Optode use to evaluate microbial planktonic respiration in oligotrophic ecosystems as an indicator of environmental stress

Medina‐Sánchez, Juan Manuel; Herrera, Guillermo A.; Durán, C.; Villar‐Argaiz, Manuel; Carrillo, Presentación

doi:10.1007/s00027-016-0515-y

Cited by 10 publications

(5 citation statements)

References 68 publications

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“…Such experiments can be informative measures of bacterial respiration and carbon processing. 19,33,34 Correlation analyses produced statistically significant relationships between O 2 losses and both DOM chemodiversity and the oxidation state of carbon. Specifically, the lower the chemodiversity and the more oxidized the PTR-DOC, the more susceptible the total DOM pool appears to be to rapid microbial consumption.…”

Section: Resultsmentioning

confidence: 97%

Understanding Dissolved Organic Matter Reactivity and Composition in Lakes and Streams Using Proton-Transfer-Reaction Mass Spectrometry (PTR-MS)

Peacock

Materić

Kothawala

et al. 2018

Environ. Sci. Technol. Lett.

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Here, we present a novel approach for investigating dissolved organic matter (DOM) composition using thermal desorption protontransfer-reaction mass spectrometry (PTR-MS), a technique that provides insight into the molecular composition of DOM < m/z 500 (termed "PTR-DOC"). The applicability of PTR-MS for understanding the relationship between DOM composition and reactivity has yet to be explored. We present results from a synoptic sampling campaign of streams and lakes in a Swedish forest catchment where we measured DOM composition using PTR-MS and traditional optical methods and conducted DOM biodegradability assays. PTR-DOC comprised ≤12% of the total DOC pool. We found significant relationships between PTR-DOC and DOM degradability; reduced chemodiversity and low concentrations of PTR-DOC were both associated with the total DOM pool being more susceptible to microbial degradation. Furthermore, molecular differences were apparent among headwater lakes, headwater streams, and lakes further down the catchment. Direct linkages between PTR-DOC and optical methods were observed. Using the quantitative data that PTR-MS generates, it could become possible to identify the fluorescing components of DOM, and the method may be particularly informative in low-DOC waters such as marine environments where PTR-DOC may dominate the total DOM pool.

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Section: Resultsmentioning

confidence: 97%

Understanding Dissolved Organic Matter Reactivity and Composition in Lakes and Streams Using Proton-Transfer-Reaction Mass Spectrometry (PTR-MS)

Peacock

Materić

Kothawala

et al. 2018

Environ. Sci. Technol. Lett.

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“…The flasks were sealed to avoid gas exchanges and incubated in the dark at 21°C for 24 h. Measurements were carried out by using an optical oxygen sensor (Fibox 3 with Oxyview 6.02 software; Presens GmbH, Regensburg, Germany). The bacterial respiration rates were calculated as the slope of the regression fit of the oxygen concentration versus time (57).…”

Section: Methodsmentioning

confidence: 99%

Light and Primary Production Shape Bacterial Activity and Community Composition of Aerobic Anoxygenic Phototrophic Bacteria in a Microcosm Experiment

Piwosz

Vrdoljak

Frenken

et al. 2020

mSphere

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Phytoplankton is a key component of aquatic microbial communities, and metabolic coupling between phytoplankton and bacteria determines the fate of dissolved organic carbon (DOC). Yet, the impact of primary production on bacterial activity and community composition remains largely unknown, as, for example, in the case of aerobic anoxygenic phototrophic (AAP) bacteria that utilize both phytoplankton-derived DOC and light as energy sources. Here, we studied how reduction of primary production in a natural freshwater community affects the bacterial community composition and its activity, focusing primarily on AAP bacteria. The bacterial respiration rate was the lowest when photosynthesis was reduced by direct inhibition of photosystem II and the highest in ambient light condition with no photosynthesis inhibition, suggesting that it was limited by carbon availability. However, bacterial assimilation rates of leucine and glucose were unaffected, indicating that increased bacterial growth efficiency (e.g., due to photoheterotrophy) can help to maintain overall bacterial production when low primary production limits DOC availability. Bacterial community composition was tightly linked to light intensity, mainly due to the increased relative abundance of light-dependent AAP bacteria. This notion shows that changes in bacterial community composition are not necessarily reflected by changes in bacterial production or growth and vice versa. Moreover, we demonstrated for the first time that light can directly affect bacterial community composition, a topic which has been neglected in studies of phytoplankton-bacteria interactions. IMPORTANCE Metabolic coupling between phytoplankton and bacteria determines the fate of dissolved organic carbon in aquatic environments, and yet how changes in the rate of primary production affect the bacterial activity and community composition remains understudied. Here, we experimentally limited the rate of primary production either by lowering light intensity or by adding a photosynthesis inhibitor. The induced decrease had a greater influence on bacterial respiration than on bacterial production and growth rate, especially at an optimal light intensity. This suggests that changes in primary production drive bacterial activity, but the effect on carbon flow may be mitigated by increased bacterial growth efficiencies, especially of light-dependent AAP bacteria. Bacterial activities were independent of changes in bacterial community composition, which were driven by light availability and AAP bacteria. This direct effect of light on composition of bacterial communities has not been documented previously.

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“…The oxygen-optode BOD method Oxygen optodes are optical sensors that are based on a chemical indicator (dynamic fluorescence quencher) (45). These robust and high-resolution sensors (46,47) have been used to study a number of oxygen-related processes in freshwater and marine systems (48)(49)(50)(51)(52), yielding the same sensitivity as the chemical Winkler method (53,54). For example, oxygen optodes have already been used in oceanography for measurements of community respiration rates in the mesopelagic and surface waters of the oligotrophic open ocean (48)(49)(50).…”

Section: Proposed New Technique For Bod Determinationmentioning

confidence: 99%

Correcting a major error in assessing organic carbon pollution in natural waters

et al. 2021

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Microbial degradation of dissolved organic carbon (DOC) in aquatic environments can cause oxygen depletion, water acidification, and CO2 emissions. These problems are caused by labile DOC (LDOC) and not refractory DOC (RDOC) that resists degradation and is thus a carbon sink. For nearly a century, chemical oxygen demand (COD) has been widely used for assessment of organic pollution in aquatic systems. Here, we show through a multicountry survey and experimental studies that COD is not an appropriate proxy of microbial degradability of organic matter because it oxidizes both LDOC and RDOC, and the latter contributes up to 90% of DOC in high-latitude forested areas. Hence, COD measurements do not provide appropriate scientific information on organic pollution in natural waters and can mislead environmental policies. We propose the replacement of the COD method with an optode-based biological oxygen demand method to accurately and efficiently assess organic pollution in natural aquatic environments.

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Optode use to evaluate microbial planktonic respiration in oligotrophic ecosystems as an indicator of environmental stress

Cited by 10 publications

References 68 publications

Understanding Dissolved Organic Matter Reactivity and Composition in Lakes and Streams Using Proton-Transfer-Reaction Mass Spectrometry (PTR-MS)

Understanding Dissolved Organic Matter Reactivity and Composition in Lakes and Streams Using Proton-Transfer-Reaction Mass Spectrometry (PTR-MS)

Light and Primary Production Shape Bacterial Activity and Community Composition of Aerobic Anoxygenic Phototrophic Bacteria in a Microcosm Experiment

Correcting a major error in assessing organic carbon pollution in natural waters

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