Metamenu

Publications

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Publications in peer reviewed journals

10 Publications found
  • Nutrient controls on carbohydrate and lignin decomposition in beech litter

    Kohl L, Wanek W, Keiblinger K, Hämmerle I, Fuchslueger L, Schneider T, Riedel K, Eberl L, Zechmeister-Boltenstern S, Richter A
    2023 - Geoderma, 429: Article 116276

    Abstract: 

    Nutrient pollution has increased plant litter nutrient concentrations in many ecosystems, which may profoundly impact litter decomposition and change the chemical composition of litter inputs to soils. Here, we report on a mesocosm experiment to study how variations in the nitrogen (N) and phosphorus (P) concentrations in Fagus sylvatica (European beech) litter from four sites differing in bedrock, atmospheric deposition, and climate affect lignin and carbohydrate loss rates and residual litter chemistry. We show with pyrolysis GC/MS and elemental analysis that nutrient concentrations had a strong influence on changes in litter chemistry during early decomposition (0–181 days), when greater lignin loss rates were associated with low P concentrations, whereas carbohydrate and bulk C loss were associated with high N concentrations. Nutrient concentrations, in contrast, did not influence changes in litter chemistry in the later decomposition stage (181–475 days), where the decomposition rates of lignin, carbohydrates, and bulk C all increased with litter N concentration and no differences in decomposition rates between major compound classes were detected. Our data indicate that these differences were related to the transition from increasing to constant or declining microbial biomass, and an associated decrease in microbial dependence on the mobilization of nutrients from the insoluble litter fraction.

  • Policy options to account for multiple chemical pollutants threatening biodiversity

    Leonie Katharina Mueller, Marlene Ågerstrand, Thomas Backhaus, Miriam Diamond, Walter Erdelen, David Evers, Ksenia Groh, Martin Scheringer, Gabriel Sigmund, Zhanyun Wang, Andreas Schäffer
    2023 - Environmental Science: Advances, in press

    Abstract: 

    Chemical pollution poses a threat to biodiversity on a global scale. This has been acknowledged in the Post-2020 Biological Diversity Framework which proposes to regulate the release of chemicals to the environment and names specific indicators focusing on pesticides, nutrients and plastic waste. We fully endorse the inclusion of these substances but argue that in order to protect biodiversity from hazardous chemicals, the scope of Target 7 should feature other groups of pollutants with potential to contribute to biodiversity loss. We propose the inclusion of non-agricultural biocides, per- and polyfluoroalkyl substances (PFASs), toxic metal(loid)s, and endocrine disrupting chemcials (EDCs). Furthermore, data on emerging pollutants (e.g., rare earth elements, industrial chemicals, liquid crystal monomers, pharmaceuticals, personal care products) need to be regularly scanned and these pollutants added to Target 7 in case of biodiversity risk. We suggest to amend Target 7 to postulate the aim for the overall reduction of chemical production and emissions, as well as the addition of the described substance groups of high concern to biodiversity for discussion and implementation in the Post-2020 Biodiversity Framework. We further elaborate on different strategies for the reduction of emissions of hazardous chemicals through chemical simplification and grouping, reduction of chemicals with non-essential use, and innovative synthesis strategies (“benign by design”). In this context the full life cycle of chemicals, i.e., production, use, end of life needs to be considered. Lastly, we propose to set up data inventories that transparently inform about production, transport and emissions of chemicals in cooperation with industry, that can serve as basis for indicators related to monitoring the effectiveness of the goals set under Target 7.

  • Small biochar particles hardly disintegrate under cryo-stress

    Gabriel Sigmund, Andrea Schmid, Hans-Peter Schmidt, Nikolas Hagemann, Thomas D. Bucheli, Thilo Hofmann
    2023 - Geoderma, 430: in press

    Abstract: 

    Physical disintegration of biochar has been postulated to determine the persistence and mobility in soil of this recalcitrant carbon pool. Therein, freeze–thaw cycling can induce substantial physical stress to biochars. We here investigated the physical disintegration and subsequent mobilisation of five different biochars under “realistic worst-case scenarios” in a laboratory soil column setup as well as in shaking and sonication batch experiments. The mobilization of carbon from biochar particles (0.25–1 mm) was investigated in the absence of clay at a pH of 6.3 with and without 80 freeze–thaw cycles. The small biochar particles used in this study did not strongly disintegrate after freeze–thaw cycling, possibly because of freezing point depression in biochar micropores. Our results in comparison with findings in literature suggest that freeze–thaw-induced physical disintegration of biochar is a process more pronounced for large biochar particles containing substantial meso- and macropores. Biochars with larger ash fractions disintegrated more, presumably because of the ash-associated formation of unstable cavities within the biochar. Physical stability of biochars produced from the same feedstock at different pyrolysis temperatures decreased with increasing aromaticity, which may be linked to a higher rigidity of more aromatic structures. Moisture content in the soil increased carbon mobilization from biochar more than physical stress such as freeze–thaw cycling. The physical disintegration of biochar and subsequent mobilization of micro-and nanosized carbon should thus be considered of minor relevance and is often not a driving factor for biochar stability in soil.

  • Analytical strategies to measure gadolinium as a wastewater marker in surface and groundwater systems

    Miguel Angel Marazuela, Martin Stockhausen, Thilo Hofmann
    2023 - MethodsX, 10: in press

    Abstract: 

    The increasing use of gadolinium (Gd)-based contrast agents in magnetic resonance imaging and the recalcitrant behavior of Gd during municipal wastewater treatment have led to increased concentrations of the tracer in aquatic environments. These anthropogenic Gd emissions to wastewater and, subsequently, to surface and groundwater systems can be exploited to calculate groundwater travel times and mixing ratios, identify wastewater inputs, and calibrate groundwater models. However, analytical complexity, costs, and the time needed to directly measure anthropogenic inputs hinder the practical use of Gd. While direct measurements with inductively coupled plasma-mass spectrometry (ICP-MS) are highly efficient and feasible, only total Gd can be detected with this approach. In unknown hydrogeological systems, the differentiation between total, anthropogenic, and geogenic Gd by interpolating rare earth element patterns requires complex sample pre-treatment and pre-concentration. Direct measurements of Gd can be obtained using anion-exchange chromatography coupled to ICP-MS but the limit of quantification will be higher. Here we provide guidelines for selecting the optimal method for the analysis of Gd as a wastewater tracer in surface-groundwater systems.

    • The cost-effectiveness of existing analytical strategies to measure Gd when used as a wastewater tracer in surface-groundwater systems is addressed
    • A novel analytical strategy for direct determination of total Gd is presented

     

  • Stromatolitic carbonates from the Middle Miocene of the western Pannonian Basin reflect trace metal availability in microbial habitats during the Badenian Salinity Crisis

    Sebastian Viehmann, Robert Kujawa, Simon V. Hohl, Nathalie Tepe, Alexandra S. Rodler, Thilo Hofmann, Erich Draganits
    2023 - Chemical Geology, 618: in press

    Abstract: 

    Stromatolitic carbonates of the Middle Miocene Oberpullendorf Basin (Austria) provide a great opportunity to study the evolution of microbial habitats under extreme environmental changes during the Badenian (Langhian and early Serravallian) Salinity Crisis. We here present the first geochemical data for Badenian stromatolites and show in a combined approach using major, trace element, and C – O isotope compositions obtained in individual stromatolitic carbonate laminae that short-term variations of palaeo-environmental conditions within the Oberpullendorf Basin coincide with individual microbialite morphologies.

    The studied carbonates were affected by both detrital contamination and post-depositional alteration processes to different degrees. While fluid-mobile elements show clear evidence for post-depositional alteration processes, the rare earth element and yttrium (REY) as well as bio-essential element (Fe, Mn, Co, Zn, Mo, W) compositions of the carbonates remained unaffected. Stromatolitic carbonates that are devoid of detrital contamination (< 300 ppm Al) show typical shale-normalized seawater-like rare earth element and yttrium (REYSN) patterns with positive LaSN, GdSN anomalies, super-chondritic Y/Ho ratios, and heavy over light REYSN enrichments in the lower stromatolite units. These features suggest an open ocean seawater influenced depositional setting at the north-western margin of the Paratethys Sea. Stratigraphically upwards, pure stromatolitic carbonates show suppressed seawater-like REYSN signatures that argue for the development of a (semi)closed lagoon with restricted access to the open sea. Seawater-like REYSN patterns in the uppermost part resemble a reappearance of open marine environmental conditions. Interestingly, geochemical data of the upper part of the section contradict the ambient fossil record, showing the urge for future interdisciplinary approaches targeting the understanding and interplay of geochemistry, palaeontology, and geomicrobiology in modern and ancient microbial habitats. Enrichment factors of bio-essential trace elements that are either used as co-factors in metalloenzymes or metal-activated enzymes in biochemical reactions can be directly linked to the reconstructed environmental conditions: Sufficient element availability is ensured during marine conditions in the lower and uppermost stratigraphic sections; in contrast, continuous decreasing element availability of these elements is directly related to the temporary development of a (semi)closed lagoon.

  • Pathometagenomics reveals susceptibility to intestinal infection by Morganella to be mediated by the blood group-related B4galnt2 gene in wild mice.

    Vallier M, Suwandi A, Ehrhardt K, Belheouane M, Berry D, Čepić A, Galeev A, Johnsen JM, Grassl GA, Baines JF
    2023 - Gut Microbes, 1: 2164448

    Abstract: 

    Infectious disease is widely considered to be a major driver of evolution. A preponderance of signatures of balancing selection at blood group-related genes is thought to be driven by inherent trade-offs in susceptibility to disease. B4galnt2 is subject to long-term balancing selection in house mice, where two divergent allele classes direct alternative tissue-specific expression of a glycosyltransferase in the intestine versus blood vessels. The blood vessel allele class leads to prolonged bleeding times similar to von Willebrand disease in humans, yet has been maintained for millions of years. Based on in vivo functional studies in inbred lab strains, it is hypothesized that the cost of prolonged bleeding times may be offset by an evolutionary trade-off involving susceptibility to a yet unknown pathogen(s). To identify candidate pathogens for which resistance could be mediated by B4galnt2 genotype, we here employed a novel "pathometagenomic" approach in a wild mouse population, which combines bacterial 16S rRNA gene-based community profiling with histopathology of gut tissue. Through subsequent isolation, genome sequencing and controlled experiments in lab mice, we show that the presence of the blood vessel allele is associated with resistance to a newly identified subspecies of Morganella morganii, a clinically important opportunistic pathogen. Given the increasing importance of zoonotic events, the approach outlined here may find useful application in the detection of emerging diseases in wild animal populations.

  • Mid-Infrared Photothermal-Fluorescence In Situ Hybridization for Functional Analysis and Genetic Identification of Single Cells

    Bai Y, Guo Z, Pereira FC, Wagner M, Cheng JX
    2023 - Anal Chem, in press
    Mid-Infrared Photothermal-Fluorescence In Situ Hybridization

    Abstract: 

    Simultaneous identification and metabolic analysis of microbes with single-cell resolution and high throughput are necessary to answer the question of "who eats what, when, and where" in complex microbial communities. Here, we present a mid-infrared photothermal-fluorescence in situ hybridization (MIP-FISH) platform that enables direct bridging of genotype and phenotype. Through multiple improvements of MIP imaging, the sensitive detection of isotopically labeled compounds incorporated into proteins of individual bacterial cells became possible, while simultaneous detection of FISH labeling with rRNA-targeted probes enabled the identification of the analyzed cells. In proof-of-concept experiments, we showed that the clear spectral red shift in the protein amide I region due to incorporation of C atoms originating from C-labeled glucose can be exploited by MIP-FISH to discriminate and identify C-labeled bacterial cells within a complex human gut microbiome sample. The presented methods open new opportunities for single-cell structure-function analyses for microbiology.

  • Differential carbon utilization enables co-existence of recently speciated Campylobacteraceae in the cow rumen epithelial microbiome.

    Strachan CR, Yu XA, Neubauer V, Mueller AJ, Wagner Ma, Zebeli Q, Selberherr E, Polz MF
    2023 - Nat Microbiol, in press

    Abstract: 

    The activities of different microbes in the cow rumen have been shown to modulate the host's ability to utilize plant biomass, while the host-rumen interface has received little attention. As datasets collected worldwide have pointed to Campylobacteraceae as particularly abundant members of the rumen epithelial microbiome, we targeted this group in a subset of seven cows with meta- and isolate genome analysis. We show that the dominant Campylobacteraceae lineage has recently speciated into two populations that were structured by genome-wide selective sweeps followed by population-specific gene import and recombination. These processes led to differences in gene expression and enzyme domain composition that correspond to the ability to utilize acetate, the main carbon source for the host, at the cost of inhibition by propionate. This trade-off in competitive ability further manifests itself in differential dynamics of the two populations in vivo. By exploring population-level adaptations that otherwise remain cryptic in culture-independent analyses, our results highlight how recent evolutionary dynamics can shape key functional roles in the rumen microbiome.

  • Gene gain facilitated endosymbiotic evolution of Chlamydiae.

    Dharamshi JE, Köstlbacher S, Schön ME, Collingro A, Ettema TJG, Horn M
    2023 - Nat Microbiol, 1: 40-54

    Abstract: 

    Chlamydiae is a bacterial phylum composed of obligate animal and protist endosymbionts. However, other members of the Planctomycetes-Verrucomicrobia-Chlamydiae superphylum are primarily free living. How Chlamydiae transitioned to an endosymbiotic lifestyle is still largely unresolved. Here we reconstructed Planctomycetes-Verrucomicrobia-Chlamydiae species relationships and modelled superphylum genome evolution. Gene content reconstruction from 11,996 gene families suggests a motile and facultatively anaerobic last common Chlamydiae ancestor that had already gained characteristic endosymbiont genes. Counter to expectations for genome streamlining in strict endosymbionts, we detected substantial gene gain within Chlamydiae. We found that divergence in energy metabolism and aerobiosis observed in extant lineages emerged later during chlamydial evolution. In particular, metabolic and aerobic genes characteristic of the more metabolically versatile protist-infecting chlamydiae were gained, such as respiratory chain complexes. Our results show that metabolic complexity can increase during endosymbiont evolution, adding an additional perspective for understanding symbiont evolutionary trajectories across the tree of life.

  • The microbiome of kidney stones and urine of patients with nephrolithiasis.

    Lemberger U, Pjevac P, Hausmann B, Berry D, Moser D, Jahrreis V, Özsoy M, Shariat SF, Veser J
    2023 - Urolithiasis, 1: 27

    Abstract: 

    The incidence of nephrolithiasis is rising worldwide. Although it is a multifactorial disease, lifestyle plays a major role in its etiology. Another considerable factor could be an aberrant microbiome. In our observational single-center study, we aimed to investigate the composition of bacteria in kidney stones and urine focusing on patients with features of metabolic syndrome. Catheterized urine and kidney stones were collected prospectively from 100 consecutive patients undergoing endoscopic nephrolithotomy between 2020 and 2021 at our clinic. Microbiome composition was analyzed via 16S rRNA gene amplicon sequencing. Detection of bacteria was successful in 24% of the analyzed kidney stones. These patients had a prolonged length of stay compared to patients without verifiable bacteria in their stones (2.9 vs 1.5 days). Patients with features of metabolic syndrome were characterized by kidney stones colonized with classical gastrointestinal bacteria and displayed a significant enrichment of Enterococcaceae and Enterobacteriaceae. Stones of patients without features of metabolic syndrome characterized by Ureaplasma and Staphylococcaceae. Patients with bacteria in their kidney stones exhibit a longer length of stay, possibly due to more complex care. Patients presenting with features of metabolic syndrome displayed a distinct stone microbiome compared to metabolically fit patients. Understanding the role of bacteria in stone formation could enable targeted therapy, prevention of post-operative complications and new therapeutic strategies.

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