Ninth international conference on - Marum

104
Abstracts of posters
Comparison of microbial communities in sub-surface sediments from Haakon Mosby mud
volcano and a non-seep site in the Barents Sea
A. G. Rike 1 , E. Eribe 1 , E. Roinaas 2 , R. Orr 3 , K. S. Jakobsen 3 , T. Kristensen 2
1 Norwegian Geotechnical Institute, P.O.Box 3930 Ullevaal Stadion, NO-0806 Oslo, Norway
2 Department of Moleculear Biosciences, University of Oslo, Norway
3 Centre for Ecological and Evolutionary Synthesis (CEES), Department of Biology, University of Oslo, Norway
The archaeal and bacterial diversity in sub-surface sediments at the Haakon Mosby Mud Volcano (HMMV) site,
located at 72.0020 o N – 14.4350 o E, and at a non-seep site (NSS) west of HMMV, at 72.0030 o N – 14.3700 o E, in
the Barents Sea was studied. Both sampling sites are located at about 1300 m water depth. HMMV has been
investigated by both geologists and biologists, and the microbial communities at different habitats have been
described (Lösekann et al 2007, Niemann et al 2006). To the best of our knowledge, the microbial diversity in
sediments not influenced by seeps in this region has not been characterized, and we were interested in studying
the differences of these two microbial habitats.
The bacterial and archaeal diversity at the sites was determined in sediments from 2-20 cm depth by 16S
ribosomal DNA (16S rDNA) sequence analysis. DNA isolated from the sediments was PCR amplified, with
universal-bacterial and -archaeal primers, and cloned into Escherichia coli. Sequences of approximately 900
bases of cloned 16S rDNA inserts were used to determine species identity, or closest relatives, by comparison
with sequences of known species. Geochemical parameters of sediments and pore water were determined to
provide an environmental context of the sediment conditions.
Altogether, 245 microbial clones (from archaea and bacteria) were sequenced from the two sites, 152 from
HMMV and 93 from the NSS. Archaeal clones represented 36% of total clones at HMMV and 26% at NSS.
All 79 archaeal clones sequenced were detected as novel and their sequences were organized into tree clusters of
Chrenarchaeota (A, B and C) and two clusters of Euryarchaeota (D and E).
The 55 archaeal clones retrieved from HMMV represent 13 different phylotypes, all belonging to the
Euryarchaeota clade E of anaerobic methane oxidizing archaea (ANME). The phylotypes are affiliated with
clusters of ANME-2A, ANME-2B, ANME-2C and ANME-3. No Crenarchaeota were detected in the HMMV
sediment investigated in this study. With the exception of two clones closely related to uncultured
Thermoplasmatales in the Euryarchaeota phylum, the other 22 clones from the NSS sample affiliated to the
Chrenarchaeota phylum. 63% of the NSS achaeal clones were close relatives of uncultured Desulfurococcus.
166 bacterial clones, 97 from HMMV and 69 from the NSS were sequenced. Uncultured Epsilonproteobacteria
accounted for 49% of the total bacterial clones in the HMMV sediments. Other main bacterial phyla detected at
HMMV were Deltaproteobacteria (12%) and Gammaproteobacteria (10%). At the NSS the dominating phyla
were Planctomycetes (25% ), Alphaproteobacteria (23%) and Obsidian Pool 11 (OP11) (14%). Out of 17
bacterial phyla only 4 (OP11 group, Chloroflexi I/II, Gammaproteobacteria I/II and Deltaproteobacteria I/II)
were common to both sites but any clones were detected at both HMMV and the NSS.
The archaeal diversity in the anaerobic methane and hydrocarbon influenced HMMV sediments was
significantly lower than in the aerobic deep cold sediments from the NSS. The bacterial diversity, however, was
great at both sites. This may indicate that the archaeal component of the microbial community is most suceptible
to seep influence than the bacterial component.
Microbial methane cycle in the Black Sea sediments and its effect on the atmosphere
and water column
I. Rusanov 1 , N. Pimenov 1 , S. Yusupov 1 , and M. Ivanov 1
1 Winogradsky Institute of Microbiology, RAS
Methane is among the major terminal products of anaerobic organic matter (OM) transformation, contributing to
the atmospheric pool of greenhouse gases. During the period of 1990–2007, a unified procedure was applied to
the radioisotope investigation of microbial methane production and oxidation, with short-term incubation under
in situ conditions.
The Black Sea area includes the following characteristic biogeochemical zones:
(1)sediments of the highly productive shallow coastal zone, river estuaries, and river alluvial deposits; (2)
extensive areas of shelf sediments, depths over 40–50 m; (3) sediments of the continental slope and deep basins,
permanently covered with anaerobic water; and (4) sediments of the methane seeps and mud volcanoes.
Methane levels of the upper 30–50 cm of the sediments from the Dnepr and Dnestr estuarine coastal zone, of the
Danube delta and prodelta, and of the coastal shallow shelf stations were rather high for marine sediments.
Methane concentration increased sharply from 0.01–0.5 ml/dm 3 at the surface sediments to 0.1–66.0 ml/dm 3 at
the depth 25–30 cm. This distribution is caused by extensive microbial methane production (up to tens of µl/dm 3
per day) in the upper 50 cm of the sediment and methane migration from the deeper sediment horizons. The