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28 terms

Microbial Control: Physical Methods

Moist Heat: Method(s)
Boiling; Autoclaving (pressure-cooking, steam heat); Pasteurization (batch method, flash, and ultrahigh-temperature pasteurization); Ultrahigh-temperature sterilization (flash-heating via super-heated steam)
Moist Heat: Actions
denatures proteins and destroys cytoplasmic membranes
Moist Heat: General Uses
disinfect, sanitize, sterilize, and pasteurize; more effective than dry heat b/c water is a more efficient conductor of heat than air
Moist Heat: Representative Uses
- disinfection of baby bottles - sanitization of restaurant cookware and tableware
Moist Heat: Representative Uses
sterilization of medical and laboratory supplies that can tolerate heat and moisture - sterilization of canned food
Moist Heat: Representative Uses
destruction of all pathogens and most spoilage microbes in dairy products, fruit juices, beer, and wine
Moist Heat: Representative Uses
sterilization of dairy products, e.g., dairy creamer served in restaurants
Dry Heat: Method(s)
Hot Air; Incineration
Dry Heat: Actions
denatures proteins, destroys membranes, oxidizes metabolic and structural chemicals
Dry Heat: General Uses
useful for material that can not be sterilized or are damaged by moist heat; less effective than moist heat, requires higher temperatures for a longer time
Dry Heat: Representative Uses
sterilization of materials that cannot be exposed to moist heat, e.g., oils, powders, glassware, metal objects
Dry Heat: Representative Uses
ultimate means of sterilization, oxidizes everything completely; used for inoculating loops, flammable contaminated medical waste, diseased carcasses
Extreme Cold: Method(s)
Refrigeration; Freezing (slow and flash)
Extreme Cold: Actions
inhibits microbial metabolism, growth and reproduction in most pathogens, predominantly mesophiles (but can induce growth in psychrophiles)
Extreme Cold: Representative Uses
food preservation
Drying: Method(s)
Desiccation; Lyophilization ("freeze-drying")
Drying: Actions
inhibits microbial metabolism, growth and reproduction in most pathogens due to removal of water
Drying: Representative Uses
food preservation
Filtration: Method(s)
use of a filter to trap particles (cells or viruses) and separate them from the fluid (liquid or gas); use of vacuum common
Filtration: Actions
physically separates microbes from air and liquids
Filtration: Representative Uses
sterilization of air and heat-materials solutions such as ophthalmic and enzymatic solutions, vaccines, and antibiotics; filtration of airborne contaminants through HEPA filter
Osmotic Pressure: Method(s)
exposure to hypertonic solutions (high concentrations of salt or sugar) to induce cell desiccation
Osmotic Pressure: Actions
inhibits microbial metabolism, growth and reproduction due to removal of water
Osmotic Pressure: General Uses
food preservation, esp. jams, jellies, honey, jerky, salted fish, pickles; fungi are more resistant to hypertonic environments due to "osmotolerance"
Radiation: Method(s)
Ionizing radiation (electron beams, gamma rays, X-rays); Non-ionizing radiation (UV light)
Radiation: Actions
disruption of hydrogen bonding, oxidizing double covalent bonds, creatin highly reactive ions which denature other molecules, esp. DNA (ionizing); formation of Pyrimidine Dimers inhibits DNA transcription and replication (non-ionizing); causing fatal mutations and cell death
Radiation: Representative Uses
sterilization of medical and laboratory equipment; food preservation (food irradiation)
Radiation: Representative Uses
disinfection and sterilization of surfaces and of transparent fluids, air and gases