Stable isotope labeling of agricultural polyesters enables demonstration of their microbial utilization in soils.
Bacteria colonize plant roots and engage in reciprocal interactions with their hosts. However, the contribution of individual taxa or groups of bacteria to plant nutrition and fitness is not well characterized due to a lack of in\uffc2\uffa0situ evidence of bacterial activity.
To address this knowledge gap, we developed an analytical approach that combines the identification and localization of individual bacteria on root surfaces via gold\uffe2\uff80\uff90based in\uffc2\uffa0situ hybridization with correlative NanoSIMS imaging of incorporated stable isotopes, indicative of metabolic activity.
We incubated Kosakonia strain DS\uffe2\uff80\uff901\uffe2\uff80\uff90associated, gnotobiotically grown rice plants with 15N\uffe2\uff80\uff93N2 gas to detect in\uffc2\uffa0situ N2 fixation activity. Bacterial cells along the rhizoplane showed\uffc2\uffa0heterogeneous patterns of 15N enrichment, ranging from the natural isotope abundance levels up to 12.07 at% 15N (average and median of 3.36 and 2.85 at% 15N, respectively, n\uffe2\uff80\uff89=\uffe2\uff80\uff89697 cells).
The presented correlative optical and chemical imaging analysis is applicable to a broad range of studies investigating plant\uffe2\uff80\uff93microbe interactions. For example, it enables verification of the in\uffc2\uffa0situ metabolic activity of host\uffe2\uff80\uff90associated commercialized strains or plant growth\uffe2\uff80\uff90promoting bacteria, thereby disentangling their role in plant nutrition. Such data facilitate the design of plant\uffe2\uff80\uff93microbe combinations for improvement of crop management.
Microbial activity in drylands tends to be confined to rare and short periods of rain. Rapid growth should be key to the maintenance of ecosystem processes in such narrow activity windows, if desiccation and rehydration cause widespread cell death due to osmotic stress. Here, simulating rain with 2H2O followed by single-cell NanoSIMS, we show that biocrust microbial communities in the Negev Desert are characterized by limited productivity, with median replication times of 6 to 19 days and restricted number of days allowing growth. Genome-resolved metatranscriptomics reveals that nearly all microbial populations resuscitate within minutes after simulated rain, independent of taxonomy, and invest their activity into repair and energy generation. Together, our data reveal a community that makes optimal use of short activity phases by fast and universal resuscitation enabling the maintenance of key ecosystem functions. We conclude that desert biocrust communities are highly adapted to surviving rapid changes in soil moisture and solute concentrations, resulting in high persistence that balances limited productivity.Microbial soil habitats are characterized by rapid shifts in substrate and nutrient availabilities, as well as chemical and physical parameters. One such parameter that can vary in soil is oxygen; thus, microbial survival is dependent on adaptation to this substrate. To better understand the metabolic abilities and adaptive strategies to oxygen-deprived environments, we combined genomics with transcriptomics of a model organism, Acidobacterium capsulatum, to explore the effect of decreasing, environmentally relevant oxygen concentrations. The decrease from 10 to 0.1\uffc2\uffa0\uffc2\uffb5M oxygen (3.6 to 0.036 pO2% present atmospheric level, respectively) caused the upregulation of the transcription of genes involved in signal transduction mechanisms, energy production and conversion and secondary metabolites biosynthesis, transport, and catabolism based on clusters of orthologous group categories. Contrary to established observations for aerobic metabolism, key genes in oxidative stress response were significantly upregulated at lower oxygen concentrations, presumably due to an NADH/NAD+ redox ratio imbalance as the cells transitioned into nanoxia. Furthermore, A. capsulatum adapted to nanoxia by inducing a respiro-fermentative metabolism and rerouting fluxes of its central carbon and energy pathways to adapt to high NADH/NAD+ redox ratios. Our results reveal physiological features and metabolic capabilities that allowed A. capsulatum to adapt to oxygen-limited conditions, which could expand into other environmentally relevant soil strains.Soils provide essential ecosystem services and represent the most diverse habitat on Earth. It has been suggested that the presence of various physico-chemically heterogeneous microhabitats supports the enormous diversity of microbial communities in soil. However, little is known about the relationship between microbial communities and their immediate environment at the micro- to millimetre scale. In this study, we examined whether bacteria, archaea, and fungi organize into distinct communities in individual 2-mm-sized soil aggregates and compared them to communities of homogenized bulk soil samples. Furthermore, we investigated their relationship to their local environment by concomitantly determining microbial community structure and physico-chemical properties from the same individual aggregates. Aggregate communities displayed exceptionally high beta-diversity, with 3\uffe2\uff80\uff934 aggregates collectively capturing more diversity than their homogenized parent soil core. Up to 20%\uffe2\uff80\uff9330% of ASVs (particularly rare ones) were unique to individual aggregates selected within a few centimetres. Aggregates and bulk soil samples showed partly different dominant phyla, indicating that taxa that are potentially driving biogeochemical processes at the small scale may not be recognized when analysing larger soil volumes. Microbial community composition and richness of individual aggregates were closely related to aggregate-specific carbon and nitrogen content, carbon stable-isotope composition, and soil moisture, indicating that aggregates provide a stable environment for sufficient time to allow co-development of communities and their environment. We conclude that the soil microbiome is a metacommunity of variable subcommunities. Our study highlights the necessity to study small, spatially coherent soil samples to better understand controls of community structure and community-mediated processes in soils.Soil microbial carbon use efficiency (CUE), defined as the ratio of organic C allocated to growth over organic C taken up, strongly affects soil carbon (C) cycling. Despite the importance of the microbial CUE for the terrestrial C cycle, very little is known about how it is affected by nutrient availability. Therefore, we studied microbial CUE and microbial biomass turnover time in soils of a long-term fertilization experiment in a temperate grassland comprising five treatments (control, PK, NK, NP, NPK). Microbial CUE and the turnover of microbial biomass were determined using a novel substrate-independent method based on incorporation of 18O from labeled water into microbial DNA. Microbial respiration was 28-37% smaller in all three N treatments (NK, NP, and NPK) compared to the control, whereas the PK treatment did not affect microbial respiration. N-fertilization decreased microbial C uptake, while the microbial growth rate was not affected. Microbial CUE ranged between 0.31 and 0.45, and was 1.3- to 1.4-fold higher in the N-fertilized soils than in the control. The turnover time ranged between 80 and 113 days and was not significantly affected by fertilization. Net primary production (NPP) and the abundance of legumes differed strongly across the treatments, and the fungal:bacterial ratio was very low in all treatments. Structural equation modeling revealed that microbial CUE was exclusively controlled by N fertilization and that neither the abundance of legumes (as a proxy for the quality of the organic matter inputs) nor NPP (as a proxy for C inputs) had an effect on microbial CUE. Our results show that N fertilization did not only decrease microbial respiration, but also microbial C uptake, indicating that less C was intracellularly processed in the N fertilized soils. The reason for reduced C uptake and increased CUE in the N-fertilization treatments is likely an inhibition of oxidative enzymes involved in the degradation of aromatic compounds by N in combination with a reduced energy requirement for microbial N acquisition in the fertilized soils. In conclusion, the study shows that N availability can control soil C cycling by affecting microbial CUE, while plant community-mediated changes in organic matter inputs and P and K availability played no important role for C partitioning of the microbial community in this temperate grassland. ", "keywords": ["FUNGAL", "2. Zero hunger", "106022 Mikrobiologie", "Nitrogen addition", "BACTERIAL", "NITROGEN DEPOSITION", "GROWTH EFFICIENCY", "FOREST FLOOR", "Nutrients", "04 agricultural and veterinary sciences", "15. Life on land", "Stoichiometry", "ORGANIC-MATTER", "RESPIRATION", "106026 \u00d6kosystemforschung", "13. Climate action", "Nutrient limitation", "Microbial growth yield", "106022 Microbiology", "0401 agriculture", " forestry", " and fisheries", "Mean residence time", "STOICHIOMETRIC CONTROLS", "ENZYME-ACTIVITY", "106026 Ecosystem research", "COMMUNITY STRUCTURE"]}, "links": [{"href": "https://doi.org/2309129852"}, {"rel": "related", "href": "https://repository.soilwise-he.eu/cat/collections/metadata:main/items/Soil%20Biology%20and%20Biochemistry", "name": "related record", "description": "related record", "type": "application/json"}, {"rel": "self", "type": "application/geo+json", "title": "2309129852", "name": "item", "description": "2309129852", "href": "https://repository.soilwise-he.eu/cat/collections/metadata:main/items/2309129852"}, {"rel": "collection", "type": "application/json", "title": "Collection", "name": "collection", "description": "Collection", "href": "https://repository.soilwise-he.eu/cat/collections/metadata:main"}], "time": {"date": "2016-06-01T00:00:00Z"}}, {"id": "11585/996230", "type": "Feature", "geometry": null, "properties": {"updated": "2026-06-26T16:28:48Z", "type": "Journal Article", "created": "2023-10-10", "title": "Beyond PLFA: Concurrent extraction of neutral and glycolipid fatty acids provides new insights into soil microbial communities", "description": "The analysis of phospholipid fatty acids (PLFAs) is one of the most common methods used to quantify the abundance, and analyse the community structure, of soil microbes. The PLFA extraction method can yield two additional lipid fractions\u2014neutral lipids and glycolipids\u2014which potentially hold additional, valuable information on soil microbial communities. Yet its quantitative sensitivity on complete neutral lipid (NLFA) and glycolipid fatty acid (GLFA) profiles has never been validated. In this study we tested (i) if the high-throughput PLFA method can be expanded to concurrently extract complete NLFA and GLFA profiles, as well as sterols, (ii) whether taxonomic specificities of signature fatty acids are retained across the three lipid fractions in pure culture strains, and (iii) whether NLFAs and GLFAs allow soil-specific fingerprinting to the same extent as PLFA analysis. By adjusting the polarity of chloroform with 2% ethanol for solid phase extraction, pure lipid standards were fully fractionated into neutral lipids, glycolipids, and phospholipids. Sterols eluted in the neutral lipid fraction, and a betaine lipid co-eluted with phospholipids. We found consistent taxonomic specificities of fatty acid markers across the three lipid fractions by analysing pure culture extracts representative of soil microbes. Fatty acid profiles from soil extracts, however, showed stronger differences between PLFAs, NLFAs, and GLFAs than between soil types. This indicates that PLFAs and NLFAs signify different community properties (biomass vs. carbon storage, putatively), and that GLFAs are sensitive markers for community traits which behave differently than PLFAs. Although we consistently found high abundances of characteristic sterols in fungal extracts, the PLFA extraction method only yielded miniscule amounts of ergosterol from soil extracts. We argue that concomitant measurement of fatty acid profiles from all three lipid fractions is a low-effort and potentially information-rich addition to the PLFA method, and discuss its applicability for soil microbial community analyses.", "keywords": ["0301 basic medicine", "2. Zero hunger", "106022 Mikrobiologie", "0303 health sciences", "15. Life on land", "Soil lipids", "03 medical and health sciences", "106026 \u00d6kosystemforschung", "NLFA", "Ergosterol", "Ergosterol; GLFA; NLFA; Phospholipid fatty acids; Soil lipids", "Phospholipid fatty acid", "soil lipids", "Phospholipid fatty acids", "106022 Microbiology", "GLFA", "106026 Ecosystem research"]}, "links": [{"href": "https://doi.org/11585/996230"}, {"rel": "related", "href": "https://repository.soilwise-he.eu/cat/collections/metadata:main/items/Soil%20Biology%20and%20Biochemistry", "name": "related record", "description": "related record", "type": "application/json"}, {"rel": "self", "type": "application/geo+json", "title": "11585/996230", "name": "item", "description": "11585/996230", "href": "https://repository.soilwise-he.eu/cat/collections/metadata:main/items/11585/996230"}, {"rel": "collection", "type": "application/json", "title": "Collection", "name": "collection", "description": "Collection", "href": "https://repository.soilwise-he.eu/cat/collections/metadata:main"}], "time": {"date": "2023-12-01T00:00:00Z"}}, {"id": "1871.1/3309bf72-4ad9-4331-981a-6fc05d319188", "type": "Feature", "geometry": null, "properties": {"license": "Open Access", "updated": "2026-06-26T16:28:59Z", "type": "Journal Article", "created": "2019-12-09", "title": "A systemic overreaction to years versus decades of warming in a subarctic grassland ecosystem", "description": "Temperature governs most biotic processes, yet we know little about how warming affects whole ecosystems. Here we examined the responses of 128\u2009components of a subarctic grassland to either 5-8 or >50\u2009years of soil warming. Warming of >50\u2009years drove the ecosystem to a new steady state possessing a distinct biotic composition and reduced species richness, biomass and soil organic matter. However, the warmed state was preceded by an overreaction to warming, which was related to organism physiology and was evident after 5-8\u2009years. Ignoring this overreaction yielded errors of >100% for 83\u2009variables when predicting their responses to a realistic warming scenario of 1\u2009\u00b0C over 50\u2009years, although some, including soil carbon content, remained stable after 5-8\u2009years. This study challenges long-term ecosystem predictions made from short-term observations, and provides a framework for characterization of ecosystem responses to sustained climate change.", "keywords": ["0301 basic medicine", "570", "Environmental management", "INCREASES", "Ecosystem ecology", "Climate Change", "Evolutionary biology", "TERM", "630", "Article", "Carbon Cycle", "3103 Ecology (for-2020)", "Soil (mesh)", "Soil", "03 medical and health sciences", "14 Life Below Water (sdg)", "SDG 13 - Climate Action", "106026 Ecosystem research", "Life Below Water", "Ecosystem", "106022 Mikrobiologie", "0303 health sciences", "31 Biological Sciences (for-2020)", "41 Environmental Sciences (for-2020)", "Ecology", "Grassland (mesh)", "Climate-change ecology", "Ecosystem (mesh)", "SHIFTS", "3104 Evolutionary biology (for-2020)", "Biological Sciences", "15. Life on land", "4104 Environmental management (for-2020)", "Grassland", "Carbon Cycle (mesh)", "106026 \u00d6kosystemforschung", "13. Climate action", "SDG 13 \u2013 Ma\u00dfnahmen zum Klimaschutz", "FEEDBACKS", "Climate Change (mesh)", "106022 Microbiology", "VEGETATION", "SENSITIVITY", "Environmental Sciences", "SOIL RESPIRATION", "RESPONSES"]}, "links": [{"href": "https://escholarship.org/content/qt99v0g8pc/qt99v0g8pc.pdf"}, {"href": "https://doi.org/1871.1/3309bf72-4ad9-4331-981a-6fc05d319188"}, {"rel": "related", "href": "https://repository.soilwise-he.eu/cat/collections/metadata:main/items/Nature%20Ecology%20%26amp%3B%20Evolution", "name": "related record", "description": "related record", "type": "application/json"}, {"rel": "self", "type": "application/geo+json", "title": "1871.1/3309bf72-4ad9-4331-981a-6fc05d319188", "name": "item", "description": "1871.1/3309bf72-4ad9-4331-981a-6fc05d319188", "href": "https://repository.soilwise-he.eu/cat/collections/metadata:main/items/1871.1/3309bf72-4ad9-4331-981a-6fc05d319188"}, {"rel": "collection", "type": "application/json", "title": "Collection", "name": "collection", "description": "Collection", "href": "https://repository.soilwise-he.eu/cat/collections/metadata:main"}], "time": {"date": "2019-12-09T00:00:00Z"}}, {"id": "20.500.11850/280881", "type": "Feature", "geometry": null, "properties": {"updated": "2026-06-26T16:29:13Z", "type": "Journal Article", "created": "2018-07-25", "title": "Biodegradation of synthetic polymers in soils: Tracking carbon into CO 2 and microbial biomass", "description": "Stable isotope labeling of agricultural polyesters enables demonstration of their microbial utilization in soils.
Due to their abilities to survive intense radiation and low water availability, hypersaline microbial mats are often suggested to be analogs of potential extraterrestrial life. However, even on Earth, the limitations imposed on microbial processes by saturation-level salinity have rarely been studied in situ . Ectomycorrhizal fungi live in close association with their host plants and form complex interactions with bacterial/archaeal communities in soil. We investigated whether abundant or rare ectomycorrhizal fungi on root-tips of young beech trees (Fagus sylvatica) shape bacterial/archaeal communities. We sequenced 16S rRNA genes and fungal internal transcribed spacer regions of individual root-tips and used ecological networks to detect the tendency of certain assemblies of fungal and bacterial/archaeal taxa to inhabit the same root-tip (i.e. modularity). Individual ectomycorrhizal root-tips hosted distinct fungal communities associated with unique bacterial/archaeal communities. The structure of the fungal-bacterial/archaeal association was determined by both, dominant and rare fungi. Integrating our data in a conceptual framework suggests that the effect of rare fungi on the bacterial/archaeal communities of ectomycorrhizal root-tips contributes to assemblages of bacteria/archaea on root-tips. This highlights the potential impact of complex fine-scale interactions between root-tip associated fungi and other soil microorganisms for the ectomycorrhizal symbiosis. Microbial life is surprisingly abundant and diverse in global desert ecosystems. In these environments, microorganisms endure a multitude of physicochemical stresses, including low water potential, carbon and nitrogen starvation, and extreme temperatures. In this review, we summarize our current understanding of the energetic mechanisms and trophic dynamics that underpin microbial function in desert ecosystems. Accumulating evidence suggests that dormancy is a common strategy that facilitates microbial survival in response to water and carbon limitation.
Significant rates of atmospheric dihydrogen (H2) consumption have been observed in temperate soils due to the activity of high-affinity enzymes, such as the group 1h [NiFe]-hydrogenase. We designed broadly inclusive primers targeting the large subunit gene (hhyL) of group 1h [NiFe]-hydrogenases for long-read sequencing to explore its taxonomic distribution across soils. This approach revealed a diverse collection of microorganisms harboring hhyL, including previously unknown groups and taxonomically not assignable sequences. Acidobacterial group 1h [NiFe]-hydrogenase genes were abundant and expressed in temperate soils. To support the participation of acidobacteria in H2 consumption, we studied two representative mesophilic soil acidobacteria, which expressed group 1h [NiFe]-hydrogenases and consumed atmospheric H2 during carbon starvation. This is the first time mesophilic acidobacteria, which are abundant in ubiquitous temperate soils, have been shown to oxidize H2 down to below atmospheric concentrations. As this physiology allows bacteria to survive periods of carbon starvation, it could explain the success of soil acidobacteria. With our long-read sequencing approach of group 1h [NiFe]-hydrogenase genes, we show that the ability to oxidize atmospheric levels of H2 is more widely distributed among soil bacteria than previously recognized and could represent a common mechanism enabling bacteria to persist during periods of carbon deprivation.Investigating active participants in the fixation of dinitrogen gas is vital as N is often a limiting factor for primary production. Biological nitrogen fixation is performed by a diverse guild of bacteria and archaea (diazotrophs), which can be free\uffe2\uff80\uff90living or symbionts. Free\uffe2\uff80\uff90living diazotrophs are widely distributed in the environment, yet our knowledge about their identity and ecophysiology is still limited. A major challenge in investigating this guild is inferring activity from genetic data as this process is highly regulated. To address this challenge, we evaluated and improved several 15N\uffe2\uff80\uff90based methods for detecting N2 fixation activity (with a focus on soil samples) and studying active diazotrophs. We compared the acetylene reduction assay and the 15N2 tracer method and demonstrated that the latter is more sensitive in samples with low activity. Additionally, tracing 15N into microbial RNA provides much higher sensitivity compared to bulk soil analysis. Active soil diazotrophs were identified with a 15N\uffe2\uff80\uff90RNA\uffe2\uff80\uff90SIP approach optimized for environmental samples and benchmarked to 15N\uffe2\uff80\uff90DNA\uffe2\uff80\uff90SIP. Lastly, we investigated the feasibility of using SIP\uffe2\uff80\uff90Raman microspectroscopy for detecting 15N\uffe2\uff80\uff90labelled cells. Taken together, these tools allow identifying and investigating active free\uffe2\uff80\uff90living diazotrophs in a highly sensitive manner in diverse environments, from bulk to the single\uffe2\uff80\uff90cell level.50\u2009years of soil warming. Warming of >50\u2009years drove the ecosystem to a new steady state possessing a distinct biotic composition and reduced species richness, biomass and soil organic matter. However, the warmed state was preceded by an overreaction to warming, which was related to organism physiology and was evident after 5-8\u2009years. Ignoring this overreaction yielded errors of >100% for 83\u2009variables when predicting their responses to a realistic warming scenario of 1\u2009\u00b0C over 50\u2009years, although some, including soil carbon content, remained stable after 5-8\u2009years. This study challenges long-term ecosystem predictions made from short-term observations, and provides a framework for characterization of ecosystem responses to sustained climate change.", "keywords": ["0301 basic medicine", "570", "Environmental management", "INCREASES", "Ecosystem ecology", "Climate Change", "Evolutionary biology", "TERM", "630", "Article", "Carbon Cycle", "Soil", "03 medical and health sciences", "SDG 13 - Climate Action", "106026 Ecosystem research", "Life Below Water", "Ecosystem", "106022 Mikrobiologie", "0303 health sciences", "Ecology", "Climate-change ecology", "SHIFTS", "Biological Sciences", "15. Life on land", "Grassland", "106026 \u00d6kosystemforschung", "13. Climate action", "SDG 13 \u2013 Ma\u00dfnahmen zum Klimaschutz", "FEEDBACKS", "106022 Microbiology", "VEGETATION", "SENSITIVITY", "Environmental Sciences", "SOIL RESPIRATION", "RESPONSES"]}, "links": [{"href": "https://escholarship.org/content/qt99v0g8pc/qt99v0g8pc.pdf"}, {"href": "https://doi.org/2994175618"}, {"rel": "related", "href": "https://repository.soilwise-he.eu/cat/collections/metadata:main/items/Nature%20Ecology%20%26amp%3B%20Evolution", "name": "related record", "description": "related record", "type": "application/json"}, {"rel": "self", "type": "application/geo+json", "title": "2994175618", "name": "item", "description": "2994175618", "href": "https://repository.soilwise-he.eu/cat/collections/metadata:main/items/2994175618"}, {"rel": "collection", "type": "application/json", "title": "Collection", "name": "collection", "description": "Collection", "href": "https://repository.soilwise-he.eu/cat/collections/metadata:main"}], "time": {"date": "2019-12-09T00:00:00Z"}}, {"id": "3045287773", "type": "Feature", "geometry": null, "properties": {"updated": "2026-06-26T16:30:08Z", "type": "Journal Article", "created": "2020-07-27", "title": "Persistence of soil organic carbon caused by functional complexity", "description": "Soil organic carbon management has the potential to aid climate change mitigation through drawdown of atmospheric carbon dioxide. To be effective, such management must account for processes influencing carbon storage and re-emission at different space and time scales. Achieving this requires a conceptual advance in our understanding to link carbon dynamics from the scales at which processes occur to the scales at which decisions are made. Here, we propose that soil carbon persistence can be understood through the lens of decomposers as a result of functional complexity derived from the interplay between spatial and temporal variation of molecular diversity and composition. For example, co-location alone can determine whether a molecule is decomposed, with rapid changes in moisture leading to transport of organic matter and constraining the fitness of the microbial community, while greater molecular diversity may increase the metabolic demand of, and thus potentially limit, decomposition. This conceptual shift accounts for emergent behaviour of the microbial community and would enable soil carbon changes to be predicted without invoking recalcitrant carbon forms that have not been observed experimentally. Functional complexity as a driver of soil carbon persistence suggests soil management should be based on constant care rather than one-time action to lock away carbon in soils.", "keywords": ["[SDE] Environmental Sciences", "DECOMPOSITION", "2. Zero hunger", "106022 Mikrobiologie", "[SDE.MCG]Environmental Sciences/Global Changes", "UNCERTAINTY", "04 agricultural and veterinary sciences", "INPUTS", "15. Life on land", "TRANSPORT", "MODEL", "[SDE.MCG] Environmental Sciences/Global Changes", "106026 \u00d6kosystemforschung", "13. Climate action", "SDG 13 \u2013 Ma\u00dfnahmen zum Klimaschutz", "[SDE]Environmental Sciences", "SDG 13 - Climate Action", "Meteorology & Atmospheric Sciences", "106022 Microbiology", "GROWTH", "0401 agriculture", " forestry", " and fisheries", "TURNOVER", "PLANT", "106026 Ecosystem research", "MATTER"]}, "links": [{"href": "http://www.nature.com/articles/s41561-020-0612-3.pdf"}, {"href": "https://escholarship.org/content/qt84n3398c/qt84n3398c.pdf"}, {"href": "https://doi.org/3045287773"}, {"rel": "related", "href": "https://repository.soilwise-he.eu/cat/collections/metadata:main/items/Nature%20Geoscience", "name": "related record", "description": "related record", "type": "application/json"}, {"rel": "self", "type": "application/geo+json", "title": "3045287773", "name": "item", "description": "3045287773", "href": "https://repository.soilwise-he.eu/cat/collections/metadata:main/items/3045287773"}, {"rel": "collection", "type": "application/json", "title": "Collection", "name": "collection", "description": "Collection", "href": "https://repository.soilwise-he.eu/cat/collections/metadata:main"}], "time": {"date": "2020-07-27T00:00:00Z"}}, {"id": "3133761231", "type": "Feature", "geometry": null, "properties": {"updated": "2026-06-26T16:30:15Z", "type": "Journal Article", "created": "2021-07-27", "title": "Ammonia-oxidizing archaea possess a wide range of cellular ammonia affinities", "description": "Abstract
Nitrification, the oxidation of ammonia to nitrate, is an essential process in the biogeochemical nitrogen cycle. The first step of nitrification, ammonia oxidation, is performed by three, often co-occurring guilds of chemolithoautotrophs: ammonia-oxidizing bacteria (AOB), archaea (AOA), and complete ammonia oxidizers (comammox). Substrate kinetics are considered to be a major niche-differentiating factor between these guilds, but few AOA strains have been kinetically characterized. Here, the ammonia oxidation kinetic properties of 12 AOA representing all major cultivated phylogenetic lineages were determined using microrespirometry. Members of the genus Nitrosocosmicus have the lowest affinity for both ammonia and total ammonium of any characterized AOA, and these values are similar to previously determined ammonia and total ammonium affinities of AOB. This contrasts previous assumptions that all AOA possess much higher substrate affinities than their comammox or AOB counterparts. The substrate affinity of ammonia oxidizers correlated with their cell surface area to volume ratios. In addition, kinetic measurements across a range of pH values supports the hypothesis that\uffe2\uff80\uff94like for AOB\uffe2\uff80\uff94ammonia and not ammonium is the substrate for the ammonia monooxygenase enzyme of AOA and comammox. Together, these data will facilitate predictions and interpretation of ammonia oxidizer community structures and provide a robust basis for establishing testable hypotheses on competition between AOB, AOA, and comammox.Biological Market Models are common evolutionary frameworks to understand the maintenance of mutualism in mycorrhizas. \uffe2\uff80\uff98Surplus C\uffe2\uff80\uff99 hypotheses provide an alternative framework where stoichiometry and source\uffe2\uff80\uff93sink dynamics govern mycorrhizal function. A critical difference between these frameworks is whether carbon transfer from plants is regulated by nutrient transfer from fungi or through source\uffe2\uff80\uff93sink dynamics. In this review, we: provide a historical perspective; summarize studies that asked whether plants transfer more carbon to fungi that transfer more nutrients; conduct a meta\uffe2\uff80\uff90analysis to assess whether mycorrhizal plant growth suppressions are related to carbon transfer; and review literature on cellular mechanisms for carbon transfer. In sum, current knowledge does not indicate that carbon transfer from plants is directly regulated by nutrient delivery from fungi. Further, mycorrhizal plant growth responses were linked to nutrient uptake rather than carbon transfer. These findings are more consistent with \uffe2\uff80\uff98Surplus C\uffe2\uff80\uff99 hypotheses than Biological Market Models. However, we also identify research gaps, and future research may uncover a mechanism directly linking carbon and nutrient transfer. Until then, we urge caution when applying economic terminology to describe mycorrhizas. We present a synthesis of ideas, consider knowledge gaps, and suggest experiments to advance the field.Nitrification, the oxidation of ammonia to nitrate, is an essential process in the biogeochemical nitrogen cycle. The first step of nitrification, ammonia oxidation, is performed by three, often co-occurring guilds of chemolithoautotrophs: ammonia-oxidizing bacteria (AOB), archaea (AOA), and complete ammonia oxidizers (comammox). Substrate kinetics are considered to be a major niche-differentiating factor between these guilds, but few AOA strains have been kinetically characterized. Here, the ammonia oxidation kinetic properties of 12 AOA representing all major cultivated phylogenetic lineages were determined using microrespirometry. Members of the genus Nitrosocosmicus have the lowest affinity for both ammonia and total ammonium of any characterized AOA, and these values are similar to previously determined ammonia and total ammonium affinities of AOB. This contrasts previous assumptions that all AOA possess much higher substrate affinities than their comammox or AOB counterparts. The substrate affinity of ammonia oxidizers correlated with their cell surface area to volume ratios. In addition, kinetic measurements across a range of pH values supports the hypothesis that\uffe2\uff80\uff94like for AOB\uffe2\uff80\uff94ammonia and not ammonium is the substrate for the ammonia monooxygenase enzyme of AOA and comammox. Together, these data will facilitate predictions and interpretation of ammonia oxidizer community structures and provide a robust basis for establishing testable hypotheses on competition between AOB, AOA, and comammox. Ammonia\uffe2\uff80\uff90oxidising archaea (AOA) are important microorganisms contributing towards the nitrogen flux in the environment. Unlike archaea from other major phyla, genetic tools are yet to be developed for the AOA, and identification of antibiotic resistance markers for selecting mutants is required for a genetic system. The aim of this study was to test the effects of selected antibiotics (hygromycin B, neomycin, apramycin, puromycin, novobiocin) on pure cultures of three well studied AOA strains, \uffe2\uff80\uff98 Candidatus Nitrosocosmicus franklandianus C13\uffe2\uff80\uff99, Nitrososphaera viennensis EN76 and Nitrosopumilus maritimus SCM1. Puromycin, hygromycin B and neomycin inhibited some but not all tested archaeal strains. All strains were resistant to apramycin and inhibited by novobiocin to various degrees. As N. viennensis EN76 was relatively more resistant to the tested antibiotics, a wider range of concentrations and compounds (chloramphenicol, trimethoprim, statins) was tested against this strain. N. viennensis EN76 was inhibited by trimethoprim, but not by chloramphenicol, and growth recovered within days in the presence of simvastatin, suggesting either degradation of, or spontaneous resistance against, this compound. This study highlights the physiological differences between different genera of AOA and has identified new candidate antibiotics for selective enrichment and the development of selectable markers for genetic systems in AOA. Investigating active participants in the fixation of dinitrogen gas is vital as N is often a limiting factor for primary production. Biological nitrogen fixation is performed by a diverse guild of bacteria and archaea (diazotrophs), which can be free\uffe2\uff80\uff90living or symbionts. Free\uffe2\uff80\uff90living diazotrophs are widely distributed in the environment, yet our knowledge about their identity and ecophysiology is still limited. A major challenge in investigating this guild is inferring activity from genetic data as this process is highly regulated. To address this challenge, we evaluated and improved several 15 N\uffe2\uff80\uff90based methods for detecting N 2 fixation activity (with a focus on soil samples) and studying active diazotrophs. We compared the acetylene reduction assay and the 15 N 2 tracer method and demonstrated that the latter is more sensitive in samples with low activity. Additionally, tracing 15 N into microbial RNA provides much higher sensitivity compared to bulk soil analysis. Active soil diazotrophs were identified with a 15 N\uffe2\uff80\uff90RNA\uffe2\uff80\uff90SIP approach optimized for environmental samples and benchmarked to 15 N\uffe2\uff80\uff90DNA\uffe2\uff80\uff90SIP. Lastly, we investigated the feasibility of using SIP\uffe2\uff80\uff90Raman microspectroscopy for detecting 15 N\uffe2\uff80\uff90labelled cells. Taken together, these tools allow identifying and investigating active free\uffe2\uff80\uff90living diazotrophs in a highly sensitive manner in diverse environments, from bulk to the single\uffe2\uff80\uff90cell level. Significant rates of atmospheric dihydrogen (H2) consumption have been observed in temperate soils due to the activity of high-affinity enzymes, such as the group 1h [NiFe]-hydrogenase. We designed broadly inclusive primers targeting the large subunit gene (hhyL) of group 1h [NiFe]-hydrogenases for long-read sequencing to explore its taxonomic distribution across soils. This approach revealed a diverse collection of microorganisms harboring hhyL, including previously unknown groups and taxonomically not assignable sequences. Acidobacterial group 1h [NiFe]-hydrogenase genes were abundant and expressed in temperate soils. To support the participation of acidobacteria in H2 consumption, we studied two representative mesophilic soil acidobacteria, which expressed group 1h [NiFe]-hydrogenases and consumed atmospheric H2 during carbon starvation. This is the first time mesophilic acidobacteria, which are abundant in ubiquitous temperate soils, have been shown to oxidize H2 down to below atmospheric concentrations. As this physiology allows bacteria to survive periods of carbon starvation, it could explain the success of soil acidobacteria. With our long-read sequencing approach of group 1h [NiFe]-hydrogenase genes, we show that the ability to oxidize atmospheric levels of H2 is more widely distributed among soil bacteria than previously recognized and could represent a common mechanism enabling bacteria to persist during periods of carbon deprivation.