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_H. halobium_ & biogenic oil?

arlin at ac.dal.ca arlin at ac.dal.ca
Thu Oct 7 08:46:27 EST 1993

Mark Thorson asks:

>Why does H. halobium exist, and what relation does it have to
>the gap in chlorophyll absorbance at the frequency of green
>light.  To be specific, was H. halobium once the dominant
>organism in the biosphere, and if so is it responsible for
>petrochemical oil?  And why the heck does it only live in one
>place in the whole world, the Dead Sea?

I agree completely that the possible biogenic origin of oil is an unresolved
question of great evolutionary interest (e.g., see Thomas Gold's interesting
speculative paper published last year: "The Deep, Hot Biosphere", PNAS 89:
6045).  But I don't quite understand what _H. halobium_ has to do with this.  Do
you have in mind a specific reason to expect that _H. halobium_ might have been
involved in oil deposition, or might have been a 'dominant' organism (is this
where the absorbance spectrum fits in)?  

_H. halobium_ is one species in a group that includes  _Halobacterium_,
_Haloferax_, _Halococcus_, _Natronobacterium_, _Haloarcula_, and
_Natronococcus_.  These halophilic archaebacteria can be found in salterns
(natural or man-made places where sea-water is dried to make salt) and inland
salt lakes (such as the Great Salt Lake, or the Dead Sea) all over the world,
not just in the Dead Sea.  Halophilic eubacteria or eukaryotes can sometimes be
found along with them, though apparently the archaebacterial halophiles are the
most extreme.  Many of these organisms were originally isolated from salt-cured
hides or fish (e.g., salt-cod) that had become infected (unrefined sea-salt
usually contains lots of viable halobacteria).  Some species (e.g., _Haloferax
volcanii_) were originally isolated from the Dead Sea, but since the Israelis
have concentrated it by severely depleting the fresh water input (the Jordan),
rumor has it that moderate halophiles like _H. volcanii_ cannot be found there


Arlin Stoltzfus
Department of Biochemistry
Dalhousie University
Halifax, Nova Scotia
internet: arlin at ac.dal.ca

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