Technological innovations in measuring and interpreting “meta-omics” datasets are now providing unprecedented mechanistic insights across diverse organisms, scales, and environmental spheres. These advances also drive the development of next-generation models to predict ecosystem function. In this session, we bring together ecologists, geochemists, and evolutionary biologists to examine the available omics toolkits for studying organisms and communities and to discuss ongoing efforts to integrate this knowledge across biological and temporal scales to address pressing Earth system science questions.
By combining eco-evolutionary insights with ecosystem-level concepts like community traits and resilience, we aim to foster future ITS sessions that apply integrated omics approaches alongside geoscience techniques for a deeper, mechanistic understanding of ecosystems.
We welcome contributions studying all Earth’s spheres (Biosphere, Atmosphere, Hydrosphere, Cryosphere, Geosphere), using a wide range of omics datasets (metagenomics, metatranscriptomics, metabolomics, proteomics, lipidomics, spectranomics, ionomics, elementomics, and isotopomics) as well as other large datasets such as trait, phenotype, inventory, pollen, and fossil records. We are particularly interested in studies involving control experiments, long-term ecological surveys, or flux networks, as well as research that provides mechanistic insights and employs big data in Earth system models or machine learning to scale patterns across space and time.
Microbiological activity on glacier and ice sheet surfaces can be a major factor responsible for their darkening. Among microbes, pigmented snow- and glacial ice-algae increase light absorption, further accelerating melting and supporting the development of pigmented algal blooms on the Greenland Ice Sheet (GrIS). The relationship between carbon-fixing algae and carbon-respiring heterotrophic microorganisms influences the amount and composition of organic matter (OM). Yet, the dynamics of the OM derived from these microbes on the GrIS remain unclear. To address this gap, we incubated algae-dominated snow and ice surface samples in situ in vented bottles under light and dark conditions. We evaluated the initial microbial community composition (via 16S and 18S rRNA gene sequencing) and characterized the changes in both dissolved and particulate OM (DOM and POM) via ultrahigh-resolution Fourier transform ion cyclotron resonance mass spectrometry. We show that glacier ice-algae habitats dominated by Ancylonema, have higher abundance of highly unsaturated and aromatic compounds resistant to bio- and photo-degradation. In contrast, snow-algae habitats dominated by Chloromonas, are enriched in bioavailable and more photosensitive unsaturated aliphatics and sulfur- and phosphorus-containing compounds. Light exposure increased water-soluble DOM compounds derived from POM, which accounted for large proportion of the initial DOM composition of both algae dominated habitats. Of these initial DOM pools, up to 50% were heterotrophically degraded in the dark, while light alone photodegraded less than 20%. The significant accumulation of light-absorbing aromatics from both POM and DOM pools at the end of the ice-algae experiments, emphasize ice-algae larger effect on altering glacier color compared to snow-algae, and thus on decreasing glacier albedo and accelerating melting.
How to cite: Rossel, P. E., Antony, R., Mourot, R., Dittmar, T., Anesio, A. M., Tranter, M., and Benning, L. G.: Organic matter variability in algal dominated habitats on the Western Greenland Ice Sheet , EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-4787, https://doi.org/10.5194/egusphere-egu25-4787, 2025.
The ablation area of the Greenland Ice Sheet (GrIS) is a biome driven by microbial activity. During the summer melt season, the weathering crust of the ice becomes a wet living skin dominated by eukaryotic glacier ice algae, particularly Ancylonema spp., which accelerate ice melt through their dark pigmentation. Cryoconite holes, formed by sediment melting into the weathering crust, also dominate the landscape of the ice surface. They are primarily inhabited by cyanobacteria as the main primary producers and also host a diverse community of bacterial, fungal and other microeukaryotic heterotrophs. This study investigates the active microbial communities and functionality of the weathering crust and cryoconites using Total RNA metatranscriptomics. With this approach, we describe the full diversity of ice surface microbial communities; assembling, annotating and analyzing jointly full-length 16S rRNA and 18S rRNA genes in addition to transcriptomes. We conducted a seasonal study over a 21-day period during the ablation season, sampling ice and cryoconite habitats. Samples were collected from five cryoconite holes and five 2-meter patches of the weathering crust ca 25km inland on the GrIS, near Ilulissat. Biomass from cryoconite holes and ice surfaces was collected at solar noon on seven sampling days during the summer. The findings highlight the dynamics and spatial variability of very different microbial communities between the weathering crust and cryoconite holes. Notably, the weathering crust is dominated by eukaryotic biomass, and spatial variability is significant; cryoconites are far more diverse, dominated by prokaryotic interactions and relatively stable temporally. A snowfall in late summer provided a window of opportunity to show that cryoconites communities are robust, while the functionality of the weathering crust, including genes associated to carbon, nitrogen and phosphorus cycling all responded to snowfall. The Total RNA approach in this study provides a powerful insight into the entire active microbial community and their functionality on glacial surfaces.
How to cite: Zervas, A., Perini, L., Feord, H., Jaarsma, A., Sipes, K., Tranter, M., Benning, L. G., and Anesio, A. M.: TotalRNA sequencing reveals active community and functional dynamics on the surface of the Greenland Ice Sheet, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-18535, https://doi.org/10.5194/egusphere-egu25-18535, 2025.
Understanding microbial activity in snowpacks is essential for unveiling the dynamics of cold ecosystems, yet little is known about how this activity changes between day and night. To address this knowledge gap, we conducted a 24-hour study on a snowpack located in the French Alps, sampling snow at five-hour intervals across different layers —from the surface to the basal layer in contact with soil.
For each layer and time point, we sampled snow to assess microbial activity using omic techniques, like metagenomic and metatranscriptomics, coupled to the analysis of environmental parameters, including sunlight duration, snow pH and temperature. Our results revealed significant diurnal variations: sunlight, pH and temperature fluctuated throughout the 24-hour period, with microbial activity showing corresponding changes. For example, algae affiliated with Chlorella and Volvox, or fungi affiliated with Rhizophagus and Penicillium, showed different transcriptomic responses to diurnal changes in surface and basal samples. These findings highlight the influence of environmental factors on microbial processes in snow and provide the first insights into how microbial activity adapts to the diurnal cycle in snowpacks.
This study contributes to understanding microbial dynamics in snow-covered ecosystems, shedding light on the interplay between microorganisms and their environment over short temporal scales.
How to cite: Schivalocchi, F., Darfeuil, S., Crouzet, A., Martins, J., Tusha, D., Jaffrezo, J. L., Piot, C., and Larose, C.: Unraveling Microbial Activity in Alpine Snow using metatranscriptomics: A 24-Hour Study of Diurnal Variations, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-1190, https://doi.org/10.5194/egusphere-egu25-1190, 2025.
The metabolic potential and activity of deep-sea microbes have not been fully explored by metatranscriptomics using the samples obtained by different sampling methods. Here, we report active deep-sea microbes obtained by the methods of Multiple in situ Nucleic Acid Collection (MISNAC), in situ microbial filtration and fixation (ISMIFF), in situ microbial filtration without fixation (ISMIFU) and the Niskin bottle at 1,038-m depth in the South China Sea. Higher biodiversity and different dominant active microbial taxa in the metatranscriptomes were detected in the MISNAC and ISMIFF samples, compared with the other two approaches. The transcriptional profiles of 40 conserved genes were similar between the MISNAC and ISMIFF samples, while expression of a quarter of these genes was not detected in the ISMIFU sample. Genes related to the CO oxidation and nitrification processes were highly transcribed in the MISNAC and ISMIFF transcriptomes, whereas genes for chemotaxis and low-oxygen adaptation were highly transcribed in the Niskin samples. Overall, our result highlights the importance of in situ sampling and preservation for more precise quantification of the ecological function of active deep-sea microbiomes.
How to cite: Wang, Y. and He, Y.: Transcriptional difference of deep-sea microorganisms under different sampling methods, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-1494, https://doi.org/10.5194/egusphere-egu25-1494, 2025.
Learning about the metabolic activities and adaptations of deep-sea microbes is a challenging task, because the collection and retrieval of samples from the deep ocean induce RNA degradation and alteration of microbial communities. Here, we employed a in situ DNA/RNA co-extraction device to collect 18 time-course nucleotide acid samples for winter and summer seasons in the South China Sea to generate metatranscriptomes and metagenomes with the minimal possible sampling perturbation. Between the two seasons, the most active eukaryotic microbes were Ciliophora, whereas the most abundant but inactive eukaryotic microbes were Retaria. In the winter, autotrophic microorganisms contributed to organic matter production by CO2 fixation associated with nitrification. In the summer, the primary source of energy originated from heterotrophic microorganisms that can utilize alkanes, aromatic compounds and carbohydrates, partially relying on anaerobic respiration in the particles. This may relate with nutrient source variations as reflected by the different levels of microbial network complexity between two seasons. Altogether, we uncovered the metabolic activities and adaptations of active microbial groups in two seasons with in situ metatranscriptomes, paving the way to identification of the real microbial contributors to element cycles in the deep ocean.
How to cite: He, Y., Baltar, F., and Wang, Y.: In situ sampling uncovers seasonal variability in community structure and metabolism of active deep-sea microbes, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-14323, https://doi.org/10.5194/egusphere-egu25-14323, 2025.
Abstract: Soil contamination from excessive pesticide use is a global issue, threatening human health and environmental sustainability. Pesticides disrupt soil microbiomes, leading to a decline in beneficial microorganisms, impaired nutrient cycling, and long-term ecosystem disturbances. Microorganisms play a crucial role in environmental preservation by breaking down xenobiotics, including pesticides. However, the pathways of pesticide degradation by microorganisms are not well understood due to limitations in current culturing techniques. To address this knowledge gap, we utilized 16S rRNA V3-V4 metagenomic sequencing to analyze farming soils in Dehradun with a history of pesticide application. Our results revealed a relative abundance of the phyla Proteobacteria, Acidobacteria, Firmicutes, and Actinobacteria in contaminated zones. Bacillus, Solibacter, and Nitrospira were the most prevalent taxa, indicating nitrogen and carbon fixation and regulation of biogeochemical cycles in extreme environments. Predictive metagenome analysis showed that core-degrading orthologs involved in membrane transport, the TCA cycle, carbohydrate metabolism, and xenobiotic degradation (such as atrazine and chlorocyclohexane degradation) were prevalent in contaminated soils. Our findings highlight the implications of abundant microbes in contaminated soils through comprehensive metagenomic approaches, paving the way for further research on gene expression frequencies and major enzyme assays for pesticide degradation.
Keywords: Metagenomics, Microbial diversity, Pesticide degradation, Taxonomy
How to cite: Mahapatra, D. M., Sinha Roy, S., and Goyal, N.: Decoding Soil Microbiomes: Metagenomic Insights into Pesticide-Contaminated Agro-Ecosystems, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-14807, https://doi.org/10.5194/egusphere-egu25-14807, 2025.
Coccidioides immitis and C. posadasii are closely related fungal pathogens that cause coccidioidomycosis, a respiratory disease also known as Valley fever. In general, Coccidioides are regarded to grow in arid to semi-arid soils in North and South America. If a person inhales these spores, they can become sick with Valley fever. The soil properties conducive for the presence of Coccidioides are not currently well defined, including whether there are differences in the soil properties conducive for each species. Recent efforts, especially over the last decade, to collect soil samples positive for Coccidioides now provide the data to begin examining these questions. We compiled Coccidioides spp. occurrence data from both previous studies and studies published on the National Center for Biotechnology Information (NCBI) database to examine the generalized soil properties associated with the presence of the pathogen. We analyzed 13 different soil properties from the California Soil Resource Lab at University of California Davis database derived from USDA-NCSS soil data and one measure of ecoregions from the US Environmental Protection Agency. Comparing the two species, we found that C. immitis was present in soils with a statistically significant higher water holding capacity and silt content than C. posadasii. Additionally, C. immitis was found in soils with significantly higher soil organic matter and calcium carbonate content than C. posadasii. This may suggest that C. immitis is more likely to grow in wetter and more productive soils compared to C. posadasii. Understanding the soil properties conducive for each Coccidioides species will allow us predict areas prone to their presence, enabling the creation of higher resolution risk maps for Valley fever and preventative messaging to at-risk populations.
How to cite: Álvarez-Gandía, Y. D., Lewis, C., Barker, B. M., Catalán-Dibene, J., Kaufeld, K. A. ., Kollath, D., Lauer, A., Mead, H., Oltean, H., Ramsey, M., Romero-Olivares, A., Bartlow, A. W., and Gorris, M. E.: Understanding soil properties conducive for Coccidioides ssp. presence in the United States , EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-7658, https://doi.org/10.5194/egusphere-egu25-7658, 2025.
Wastewater-based epidemiology (WBE) is increasingly recognized as a pivotal tool for tracking community health trends, including viral pathogens and antimicrobial resistance (AMR). This study integrates the surveillance of SARS-CoV-2 genes and AMR in wastewater samples collected from wastewater treatment plants (WWTPs) in Dehradun, India, during the COVID-19 pandemic. By combining genomic and molecular analyses, this research offers a dual perspective on two significant public health threats: the emergence of SARS-CoV-2 variants and the escalating burden of AMR. Weekly wastewater samples were collected from eight WWTPs between June 2022 and July 2023. SARS-CoV-2 RNA was quantified using real-time PCR assays targeting N, S, and ORF-1ab genes. At the same time, AMR was assessed through 16S rRNA gene sequencing and qPCR to detect resistance genes across multiple antibiotic classes, including aminoglycosides, β-lactams, macrolides, and tetracyclines. Seasonal variations, gene abundance, and correlations between SARS-CoV-2 and AMR markers were analyzed to understand the dynamics of these health risks in the urban environment. In this respect, SARS-CoV-2 analysis revealed 68 distinct lineages, dominated by Omicron recombinant variants XAP, XBB.1.16.1, and XBB.1.22 in March and April 2023, making up more than 50% of the total abundance. Such variants carried mutations that could increase transmissibility, underlying the importance of wastewater monitoring in tracking viral evolution. Meanwhile, AMR surveillance highlighted significant seasonal trends in the abundance of antibiotic-resistance genes (ARGs). Tetracycline resistance surged to 34.35% during the monsoon season at the Kargi WWTP, compared to 12.98% in winter. In contrast, macrolide resistance peaked at 35.87% in winter and decreased to 15.35% during the monsoon season. Resistant genes, such as tetX, ermF, blaOXA-50, and aadA1, were frequently detected, with aminoglycosides and tetracyclines consistently showing high resistance levels across sites and seasons. The simultaneous presence of SARS-CoV-2 RNA and ARGs in wastewater underscores the role of WWTPs as reservoirs and conduits for emerging public health threats. Climatic factors, anthropogenic activities, and proximity to healthcare facilities impact the distribution of resistant genes and viral variants. Notably, the effective removal of SARS-CoV-2 genes in municipal WWTPs (~50% gene reduction) highlights the possibility of targeted interventions to mitigate pathogen spread. However, the continued presence of resistant genes despite treatment raises concerns about environmental and public health risks. This study illustrated the potential for integrated viral and AMR wastewater surveillance to deliver community health intelligence in real-time. Thus, by monitoring SARS-CoV-2 variants alongside AMR trends, WBE can be an early warning system for emerging health threats, informing public health policy and environmental management strategies.
Keywords: antimicrobial-resistance; Covid-19; resistant genes; wastewater-based epidemiology
How to cite: Dogra, S. and Kumar, M.: The co-occurrence of Viral Pathogens and Antimicrobial-Resistance (AMR) markers from urban wastewater treatment plants in India, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-13669, https://doi.org/10.5194/egusphere-egu25-13669, 2025.
The use of glacial rock flour as an agricultural soil amendment gained increasing interest due to its fine particle size, potential to deliver crop-essential nutrients, and capacity for Mg or Ca-rich silicates to enhance rock weathering to capture atmospheric CO2 in carbonate form. Additionally, some studies have observed that rock flour amendments can reduce N2O flux. Plant growth, carbon storage, and soil emissions are all influenced by microorganisms in soil, which actively participate in biotic weathering processes that release plant-essential nutrients like phosphate, potassium, and sulfur from minerals. Furthermore, microorganisms drive nitrogen and carbon cycling, which influences soil fertility and greenhouse gas emissions. Thus, the unknown impact of glacial flour application to soil microbial communities must be investigated. Our study aimed to assess a French agricultural soil microbial community responds to varying glacial rock flour application rates during a 12-week microcosm experiment. The granitic glacial flour selected for study originated from Mer de Glace (French Alps). To understand the microbial community’s response, we focused on taxonomic shifts, relative abundance of genes related to nitrogen cycling and nutrient access, and geochemical shifts between baseline and 12-week samples. We hypothesized that glacial flour amendment would select for a community that would reduce nitrogen losses through N2O and demonstrate improved ability to access flour-bound nutrients particularly at higher application rates compared to the control soil. To test this hypothesis, we conducted a 12-week microcosm study where glacial rock flour was added to 50 g of agricultural soil at rates of 0, 0.5, 2, 5, 10, 20, 30, 50, 80, 115, and 157 t ha-1. Each treatment had 12 replicates and one replicate per treatment was destructively sampled each week for analysis. For the higher application rates (30-157 t ha-1), a quartz powder control was included to account for potential changes in soil structure. Replicates remaining in the experiment were watered once per week up to 80% of water holding capacity to simulate agricultural irrigation or rainfall events. DNA was extracted from all samples for downstream analyses and subsamples from baseline and endpoint were retained for geochemical analyses. Quantitative polymerase chain reaction (qPCR) was performed on the 16S and 18S genes to quantify bacterial and fungal abundance, respectively. Metabarcoding of the v3-v4 region of the 16S rRNA gene (rrs) was done to track taxonomic changes in the bacterial population over the course of the experiment. Inorganic nitrogen species were quantified in the baseline and 12-week samples. Preliminary results showed that bacterial communities exhibited differential growth in response to amendments above 5-10 t ha-1 compared to those below, with shifts occurring at week 4 and week 10 of the experiment. Glacial flour application of 30 and 50 t ha-1 resulted in the lowest percent loss of inorganic nitrogen from baseline to week 12 compared to other application rates. These initial findings indicate that glacial rock flour application rates may significantly influence the soil microbial community, with important implications for nitrogen cycling and nutrient accessibility.
How to cite: Sampsell, K., Wild, B., Vogel, T., and Larose, C.: Soil microbial community response to glacial rock flour amendment: insights from a microcosm experiment, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-3250, https://doi.org/10.5194/egusphere-egu25-3250, 2025.
Groundwater health is increasingly threatened by climate change, which alters precipitation patterns, leading to groundwater recharge shifts. These shifts impact subsurface microbial communities, crucial for maintaining ecosystem functions. In this decade-long study of carbonate aquifers, we analyzed 815 bacterial 16S rRNA gene datasets, 226 dissolved organic matter (DOM) profiles, 387 metabolomic datasets, and 174 seepage microbiome sequences. Our findings reveal distinct short- and long-term temporal patterns of groundwater microbiomes driven by environmental fluctuations. Microbiomes of hydrologically connected aquifers exhibit lower temporal stability due to stochastic processes and greater susceptibility to surface disturbances, yet they demonstrate remarkable resilience. Conversely, isolated aquifer microbiomes show resistance to short-term changes, governed by deterministic processes, but exhibit reduced stability under prolonged stress. Variability in seepage-associated microorganisms, DOM, and metabolic diversity further drive microbiome dynamics. While shifts in DOM influence the potential functions of the microbiome, its overall functional potential demonstrates high temporal stability and resilience over time, largely due to functional redundancy. These findings highlight the dual vulnerability of groundwater systems to acute and chronic pressures, emphasizing the critical need for sustainable management strategies to mitigate the impacts of hydroclimatic extremes.
How to cite: Wang, H., Herrmann, M., Schroeter, S. A., Zerfaß, C., Lehmann, R., Lehmann, K., Ivanova, A., Pohnert, G., Gleixner, G., Trumbore, S. E., Totsche, K. U., and Küsel, K.: Balancing Act: Groundwater microbiomes' resilience and vulnerability to hydroclimatic extremes, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-8846, https://doi.org/10.5194/egusphere-egu25-8846, 2025.
The microbiologically-driven darkening of bare ice surfaces on the western Greenland Ice Sheet is significantly enhancing melting, contributing to sea level rise. Among microorganisms, purple-brown pigmented glacial ice algae (mainly members of Ancylonema alaskanum and Ancylonema nordenskiöldi) are key contributors to the ice surface darkening and the associated surface albedo reduction. It is known that the glacial ice algae actively replicate and spread across vast ice surface areas during the summer melt season. However, the metabolic pathways driving the glacial ice algal bloom development are still poorly understood. To address this knowledge gap, we used an untargeted endometabolomics approach to explore the dynamics and metabolic potential of glacier ice algal blooms and the role of the environment on their metabolic responses. We analyzed glacial ice algae-dominated surface ice samples from various locations across the western Greenland Ice Sheet using high-resolution mass spectrometry to annotate the metabolome of the algae-dominated samples. Combined with physical and chemical environmental data describing their constantly changing habitat (e.g., temperature, light response, cell numbers) we derived novel insights into the metabolic activity of the glacial ice algae and their biochemical adaptations to glacier conditions. Our data contribute to improving our understanding of the link between ice darkening and microbial activity.
How to cite: Majumder, A., Jaeger, C., Lisec, J., E Rossel, P., Tranter, M., M Anesio, A., and G Benning, L.: Metabolic profiles of glacial ice algal-dominated habitats across the western Greenland ice sheet., EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-12311, https://doi.org/10.5194/egusphere-egu25-12311, 2025.
The cryosphere encompasses a wide range of perennial microbial habitats including glaciers, lakes, seas, rivers, and soils. These habitats pose intrinsic seasonally-variable challenges for microbial populations, whose activity may be temporarily constrained. Microbial dynamics in these environments during the summer and (to a lesser extent) spring have been extensively studied, however the winter season remains largely unexplored. During the winter period, microbial activity may be constrained by freezing temperatures, limited availability of liquid water, and the absence of light and thus photosynthetic carbon input. Critical aspects of microbial activity, including metabolic processes, winter-specific community profiles, and their unique functional roles in ecological processes, are still poorly understood. To address this knowledge gap, we examined microbial activity during the winter months in a range of aquatic and terrestrial Arctic habitats. Using metatranscriptomic techniques, we identified active microorganisms and uncovered their core metabolic requirements for sustaining activity. We also employed BONCAT (bioorthogonal noncanonical amino acid tagging) to assess the ratio of live to dead microbes across different habitats and utilized qPCR and RT-qPCR to quantify organism abundance. Our results revealed significant differences in community composition, abundance, and activity across environments. Notably, glacial snow and lake slush snow exhibited high RNA-to-DNA ratios, with distinct differences in microbial diversity. Lake slush snow, in particular, displayed a more uneven microbial community compared to its snow counterpart. In contrast, soil showed very low activity despite a high DNA content. Among the ice cores, glacial ice exhibited both high diversity and moderate microbial activity. Overall, our findings suggest that microbial communities in winter are active, with activity levels varying across different habitats. These variations may be driven by factors such as differences in microbial seeding sources and the availability of free water. Despite limited energy reserves, we suggest that winter microbial communities contribute to the mineralization and recycling of biomass and elements, playing a crucial role in sustaining ecological processes in the Arctic cryosphere.
How to cite: Singh, H., Bradley, J. A., Vogel, T. M., and Larose, C.: Exploring microbial activity and metabolic requirement during the polar winter of the Arctic, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-20154, https://doi.org/10.5194/egusphere-egu25-20154, 2025.
Glacier ice algae of the streptophyte genus Ancylonema live on glaciers globally, including the Greenland Ice Sheet, and bloom despite low temperatures, low nutrient availability, and very high light intensities. In polar regions, the long polar night also imposes additional abiotic stressors. However, the cellular mechanisms responsible for Ancylonema’s resistance and adaptation to high light stress or to prolonged darkness during the polar winter are not known. We addressed this knowledge gap by evaluating the functional responses of a Greenland Ice Sheet Ancylonema-dominated microbiome to in-situ light conditions and continual darkness during a 12-day period using amplicon sequencing, metatranscriptomics, and metaproteomics. The microbial community did not substantially change during the 12 days of dark incubation; however, heterotrophs became more transcriptionally active in the dark. Metatranscriptomic and metaproteomic analyses showed that Ancylonema cells underwent high oxidative stress in the light. However, after 12 days in darkness, the algal cells retained functional photosynthetic machinery but downregulated their expression of early shikimate pathway enzyme transcripts. Transcriptional reprogramming linked to sugar uptake and phytohormone signalling was also identified in the dark, providing an insight into the first steps towards algal cell survival through the polar night. These results give us a novel understanding of the gene expression dynamics of glacier ice algae under changing light conditions, providing important clues regarding their adaptation to a harsh and extremely variable environment.
How to cite: Feord, H. K., Keuschnig, C., Trivedi, C. B., Mourot, R., Zervas, A., Turpin-Jelfs, T., Tranter, M., Anesio, A. M., Adrian, L., and Benning, L. G.: Survival strategies of supraglacial algae-dominated communities in the transition from high light to continual darkness on the Greenland Ice Sheet, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-16283, https://doi.org/10.5194/egusphere-egu25-16283, 2025.
Deep Underground laboratories are unique environments for exploring the impact of ultralow radioactivity on living organisms. They also provide unique features for running long term controlled low-dose experiments.
Evolution is an on-going process, and it can be studied experimentally in organisms with rapid generations. The E. coli Long-Term Evolution Experiment (LTEE) is an ongoing study in experimental evolution begun by Richard Lenski at the University of California, which has been tracking genetic changes in 12 initially identical populations of asexual Escherichia coli bacteria since 24 February 1988 on more than 60.000 generations.
A first evolution experiment conducted at Modane Underground Laboratory with the same E. Coli strain and the same growth medium used by Richard Lensky and collaborators has shown no change in the fitness trajectory over 500 generations when radiative background was reduced by a factor 6 from 150 to 26 nGy/hr. Monte-Carlo simulation of the experimental set-up showed that 40K in the E. Coli culture medium (Davis Medium) was the almost exclusive source of radioactivity to the bacterial strains, representing 99% of the dose received.
Potassium has three naturally occurring isotopes: 39K (93.258%) and 41K (6.730%) are stable, while 40K (0.012%) is radioactive, with a half-life of 1.25 billion years. As 40K in the nutritive medium was the main obstacle to the reduction of the dose received by the bacterial strains during this experiment, depleting 40K in the potassium used to feed the bacteria would reduce significantly the dose received and allow exploring further the ultralow radioactivity frontier. Reciprocally, enriching the potassium in 40K would increase the dose absorbed by the bacteria without changing any other physico-chemical parameters.
We therefore propose to compare the fitness trajectories over 1000 generations of the same E. Coli strain using Davis Medium (DM) nutritive media either enriched or depleted in 40K. Although the isotopic composition of natural Potassium is very stable, potassium enriched in 39K and depleted 10 times in 40K can be purchased from commercial vendors for less than 10 € per milligram. To enrich natural potassium in 40K, a promising approach is through neutron irradiation.
Repeating the same experiment using DM nutritive media that differ only by the isotopic composition of the potassium allows isolating the sole impact of radiation on the evolutionary path of the bacteria. Increasing 40K isotopic fraction increases proportionally the absorbed dose and radiation induced mutations are expected to modify the strain evolutionary paths when they exceed the spontaneous mutation rate.
These experiments could be performed in several Deep Underground Laboratories to compare the observed fitness trajectories and quantify the reproducibility of the observed evolutionary paths.
How to cite: Breton, V., Fois, G., Insa, C., Maigne, L., and Biron, D.: Deep Underground Long Term Evolution Experiments, a key to understand the impact of low doses on living organisms, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-18428, https://doi.org/10.5194/egusphere-egu25-18428, 2025.
