Question

What volume of phage preparation at 1.6 x 1011 pfu/ml is required to infect a 33 ml culture of bacteria at A600 0.4 at a multiplicity of infection (MOI) of 3? (A600 1.0 = 1 x 109 cells/ml).

Answer 1

MOI = (phage forming units per mL × volume of viral suspension used) / (bacterial cells per mL × volume of bacterial suspension used)

PFU per mL = 1.6 × 10^11 phages per mL

Volume of viral suspension = ? = V

Volume of bacterial suspension = 33 mL

A600 1 = 10^9 cells per mL

A600 0.4 = 10^9 × 0.4 = 4 × 10^8 cells per mL

MOI = 3

3 = (1.6 × 10^11 × V) / (33 × 4 × 10^8)

3 = 1.6 × 10^3 × V / 132

V = 132 × 3 / 1.6 × 10^3 = 0.2475 mL

Volume of phage suspension = 0.2475 mL

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