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| Titel |
Production and transformation of dissolved neutral sugars and amino acids by bacteria in seawater |
| VerfasserIn |
L. Jørgensen, O. J. Lechtenfeld, R. Benner, M. Middelboe, C. A. Stedmon |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1726-4170
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| Digitales Dokument |
URL |
| Erschienen |
In: Biogeosciences ; 11, no. 19 ; Nr. 11, no. 19 (2014-10-07), S.5349-5363 |
| Datensatznummer |
250117622
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| Publikation (Nr.) |
 copernicus.org/bg-11-5349-2014.pdf |
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| Zusammenfassung |
| Dissolved organic matter (DOM) in the ocean consists of a heterogeneous
mixture of molecules, most of which are of unknown origin. Neutral sugars and
amino acids are among the few recognizable biomolecules in DOM, and the
molecular composition of these biomolecules is shaped primarily by biological
production and degradation processes. This study provides insight into the
bioavailability of biomolecules as well as the chemical composition of DOM
produced by bacteria. The molecular compositions of combined neutral sugars
and amino acids were investigated in DOM produced by bacteria and in DOM
remaining after 32 days of bacterial degradation. Results from bioassay
incubations with natural seawater (sampled from water masses originating from
the surface waters of the Arctic Ocean and the North Atlantic Ocean) and
artificial seawater indicate that the molecular compositions following
bacterial degradation are not strongly influenced by the initial substrate or
bacterial community. The molecular composition of neutral sugars released by
bacteria was characterized by a high glucose content (47 mol %) and
heterogeneous contributions from other neutral sugars (3–14 mol %). DOM
remaining after bacterial degradation was characterized by a high galactose
content (33 mol %), followed by glucose (22 mol %) and the
remaining neutral sugars (7–11 mol %). The ratio of D-amino acids to
L-amino acids increased during the experiments as a response to bacterial
degradation, and after 32 days, the D/L ratios of aspartic
acid, glutamic acid, serine and alanine reached around 0.79, 0.32, 0.30 and
0.51 in all treatments, respectively. The striking similarity in neutral
sugar and amino acid compositions between natural (representing marine
semi-labile and refractory DOM) and artificial (representing bacterially
produced DOM) seawater samples, suggests that microbes transform bioavailable
neutral sugars and amino acids into a common, more persistent form. |
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