If O2 is available at circumneutral pH, Fe2+ rapidly oxidized to Fe3+, which precipitates as FeO(OH). Neutrophilic iron oxidizing bacteria have evolved mechanisms prevent self-encrustation in iron. Hitherto, no mechanism has been proposed for cyanobacteria from rich environments; these produce but are seldom found encrusted We used two sets of illuminated reactors connected groundwater aquifers with different concentrations (0.9 µM vs. 26 µM) the Äspö Hard Rock Laboratory, Sweden....

Abstract The deep biosphere is one of the least understood ecosystems on Earth. Although most microbiological studies in this system have focused prokaryotes and neglected microeukaryotes, recent discoveries revealed existence fossil active fungi marine sediments sub-seafloor basalts, with proposed importance for subsurface energy cycle. However, continental crystalline rocks are surprisingly few. Consequently, characteristics processes fungus-prokaryote interactions vast environment remain...

Little research has been conducted on microbial diversity deep under the Earth's surface. In this study, communities of three terrestrial subsurface aquifers were investigated. Temporal community data over 6 years revealed that phylogenetic structure and dynamics highly dependent degree isolation from earth surface biomes. The at shallow site was most dynamic dominated by sulfur-oxidizing genera Sulfurovum or Sulfurimonas all-time points. in meteoric water filled intermediate aquifer (water...

Precipitation of exceptionally 13C-depleted authigenic carbonate is a result of, and thus tracer for, sulphate-dependent anaerobic methane oxidation, particularly in marine sediments. Although these carbonates typically are less depleted 13C than the source methane, because incorporation C also from other sources, they far more (δ13C as light -69‰ V-PDB) formed where no involved. Here we show that oxidation biogenic carbon-poor deep groundwater fractured granitoid rocks has resulted...

Abstract Fractured rocks of impact craters may be suitable hosts for deep microbial communities on Earth and potentially other terrestrial planets, yet direct evidence remains elusive. Here, we present a study the largest crater Europe, Devonian Siljan structure, showing that structures can important unexplored long-term activity. Secondary carbonate minerals dated to 80 ± 5 22 3 million years, thus postdating by more than 300 have isotopic signatures revealing both methanogenesis anaerobic...

ABSTRACT Time‐of‐Flight Secondary Ion Mass Spectrometry (ToF‐SIMS) with a bismuth cluster primary ion source was used for analysing microbial lipid biomarkers in 10‐µm‐thick microscopic cryosections of methanotrophic mats from the Black Sea. Without further sample preparation, archaeal isopranyl glycerol di‐ and tetraether core lipids, together their intact diglycoside (gentiobiosyl‐) derivatives, were simultaneously identified by exact mass determination. Utilizing imaging capability...

In the deep biosphere, microbial sulfate reduction (MSR) is exploited for energy. Here, we show that, in fractured continental crystalline bedrock three areas Sweden, this process produced sulfide that reacted with iron to form pyrite extremely enriched 34 S relative 32 S. As documented by secondary ion mass spectrometry (SIMS) microanalyses, δ34 Spyrite values are up +132‰V-CDT and a total range of 186‰. The lightest (-54‰) suggest very large fractionation during MSR from an initial (δ34...

Oxidation and reduction of iron can occur through abiotic (chemical) biotic (microbial) processes. Abiotic oxidation is a function pH O2 concentration. Biotic carried out by diverse group bacteria, using or NO3 as terminal electron acceptors. At circumneutral pH, both processes at similar rates compete with each other. catalyzed iron-sulfur minerals different types organic compounds, whereas microorganisms, often chemical agents to dissolve solid minerals. We used oxidizing microbial mats...

Stromatolitic iron-rich structures have been reported from many ancient environments and are often described as Frutexites, a cryptic microfossil. Although microbial formation of such is likely, clear relation to precursor lacking so far. Here we report recent iron oxidizing biofilms which resemble the Frutexites structures. The living Frutexites-like were sampled at 160 m depth in Äspö Hard Rock Laboratory Sweden. Investigations using microscopy, 454 pyrosequencing, FISH, Raman...

As meso-order predators, snow petrels (Pagodroma nivea) play a significant role in the Antarctic food web. Changes their abundance can be related to availability of prey and thus provide an indication ecosystem health. The foraging grounds lie within pack ice open waters Southern Ocean, while nesting sites are restricted ice-free areas on mainland surrounding islands. Modern observations birds allow conclusions drawn about breeding performance ecology relation environmental parameters, such...

RATIONALE Over the last decade, high lateral resolution and imaging capabilities of time‐of‐flight secondary ion mass spectrometry (ToF‐SIMS) have increasingly stimulated interest in studying organic molecules complex environmental materials. However, unlike with established spectrometric techniques, use ToF‐SIMS biogeosciences is still hampered by a lack reference spectra relevant biomarker compounds. Here we present interpret ten different cyclic lipids that are frequently used as...

Abstract. Organic matter in Archean hydrothermal cherts may provide an important archive for molecular traces of the earliest life on Earth. The geobiological interpretation this archive, however, requires a sound understanding organic preservation and alteration systems. Here we report (including biosignatures) enclosed hydrothermally influenced Pleistocene Lake Magadi (Kenya; High Beds Green Beds). contain low carbon (< 0.4 wt %) that occurs form finely dispersed clots, layers, or...

MRI-based whole-brain manual segmentation methods are considered the gold standard for brain volumetric analysis but time-consuming and prone to human error. Automated tools like FreeSurfer can identify differences in volumes between healthy non-healthy individuals. Deep-learning-based tools, such as FastSurfer, offer faster processing times, further validation is needed, particularly pediatric cases. This study aims validate FastSurfer against a cohort compare volume estimates with...

MRI-based whole-brain manual segmentation methods are considered the gold standard for brain volumetric analysis but time-consuming and prone to human error. Automated tools like FreeSurfer can identify differences in volumes between healthy non-healthy individuals. Deep-learning-based tools, such as FastSurfer, offer faster processing times, further validation is needed, particularly pediatric cases. This study aims validate FastSurfer against a cohort compare volume estimates with...

Abstract In recent years, time‐of‐flight secondary ion mass spectrometry (ToF‐SIMS) with cluster sources has opened new perspectives for the analysis of lipid biomarkers in geobiology and organic geochemistry. However, published ToF‐SIMS reference spectra relevant compounds are still sparse, influence chemical environment (matrix) on ionisation molecules their fragmentation is not well explored. This study presents eight glycerolipids as common target biomarker studies, namely ester‐...

Abstract Fracture minerals within the 1.8‐Ga‐old Äspö Diorite (Sweden) were investigated for fossil traces of subterranean microbial activity. To track potential organic and inorganic biosignatures, an approach combining complementary analytical techniques high lateral resolution was applied to drill core material obtained at −450 m depth in Hard Rock Laboratory. This included polarization microscopy, time‐of‐flight secondary ion mass spectrometry (ToF‐SIMS), confocal Raman electron...

Processes of iron mineralization are great significance to the understanding Early-Earth geochemistry. Of specific interest processes at circumneutral pH, where chemical oxidation Fe can outcompete biological oxidation. To better understand microbially-induced mineral formation and composition involved microbial communities, we set up a series flow-reactors in Äspö Hard Rock Laboratory, 3.6 km tunnel that runs under Baltic Sea. Various aquifers Fe2+-rich brackish saline waters penetrate...

Abstract Recent discoveries of extant and fossilized communities indicate that eukaryotes, including fungi, inhabit energy-poor anoxic environments deep within the fractured igneous crust. This subterranean biosphere may constitute largest fungal habitat on our planet, but knowledge abyssal fungi their syntrophic interactions with prokaryotes concomitant metabolisms is scarce. Here we report findings fossilized, chitin-bearing hyphae at ~540 m depth in bedrock Siljan impact structure, crater...

The formation of algal and cyanobacterial blooms caused by the eutrophication water bodies is a growing global concern. To examine impact extreme weather events on blooms, eutrophication-related parameters (e.g., temperature, nitrate, ammonium, nitrite, soluble reactive phosphate (SRP)) were quantitatively assessed monthly over three years (2017–2019) at Lake Seeburg (Central Germany), shallow eutrophic lake with regular blooms. In addition, SRP concentrations in sediment pore for one year...