Chapter 23 Slide

Chapter 23 Slide - BIO 205 Chapter 23 Physical and Chemical...

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Unformatted text preview: BIO 205 Chapter 23 Physical and Chemical Control of Microorganisms Sterilization and Sanitation Are Key to Good Public Health • Sterilization involves destruction of all living microbes, spores, and viruses • Sterile objects become contaminated when exposed to air and surroundings • Sanitization reduces the numbers of pathogens or discourages their growth General Principles of Microbial Control Heat Is One of the Most Common Physical Control Methods At heats above the growth range: • proteins and nucleic acids are destroyed • water is removed Physical Methods of Control • Each microbial species has a thermal death time for a given temperature Each species has a thermal death point: • the minimum temperature at which it dies in a given time period Incineration uses direct flame to kill microbes Dry and Moist Heat Are Applied Differently • Dry heat requires long periods of exposure to high temperatures The heat changes microbial proteins and removes water, slowly burning the microbes • Moist heat (like boiling water) is faster and effective at a lower temperature than dry heat It kills microbes by denaturing their proteins Boiling water may not kill all spores or inactivate all viruses...
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This note was uploaded on 04/17/2009 for the course MIC 201 taught by Professor Lacroix during the Spring '08 term at Rhode Island.

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Chapter 23 Slide - BIO 205 Chapter 23 Physical and Chemical...

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