lecture notes-bioreactor analysis and operation-4-sterilization-web

# Lecture notes-bioreactor analysis and operation-4-sterilization-web

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Sterilization on a practical basis means the absence of any detectable viable organism. : only the desired organism is detectably present. Sterilization methods : Medium & equipment: . Heat-sensitive materials in medium: (microfiltrator pore sizes<0.2μm). Heat-sensitive equipment: UV radiation (energy intensive) or chemical agents (toxic to the desired culture. e.g.70% ethanol-water, and ethylene oxide (gas). Gas (air): sterilized through adiabatic compression process for supplying oxygen (~220 0 C) followed by (e.g.

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Sterilization Thermal deactivation The probability of an unsuccessful sterilization: 1- P 0 (t) The probability of extinction (successful sterilization): P 0 (t)=[1-p(t)] N 0 where p(t) is the probability that an individual will still be viable at time t. N 0 is the number of individuals (cells or spores) initially present. Assume first order death rate: p(t)=e -k d t 1- P 0 (t)=1-[1-p(t)] N 0 = 1-[1-e -k d t ] N 0 where the specific death rate k d = αe -E0d/RT (1/time), constant at specified T. E od is the activation energy for the death of the organism.
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Lecture notes-bioreactor analysis and operation-4-sterilization-web

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