physical methods or microbial control

what are the physical methods of microbial control

heat, cold and radiation

moist heat

kills microbes by denaturing and coagulating proteins that require low temp and short exposure compared to dry heat

boiling, pasteurization and autoclaving are examples of

moist heat method to kill microbes

dry heat

kills microbes by using hot air or direct flames to denature and dehydrate cells and proteins

very high temp of dry heat….

oxidized cells and burns them to ashes

incineration and hot air ovens are examples of

dry heat method to kill microbes

cold is microbistatic meaning….

it slows/stops microbial growth but does not kill the microbes

coldness can…

preserve microbial cultures

desiccation (cold)

drying or removing water from cells. Some microbes die but others survive and are preserved

lyophilization (cold)

freezing and drying that removes water while preserving microbes for long term storage for years

ionizing radiation

uses gamma rays or x rays to sterilize materials sensitive to heat or chemicals (high energy radiation for deep penetration)

non ionizing radiation

uses UV light to damage microbial DNA but has poor penetration and requires direct exposure

what is used to disinfect exposed surfaces, air and some liquids

non-ionizing radiation