June 7 1990
Although plate lysates assayed by this method usually give a clear lambda DNA band on a gel occasionally there may be enough bacterial DNA in the lysate to interfere with visualiziation of the phage band. The bacterial DNA in the sample can be degraded with DNaseI prior to adding the dye mix as follows: add 1-2 ul of 0.1 ug DNAseI/ml (fresh dilution) and incubate for 30 minutes at 37 degrees C. This step is always necessary when liquid lysates are assayed.
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.