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| Titel |
Tracking heterotrophic and autotrophic carbon cycling by magnetotactic bacteria in freshwater sediments using DNA stable isotope probing |
| VerfasserIn |
Ömer Kürşat Coşkun, Sophie Roud, Kuang He, Nikolai Petersen, Stuart Gilder, William D. Orsi |
| Konferenz |
EGU General Assembly 2017
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| Medientyp |
Artikel
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| Sprache |
en
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 19 (2017) |
| Datensatznummer |
250151188
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| Publikation (Nr.) |
 EGU/EGU2017-15745.pdf |
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| Zusammenfassung |
| Magnetotactic bacteria (MTB) are diverse, widespread, motile prokaryotes which
biomineralize nanosize magnetic minerals, either magnetite or gregite, under highly
conserved genetic control and have magnetotaxis to align their position in aquatic
environment according to Earth’s magnetic field. They play important roles on some
geobiological cycle of important minerals such as iron, sulphur, nitrogen and carbon. Yet, to
date, their importance in carbon cycle and carbon source in their natural environment have
not been previously studied. In this study, we focused on freshwater benthic carbon cycling of
MTB and total bacteria using DNA stable isotope probing (DNA-SIP) technique coupled
with quantitative PCR (qPCR). Pond sediments from Unterlippach (Germany) were amended
with 13C-labelled sodium bicarbonate and 13C-labelled organic matter, and incubated in the
dark over a two week time period. Applying separate qPCR assays specific for total bacteria
and MTB, respectively, allowed us to estimate the contribution of MTB to total
heterotrophic and autotrophic carbon cycling via DNA-SIP. After one week, there was a
slight degree of autotrophic activity which increased markedly after two weeks.
Comparing total DNA to the qPCR data revealed that changes in the buoyant density of
DNA was due mainly to autotrophic bacterial production. DNA-SIP also identified
heterotrophic utilization of 13C-labelled organic matter by MTB after 1 week. The qPCR
data also allowed us to estimate uptake rates based on the incubation times for
heterotrophic and autotrophic MTB. High-throughput DNA sequencing of 16S rRNA
genes showed that most of the MTB involved in carbon cycling were related to the
Magnetococcus genus. This study sheds light on the carbon sources for MTB in a
natural environment and helps unravel their ecological role in the carbon cycle. |
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