Lab 22 Flashcards
generally, ___ kills microbes; ____ inhibits microbial growth
heat, cold
name the 5 optimal growth ranges
psychrophilic, psychrotrophic, mesophilic, thermophilic, and hyperthermophilic
0C-20C
psychrophilic
20C-30C
psychrotrophic
25C-40C
mesophilic
45C-65C
thermophilic
80C and higher
hyperthermophilic
denatures enzymes, dehydrates microbes, and kills by oxidation effects
dry heat
Standard application of dry heat in a hot-air oven is _____ for ___ hours.
170C, 2
transfers heat energy to the microbial cell more efficiently than dry air, resulting in the denaturation of enzymes
moisture
name the 3 moist heat methods
pasteurization, boiling, and autoclaving
In _____, the temperature is maintained at 63 C for 30 minutes, or 72 C for 15 minutes to kill designated organisms that are pathogenic or cause spoilage
pasteurization
______ (100 C) for 10 minutes will kill vegetative bacterial cells; however, it does not inactivate endospores
boiling
most effective method of moist heat sterilization
autoclaving
15 psi, at 121 C for 15 minutes. usually sufficient to kill endospores and render materials sterile
standard condition for autoclaving
length of time required to kill all bacteria in a liquid culture at a given termperature
Thermal Death Time (TDT)
the temperature required to kill all bacteria in a liquid culture in 10 inutes
Thermal Death Point (TDP)
the time, in minutes, in which 90% of a population of bacteria at a given temperature will be killed
Decimal Reduction Time (DRT, or D value)
