question 5?

5. (15 points) A steam sterilizer is used to sterilize liquid medium for fermentation. The initial concentration of contaminating organisms is 108 per litre. For design purposes, the final acceptable level of contamination should be taken to be 103 cells; this corresponds to a risk that one batch in a thousand will remain contaminated even after the sterilization process is completed. For how long should 1m3 medium be treated if the temperature is: (a) 80C (b) 121C (c) 140C To be safe, assume that the contaminants present are spores of Bacillus stearothermophilus, one of the most heat-resistant microorganisms known. For these spores the activation energy for thermal death is 283kJgmol1 and the Arrhenius constant is 1036.2s1