Why are anaerobic organisms simple and aerobic organisms complex?

Andreas Brune Andreas.Brune at uni-konstanz.de
Mon Nov 27 03:39:13 EST 1995

In article <49b4diINNbb1 at woozle.mel.dbe.CSIRO.AU>,
   deanh at tigger.mel.dbe.csiro.au (Dean Hewish) wrote:
>There are probably several answers to this.
>Firstly, it is hard to find a nice, cozy, anaerobic environment that is
>large enough to fit an elephant or two. The exception is the bottom of
>the ocean, particularly near hydrothermal vents, where there are large,
>complex organisms that get by on an essentially anaerobic life-style;
>relying on sulphur oxidation instead. But even there it is the bacteria
>in their tissues that do all the hard work.

Dean, while I won't argue your point about the anaerobic elephant, I have 
to correct you about the hydrothermal vents. The symbionts in the 
trophosomes of pogonophores and in other symbioses of sulfur- and methane-
oxidizing bacteria with invertebrates are AEROBIC organisms, since their 
energy metabolism depends on the presence of oxygen as electron acceptor. 
Since such symbioses generally seem render the host a chemolithoautotrophic 
organism they represent very interesting evolutionary phenomena, but they
can't serve as an example 'why anaerobic organisms are so simple'.

I agree with your second point, though, where you stress the smaller
energy yields of anaerobic processes.


Andreas Brune

Dr. Andreas Brune * Mikrobielle Oekologie * Fakult. f. Biologie * Universitaet Konstanz * Postfach 5560, M654 * 78434 Konstanz * Germany * Phone: +49-7531-883282 * Fax: +49-7531-882966


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