Diluting Bacteriophage

1. DILUTING BACTERIOPHAGE
DR. S. SIVASANKARA NARAYANI., M.SC., M.PHIL., PH.D., MRSB (UK)
26-09-2021
DR.SS

2. A phage stock has a concentration of 2.5 x 109 PFU/ml. How can the
stock be diluted and plated to give 500 plaques on a plate?
The number of plaques counted
Concentration of phage =
dilution factor.
= 500PFU
2.5x109PFU
mL
2.5x109PFU (x ml)
mL
500PFU
=
XmL
x ml
500PFU
=
2.5x109PFU
= 2x10-7
Therefore, the phage stock must be diluted by 2 x 10-7 .
26-09-2021
DR.SS

3. 0.1mL 0.2mL 0.1mL
X X X 0.1mL
10mL 10mL 10mL
(1x 10-2) x (2x 10-2) x (1x 10-2 ) x (1x 10-1mL) = 2x 10-7mL
2.5 x 10-9mL – 9.9ml -9.8ml -9.9ml -Plate
0.1ml 0.2ml 0.1ml 0.1ml
The phage stock must be diluted by 2 x 10-7
26-09-2021
DR.SS

4. REFERENCE
• Calculations for molecular biology and Biotechnology – A Guide
to mathematics in the laboratory, Second Edition – Frank. H.
Stephenson
26-09-2021
sivasan91@gmail.com
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5. 26-09-2021
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