25th International Meeting on Organic Geochemistry IMOG 2011

O-14
Exploring the diversity of archaeal ether lipids in marine
sediments
Xiaolei Liu 1 , Julius Lipp 1 , Jeffrey Simpson 3 , Roger Summons 2 , Kai-Uwe Hinrichs 1
1 MARUM, University of Bremen, Bremen, Germany, 2 Department of Earth, Atmospheric and Planetary
Sciences, Massachusetts Institute of Technology, Cambridge, United States of America, 3 Department of
Chemistry, Massachusetts Institute of Technology, Cambridge, United States of America (corresponding
author:xliu@uni-bremen.de)
Archaeal lipids, such as glycerol diethers and
tetraethers, are common in marine sediments, and
their structural diversity is high [1]. The main
compounds studied to date include derivatives of
glycerol dibiphytanyl glycerol tetraethers (GDGTs)
and archaeol. We have now detected and/or identified
several novel groups of related ether lipid compounds
that expand the currently known pool of archaeal
ether lipid derivatives.
Most studies in the past decade have adopted the
protocol by Hopmans et al. [2] or slight modifications
thereof for the detection of archaeal core lipids. By
modifying the polarity gradient of the mobile phase
and expanding the scanned mass range, numerous
exotic archaeal lipids were revealed. Most of their
structural assignments are still based on interpretation
of mass spectra and therefore remain tentative but
selected compounds were also characterized by NMR
analysis.
Among the groups of novel lipids are glycerol dibiphytanol
diethers (GDDs); these lipids coexist with
their corresponding GDGTs in a wide range of
sediments and archaeal cultures., An example is
provided in Fig. 1, illustrating the structure of GDGT-0
and its GDD derivative. Given similar ring distributions
in a set of globally distributed marine sediments (Fig.
1), the biological source of GDDs and GDGTs is
probably identical. Multiple lines of circumstantial
evidence argue against their artificial formation during
sample preparation. The presence of GDDs may be
relevant to biosynthesis of archaeal lipids as well as
to the fate and degradation of GDGTs in marine
sediments, including the recently postulated recycling
of these compounds by benthic archaea [3]. We will
discuss the distribution and significance of this and
other novel groups of GDGT derivatives.
Fig. 1 Plot of 12 marine sediments showing the
relative abundance of GDGT-0 and GDD-0 in their
respective molecular series together with the
structures of both molecules.
References
[1] Schouten, S., Hopmans, E.C., Pancost, R.D.,
Sinninghe Damsté, J.S. (2000) Proc. Natl. Acad.
Sci. USA 97, 14421-14426.
[2] Hopmans, E.C., et al. (2000) Rap. Comm. Mass
Spectrom.14, 585-589.
[3] Takano, Y., et al. (2010) Nature Geosci. 3, 858-
861.
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