Bacterial Taxonomy

Jeffrey Stobernack h0444pu6 at student.hu-berlin.de
Fri Jul 9 08:06:30 EST 1999

Will it ever be possible to make a good taxonomy of microorganismen? Its
surely possible do describe major groups of Bacteria, but I think, when you
want to make taxonomy on the level of genus oder species, you would have to
write a new book every month.


John Ireland schrieb:

> Okay, here is a little question I would like some opinions on.  As I
> understand it, at present bacteria are speciated at the level of <70%
> total DNA/DNA hybridization with other known species under strict
> conditions.  In addition some guidelines have been put forth dealing
> with assessing speciation using the 16S RNA sequence homology data, I
> think they use <95% homology.  Even with these guidelines things in the
> world of bacterial taxonomy seem at times to be more arguements in
> semantics rather than science.  My question for discussion is as to how
> the advent of whole genome analysis is going to alter the viewpoints of
> taxonomy and what would be approiate guidelines for speciation of
> bacteria.  Here are two incidents to consider in this (I apologize for a
> lack of references at the moment, or lab is in the process of moving
> cross country and things are already in boxes, including my files).
> First, some strains of E.coli can contain up to 1 Mb of stablly
> maintained DNA in addition to that which was sequenced in the original
> sequencing project.  Second, certain groups of bacteria (most notably
> the B. cereus/thurengensis/anthracis group) have identical 16S RNA
> sequences (within experimental error) and no reliable DNA/DNA
> hybridization values, yet exhibit such diverse phenotypes that it would
> be hard to classically combine them in the same species (this may be the
> first test of any new criteria since I think both B. anthracis and B.
> cereus are being totally sequenced).
> This has been a question which I have been interested in for a while and
> I would like to just solicite opions on it.  Thanks for your time.
> John Ireland
> Ph.D. canidate
> Duke University Medical Center

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