Lecture+14-Control+of+microbes

Hhpwwwkrackelercomproducts1006 autoclavesupplies21440

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Unformatted text preview: acid pH •  Organic maher can protect microbes –  Bacteria growing in biofilms are more resistant to treatments than free- living bacteria Mechanisms of Cell Damage •  An7microbial agents target key cell components –  DNA, ribosomes, key enzymes, cell wall, membranes •  Damage that cannot be repaired = death •  An7microbials are classified as physical or chemical agents •  Many agents have mul7ple targets –  Some are specific Physical Agents •  High Temperatures –  Autoclave –  Boiling and Pasteuriza7on –  Dry heat •  Osmo7c pressure •  Radia7on •  Filtra7on •  Low temperatures •  Oxygen exclusion •  Dessica7on High Temperatures Moist Heat, Under Pressure •  Autoclave – steam under pressure –  Denatures proteins and nucleic acids, disrupts cell membrane •  Larger quan77es require more 7me –  Interior temperature needs to meet 7me/ temp requirements Autoclave Condi7ons •  Typical condi7ons: –  121°C –  15 psi –  15 minutes •  Kills spores •  Not all materials can withstand autoclaving Autoclave indicators •  Autoclave tape changes color if process was run at proper 7me/temp •  Bacillus stearothermophilus is an indicator organism for the autoclave hhp://www.krackeler.com/products/1006- Autoclave+Supplies/21440- Sterikon%26%23174%3B+plus+Bioindicators+for+Steam+Autoclaves.htm High Temperature Moist, Not Under Pressure •  Boiling – disinfects, but does not sterilize –  Spores are not killed –  Used when object cannot withstand autoclave condi7ons High Temperature Moist, Not Under Pressure •  Pasteuriza7on –  Sub- boiling temperatures –  Sani7zes liquids •  Milk, beer, juices •  Normal condi7ons (“batch pasteuriza7on”) –  62.8°C –  30 minutes Pasteuriza7on Two Newer Metho...
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This note was uploaded on 05/03/2013 for the course BIO 2400 taught by Professor Mclean during the Spring '09 term at Texas State.

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