Question

you are given 1.0 ml of a solution with 5.3 x 107 pfu/ml concentration. you are asked to produce a solution that contains less than 60 pfu/ml.what is the minimum amount of 1:10 dilutions you must perform to achieve this? hint: consider what a 1:10 dilution does to the 107 term of 5.3 x 107 pfu/ml

Answer 1

To dilute a solution from a concentration of 5.3 x 10^7 pfu/ml to less than 60 pfu/ml, a minimum of six 1:10 dilutions are required.

Step-by-step explanation:

To achieve a solution with a concentration of less than 60 pfu/ml from a starting concentration of 5.3 x 107 pfu/ml, we need to perform a series of 1:10 dilutions. Each 1:10 dilution decreases the exponent in the concentration by 1. Starting at 107, we need to reach an exponent that gives us a number smaller than 60 when multiplied by 5.3. To find the minimum number of dilutions required:

• After 1 dilution: 5.3 x 106 pfu/ml
• After 2 dilutions: 5.3 x 105 pfu/ml
• After 3 dilutions: 5.3 x 104 pfu/ml
• After 4 dilutions: 5.3 x 103 pfu/ml
• After 5 dilutions: 5.3 x 102 pfu/ml
• After 6 dilutions: 5.3 x 101 pfu/ml = 53 pfu/ml

Therefore, the minimum number of 1:10 dilutions needed is six to bring the concentration down to a level below 60 pfu/ml.