Exploring Soil Microbial Metabolism: Insights from Heat, CO2 emission and Isotope Analysis using a Novel Macrocalorespirometer 0 15161

Projekt
POF4 - T704D6007 - DriverPool
Beschreibung
Exploring Soil Microbial Metabolism: Insights from Heat, CO2 emission and Isotope Analysis using a Novel Macrocalorespirometer

Abstract
As the largest terrestrial carbon sink, soil plays a pivotal role in the carbon cycle. Soil microorganisms are fundamental to all biochemical processes in soil, ensuring its fertility and supporting a balanced ecosystem. Through their metabolic activities, these microorganisms drive energy and matter flows, mineralizing organic matter and releasing heat and CO2, which can be measured via calorespirometry. Conventional calorespirometric techniques involve the use of isothermal microcalorimeters (IMCs). However, those techniques have limitations, such as low sample throughput, small sample sizes, oxygen limitation, and indirect CO2 measurements. In order to overcome these disadvantages, we have developed a multi-channel macrocalorespirometer (CR-24) for soil analysis. To demonstrate its application, agricultural soil (Dikopshof, Luvisol) amended with 12C (unlabelled) and 13C (labelled) glucose was used in three experiments with two different glucose concentrations. Comparisons with commercial IMCs using conventional calorespirometric measurements validated the suitability of CR-24 for soil studies, providing reliable heat, CO2 measurements and calorespirometric ratios that align with known ranges for the aerobic degradation of carbohydrates. Additionally, as an attempt to harvest more information about the incorporation of carbon into the soil organic matter (SOM), soil samples amended with 13C glucose underwent time-dependent mass spectrometric measurements (m/z 44, 12C; m/z 45, 13C) using thermogravimetry-differential scanning calorimetry-quadrupole mass spectrometry (TG-DSC-QMS). Coupling calorespirometric and mass spectrometric results demonstrated that complementary analyses can yield more detailed information about soil organic matter (SOM) composition, the fate of carbon in SOM and the mechanisms of its utilization.

Results
Five key points emerge from the findings. Firstly, CR-24 provides broader measurement capabilities compared to commercial IMCs, which are limited by smaller ampoule sizes and lower sample throughput. Additionally, to accurately measure CO2 via the NaOH trap in commercial IMCs, the ampoules must remain sealed, significantly restricting the amount of soil and carbon that can be used without incurring oxygen limitation. Secondly, the CER in CR-24, used to calculate the dynamic CR, is a continuous online recording, making it more representative of ongoing microbial metabolism. However, its interpretation is complicated by the device’s low thermal stability, leading to noise in the data. Thirdly, the drop in the CR curve is also related to the time shift between the P and CER curves. A phenomenon that requires further investigation, particularly with other carbon compounds. Fourthly, the larger sample size in CR-24 may better mimic natural soil conditions, contributing to the distinct P dynamics observed. Lastly, integrating calorespirometric measurements with other analyses, such as TG-DSC-QMS, can provide deeper insights into the biochemical processes involved in SOM degradation.

Conclusion
The newly developed macrocalorespirometer CR-24 offers promising capabilities for soil studies, making it a potentially valuable tool in this field. Its key features include (i) the simultaneous measurement of heat production rate and CER on a single sample, (ii) a large sample volume, and (iii) the ability to operate at high throughput. The first feature minimizes errors that could arise from conducting experiments in separate reactor vessels with potentially slight differences in the measuring conditions. The second reduces the impact of soil heterogeneity on the measurement result and minimizes the need for aeration creating thermal disturbances, and the third is crucial for the rapid screening of multiple soil samples or series of measurements. Additionally, CR-24 has the potential to measure undisturbed soil samples simultaneously.
However, to fully leverage the capabilities of CR-24, several improvements are necessary. First, the temperature stability of the heat sink needs enhancement. This could be achieved by better temperature control and improving the insulating materials. Second, refining the data analysis methods is crucial to accurately determine when the metabolic heat surpasses the initial thermal disturbances caused by sample insertion. These disturbances are primarily due to temperature differences between the soil sample and the heat sink. This challenge is especially pronounced for substrates which are metabolized rapidly, such as glucose. Precisely identifying the moment when the metabolic signal is no longer influenced by thermal equilibration will allow for more accurate interpretations of carbon turnover. These technical improvements will naturally lead to a better-defined baseline, simplifying signal evaluation and enhancing the overall accuracy of the calorimetric measurements.
Finally, integrating calorespirometric data with additional soil analyses will provide valuable insights into carbon allocation, storage within various pools, and overall carbon usage. This integrative approach could significantly advance our understanding of carbon sequestration mechanisms in soil, which is essential for developing sustainable soil management practices and promoting resilient ecosystems. Such advancements could contribute to more effective strategies for maintaining soil health and addressing critical environmental challenges, such as climate change and sustainable agriculture.
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Metadaten Kataloge
Dublin Core
URI
https://www.ufz.de/record/dmp/archive/15161
Thema
heat production rate
CO2 evolution rate
calorespirometric ratio
soil organic matter
calorespirometry
mass spectrometry
soil carbon pool
Veröffenlichungsdatum
2025
Datenart
Sammlung verschiedener Daten
Datenqualität
qualitätsgesicherte Daten
Datenstatus
bearbeitete Daten
Datenformat
xlsx
Urheber
Di Lodovico, Eliana
Beitragende
Di Lodovico, Eliana
Maskow, Thomas
Herausgeber
Helmholtz-Centre for Environmental Research
Rechteinhaber
Helmholtz-Centre for Environmental Research
Kontakt
Eliana Di Lodovico <eliana.di-lodovico@ufz.de>, <eliana.dilodovico@rptu.de>
Thomas Maskow <thomas.maskow@ufz.de>
Zeitpunkt oder -bereich der Erzeugung der Daten
15.07.2024 - 05.09.2024
Sprache des Inhalts
Englisch
Zugriffsrechte
freier Zugriff