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9. Abundance of Human Pathogenic Microorganisms in the Halophyte Salicornia europaea L.: Influence of the Chemical Composition of Shoots and Soils.

Author

Marangi, Matteo, Szymanska, Sonia, Eckhardt, Kai-Uwe, Beske, Felix, Jandl, Gerald, Hrynkiewicz, Katarzyna, Pétillon, Julien, Baum, Christel, and Leinweber, Peter

Subjects
ESCHERICHIA coli, GAS chromatography/Mass spectrometry (GC-MS), SOIL salinity, PATHOGENIC bacteria, PATHOGENIC microorganisms
Abstract

Salicornia europaea L. is a halophilic plant species belonging to Chenopodiaceae, whose shoots are used as a vegetable. Since the shoots can be eaten raw, the objective of the present study was to investigate possible controls on the abundance of human pathogenic microorganisms (HPMOs) in the shoots as a health risk. For this reason, the molecular-chemical composition of shoots, site-specific soil organic matter (bulk and rhizosphere), and soil pH and salinity were analyzed. Plant and soil samples were taken from two test sites with differing salinity levels in France (a young and an old marsh). We hypothesized that the chemical traits of plants and soils could suppress or promote HPMOs and, thus, serve as risk indicators for food quality. The chemical traits of shoots and bulk and rhizosphere soil were measured through thermochemolysis using gas chromatography/mass spectrometry (GC/MS). The densities of cultivable HPMOs (Salmonella enterica, Escherichia coli, and Listeria monocytogenes) were determined in plant shoots, rhizosphere soil, and bulk soil using selective media. Negative correlations between lignin content in the shoots and the abundance of S. enterica, as well as between lignin content in bulk soil and the abundance of E. coli, are explained by the lignin-based rigidity and its protective effect on the cell wall. In the shoot samples, the content of lipids was positively correlated with the abundance of E. coli. The abundance of E. coli, S. enterica, and L. monocytogenes in bulk soil decreased with increasing soil pH, which is linked to increased salinity. Therefore, soil salinity is proposed as a tool to decrease HPMO contamination in S. europaea and ensure its food safety. [ABSTRACT FROM AUTHOR]

Published
2024
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18. Variety and Site Drive Salix Mixture Effects on Soil Organic Matter Chemistry and Soil Carbon Accumulation.

Author

Jensen, Joel, Fransson, Petra, Baum, Christel, Leinweber, Peter, Eckhardt, Kai-Uwe, and Weih, Martin

Subjects
SOIL chemistry, IONS, POTTING soils, ULTRAHIGH vacuum, ORGANIC chemistry, NUTRIENT cycles
Abstract

Soil organic matter (SOM) is essential for nutrient cycling and soil carbon (C) accumulation, both of which are heavily influenced by the quality and quantity of plant litter. Since SOM dynamics in relation to plant diversity are poorly understood, we investigated the effects of willow variety and mixture, and site on the soil C stocks, SOM chemical composition and thermal stability. Using pyrolysis-field ionization mass spectrometry (Py-FIMS), a method of stepwise thermal degradation in ultrahigh vacuum combined with soft ionization in a high electric field, followed by mass-spectrometric separation and detection of molecular ions, we analyzed SOM in the top 10 cm of soil from two 7-year-old experimental sites in Germany and Sweden. Monocultures and mixtures of two willow varieties (Salix spp.) belonging to different species were grown at the experimental plots. Overall, site had the strongest effect on SOM quality. The results showed significant variability across sites for willow identity and mixture effects on C accumulation and SOM chemistry. In the German site (Rostock), yearly soil C accumulation was higher (p < 0.05) for variety 'Loden' (1.0 Mg C ha−1 year−1) compared to 'Tora' (0.5 Mg C ha−1 year−1), whilst in the Swedish site (Uppsala), both varieties exhibited similar soil C accumulation rates of around 0.6 Mg C ha−1 year−1. Willow variety identity significantly affected SOM quality at both sites, while mixing had minor effects. Our findings emphasize the significance of site-specific context and variety and species identity in shaping soil C accumulation in willow plantations. [ABSTRACT FROM AUTHOR]

Published
2024
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23. Interaction of Polar and Nonpolar Organic Pollutants with Soil Organic Matter: Sorption Experiments and Molecular Dynamics Simulation

Author

Ahmed, Ashour A., Thiele-Bruhn, Sören, Aziz, Saadullah G., Hilal, Rifaat H., Elroby, Shaaban A., Al-Youbi, Abdulrahman O., Leinweber, Peter, and Kühn, Oliver

Subjects
Physics - Chemical Physics
Abstract

The fate of organic pollutants in the environment is influenced by several factors including the type and strength of their interactions with soil components especially SOM. However, a molecular level answer to the question How organic pollutants interact with SOM? is lacking. In order to explore mechanisms of this interaction, we have developed a new SOM model followed by carrying out molecular dynamics (MD) simulations in parallel with sorption experiments. The new SOM model comprises free SOM functional groups (carboxylic acid and naphthalene) as well as SOM cavities (with two different sizes), representing the soil voids, containing the same SOM functional groups. To examine the effect of the hydrophobicity on the interaction, the organic pollutants hexachlorobenzene (HCB, non-polar) and sulfanilamide (SAA, polar) were considered. The experimental and the theoretical outcomes explored four major points regarding sorption of SAA and HCB on soil. 1. The interaction depends on the SOM chemical composition more than the SOM content. 2. The interaction causes a site-specific adsorption on the soil surfaces. 3. Sorption hysteresis occurs, which can be explained by inclusion of these pollutants inside soil voids. 4. It was observed that the hydrophobic HCB is adsorbed on soil stronger than the hydrophilic SAA. Moreover, the theoretical results showed that HCB forms stable complexes with all SOM models in the aqueous solution while most of SAA complexes are accompanied by dissociation. The SOM-cavity modeling showed a significant effect on binding of organic pollutants to SOM.

Published
2014
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26. How Soil Organic Matter Composition Controls Hexachlorobenzene-Soil-Interactions: Adsorption Isotherms and Quantum Chemical Modelling

Author

Ahmed, Ashour, Leinweber, Peter, and Kühn, Oliver

Subjects
Physics - Chemical Physics
Abstract

Hazardous persistent organic pollutants (POPs) interact in soil with the soil organic matter (SOM) but this interaction is insufficiently understood at the molecular level. We investigated the adsorption of hexachlorobenzene (HCB) on soil samples with systematically modified SOM. These samples included the original soil, the soil modified by adding a hot water extract (HWE) fraction (soil+3 HWE and soil+6 HWE), and the pyrolyzed soil. The SOM contents increased in the order pyrolyzed soil < original soil < soil+3 HWE < soil+6 HWE. For the latter three samples this order was also valid for the HCB adsorption. The pyrolyzed soil adsorbed more HCB than the other samples at low initial concentrations, but at higher concentrations the HCB adsorption became weaker than in the samples with HWE addition. This adsorption behaviour combined with the differences in the chemical composition between the soil samples suggested that alkylated aromatic, phenol, and lignin monomer compounds contributed most to the HCB adsorption. To obtain a molecular level understanding, a test set has been developed on the basis of elemental analysis which comprises 32 representative soil constituents. The calculated binding free energy for HCB with each representative system shows that HCB binds to SOM stronger than to soil minerals. For SOM, HCB binds to alkylated aromatic, phenols, lignin monomers, and hydrophobic aliphatic compounds stronger than to polar aliphatic compounds confirming the above adsorption isotherms. Moreover, quantitative structure-activity relationship (QSAR) of the binding free energy with independent physical properties of the test set systems for the first time indicated that the polarizability, the partial charge on the carbon atoms, and the molar volume are the most important properties controlling HCB-SOM interactions.

Published
2013

32. Soil management effects on soil organic matter properties and carbon sequestration (SOMPACS)

Author

Weber, Jerzy, primary, Leinweber, Peter, additional, Kuzyakov, Yakov, additional, Hewelke, Edyta, additional, Frąc, Magdalena, additional, Hayes, Michael, additional, Boguzas, Vaclovas, additional, Gregory, Andy, additional, Mielnik, Lilla, additional, Norton, Urszula, additional, Jerzykiewicz, Maria, additional, Debicka, Magdalena, additional, Jamroz, Elżbieta, additional, Ćwieląg-Piasecka, Irmina, additional, and Kocowicz, Andrzej, additional

Published
2023
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36. Soil research challenges in response to emerging agricultural soil management practices

Author

Techen, Anja-K., primary, Helming, Katharina, additional, Brüggemann, Nicolas, additional, Veldkamp, Edzo, additional, Reinhold-Hurek, Barbara, additional, Lorenz, Marco, additional, Bartke, Stephan, additional, Heinrich, Uwe, additional, Amelung, Wulf, additional, Augustin, Katja, additional, Boy, Jens, additional, Corre, Marife, additional, Duttman, Rainer, additional, Gebbers, Robin, additional, Gentsch, Norman, additional, Grosch, Rita, additional, Guggenberger, Georg, additional, Kern, Jürgen, additional, Kiese, Ralf, additional, Kuhwald, Michael, additional, Leinweber, Peter, additional, Schloter, Michael, additional, Wiesmeier, Martin, additional, Winkelmann, Traud, additional, and Vogel, Hans-Jörg, additional

Published
2020
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38. Biological soil crusts along a climatic gradient in Chile: Richness and imprints of phototrophic microorganisms in phosphorus biogeochemical cycling

Author

Baumann, Karen, Jung, Patrick, Samolov, Elena, Lehnert, Lukas W., Büdel, Burkhard, Karsten, Ulf, Bendix, Jörg, Achilles, Sebastian, Schermer, Michael, Matus, Francisco, Oses, Rómulo, Osses, Pablo, Morshedizad, Mohsen, Oehlschläger, Claudia, Hu, Yongfeng, Klysubun, Wantana, and Leinweber, Peter

Published
2018
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48. The dark side of orange: Multiorganismic continuum dynamics within a lichen of the Atacama Desert.

Author

Jung, Patrick, Baumann, Karen, Emrich, Dina, Schermer, Michael, Eckhardt, Kai-Uwe, Jandl, Gerald, Leinweber, Peter, Harion, Felix, Wruck, Andreas, Grube, Martin, Büdel, Burkhard, and Lakatos, Michael

Subjects
LICHENS, ORANGES, SECONDARY metabolism, SURFACE roughness, BASE isolation system, DESERTS
Abstract

Over the decades our understanding of lichens has shifted to the fact that they are multiorganismic, symbiotic microecosystems, with their complex interactions coming to the fore due to recent advances in microbiomics. Here, we present a mutualistic-parasitic continuum dynamics scenario between an orange lichen and a lichenicolous fungus from the Atacama Desert leading to the decay of the lichen's photobiont and leaving behind a black lichen thallus. Based on isolation, sequencing, and ecophysiological approaches including metabolic screenings of the symbionts, we depict consequences upon infection with the lichenicolous fungus. This spans from a loss of the lichen's photosynthetic activity and an increased roughness of its surface to an inhibition of the parietin synthesis as a shared pathway between the photobiont and the mycobiont, including a shift of secondary metabolism products. This degree of relations has rarely been documented before, although lichenicolous fungi have been studied for over 200 years, adding an additional level to the view of interactions within lichens. [ABSTRACT FROM AUTHOR]

Published
2024
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