MIC 205 1st Edition Lecture 11Outline of Last Lecture I. Physical Requirements for Growth (Environmental)II. Microbial ControlIII. Microbial DeathOutline of Current Lecture IV. Physical Methods of Microbial ControlV. Chemical Methods of Microbial ControlCurrent Lecture Physical Methods of Microbial Control- Exposure to extreme heat (heat kills)o -Cidal processo Denature protein, disrupt nucleic acidso Moist heat is better than dry heat (reactions happen in water, carries more thermal energy than air molecules) Achieve sterility (autoclave-in moist)- Autoclave = applies pressure to make water boil at higher temps Incineration—ultimate means of sterilization (as hot and as long as possible to kill everything) Can achieve by boilingo Pasteurization—NOT sterilization Small amounts of heat for short time Doesn’t kill heat tolerant microbes Kills some spoilage microbes- Exposure to extreme cold(does not kill-inhibits)o Inhibit growtho -Static processo Freezing into ice, causes dehydration and splits up the cellsThese notes represent a detailed interpretation of the professor’s lecture. GradeBuddy is best used as a supplement to your own notes, not as a substitute.o Lyophilization = freeze drying (prevents ice crystal formation and removes water)- Desiccation- remove water (dry out)o –static processo Capsule to preserve structureo Dehydrated microbes can be rehydrated and brought back to lifeo Salt Induced—osmotic pressure causes desiccation and water leaves cell- Filtrationo Physically removes microbes from liquidso Can achieve sterility (cellular)- Osmotic Pressure- Radiationo Short wavelength o DNA becomes nonfunctionalo Achieve sterility UV light- nonionizing radiation Gamma rays- ionizing radiation, dislodge electronsChemical Methods of Microbial Control**Types, class, examples, application- Phenolso Denature cell membrane Used in healthcare settingso Ex) Lysol, chlorseptic- Alcoholso Control microbial growth, short contact time, denature cell membranes, HIGH penetration Great used on skin (swab)o Ex) isopropyl, methanol, ethanol- Halogenso Ex) chlorine, iodine, fluorineo Damage enzymes by oxidation or denature- Oxidizing agentso Ex) hydrogen peroxide, ozoneo Oxidize microbial enzymes and cell membrane lipidso Toxic form of oxygen In healthcare/industrial settings- Surfactantso Ex) soaps, detergentso Reduce surface tension, solubilize lipids, dissolve solutes- Heavy metalso Ex) lead, copper, silver, mercuryo Alter 3D shape of protein eliminating function Mercury in thermometers Fish tanks Vaccines - Aldehydeso Ex) formaldehydeo Preserve materials, killing agent cadavers- Gaseous agentso Ex) ethyl oxides, ether gaso Denature proteins and DNA In dental offices for dental tools- Antimicrobics (drugs)o Chemicals like antibiotics that can target specific microbes Treat disease in humans Promote microbial
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