Geology Reference
In-Depth Information
Modern Bacteria (
Oscillatoria
sp.) experimented hydrothermally at 350 deg C/700Bars/24hr
*
C
16
FA
Amide
Amide
*
C
18
FA
C
16
uFA
C
15
_
_
+
C
14
FA
+
+
+
+
_
_
+
C
10
_
_
+
_
_
+
B
+
+
+
P
_
_
P
Unresolved complex mixture
Retention time
Fig. 10.2
Gas chromatographic analysis of experimentally heated
Oscillatoria
after solvent
extraction, thermodesorption and pyrolysis. Symbols same as in Fig.
10.1
. Additionally,
+:
n
-alkane, −:
n
-alkene. Note presence of alkane alkene peaks after the experiment signifying
presence of macromolecularly bound aliphatic moieties
aliphatic component in the heated bacterium. This experiment demonstrates that
although bacteria consist of degradable biopolymers, diagenesis of bacterial bio-
mass can lead to the formation of a lipid-rich aliphatic geomacromolecule, as has
now been demonstrated for leaves (Gupta et al.
2007
), arthropods (Gupta et al.
2006
) and algae (Versteegh et al.
2004
; de Leeuw et al.
2006
; Kodner et al.
2009
).
The experiment further demonstrates that lipids need a biopolymeric substrate to
form an insoluble geopolymer, as evidenced by formation of a solvent soluble poly-
mer when only the fatty acid mixture was hydrothermally heated. Notwithstanding
the simulated fossilization employed here (Stankiewicz et al.
2000
), this experiment
does produce a solvent insoluble, high molecular weight material that is similar in
composition to immature kerogen in ancient sediments. Thus, bacteria, along with
higher plants and algae all have the capacity to contribute refractory organic carbon
to sediments, a point that is especially important in the context of the early part of
Earth history when life was largely microbial.
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