Benthic archaea as potential sources of tetraether membrane lipids in sediments across an oxygen minimum zone
<p>Benthic archaea comprise a significant part of the total prokaryotic biomass in marine sediments. Recent genomic surveys suggest they are largely involved in anaerobic processing of organic matter, but the distribution and abundance of these archaeal groups are still largely unknown. Arc...
| Main Authors: | , , , , |
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| Format: | Article |
| Language: | English |
| Published: |
Copernicus Publications
2018-07-01
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| Series: | Biogeosciences |
| Online Access: | https://www.biogeosciences.net/15/4047/2018/bg-15-4047-2018.pdf |
| Summary: | <p>Benthic archaea comprise a significant part of the total prokaryotic biomass
in marine sediments. Recent genomic surveys suggest they are largely involved
in anaerobic processing of organic matter, but the distribution and abundance
of these archaeal groups are still largely unknown. Archaeal membrane lipids
composed of isoprenoid diethers or tetraethers (glycerol dibiphytanyl
glycerol tetraether, GDGT) are often used as archaeal biomarkers. Here, we
compare the archaeal diversity and intact polar lipid (IPL) composition in
both surface (0–0.5 cm) and subsurface (10–12 cm) sediments recovered
within, just below, and well below the oxygen minimum zone (OMZ) of the
Arabian Sea. Archaeal 16S rRNA gene amplicon sequencing revealed a
predominance of Thaumarchaeota (Marine Group I, MG-I) in oxygenated
sediments. Quantification of archaeal 16S rRNA and ammonia monoxygenase
(<i>amo</i>A) of Thaumarchaeota genes and their transcripts indicated the
presence of an active in situ benthic population, which coincided with a
high relative abundance of hexose phosphohexose crenarchaeol, a specific
biomarker for living Thaumarchaeota. On the other hand, anoxic surface
sediments within the OMZ and all subsurface sediments were dominated by
archaea belonging to the Miscellaneous Crenarchaeota Group (MCG), the
Thermoplasmatales and archaea of the DPANN (superphylum grouping Micrarchaeota, Diapherotrites, Aenigmarchaeota, Nanohaloarchaeota, Parvarchaeota, Nanoarchaeota, Pacearchaeota and Woesearchaeota). Members of the MCG were diverse, with a dominance of subgroup
MCG-12 in anoxic surface sediments. This coincided with a high relative
abundance of IPL GDGT-0 with an unknown polar head group. Subsurface anoxic
sediments were characterized by higher relative abundance of GDGT-0, -2 and
-3 with dihexose IPL types, GDGT-0 with a cyclopentanetetraol molecule and
hexose, as well as the presence of specific MCG subgroups, suggesting that
these groups could be the biological sources of these archaeal lipids.</p> |
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| ISSN: | 1726-4170 1726-4189 |