Scanning Electron Microscope

K N and P J Harris ecoli at
Mon Mar 25 14:26:00 EST 1996

> ==========
> bionet/microbiology #2407, from rmcgehee at, 1162 chars, Tue 
 19 Mar 1996 19:26:54 -0
> ----------
> Article: 3358 of bionet.microbiology
> Path:!!btnet!!d
> From: Robert McGehee <rmcgehee at>
> Newsgroups: bionet.microbiology
> Subject: Scanning Electron Microscope
> Date: Tue, 19 Mar 1996 19:26:54 -0600
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> Hello, I am working on research project using A. tumefaciens and 
> to take a scanning electron micrograph of them and have had some 
> problems.  Initially, cells were removed from agar plates and dried on 
> copper before being gold-coated.  Upon viewing, the microscope could 
> resolve the different cells, only a large mass.  Is there a special 
> method for viewing bacterial cells under a SEM?  I will try drying 
> at a significantly less concenetration however.  Any suggestions?
> Robert
> respond: rmcgehee at
I've had similar poor results with SEM. It might be that the medium used 
encouraged too much mucilage, gum, capsule etc. Usually due to a high 
C:N ratio. (Remember Agrobacteria are close cousins of Rhizobium which 
can be prolific gum producers.) The gum simply "smooths out" any surface 
details you might see. Try 'em on a weak low CHO medium instead.
Peter Harris,
Department of Soil Science, 
Reading University, UK.

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