Divergence of bacilli and the purple bacteria

Diane Stothard dstothar at magnus.acs.ohio-state.edu
Tue Feb 22 13:51:40 EST 1994

In article <1994Feb19.165753.20988 at dal1>,  <aroger at ac.dal.ca> wrote:
>In article <2k1fin$ev6 at usenet.INS.CWRU.Edu>, bl275 at cleveland.Freenet.Edu (Dan
Diaz) writes:
>> i am writing a paper on an e. coli gene which i have recently discovered
>> has much the same sequence and adjacent markers in bacillus
>> stearothermophilus.  i would like to be able to comment on the divergence
>> point between these two bacteria.
>> how long ago did these bugs diverge?  what reference should i cite in my
>> paper?
>> thanks
>> diz
>I'd love to hear a really rigourous answer to this question.  But for
>now, I can at least give a ballpark figure (highly qualified).
>IF the cyanobacterial fossils from 3.5bya are really cyanobacterial and,
>IF this state is derived in bacteria (that is, if the ancestral state
>of eubacteria is not cyanobacterial-like in growth properties and
>photosynthetic properties), then it appears (PROVIDING the 16S rRNA
>trees are accurate) that most eubacterial phyla diverged almost
>simultaneously prior to 3.5bya.  That would place the divergence time
>between a gram positive (bacillus) and a gamma proteobacterium (E.coli)
>prior to 3.5bya.
>There are a lot of if's in this estimate.  If you need a reference for
>cyanobacterial fossils, look in Science last year for an article
>by Bill Schopf.
>Andrew Roger
>Dept. of Biochemistry
>Dalhousie University
>aroger at ac.dal.ca

The estimates I have are from the sequences of the 16S rRNA genes using the 
Ochman and Wilson clock for B. subtilis and E. coli. These two genes are 23-28%
divergent and therefore, using the 16S molecular clock, they are 1.14-1.5 
billion years apart, which is the time of the emergence of eukaryotic cells. 
You can agree or disagree with this estimate based on your faith in the Ochman 
and Wilson clock  :)

Diane Stothard
Department of Molecular Genetics
The Ohio State University

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