Question

A plaque assay is performed beginning with 1 mL of a solution containing bacteriophages. This solution is serially diluted 4 times by combining 0.1 mL of each sequential dilution with 9.9 mL of liquid medium. Then 0.1 mL of the final dilution is plated in the plaque assay and yields 28 plaques.What is the initial density of bacteriophages in the original 1 mL? Recall that initial phage density = (plaque number/mL) × (dilution factor). (It is not A or C)

a.2.8 x 10⁶ pfu/ml

b.2.8 x 10¹⁶pfu/ml

c.2.8 x 10⁸ pfu/ml

d.1.4 x 10⁸ pfu/ml

e.5.6 x 10⁸ pfu/ml

Answer 1

Given that, 0.1 mL of diluted suspension yielded 28 plaques; therefore, the number of plaque forming units = b.2.8 x 10¹⁶pfu/ml