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Unformatted text preview: MODULE 11 11a) Overview and Heat Sterilization Large part of microbiology involves preventing microbial growth in: o Food o Industrial processes o Healthcare environments o Water systems Strategies to control microbial growth: o Heat sterilization Spores are heat resistant, so would need high heat o Radiation o Filter sterilization for liquids, size selection o Chemical controls like antiseptics, disinfectants and sterilants Heat sterilization o Mesophilic organism with optimum growth at 37 o Survival fraction (log scale) decreases with time o Decimal reduction time (D): time it takes to reduce survival fraction by tenfold or one log at a given temperature o Decimal reduction time decreases with higher temperature (steeper slope) o Autoclave: chamber that allows steam to entrance under high pressure As steam flows into autoclave, pressure increases allowing temperatures of over 100 degrees Typically, temp of about 121 used to ensure spore destruction Endospores have decimal reduction time of 4-5 minutes Dry heat can also be used to sterilize by heating in an oven o...
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This note was uploaded on 06/26/2011 for the course BIOL 140 taught by Professor Dr.joshneufeld during the Winter '10 term at Waterloo.
- Winter '10