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PubMed2026

Electron shuttles facilitate methane-dependent arsenate reduction in paddy soils.

Methane-dependent arsenate reduction (M-AsR) occurs widely in paddy soils and can substantially enhance arsenic mobilization, posing potential ecological risks. However, the role of electron shuttles in this process remains poorly understood. In this study, we investigated the influence of anthraquinone-2,6-disulfonate (AQDS) on M-AsR in paddy soils. Fourteen-day incubation showed that 1 mmol/L AQDS facilitated 50.88 % of arsenate reduction and 31.31 % of methane oxidation. Quantitative polymerase chain reaction analysis revealed that AQDS significantly increased the abundance of functional genes associated with arsenate reduction (arrA, arsC) and anaerobic methane oxidation (mcrA) (P < 0.05). Microbial community analysis revealed that AQDS addition enriched Cloacibacterium, Sphingorhabdus, and Methylocystis, while decreasing the relative abundance of Methylobacter and Methylomonas. These findings indicate that electron shuttles facilitate M-AsR by modulating functional microbial populations, providing valuable insights into arsenic biogeochemistry and the coupled cycling of methane and arsenic in paddy soils.

Methane↗

PubMed2026

Elevation-structured viral ecological strategies along glacier-fed rivers on the Qinghai-Tibet Plateau.

The Qinghai-Tibet Plateau, a climate-vulnerable source of Asia's major rivers, harbors underexplored viral communities critical to ecosystem functions. By integrating 597 metagenomes from the Yangtze, Yellow, Lancang, and Yarlung Tsangpo rivers with 85 public available glacial metagenomes (Tibetan Glacier Genome and Gene catalog), we built the Glacier-to-River Virome Catalogue, encompassing 36,358 vOTUs and 897,250 viral protein clusters, to decode viral adaptation and ecological influence across elevation gradients. Our results reveal that high-altitude conditions favor viruses with elevated Guanine-Cytosine content, larger genomes and more cold-adaptation genes. A central finding is a systematic viral lifestyle shift from temperate in glaciated regions to lytic viruses downstream, accompanied with decline of pathogens carrying antibiotic resistance genes along the glacier-to-river gradients. Further, viral auxiliary metabolic genes transition from glacier nutrient scavenging (e.g., nitrogen and sulfur transporters) to downstream mineralization processes (e.g., denitrification) in plains highlights their role in biogeochemical cycling. These findings position viruses as pivotal regulators of microbial community structural and functional dynamics to glacier-to-river gradient change and biogeochemistry in the Qinghai-Tibet Plateau, providing critical insights into climate response in vulnerable Asian water towers.

Ice Cover↗

PubMed2026

Minimizing decompression and warming during deep seawater collection increases abundance and activity of autochthonous bacteria and archaea.

The deep ocean hosts autochthonous pressure-adapted microorganisms that are unique to this environment, as well as allochthonous pressure-sensitive members transported from shallow depths by vertical advection and particle-sinking. However, conventional sampling instruments decompress and warm deep-sea samples during retrieval, potentially altering microbial properties when studied ex situ. Here, we assess this potential sampling bias by comparing seawater microbial communities collected with or without measures aimed at minimizing pressure and temperature effects. When compared to samples collected under pressurized conditions, conventional sampling (using Niskin bottles) was found to affect prokaryotic cells retrieved by reducing their total numbers, diminishing protein synthesis activity (>10%), and also causing overall shifts in the community composition. The most significant compositional change was a >20% decrease in metagenomic archaeal representation (TACK-group/Thaumarchaeota/Nitrososphaerota). Deep-sea bacterial groups had mixed responses to preserving pressure during retrieval, with some groups exhibiting higher representation when samples were maintained pressurized (e.g. members of the family Pelagibacteraceae, unclassified Thiotricales, Thioglobaceae, and Chitinophagaceae), whereas others increased their representation when decompressed (e.g. Burkholderiaceae, Comamonadaceae, and Oxalobacteraceae). This study reveals the existence of bias introduced by the complete decompression of samples retrieved with traditional instrumentation, as well as a decrease in overall bacterial activity when samples are completely decompressed during retrieval. Additionally, incubations lasting for >24 h were shown to transform the original prokaryotic community composition. Precautions addressing these effects are necessary to enhance the reliability of ex situ measurements and improve our understanding of deep-sea microbial ecology and biogeochemistry.

Seawater↗

PubMed2024

A novel Alteromonas phage with tail fiber containing six potential iron-binding domains.

Viruses play a vital role in regulating microbial communities, contributing to biogeochemical cycles of carbon, nitrogen, and essential metals. Alteromonas is widespread and plays an essential role in marine microbial ecology. However, there is limited knowledge about the interactions of Alteromonas and its viruses (alterophages). This study isolated a novel podovirus, vB_AmeP-R22Y (R22Y), which infects Alteromonas marina SW-47 (T). Phylogenetic analysis suggested that R22Y represented a novel viral genus within the Schitoviridae family. R22Y exhibited a broad host range and a relatively large burst size, exerting an important impact on the adaptability and dynamics of host populations. Two auxiliary metabolic genes, encoding Acyl carrier protein and AAA domain-containing protein, were predicted in R22Y, which may potentially assist in host fatty acid metabolism and VB12 biosynthesis, respectively. Remarkably, the prediction of the R22Y tail fiber structure revealed six conserved histidine residues (HxH motifs) that could potentially bind iron ions, suggesting that alterophages may function as organic iron-binding ligands in the marine environment. Our isolation and characterization of R22Y complements the Trojan Horse hypothesis, proposes the possible role of alterophages for marine iron biogeochemical cycling, and provides new insights into phage-host interactions in the iron-limited ocean.IMPORTANCEIron (Fe), as an essential micronutrient, is often a limiting factor for microbial growth in marine ecosystems. The Trojan Horse hypothesis suggests that iron in the phage tail fibers is recognized by the host's siderophore-bound iron receptor, enabling the phage to attach and initiate infection. The potential role of phages as iron-binding ligands has significant implications for oceanic trace metal biogeochemistry. In this study, we isolated a new phage R22Y with the potential to bind iron ions, using Alteromonas, a major siderophore producer, as the host. The tail fiber structure of R22Y exhibits six conserved HxH motifs, suggesting that each phage could potentially bind up to 36 iron ions. R22Y may contribute to colloidal organically complexed dissolved iron in the marine environment. This finding provides further insights into the Trojan Horse hypothesis, suggesting that alterophages may act as natural iron-binding ligands in the marine environment.

Bacteriophages↗

PubMed2026

Ocean warming enhances iron use efficiencies of marine ammonia-oxidizing archaea.

Ammonia-oxidizing archaea (AOA) are among the most abundant microorganisms in the ocean, playing a fundamental role in the marine nitrogen cycle. Although temperature and trace metal availability each individually influence the growth and activity of marine AOA, there is only a very limited understanding of the interactive effects of these two major factors on AOA in the rapidly changing ocean. Here, we show that the iron requirements of the model marine AOA species Nitrosopumilus maritimus SCM1 are highly sensitive to temperature changes. A 5 °C increase in growth temperature reduced SCM1 iron requirements by >80%, and was associated with a substantial increase in iron use efficiencies (IUE, mol C fixed/h/mol cellular Fe) under iron-limited and warming conditions. A thermally enhanced IUE enables SCM1 to more efficiently utilize scarce available iron supplies to support its growth. Whole-cell proteomic analysis revealed that iron limitation decreased expression of a ferredoxin and increased expression of a copper-dependent plastocyanin that became more pronounced with warming, suggesting coordinated electron transport response regulation under combined iron and temperature stress. The global impacts of these temperature-dependent changes to AOA iron demands were assessed using sensitivity experiments with a state-of-the-art biogeochemical model. Simulations showed that impacts on nitrification were concentrated at higher latitudes, but the alterations to ammonia concentrations were redistributed toward lower latitudes by mode and intermediate water transport. These findings reveal a previously unrecognized mechanism by which ocean warming may alleviate iron limitation of AOA, enhance their ecological competitiveness, and reshape ocean nitrogen cycling throughout marine ecosystems.

Iron↗

PubMed2026

Elements on the move: How ungulate migration expands Alpine biogeochemical footprints.

Through depositing waste products, animals influence the spatial distribution of elements across landscapes. Yet the relationship between animal movement and element distribution remains poorly characterized. We developed a spatially explicit agent-based model to test how migratory versus resident red deer (Cervus elaphus) influence nitrogen redistribution across an alpine landscape in the Central-Eastern Italian Alps. Specifically, we asked how both local-scale and landscape-scale movement alter the spatial extent and magnitude of nitrogen deposition. We parameterized our model with GPS telemetry from 2021 to 2024 and remotely sensed vegetation data. We simulated four different scenarios which allowed us to disentangle the relative effects of large-scale (migration persisting) and fine-scale (resident behaviour) movement: (i) mixed migratory-resident (300 deer), (ii) fully resident (300 deer), (iii) reduced resident (150 deer) and (iv) reduced migratory (150 deer). The potential for nitrogen intake, assimilation, and excretion occurred hourly across a seasonally dynamic landscape. Across all scenarios, tree cover density and slope consistently emerged as positive predictors of nitrogen transport. Thus, regardless of resident or migratory status, red deer act as mediators of local element transport. Similarly, proximity to roads/trails reduced nitrogen inputs and created closed systems, indicating that barriers constrain both local and landscape-scale element transport. Migration substantially expanded the spatial extent of nitrogen redistribution and enabled the upward movement of elements, both locally upslope and into higher elevation habitats, effectively transporting elements against gravitational forces. Consequently, the loss of migration is likely to weaken these large-scale element linkages and reduce associated ecosystem functions. Our results demonstrate that different animal movement patterns play distinct and complementary roles in connecting element pools across landscapes. While both resident and migrant foraging redistribute elements locally, migratory movements link lowland and alpine habitats, expanding the spatial reach of element redistribution. Thus, loss of migration not only reduces the spatial extent of element distribution but also alters the topographic pathways through which elements are cycled. These findings highlight the broader ecosystem consequences of declining animal movement extent, and migration in particular, and underscore the importance of conserving behavioural diversity to maintain element heterogeneity and ecosystem functioning in mountain systems.

animal ecology↗