Interaction of microorganisms and dissolved organic matter in the subterranean estuary of Spiekeroog beach
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PROVIDER: PRJEB90976 | ENA |
REPOSITORIES: ENA
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Project description:Iron that precipitates under aerobic conditions in natural aquatic systems scavenges dissolved organic matter (DOM) from solution. Subterranean estuaries (STEs) are of major importance for land-ocean biogeochemical fluxes. Their specific redox boundaries, coined the "iron curtain" due to the abundance of precipitated iron(III) (oxy)hydroxides, are hot spots for the removal and redissolution of iron, associated nutrients, and DOM. We used ultra-high-resolution electrospray ionization Fourier transform ion cyclotron resonance mass spectrometry to molecularly characterize the iron-coagulating fractions of 32 groundwater and seawater DOM samples along a salinity gradient from a shallow STE on Spiekeroog Island, North Sea, Germany, and linked our findings to trace metal and nutrient concentrations. We found systematic iron coagulation of large (>450 Da), oxygen-rich, and highly aromatic DOM molecules of terrestrial origin. The extent of coagulation increased with growing terrestrial influence along the salinity gradient. Our study is the first to show that the iron curtain may be capable of retaining terrigenous DOM fractions in marine sediments. We hypothesize that the iron curtain serves as an inorganic modulator for the supply of DOM from groundwaters to the sea, and that the STE has the potential to act as a temporal storage or even sink for terrigenous aromatic DOM compounds.
| S-EPMC5299545 | biostudies-literature
Project description:In this study we performed sediment incubations in flow-through reactors (FTRs) with deep (6 m depth) STE groundwater of low (~1.6) and high salinity (~29.1). FTR setups were sampled daily for quantification of dissolved organic carbon (DOC), and at start and end (day 13) of the incubation for analysis of DOM composition, microbial cell numbers and community composition.
| PRJEB80523 | ENA
Project description:Microbes incubated Microplastics-derived dissolved organic matter Raw sequence reads
| PRJNA800179 | ENA
Project description:DOM extraction in oceanic samples was carried out using PPL cartridges.
2022-11-09 | MSV000090678 | MassIVE
Project description:The repeated evolution of similar phenotypes in independent lineages often occurs in response to similar environmental pressures, through similar or different molecular pathways. Recently, a repeatedly occurring mutation R263Q in a conserved domain of the protein Cryptochrome-1 (CRY1) was reported in multiple species inhabiting subterranean environments. Cryptochromes regulate circadian rhythms, and glucose and lipid metabolism. Subterranean species show changes to their circadian rhythm and metabolic pathways, making it likely that this mutation in CRY1 contributes to adaptive phenotypic changes. To identify the functional consequences of the CRY1 R263Q mutation, we generated a mouse model homozygous for this mutation. Indirect calorimetry experiments revealed delayed locomotor activity, energy expenditure and feeding patterns of mutant mice in the dark phase, but no further metabolic phenotypes – unlike a full loss of function of CRY1. Gene expression analyses showed altered expression of several canonical circadian genes in the livers of the mutant mice, fortifying the notion that CRY1 R263Q impacts metabolism. Our data provide the first characterization of a novel mutation that has repeatedly evolved in subterranean environments, supporting the idea that shared environmental constraints can drive the evolution of similar phenotypes through similar genetic changes.
2025-07-23 | GSE277611 | GEO
Project description:River-to-lake transitional areas are biogeochemically active ecosystems that can alter the amount and composition of dissolved organic matter (DOM) as it moves through the aquatic continuum. However, few studies have directly measured carbon processing and assessed the carbon budget of freshwater rivermouths. We compiled measurements of dissolved organic carbon (DOC) and DOM in several water column (light and dark) and sediment incubation experiments conducted in the mouth of the Fox river (Fox rivermouth) upstream from Green Bay, Lake Michigan. Despite variation in the direction of DOC fluxes from sediments, we found that the Fox rivermouth was a net sink of DOC where water column DOC mineralization outweighed the release of DOC from sediments at the rivermouth scale. Although we found DOM composition also changed during our experiments, alterations in DOM optical properties were largely independent of the direction of sediment DOC fluxes. We found a consistent decrease in humic-like and fulvic-like terrestrial DOM and a consistent increase in the overall microbial composition of rivermouth DOM during our incubations. Moreover, greater ambient total dissolved phosphorus concentrations were positively associated with the consumption of terrestrial humic-like, microbial protein-like, and more recently derived DOM but had no effect on bulk DOC in the water column. Unexplained variation indicates that other environmental controls and water column processes affect the processing of DOM in this rivermouth. Nonetheless, the Fox rivermouth appears capable of substantial DOM transformation with implications for the composition of DOM entering Lake Michigan.Supplementary informationThe online version contains supplementary material available at 10.1007/s10533-022-01000-z.
| S-EPMC10121504 | biostudies-literature
Project description:Natural dissolved organic matter (DOM) comprises a broad range of dissolved organic molecules in aquatic systems and is among the most complex molecular mixtures known. Here we show, by comparing detailed structural fingerprints of individual molecular formulae in DOM from a set of four marine and one freshwater environments, that a major component of DOM is molecularly indistinguishable in these diverse samples. Molecular conformity was not only apparent by the co-occurrence of thousands of identical molecular formulae, but also by identical structural features of those isomers that collectively represent a molecular formula. The presence of a large pool of compounds with identical structural features in DOM is likely the result of a cascade of degradation processes or common synthetic pathways that ultimately lead to the formation of a universal background, regardless of origin and history of the organic material. This novel insight impacts our understanding of long-term turnover of DOM as the underlying mechanisms are possibly universal.
| S-EPMC6085399 | biostudies-literature
Project description:Solar photoexcitation of chromophoric groups in dissolved organic matter (DOM), when coupled to photoreduction of ubiquitous Fe(III)-oxide nanoparticles, can significantly accelerate DOM degradation in near-surface terrestrial systems, but the mechanisms of these reactions remain elusive. We examined the photolysis of chromophoric soil DOM coated onto hematite nanoplatelets featuring (001) exposed facets using a combination of molecular spectroscopies and density functional theory (DFT) computations. Reactive oxygen species (ROS) probed by electron paramagnetic resonance (EPR) spectroscopy revealed that both singlet oxygen and superoxide are the predominant ROS responsible for DOM degradation. DFT calculations confirmed that Fe(II) on the hematite (001) surface, created by interfacial electron transfer from photoexcited chromophores in DOM, can reduce dioxygen molecules to superoxide radicals (•O2-) through a one-electron transfer process. 1H nuclear magnetic resonance (NMR) and electrospray ionization Fourier-transform ion cyclotron resonance mass spectrometry (ESI-FTICR-MS) spectroscopies show that the association of DOM with hematite enhances the cleavage of aromatic groups during photodegradation. The findings point to a pivotal role for organic matter at the interface that guides specific ROS generation and the subsequent photodegradation process, as well as the prospect of using ROS signatures as a forensic tool to help interpret more complicated field-relevant systems.
| S-EPMC10867828 | biostudies-literature
Project description:Reactive iron and organic carbon are intimately associated in soils and sediments. However, to date, the organic compounds involved are uncharacterized on the molecular level. At redox interfaces in peatlands, where the biogeochemical cycles of iron and dissolved organic matter (DOM) are coupled, this issue can readily be studied. We found that precipitation of iron hydroxides at the oxic surface layer of two rewetted fens removed a large fraction of DOM via coagulation. On aeration of anoxic fen pore waters, >90% of dissolved iron and 27 ± 7% (mean ± SD) of dissolved organic carbon were rapidly (within 24 h) removed. Using ultra-high-resolution MS, we show that vascular plant-derived aromatic and pyrogenic compounds were preferentially retained, whereas the majority of carboxyl-rich aliphatic acids remained in solution. We propose that redox interfaces, which are ubiquitous in marine and terrestrial settings, are selective yet intermediate barriers that limit the flux of land-derived DOM to oceanic waters.
| S-EPMC3690857 | biostudies-other
Project description:Subterranean estuaries extend inland into density-stratified coastal carbonate aquifers containing a surprising diversity of endemic animals (mostly crustaceans) within a highly oligotrophic habitat. How complex ecosystems (termed anchialine) thrive in this globally distributed, cryptic environment is poorly understood. Here, we demonstrate that a microbial loop shuttles methane and dissolved organic carbon (DOC) to higher trophic levels of the anchialine food web in the Yucatan Peninsula (Mexico). Methane and DOC production and consumption within the coastal groundwater correspond with a microbial community capable of methanotrophy, heterotrophy, and chemoautotrophy, based on characterization by 16S rRNA gene amplicon sequencing and respiratory quinone composition. Fatty acid and bulk stable carbon isotope values of cave-adapted shrimp suggest that carbon from methanotrophic bacteria comprises 21% of their diet, on average. These findings reveal a heretofore unrecognized subterranean methane sink and contribute to our understanding of the carbon cycle and ecosystem function of karst subterranean estuaries.
| S-EPMC5703975 | biostudies-literature