lambda plaque assay - Mg+ maltose?

Fernando Leal fleal at
Thu Feb 3 10:41:31 EST 2000

Hi Gerd,
Lambda phages have a single tail fiber (product of the J gene) located at the
tip of the virion tail that
is responsible for specific recognition of its E. coli host. The J protein fiber
(the antireceptor)
recognizes an integral protein (the lamB protein, the receptor) in the outer
membrane of E. coli, which
is responsible for specific transport of the sugar maltose. The lamB gene is
induced (expressed) in
presence of maltose and absence of glucose.
Mg confers higher stability to lambda capsides and helps to stabish
electrostatic interactions
recptor/antireceptor for efficient binding.

  owner-microbio at wrote:

> Hei,
> As a stand-in, I am teaching a microbiology labcourse, where one of the
> experiments involves titration of Lambda phages (NK1316) by plaque assay
> using E.coli LE392. The protocol says: grow the cells in medium with maltose
> and MgSO4, before infecting with phages diluted in buffer containing Mg. I
> remember having used the same additions screening a genomic library in
> Lambda, years ago, so these additions seems to be common.
> My question is: What is the effect of maltose, and Mg?
> There really is not time enough to figure that out by experimentation.
> Gerd


Fernando Leal Sanchez
Profesor Titular de Microbiologia
Departamento de Microbiologia y Genetica
Universidad de Salamanca

Ed. Dpt. Biologia  Lab. 218
Plaza de los Doctores de la Reina s/n
37007  Salamanca

Tfno: 34-923-294732
Fax:   34-923-224876
E-mail: fleal at


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