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Method: Gel Assay to Determine DNA Content of Phage Lysates

June 7 1990

Srini Ramachandra


Time required:


  1. To 10 ul of lysate add 4 ul of 2.5X SDS-EDTA dye mix (recipe is in the lambda media and solutions section).
  2. Heat sample to 65 degrees C for 5 minutes and load onto an agarose gel. Also load three lambda DNA concentration standards of 10 ng 50 ng and 100 ng. Run the gel until the 2 dyes have separated about 1 cm stain and photograph.
  3. Compare the lysate sample to the standards and estimate the amount of DNA. Good plate lysates usually have 50-100 ng DNA/10ul. Good liquid lysates have 10-50 ng DNA/10ul.


    By the gel assay 10 ul of lysate has 50 ng DNA. If 3.0 ml of the lysate is processed and if we assume a 70% recovery of DNA in the 20 ul final volume the result will be 525 ng DNA/ul TE.


Arber W. Enquist L. Hohn B. Murray N. and K. Murray. (1983). Experimental methods for use with lambda . In: Lambda II (Eds.: R. Hendrix J. Roberts F. Stahl and R. Weisberg) pp. 433-466. Cold Spring Harbor Laboratory Cold Spring Harbor New York.

Helms C. Dutchik J.E. and M.V. Olson. (1987). "A lambda DNA protocol based on purification of phage on DEAE cellulose". In: Meth. Enzymol. 153: p 69-82. Eds.:R. Wu L. Grossman. Academic Press.