Effect of dissolved organic carbon quality on microbial decomposition and nitrification rates in stream sediments

Abstract. A significant amount of carbon is transported to the ocean as dissolved organic carbon (DOC) in rivers. During transport, it can be transformed through microbial consumption and photochemical oxidation. In dark incubation experiments with water from the Tana River, Kenya, we examined the consumption of DOC through microbial decomposition and the associated change in its carbon stable isotope composition (δ13C). In 15 of the 18 incubations, DOC concentrations decreased significantly by 10 to 60 %, with most of the decomposition taking place within the first 24–48 h. After 8 days, the remaining DOC was up to 3 ‰ more depleted in 13C compared with the initial pool, and the change in δ13C correlated strongly with the fraction of DOC remaining. We propose that the shift in δ13C is consistent with greater microbial lability of DOC originating from herbaceous C4 vegetation than DOC derived from woody C3 vegetation in the semi-arid lower Tana. The findings complement earlier data that riverine C sources do not necessarily reflect their proportion in the catchment: besides spatial distribution, also processing within the river can further influence the riverine δ13C.

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Rapid Growth of Planktonic Vibrio cholerae Non-O1/Non-O139 Strains in a Large Alkaline Lake in Austria: Dependence on Temperature and Dissolved Organic Carbon Quality

Applied and Environmental Microbiology ◽

10.1128/aem.01739-07 ◽

2008 ◽

Vol 74 (7) ◽

pp. 2004-2015 ◽

Cited By ~ 40

Author(s):

Alexander K. T. Kirschner ◽

Jane Schlesinger ◽

Andreas H. Farnleitner ◽

Romana Hornek ◽

Beate Süß ◽

...

Keyword(s):

Organic Carbon ◽

Dissolved Organic Carbon ◽

Vibrio Cholerae ◽

Growth Rates ◽

Monitoring Program ◽

Growth Yield ◽

Toxin Gene ◽

Carbon Quality ◽

Pathogenic Genes ◽

Specific Growth Rates

ABSTRACT Vibrio cholerae non-O1/non-O139 strains have caused several cases of ear, wound, and blood infections, including one lethal case of septicemia in Austria, during recent years. All of these cases had a history of local recreational activities in the large eastern Austrian lake Neusiedler See. Thus, a monitoring program was started to investigate the prevalence of V. cholerae strains in the lake over several years. Genetic analyses of isolated strains revealed the presence of a variety of pathogenic genes, but in no case did we detect the cholera toxin gene or the toxin-coregulated pilus gene, both of which are prerequisites for the pathogen to be able to cause cholera. In addition, experiments were performed to elucidate the preferred ecological niche of this pathogen. As size filtration experiments indicated and laboratory microcosms showed, endemic V. cholerae could rapidly grow in a free-living state in natural lake water at growth rates similar to those of the bulk natural bacterial population. Temperature and the quality of dissolved organic carbon had a highly significant influence on V. cholerae growth. Specific growth rates, growth yield, and enzyme activity decreased markedly with increasing concentrations of high-molecular-weight substances, indicating that the humic substances originating from the extensive reed belt in the lake can inhibit V. cholerae growth.

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Tracing Aquatic Priming Effect During Microbial Decomposition of Terrestrial Dissolved Organic Carbon in Chemostat Experiments

Microbial Ecology ◽

10.1007/s00248-017-0976-0 ◽

2017 ◽

Vol 74 (3) ◽

pp. 534-549 ◽

Cited By ~ 6

Author(s):

Karoline Morling ◽

Julia Raeke ◽

Norbert Kamjunke ◽

Thorsten Reemtsma ◽

Jörg Tittel

Keyword(s):

Organic Carbon ◽

Dissolved Organic Carbon ◽

Priming Effect ◽

Microbial Decomposition

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Drivers of dissolved organic carbon export in a subarctic catchment: Importance of microbial decomposition, sorption-desorption, peatland and lateral flow

The Science of The Total Environment ◽

10.1016/j.scitotenv.2017.11.252 ◽

2018 ◽

Vol 622-623 ◽

pp. 260-274 ◽

Cited By ~ 13

Author(s):

Jing Tang ◽

Alla Y. Yurova ◽

Guy Schurgers ◽

Paul A. Miller ◽

Stefan Olin ◽

...

Keyword(s):

Organic Carbon ◽

Dissolved Organic Carbon ◽

Lateral Flow ◽

Carbon Export ◽

Microbial Decomposition

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Available Dissolved Organic Carbon Alters Uptake and Recycling of Phosphorus and Nitrogen from River Sediments

Water ◽

10.3390/w12123321 ◽

2020 ◽

Vol 12 (12) ◽

pp. 3321

Author(s):

Marc Stutter ◽

Daniel Graeber ◽

Gabriele Weigelhofer

Keyword(s):

Organic Carbon ◽

Dissolved Organic Carbon ◽

Nutrient Uptake ◽

Inorganic Nitrogen ◽

River Sediments ◽

Carbon Sources ◽

P Uptake ◽

Stream Sediments ◽

Organic C ◽

Flow Through

Concurrent with nutrient pollution, agriculture has significantly impacted the quantity, composition, and bioavailability of catchment-derived dissolved organic carbon (DOC) in stream ecosystems. Based on the stoichiometric theory, we tested the hypothesis that bioavailable DOC will stimulate the heterotrophic uptake of soluble reactive P (SRP) and inorganic nitrogen in stream sediments. In a simplified laboratory column flow-through study, we exposed stream sediments to additions of glucose, nitrate, and phosphate alone and in combination (+C, +NP, +CNP), and calculated gross and net changes in DOC and nutrients via a mass balance approach. Our results show that glucose-C increased nutrient uptake, but also that NP additions resulted in the enhanced consumption of both native and added organic C. The effects of C addition were stronger on N than P uptake, presumably because labile C stimulated both assimilation and denitrification, while part of the P uptake was due to adsorption. Internal cycling affected net nutrient uptake due to losses of dissolved organically-complexed P and N (DOP and DON). Overall, our study shows that increases in the stoichiometric availability of organic carbon can stimulate N and P sequestration in nutrient-polluted stream sediments. Future studies are required to assess the effects of complex organic carbon sources on nutrient uptake in stream sediments under different environmental conditions, and whether these stoichiometric relations are relevant for ecosystem management.

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Dissolved organic carbon lability and stable isotope shifts during microbial decomposition in a tropical river system

Biogeosciences ◽

10.5194/bg-13-517-2016 ◽

2016 ◽

Vol 13 (2) ◽

pp. 517-525 ◽

Cited By ~ 10

Author(s):

N. Geeraert ◽

F. O. Omengo ◽

G. Govers ◽

S. Bouillon

Keyword(s):

Stable Isotope ◽

Organic Carbon ◽

Dissolved Organic Carbon ◽

Isotope Composition ◽

River System ◽

Distribution Patterns ◽

Photochemical Oxidation ◽

Microbial Decomposition ◽

Tana River ◽

Isotope Concentration

Abstract. A significant amount of carbon is transported to the ocean as dissolved organic carbon (DOC) in rivers. During transport, it can be transformed through microbial consumption and photochemical oxidation. In dark incubation experiments with water from the Tana River, Kenya, we examined the consumption of DOC through microbial decomposition and the associated change in its carbon stable isotope composition (δ13C). In 15 of the 18 incubations, DOC concentrations decreased significantly by 10 to 60 %, with most of the decomposition taking place within the first 24–48 h. After 8 days, the remaining DOC was up to 3 ‰ more depleted in 13C compared with the initial pool, and the change in δ13C correlated strongly with the fraction of DOC remaining. We hypothesize that the shift in δ13C is consistent with greater microbial lability of DOC originating from herbaceous C4 vegetation than DOC derived from woody C3 vegetation in the semi-arid lower Tana. The results complement earlier findings that the stable isotope concentration of riverine DOC does not necessarily reflect the proportion of C3 and C4-derived DOC in the catchment: besides spatial distribution patterns of different vegetation types, processing within the river can further influence the δ13C of riverine OC.

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