25th International Meeting on Organic Geochemistry IMOG 2011

P-432
Thermally stable anammox biomarker lipids produced during
hydrous pyrolysis
Darci Rush 1 , Andrea Jaeschke 1,2 , Stefan Schouten 1 , Jaap Sinninghe Damsté 1
1 NIOZ Royal Netherlands Institute for Sea Research, Department of Marine Organic Biogeochemistry, Den
Hoorn, Netherlands, 2 ETH Zürich, Institute of Geochemistry and Petrology, Zurich, Switzerland
(corresponding author:darci.rush@nioz.nl)
The anaerobic oxidation of ammonium (anammox)
has been shown to account for a significant part of the
loss of fixed inorganic nitrogen from the world‘s
oceans [1]. Anammox is performed by a bacterial
group within the Planctomycetes. The cells of these
bacteria contain a specialized organelle-like
compartment, named the anammoxosome.
Ladderane lipids surround the anammoxosome,
protecting cell function from the diffusion of the toxic
intermediates of the anammox reaction. Ladderanes
are unique to anammox bacteria and their presence in
modern environmental settings is a biomarker of the
occurrence of anammox [2]. Other lipids found to be
common in anammox cultures include hopanoids,
9,14-dimethylpentadecanoic and 10-methylhexadecanoic
acids, and squalene [3]. Understanding the
role of anammox in different environments is crucial in
characterizing the nitrogen cycle. However, little is
known of the importance of anammox in past nitrogen
cycling, as ladderanes are thermally labile (due to
their cyclobutane structure [5]) and do not preserve
well as such in the sediment record.
In this study we investigated the potential production
of thermally stable lipids derived from ladderane
lipids. For this, anammox biomass was artificially
matured by hydrous pyrolysis for 72 hours at
temperatures between 120 and 365°C.
The anammox biomass residue was extracted after
the hydrous pyrolysis experiments. Analyses using
HPLC/APCI-MS/MS indicated that during thermal
maturation, ladderane lipids undergo similar structural
rearrangements as those observed during GC
analyses i.e., opening of a cyclobutane ring and
formation of a double bonded ladderane [5].
Fig. 1. Weight of oil generated during hydrous
pyrolysis experiment as a function of temperature.
Oil was
generated at hydrous pyrolysis temperatures between
220 to 365°C (Fig. 1) and analyzed for degradation
products.
GC-MS analyses of the aliphatic fractions of these oils
showed the presence of C29-C35 hopenes and
hopanes as well as other lipids that, to our
knowledge, have not previously been identified.
Some of the alkanes had a m/z fragment of 161, also
found in mass spectra of ladderane fatty acids,
indicating they may be products derived there from.
Furthermore, they were comprised of C16 to C19
homologs, in agreement with a decarboxylation of
C18-C20 ladderane fatty acids. The presence of these
lipids at hydrous pyrolysis temperatures above 260°C
indicate that they are thermally stable and may be
better suited as biomarkers for anammox activity in
mature sediments. Preliminary identification of these
components suggests that their carbon chain lengths
are in agreement with a structural rearrangement of
the C18-C20 ladderane fatty acids. We are currently
isolating the alkanes by preparative GC for rigorous
identification by NMR techniques.
[1] Hamersley, M.R., et al. (2007) Limnol. Oceanogr.
52, 923-933.
[2] Kuypers M.M.M. et al. (2003) Nature 422, 608-
611.
[3] Sinninghe Damsté, J.S., et al. (2005) FEBS
Journal 272, 4270-4283.
[4] Lewan, M.D. et al. (1979) Science 203,897-899.
[5] Jaeschke, A. et al. (2008) Org. Geochem. 39,
1735-1741.
Fig. 2. Oil generated at 260°C. (a) Total Ion Current
and (b) mass chromatogram of m/z 161 revealing the
unknown ladderane products .
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