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Systems Microbiolog8 - ° If you’re sterilizing something...

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Systems Microbiology 􀂃 Microbial growth control o Physical antimicrobial control o Chemicals that are used externally o Antimicrobial agents used internally o Antimicrobial drug resistance and discovery of new drugs 􀂃 Physical antimicrobial control o Anything that you’d expect is injurious to your cells is likely injurious to bacterial cells as well o Heat – the most common means of controlling bacterial populations o Radiation o Filtration – removes the bacteria, rather than killing them 􀂃 Heat o Measuring heat sterilization 􀂃 Graph: survival fraction vs. time 􀂃 Death time (10-fold reduction at a given temperature) 􀂃 Thermal death time – easier to determine o Autoclave 􀂃 Steam at very high pressures – a giant pressure cooker 􀂃 Steam at 121 degrees Celsius 􀂃 Sterilizes things that can survive that high temperature
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Unformatted text preview: ° If you’re sterilizing something very large, like a large vat of liquid, it’s difficult for the steam to penetrate ° If you’re autoclaving something like surgical instruments, you wrap them in a porous material first, so that microbes don’t get back onto them after they’re autoclaved o Pasteurization ° At the time that this was invented at the turn of the last century, there were huge problems with pathogens transmitted through milk, such as tuberculosis ° You need to very carefully control both the absolute temperature and the flow of the milk through the machine ° Flash pasteurization is 71 degrees Celsius for 15 seconds ° There is always the possibility today of picking up pathogens like Listeria, Salmonella, and E. coli if you consume non-pasteurized dairy...
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