Divergence of bacilli and the purple bacteria

aroger at ac.dal.ca aroger at ac.dal.ca
Sat Feb 19 15:57:53 EST 1994

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

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