaturing)

barophiles

adapted to high pressures

barotolerant organisms

grow at high, but not super high pressures

barosenstive organisms

die at high pressure (all mammals)

halophiles

need a high concentration of NaCl

neutralophiles

grow at pH 5-8

acidophiles

grow at pH 0-5

alklophiles

grow at pH 9-11

pasteurization

63 C for 30 minutes (does not sterilize but does kill pathogens present and slows spoilage)

flash pasteurization

72 C for 15 seconds (does NOT kill all cells)

UHT - ultra high temperature

150 C for 3 seconds

autoclave

steam cooker 121 C for 20 minutes (kills all bacteria and endospores)

penicillin

blocks cell wall synthesis

probiotics

good bacteria

bacteriophage

viruses that attack bacteria