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| Titel |
Variable enzymatic activity of prokaryotes under different hydrological settings in a river floodplain of the Danube |
| VerfasserIn |
Anna Sieczko, Karin Meisterl, Peter Peduzzi |
| Konferenz |
EGU General Assembly 2013
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 15 (2013) |
| Datensatznummer |
250080434
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| Zusammenfassung |
| This study tackles the role of different hydrological settings in a river-floodplain for organic matter processing by bacteria. Sampling locations in the Danube river-floodplain near Vienna (Austria) were chosen in a way that they represent a gradient of connectivity to the main river. We focused on the influence of variable hydrological connectivity and retention on microbial substrate utilization in the different subsystems of this river-floodplain section. We investigated extracellular enzymatic activity (EEA) both associated with particles (PA) and in the ambient water (FL). The activity of six enzymes was assessed: enzymes involved in the metabolism of carbon (β-d-glucosidase, α-d-glucosidase, β-d-xylosidase, cellobiohydrolase), peptide (endopeptidase [Endo]) and for degradation of refractory lignin material (phenol oxidase [PhOx]). We hypothesized that the degree of connectivity and water exchange in floodplain lakes influences prokaryotic enzymatic activity and productivity both on particles and in the surrounding water. The strong correlation between endopeptidase and phenol oxidase of the FL fraction in all locations suggests a tight coupling of enzymes responsible for utilization of labile and refractory material. Our results indicate that particle-associated bacterial growth in frequently flooded locations was supported by allochthonous carbon derived from polysaccharide hydrolysis, whereas in isolated locations, bacterial biomass was fuelled with carbon obtained largely from lignin utilization. This implies that prolonged residence time in isolated locations allows more refractory material to be utilized. Most of the enzymes (PA and FL) did not show clear dependencies on the degree of connectivity. However, phenol oxidase displayed an interesting pattern: activity of PhOx in ambient water decreased, whereas PA PhOx increased, together with the degree of connectivity. The study also demonstrates enhanced metabolism of the PA bacterial community and a strong coupling between EEA and bacterial growth associated with particles. |
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