Roy Goodacre rrg at aber.ac.uk
Mon Mar 4 08:34:59 EST 1996

|I have spent 30 years on bacterial identification. We have only 
|experience with 'heterotrophic mesophilic groups'

|Today, I would say there are 3 kinds of approaches:

|1. 16S rRNA sequencing. - The rich man's choice
|2. Phenotyping or chemotyping
|   A: 10-40 tests - Routine
|   B: 30-200 tests - Reference laboratories.

One phenotypic beased method which falls neatly into this category is 
pyrolysis mass spectrometry (PyMS)

The major advantages that PyMS has over other diagnostic methods is that it 
is rapid, both for a single sample and in the (automated) throughput of 
samples.  Typical sample time is less than 2 minutes.  It is applicable to all 
(culturable) micro-organisms and is sensitive enough to allow the analysis of 
a single colony (typically 10^6 cells) from a culture plate.

Pyrolysis is the thermal degradation of complex material in an inert 
atmosphere or a vacuum.  It causes molecules to cleave at their weakest points 
to produce smaller, volatile fragments called pyrolysate.  A mass spectrometer 
can then be used to separate the components of the pyrolysate on the basis of 
their mass-to-charge ratio (m/z) to produce a pyrolysis mass spectrum which 
can then be used as a "chemical profile" or fingerprint of the complex 
material analysed.

General idea is that you analyse your unknowns with reference strains and then 
observe which reference strain looks most like your unknown.  For more 
information visit the Aberystwyth PyMS home page 

|3. Miscellanous methods - When you know what you are looking for.
|   Serology (Salmonella), selective medium (Legionella), PCR      
|   (Mycobacterium), etc.


Dr Roy Goodacre
E-mail: rrg at aber.ac.uk      http://gepasi.dbs.aber.ac.uk/roy/rgcv.htm		
Voice : +44 (0)1970 621947                    Fax: +44 (0)1970 622354			
Snail : Inst Biol Sci, Univ Wales, Aberystwyth, Dyfed SY23 3DA, WALES

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