Question

If a sterilization procedure has a decimal reduction time of 10 minutes, how long would it take to reduce a microbial population from 100,000 cells to 10 cells?

please give step by step instruction, thank you.

Answer 1

Solution: 40 minutes

Decimal reduction time or D-value is the time required to kill 90% of microorganisms (ie 10% is still alive)

In the question, it is given that, the decimal reduction time is 10 minutes

Total number of microbial cells = 100000 cells

• Number of cells remaining after 10 minutes of first treatment = (10/100) x 100000 = 10000 (10000 cells represent the remaining 10 % of cells after killing the 90% of cells)
• Number of cells remaining after 20 minutes = (10/100) x 10000 = 1000
• Number of cells remaining after 30 minutes = (10/100) x 1000 = 100
• Number of cells remaining after 40 minutes = (10/100) x 100= 10

Therefore, a sterilization procedure with decimal reduction time of 10 minutes, will take 40 minutes to reduce a microbial population from 100,000 cells to 10 cells