A simplified method of recovering CO2 from bacterioplankton respiration for isotopic analysis

doi:10.1016/j.mimet.2015.12.008

Journal of Microbiological Methods

Volume 121, February 2016, Pages 8-10

https://doi.org/10.1016/j.mimet.2015.12.008 Get rights and content

Highlights

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A simplified method for recovery of respired CO₂ by bacteria is presented.
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The method allows analysis of δ¹³C and Δ¹⁴C.
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Results suggest a selective respiration of older organic carbon.

Abstract

A method for recovering CO₂ respired by bacterioplankton for analysis of carbon isotopes was adapted for use with standard laboratory equipment without a technically demanding harvest line. The recovered CO₂ was more depleted in ¹⁴C than the dissolved organic carbon (DOC) source, which suggests a selective respiration of older carbon.

Section snippets

Conflict of interest

The authors declare no conflicts of interest.

Acknowledgments

We thank U. Link, E. Ruschak, Y. Rosenlöcher and F. Zander for their technical assistance in the lab and field, and I. Siebert for the carbon concentration analyses. We also wish to thank the members of the Stable Isotope Facility, Davis (USA) and the Radiocarbon Laboratory, Poznan (Poland) for analyzing the carbon isotopes. This work was funded by the German Federal Ministry of Education and Research (grant number 02WT1290A).

References (12)

K. Kalbitz et al.
Biodegradation of soil-derived dissolved organic matter as related to its properties
Geoderma
(2003)
P.E. Rossel et al.
Molecular composition of dissolved organic matter from a wetland plant (Juncus effusus) after photochemical and microbial decomposition (1.25 yr): common features with deep sea dissolved organic matter
Org. Geochem.
(2013)
D. Bastviken et al.
Degradation of dissolved organic matter in oxic and anoxic lake water
Limnol. Oceanogr.
(2004)
J.B. Cotner et al.
Small players, large role: microbial influence on biogeochemical processes in pelagic aquatic ecosystems
Ecosystems
(2002)
N. Kamjunke et al.
High heterotrophic bacterial production in acidic, iron-rich mining lakes
Microb. Ecol.
(2005)
S.L. McCallister et al.
Evidence for the respiration of ancient terrestrial organic C in northern temperate lakes and streams
PNAS
(2012)

There are more references available in the full text version of this article.

Cited by (8)

Lagrangian profiles of riverine autotrophy, organic matter transformation, and micropollutants at extreme drought
2022, Science of the Total Environment
Citation Excerpt :
The details are described and referenced in the SI. Decomposition experiments were performed with water from five stations (km 4, km 185, km 338, km 422, km 585) according the method of Morling et al. (2016). Briefly, river water was filtered, acified and and bubbled to remove inorganic carbon, re-adjusted to original pH, inoculated with bacteria, and incubated for 20 days in the dark (see SI for details).
On their way from inland to the ocean, flowing water bodies, their constituents and their biotic communities are exposed to complex transport and transformation processes. However, detailed process knowledge as revealed by Lagrangian measurements adjusted to travel time is rare in large rivers, in particular at hydrological extremes. To fill this gap, we investigated autotrophic processes, heterotrophic carbon utilization, and micropollutant concentrations applying a Lagrangian sampling design in a 600 km section of the River Elbe (Germany) at historically low discharge. Under base flow conditions, we expect the maximum intensity of instream processes and of point source impacts. Phytoplankton biomass and photosynthesis increased from upstream to downstream sites but maximum chlorophyll concentration was lower than at mean discharge. Concentrations of dissolved macronutrients decreased to almost complete phosphate depletion and low nitrate values. The longitudinal increase of bacterial abundance and production was less pronounced than in wetter years and bacterial community composition changed downstream. Molecular analyses revealed a longitudinal increase of many DOM components due to microbial production, whereas saturated lipid-like DOM, unsaturated aromatics and polyphenols, and some CHOS surfactants declined. In decomposition experiments, DOM components with high O/C ratios and high masses decreased whereas those with low O/C ratios, low masses, and high nitrogen content increased at all sites. Radiocarbon age analyses showed that DOC was relatively old (890–1870 years B.P.), whereas the mineralized fraction was much younger suggesting predominant oxidation of algal lysis products and exudates particularly at downstream sites. Micropollutants determining toxicity for algae (terbuthylazine, terbutryn, isoproturon and lenacil), hexachlorocyclohexanes and DDTs showed higher concentrations from the middle towards the downstream part but calculated toxicity was not negatively correlated to phytoplankton. Overall, autotrophic and heterotrophic process rates and micropollutant concentrations increased from up- to downstream reaches, but their magnitudes were not distinctly different to conditions at medium discharges.
Discharge determines production of, decomposition of and quality changes in dissolved organic carbon in pre-dams of drinking water reservoirs
2017, Science of the Total Environment
Citation Excerpt :
The percentage of microbially decomposed DOC was related to the average WRT of the pre-dams. To obtain radiocarbon ages of microbially respired CO2 during DOC decomposition, experiments were carried out with water taken from the pre-dams Rappbode and Rote Mulde from April to September 2014 as according to Morling et al. (2016). In brief, approximately 60 L of water was taken from the pre-dams (1.5 m depth) and transported to the lab where the water samples were sterilized through filtration (0.2 μm), and subsamples for carbon isotope analysis of the start DOC were taken and enriched as described in Tittel et al. (2013).
Pre-dams are small reservoirs constructed upstream of the main drinking water reservoirs and are used for nutrient removal and sediment trapping. Little is known about the role of pre-dams regarding the production and decomposition of dissolved organic carbon (DOC) in relation to discharge and how this affects the quality of DOC in the water. We combined quantitative and qualitative investigations under different hydrological conditions at three pre-dams exhibiting a gradient from oligotrophic/high-DOC to eutrophic/low-DOC. All pre-dams were mainly autotrophic in their upper water layers. The ratio of OC production to total gained OC (i.e. OC import + OC production) decreased with increasing discharge. On average, 0–30% of the total gained OC was produced within the pre-dams. The amount of microbially decomposed DOC increased with the average water residence time (WRT) and with the trophic status of the pre-dams. Radiocarbon analyses of respired CO₂ revealed that heterotrophic bacteria preferentially utilized old DOC components (195–395 years before present) under base flow conditions, whereas younger components (modern, i.e. OC produced after 1950) were utilized at high discharge. DOC quality changed significantly over the year within the pre-dams: High proportions of algae-derived DOC were observed during base flow in summer, and the freshness index (β/α ratio) decreased significantly with higher discharges. DOC production and quality changes in response to hydrological conditions should be considered for future water quality management in reservoirs, as climate scenarios for temperate regions predict decreased runoffs leading to longer WRT and increased eutrophication and production of algae-derived OC.
Effects of microbial-converted ancient permafrost organic carbon on the growth and reproduction of Daphnia magna
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Biogeochemical tools for characterizing organic carbon in inland aquatic ecosystems
2018, Limnology And Oceanography Letters
Redox Conditions Affect Dissolved Organic Carbon Quality in Stratified Freshwaters
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Journal of Microbiological Methods

Highlights

Abstract

Section snippets

Conflict of interest

Acknowledgments

References (12)

Biodegradation of soil-derived dissolved organic matter as related to its properties

Geoderma

Molecular composition of dissolved organic matter from a wetland plant (Juncus effusus) after photochemical and microbial decomposition (1.25 yr): common features with deep sea dissolved organic matter

Org. Geochem.

Degradation of dissolved organic matter in oxic and anoxic lake water

Limnol. Oceanogr.

Small players, large role: microbial influence on biogeochemical processes in pelagic aquatic ecosystems

Ecosystems

High heterotrophic bacterial production in acidic, iron-rich mining lakes

Microb. Ecol.

Evidence for the respiration of ancient terrestrial organic C in northern temperate lakes and streams

PNAS

Cited by (8)

Lagrangian profiles of riverine autotrophy, organic matter transformation, and micropollutants at extreme drought

Discharge determines production of, decomposition of and quality changes in dissolved organic carbon in pre-dams of drinking water reservoirs

Effects of microbial-converted ancient permafrost organic carbon on the growth and reproduction of Daphnia magna

Biogeochemical tools for characterizing organic carbon in inland aquatic ecosystems

Redox Conditions Affect Dissolved Organic Carbon Quality in Stratified Freshwaters

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

NoteA simplified method of recovering CO2 from bacterioplankton respiration for isotopic analysis

Highlights

Abstract

Section snippets

Conflict of interest

Acknowledgments

Geoderma

Org. Geochem.

Degradation of dissolved organic matter in oxic and anoxic lake water

Limnol. Oceanogr.

Small players, large role: microbial influence on biogeochemical processes in pelagic aquatic ecosystems

Ecosystems

High heterotrophic bacterial production in acidic, iron-rich mining lakes

Microb. Ecol.

Evidence for the respiration of ancient terrestrial organic C in northern temperate lakes and streams

PNAS

Note
A simplified method of recovering CO₂ from bacterioplankton respiration for isotopic analysis