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Ch.5: Control of Microbal Growth

destroying all forms of microbal life
destroying pathogen & growing cells, but not spores and viruses
a chemical that quickly KILLS microbes but not necessary spores
inhibiting BACTERIAL growth but not killing the cells
the absence of pathogens from an object or area
the temporary removal of microbes
reducing pathogens to safe levels for the general public
opportunistic pathogen
CAUSES DISEASE under unusual conditions
the most common method used to kill microbes
thermal death point
the lowest TEMPERATURE required to KILL all the microbe in 10 minutes
thermal death time
the minimum TIME needed to KILL all microbes at a given TEMPERATURE
decimal reduction time
the time required for 90% to be killed at a certain temperature
passing through small pores
drying out
ionizing radiation
short wavelength high energy rays, react with water to form TOXIC oxygen molecules
nonionizing radiation
long wavelengths that damage DNA or heat water in cells
damages the cell membrane and proteins and kills everyting
damages the microbes cell, but not spores
[flourine, chlorine, bromine, iodine] react with H2O to form acids and damage amino & fatty acids
it kills bacteria and fungi but not spores or virus, by damaging membranes and proteins
heavy metals
high atomic WEIGHT elements [ag, hg, cu, zu] damage proteins
surface active agents
lower SURFACE tension and break membranes into tiny droplets
quaternary ammonium compounds
change cell permeability causing the cytoplasm to leak out
inhibits molds, are safe for humans
damage proteins, kill bacteria and viruses in minutes, kills spores in a few hours
gaseous chemosterilizers
denature proteins, kill all microbe and spores, but may cause CANCER
oxidizing agents
produce toxic OXYgen molecules and some spores
phenol coefficient test
compares the effect of a test chemical with phenol
dilution test
bacteria are added to serial DILUTIONS of the TEST chemical and the amount
filter paper
a piece of filter paper that has been soaked with the test chemical is placed on top of bacteria growing in a petri dish and the zone of inhibition is measured