In:
Biogeosciences, Copernicus GmbH, Vol. 17, No. 2 ( 2020-01-22), p. 317-330
Abstract:
Abstract. Butanetriol and pentanetriol dialkyl glycerol tetraethers (BDGTs and PDGTs)
are membrane lipids, recently discovered in sedimentary environments and in
the methanogenic archaeon Methanomassiliicoccus luminyensis. They
possess an unusual structure, which challenges fundamental assumptions in
lipid biochemistry. Indeed, they bear a butanetriol or a pentanetriol
backbone instead of a glycerol at one end of their core structure. In this
study, we unambiguously located the additional methyl group of the BDGT
compound on the C3 carbon of the lipid backbone via high-field nuclear
magnetic resonance (NMR) experiments. We further systematically explored the
abundance, distribution and isotopic composition of BDGTs and PDGTs as both
intact polar and core lipid forms in marine sediments collected in
contrasting environments of the Mediterranean Sea and Black Sea. High
proportions of intact polar BDGTs and PDGTs in the deeper methane-laden
sedimentary layers and relatively 13C-depleted BDGTs, especially in
the Rhone Delta and in the Black Sea, are in agreement with a probable
methanogenic source for these lipids. However, contributions from
heterotrophic Archaea to BDGTs (and PDGTs) cannot be excluded, particularly
in the eastern Mediterranean Sea, and contrasting BDGT and PDGT headgroup
distribution patterns were observed between the different sites studied. This
points to additional, non-methanogenic, archaeal sources for these lipids.
Type of Medium:
Online Resource
ISSN:
1726-4189
DOI:
10.5194/bg-17-317-2020
DOI:
10.5194/bg-17-317-2020-supplement
Language:
English
Publisher:
Copernicus GmbH
Publication Date:
2020
detail.hit.zdb_id:
2158181-2
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