What causes the plaque size difference?

Michael Benedik bchs1b at Elroy.UH.EDU
Thu Nov 12 01:16:21 EST 1992

In article <921111090655.2e58 at VTHVAX.TAMU.EDU>, MCAO at VTHVAX.TAMU.EDU writes:
>Hi, Dear netters: I raised a question two days ago about the "phage size". I am
>sorry I did not make it clear. Here phage size I mean plaque size. Each time
>when I grow the phage bearing the cDNA library, the size of the plaque varies.
>					Ming Cao

There are a number of parameters which affect plaque size. Different
phages in a library will certainly have different plaque sizes depending
upon the insert size and probably the base sequence to some extent.
Other parameters that affect plaque size for a given phage stock
include the genotype of the host strain, the growth conditions of the
host and age of the plating cells, the number of plating cells you
use, the wetness of the plates you actually use, the temperature and
time you adsorb phage to cells. Among other factors.

If you want big juicy plaques the approach is: 1) use fresh plating
cells grown with maltose, 2) be sure it is a healthy genotype for
phages like C600 or LE392 (many others also ok), 3) use FRESH poured
plates (2-3 days) which are still very moist, 4) minimize the number of
cells you use for the lawn, 5) use tryptone plates instead of LB

Not all of these are essential, but these are the general rules for
consistent large plaques. For small plaques do the opposite. The use
of more plating cells is the most reproducible way to decrease plaque
size, or the choice of a poor genotypic strain.

 Michael Benedik				INTERNET: Benedik at uh.edu
 Dept. of Biochemical & Biophysical Sciences	
 University of Houston				BITNET: Benedik at uhou

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