1. Label four tubes for each microorganism culture provided with the initials of the microorganism being used and with the letter representing one of the following heating method:
C = Control (incubate room temperature)
B = Boiling ( 100oC for 10 minutes)
P = Pasteurization ( 63oC for 30 minutes)
A = Autoclave ( 121oC for 15 minutes at 15 psi)
2. Aseptically transfer 1 ml of E .coli or B. subtilis culture to each of the marked tube containing nutrient broth but 1 ml of A. niger is transferred into malt yeast extract tube.
3. Place the labeled tubes into the rack or container into the following heating system and for the time periods indicated.
4. After each heating process has been complete, allow the culture to cool.
5. Incubate all tubes at 37oC for 24 hrs.
6. After incubation, examine the presence of growth as indicated by turbidity in each culture tube.