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| Titel |
Microbial life in volcanic/geothermal areas: how soil geochemistry shapes microbial communities |
| VerfasserIn |
Antonina Lisa Gagliano, Walter D'Alessandro, Andrea Franzetti, Francesco Parello, Marcello Tagliavia, Paola Quatrini |
| Konferenz |
EGU General Assembly 2015
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 17 (2015) |
| Datensatznummer |
250101404
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| Publikation (Nr.) |
 EGU/EGU2015-536.pdf |
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| Zusammenfassung |
| Extreme environments, such as volcanic/geothermal areas, are sites of complex interactions
between geosphere and biosphere. Although biotic and abiotic components are
strictly related, they were separately studied for long time. Nowadays, innovative and
interdisciplinary approaches are available to explore microbial life thriving in these
environments. Pantelleria island (Italy) hosts a high enthalpy geothermal system
characterized by high CH4 and low H2S fluxes. Two selected sites, FAV1 and FAV2, located
at Favara Grande, the main exhalative area of the island, show similar physical conditions
with a surface temperature close to 60Ë C and a soil gas composition enriched in CH4,
H2 and CO2. FAV1 soil is characterized by harsher conditions (pH 3.4 and 12%
of H2O content); conversely, milder conditions were recorded at site FAV2 (pH
5.8 and 4% of H2O content). High methanotrophic activity (59.2 nmol g-1 h-1)
and wide diversity of methanotrophic bacteria were preliminary detected at FAV2,
while no activity was detected at FAV1(1). Our aim was to investigate how the soil
microbial communities of these two close geothermal sites at Pantelleria island respond
to different geochemical conditions. Bacterial and Archaeal communities of the
sites were investigated by MiSeq Illumina sequencing of hypervariable regions
of the 16S rRNA gene. More than 33,000 reads were obtained for Bacteria and
Archaea from soil samples of the two sites. At FAV1 99% of the bacterial sequences
were assigned to four main phyla (Proteobacteria, Firmicutes, Actinobacteria and
Chloroflexi). FAV2 sequences were distributed in the same phyla with the exception of
Chloroflexi that was represented below 1%. Results indicate a high abundance of
thermo-acidophilic chemolithotrophs in site FAV1 dominated by Acidithiobacillus
ferrooxidans (25%), Nitrosococcus halophilus (10%), Alicyclobacillus spp. (7%) and the rare
species Ktedonobacter racemifer (11%). The bacterial community at FAV2 soil is
dominated by the methanotrophs (~40% of the reads) Methylocaldum gracile,
Beijerinckia sp. and Methylobacterium sp.. The Archaea assemblages are similar
in both sites and dominated by the moderately thermophilic chemolithotrophic
ammonia-oxidating candidate species Nitrososphaera gargensis, in the phylum
Thaumarchaeota. Volcanic/geothermal activities represent a complex phenomenon, this
shaping different and peculiar microbial niches even at adjacent sites. Lower pH, higher
water, NH4+ and H2content are probably the discriminating factors that prevent
methanotrophy at FAV1 and favor chemolithotrophy. Site FAV2 hosts an extraordinary
diversity of methanotrophs due to large supply of CH4, scarce presence of inhibitors of
methanotrophy (H2S and NH3) and slightly acidic soil pH. This study integrates geochemical
and biological information to move a step ahead in the still scarce knowledge on the
complex ecology of microbes living in geothermal sites and their interactions with the
geosphere.
(1)Gagliano et al., 2014 Biogeosciences, 11, 5865–5875 |
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