Lecture+14-Control+of+microbes

Gram nega7ve endotoxins such as lps bugs are killed

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Unformatted text preview: ds 1.  HTST (high temp/short 7me) –  71.7°C, 15 sec 2.  UHT (ultra high temperature) –  141°C (under pressure), 2 sec •  Both result increase shelf life of milk –  30 day shelf life versus ~12 days –  If unopened, can be stored at room temp –  Not truly sterile – spores can survive High Temperature Dry Heat •  Hot air steriliza7on –  For material unable to withstand steam –  Hot air oven held at 70°C or higher •  Incinera7on –  Flaming your loop in lab –  Disposal of biological materials A bench top incinerator Low Temperatures •  Refrigera7on –  Bacteriosta7c –  Most commonly used for food preserva7on Dessica7on •  Bacteriosta7c •  Removes water, reduces Aw •  Example: Food preserva7on – Dried noodles, spices Osmo7c Pressure •  Bacteriosta7c •  Elevated sugar content in jams, salted meat •  More effec7ve against bacteria than molds Normal cell in Plasmolyzed cell in isotonic solu7on hypertonic solu7on hhp://classes.midlandstech.edu/carterp/Courses/bio225/chap06/lecture1.htm Radia7on •  Ionizing: end result is DNA damage –  Wavelength <1 nm (gamma rays, X- rays) –  Waves penetrate deeply •  Non- ionizing: DNA damage –  Wavelength >1 nm (UV light) –  Good for surface steriliza7on –  Low penetra7ng power Filtra7on •  Separates bacteria from liquid •  Can also be used with air –  HEPA filter •  Filter sample through a membrane –  Membrane has holes smaller than bacteria –  Membrane traps bugs, sample flows through Filtra7on Filtra7on •  Good for liquids that cannot be autoclaved –  Vaccines, enzymes, an7bio7cs •  Won’t remove viruses –  smaller than pores...
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