For each set of dilutions (bleach and mouthwash), the first tube contained a 1:11 dilution (0.5 mL of agent was added to 5.0 mL of nutrient broth). What was the dilution of the MIC for the mouthwash and the bleach? Hint: You will have to calculate the dilution of each tube 2 – 4.

In the serial dilutions for MIC test, the volume of nutrient broth in each tube should be equal: 5.0 mL. And the volume of agent in each dilution should also be similar: 0.5 mL.

The serial dilutions was as following:

Tube 1: 0.5/5.5
Tube 2: 0.5 mL of tube 1 was diluted with 5.0 mL broth. Then, the dilution of tube 2 is (1:11) * (1:11) = (0.5/5.5) * (0.5/5.5) = 1:121 = 8.26 * 10^-3
Tube 3: We perform the similar calculation. Thus, the result is 1:1331 = 7.51 * 10^-4
Tube 4: It is 1:14641 = 6.83 * 10^-5.

adioabiola adioabiola · Answer 2 · 2021-12-05T03:29:04+01:00

The dilution of each tube are as follows;

Tube 2; 8.26 × 10-³
Tube 3; 7.5 × 10-⁴
Tube 4; 6.83 × 10-⁵

For each time a dilution is further diluted;

The dilution ratio is; 1 : 11; In essence, 0.5 mL of agent was added to 5.0 mL of nutrient broth.

For the first tube; dilution factor is; 1 : 11 = 9.1× 10-²

For the second tube; 0.5mL of the first tube was added to 5.0mL of the nutrient broth; The dilution factor is then; (1/11) × (1/11) = 1/121 = 8.26 × 10-³.

For the third tube; 0.5mL of the second tube was added to 5.0mL of the nutrient broth; The dilution factor is then; (1/11) × (1/11) ×(1/11) = 1/121 = 7.5 × 10-⁴.

For the fourth tube; 0.5mL of the third tube was added to 5.0mL of the nutrient broth; The dilution factor is then; (1/11) × (1/11) × (1/11) × (1/11) = 1/14641 = 6.83 × 10-⁵.