Selective increase of antibiotic-resistant denitrifiers drives N2O production in ciprofloxacin-contaminated soils.

Agricultural systems significantly contribute to global N2O emissions, which is intensified by excessive fertilization and antibiotic residues, attracting global concerns. However, the dynamics and pathways of antibiotics-induced soil N2O production coupled with microbial metabolism remain controversial. Here, we explored the pathways of N2O production in agricultural soils exposed to ciprofloxacin (CIP), and revealed the underlying mechanisms of CIP degradation and the associated microbial metabolisms using 15N-isotope labeling and molecular techniques. CIP exposure significantly increases the total soil N2O production rate. This is attributed to an unexpected shift from heterotrophic and autotrophic nitrification to denitrification and an increased abundance of denitrifiers Methylobacillus members under CIP exposure. The most striking strain M. flagellatus KT is further discovered to harbor N2O-producing genes but lacks a N2O-reducing gene, thereby stimulating denitrification-based N2O production. Moreover, this denitrifying strain is probably capable of utilizing the byproducts of CIP as carbon sources, evidenced by genes associated with CIP resistance and degradation. Molecular docking further shows that CIP is well ordered in the catalytic active site of CotA laccase, thus affirming the potential for this strain to degrade CIP. These findings advance the mechanistic insights into N2O production within terrestrial ecosystems coupled with the organic contaminants degradation.

Enhancing soil gross nitrogen transformation through regulation of microbial nitrogen-cycling genes by biodegradable microplastics.

Microplastics (MPs) in agricultural plastic film mulching system changes microbial functions and nutrient dynamics in soils. However, how biodegradable MPs impact the soil gross nitrogen (N) transformations and crop N uptake remain significantly unknown. In this study, we conducted a paired labeling 15N tracer experiment and microbial N-cycling gene analysis to investigate the dynamics and mechanisms of soil gross N transformation processes in soils amended with conventional (polyethylene, PE) and biodegradable (polybutylene adipate co-terephthalate, PBAT) MPs at concentrations of 0 %, 0.5 %, and 2 % (w/w). The biodegradable MPs-amended soils showed higher gross N mineralization rates (0.5-16 times) and plant N uptake rates (16-32 %) than soils without MPs (CK) and with conventional MPs. The MPs (both PE and PBAT) with high concentration (2 %) increased gross N mineralization rates compared to low concentration (0.5 %). Compare to CK, MPs decreased the soil gross nitrification rates, except for PBAT with 2 % concentration; while PE with 0.5 % concentration and PBAT with 2 % concentration increased but PBAT with 0.5 % concentration decreased the gross N immobilization rates significantly. The results indicated that there were both a concentration effect and a material effect of MPs on soil gross N transformations. Biodegradable MPs increased N-cycling gene abundance by 60-103 %; while there was no difference in the abundance of total N-cycling genes between soils without MPs and with conventional MPs. In summary, biodegradable MPs increased N cycling gene abundance by providing enriched nutrient substrates and enhancing microbial biomass, thereby promoting gross N transformation processes and maize N uptake in short-term. These findings provide insights into the potential consequences associated with the exposure of biodegradable MPs, particularly their impact on soil N cycling processes.

Nutrient responses of vascular plants to N2-fixing tree Alnus hirsuta encroachment in a boreal peatland.

The N2-fixing trees Alnus spp. have been widely encroaching into boreal peatlands, but the nutrient responses of native vascular plants remain unclear. Here, we compared nutrient concentrations and isotope signal of six common plants (Betula fruticosa, Salix rosmarinifolia, Vaccinium uliginosum, Rhododendron tomentosum, Chamaedaphne calyculata, and Eriophorum vaginatum) between Alnus hirsuta island and open peatland and assessed plant nutrient responses to A. hirsuta encroachment in boreal peatlands. Alnus hirsuta encroachment increased nitrogen (N) concentration of leaf, branch, and stem. Despite no significant interspecific difference in branch and stem, the increment magnitude of leaf N concentration varied among species, with greatest magnitude for R. tomentosum (55.1% ± 40.7%) and lowest for E. vaginatum (9.80% ± 4.40%) and B. fruticosa (18.4% ± 10.7%). Except for E. vaginatum, the significant increase in δ15N occurred for all organs of shrubs, with interspecific differences in change of leaf δ15N. According to the mass balance equation involving leaf δ15N, R. tomentosum and E. vaginatum, respectively, obtained highest (40.5% ± 19.8%) and lowest proportions (-14.0% ± 30.5%) of N from A. hirsuta. Moreover, the increment magnitudes of leaf N concentration showed a positive linear relationship with the proportion of N from A. hirsuta. In addition, A. hirsuta encroachment reduced leaf phosphorus (P) concentration of deciduous shrubs (i.e., B. fruticosa, S. rosmarinifolia, and V. uliginosum), thus increasing N:P ratio. These findings indicate that Alnus encroachment improves native plant N status and selectively intensifies P limitation of native deciduous shrubs, and highlight that the N acquisition from the symbiotic N2-fixing system regulates plant N responses in boreal peatlands.

Association between frailty and hypoproteinaemia in older patients: meta-analysis and systematic review.

OBJECTIVE: Frailty and hypoproteinaemia are common in older individuals. Although there is evidence of a correlation between frailty and hypoproteinaemia, the relationship between frailty and hypoproteinaemia in hospitalized/critically ill and older community residents has not been clarified. Therefore, the aim of our meta-analysis was to evaluate the associations between frailty and hypoproteinaemia in different types of patients. METHODS: A systematic retrieval of articles published in the PubMed, Embase, Medline, Web of Science, Cochrane, Wanfang, and CNKI databases from their establishment to April 2024 was performed to search for studies on the associations between severity of frailty or prefrailty and hypoproteinaemia in older adults. The Newcastle‒Ottawa Scale and the Agency for Healthcare Research and Quality Scale were used to assess study quality. RESULTS: Twenty-two studies were included including 90,351 frail older people were included. Meta-analysis revealed an association between frailty or prefrailty and hypoproteinaemia (OR = 2.37, 95% CI: 1.47, 3.83; OR = 1.62, 95% CI: 1.23, 2.15), there was no significant difference in the risk of hypoproteinaemia between patients with severe frailty and those with low or moderate frailty (OR = 0.62, 95% CI:0.44, 0.87). The effect of frailty on the occurrence of hypoproteinaemia was more obvious in hospitalized patients/critically ill patients than in surgical patients (OR = 3.75, 95% CI: 2.36, 5.96), followed by older community residents (OR = 2.30, 95% CI: 1.18, 4.49). CONCLUSION: Frailty is associated with hypoproteinaemia in surgical patients, hospitalized older patients and older community residents. Future studies should focus on the benefits of albumin supplementation in preventing or alleviating frailty and related outcomes in the future.

Signature Search Polestar: A comprehensive drug repurposing method evaluation assistant for customized oncogenic signature.

SUMMARY: The burgeoning high-throughput technologies have led to a significant surge in the scale of pharmacotranscriptomic datasets, especially for oncology. Signature search methods (SSMs), utilizing oncogenic signatures formed by differentially expressed genes through sequencing, have been instrumental in anti-cancer drug screening and identifying mechanisms of action without relying on prior knowledge. However, various studies have found that different SSMs exhibit varying performance across pharmacotranscriptomic datasets. In addition, the size of the oncogenic signature can also significantly impact the result of drug repurposing. Therefore, finding the optimal SSMs and customized oncogenic signature for a specific disease remains a challenge. To address this, we introduce Signature Search Polestar (SSP), a webserver integrating the largest pharmacotranscriptomic datasets of anti-cancer drugs from LINCS L1000 with five state-of-the-art SSMs (XSum, CMap, GSEA, ZhangScore, XCos). SSP provides three main modules: Benchmark, Robustness, and Application. Benchmark uses two indices, Area Under the Curve and Enrichment Score, based on drug annotations to evaluate SSMs at different oncogenic signature sizes. Robustness, applicable when drug annotations are insufficient, uses a performance score based on drug self-retrieval for evaluation. Application provides three screening strategies, single method, SS_all, and SS_cross, allowing users to freely utilize optimal SSMs with tailored oncogenic signature for drug repurposing. AVAILABILITY AND IMPLEMENTATION: SSP is free at https://web.biotcm.net/SSP/. The current version of SSP is archived in https://doi.org/10.6084/m9.figshare.26524741.v1, allowing users to directly use or customize their own SSP webserver. SUPPLEMENTARY INFORMATION: Supplementary data are available at Bioinformatics online.

Nitrifying niche in estuaries is expanded by the plastisphere.

The estuarine plastisphere, a novel ecological habitat in the Anthropocene, has garnered global concerns. Recent geochemical evidence has pointed out its potential role in influencing nitrogen biogeochemistry. However, the biogeochemical significance of the plastisphere and its mechanisms regulating nitrogen cycling remain elusive. Using 15N- and 13C-labelling coupled with metagenomics and metatranscriptomics, here we unveil that the plastisphere likely acts as an underappreciated nitrifying niche in estuarine ecosystems, exhibiting a 0.9 ~ 12-fold higher activity of bacteria-mediated nitrification compared to surrounding seawater and other biofilms (stone, wood and glass biofilms). The shift of active nitrifiers from O2-sensitive nitrifiers in the seawater to nitrifiers with versatile metabolisms in the plastisphere, combined with the potential interspecific cooperation of nitrifying substrate exchange observed among the plastisphere nitrifiers, collectively results in the unique nitrifying niche. Our findings highlight the plastisphere as an emerging nitrifying niche in estuarine environment, and deepen the mechanistic understanding of its contribution to marine biogeochemistry.

Prodrug-inspired adenosine triphosphate-activatable celastrol-Fe(III) chelate for cancer therapy.

Celastrol (CEL), an active compound isolated from the root of Tripterygium wilfordii, exhibits broad anticancer activities. However, its poor stability, narrow therapeutic window and numerous adverse effects limit its applications in vivo. In this study, an adenosine triphosphate (ATP) activatable CEL-Fe(III) chelate was designed, synthesized, and then encapsulated with a reactive oxygen species (ROS)-responsive polymer to obtain CEL-Fe nanoparticles (CEL-Fe NPs). In normal tissues, CEL-Fe NPs maintain structural stability and exhibit reduced systemic toxicity, while at the tumor site, an ATP-ROS-rich tumor microenvironment, drug release is triggered by ROS, and antitumor potency is restored by competitive binding of ATP. This intelligent CEL delivery system improves the biosafety and bioavailability of CEL for cancer therapy. Such a CEL-metal chelate strategy not only mitigates the challenges associated with CEL but also opens avenues for the generation of CEL derivatives, thereby expanding the therapeutic potential of CEL in clinical settings.

High-Strength, Thin, and Lightweight Solid Polymer Electrolyte for Superior All-Solid-State Sodium Metal Batteries.

The utilization of solid polymer electrolytes (SPEs) in all-solid-state sodium metal batteries has been extensively explored due to their excellent flexibility, processability adaptability to match roll-to-roll manufacturing processes, and good interfacial contact with a high-capacity Na anode; however, SPEs are still impeded by their inadequate mechanical strength, excessive thickness, and poor stability with Na anodes. Herein, a robust, thin, and cost-effective polyethylene (PE) film is employed as a skeleton for infiltrating poly(ethylene oxide)-sodium bis(trifluoromethanesulfonyl)imide (PEO/NaTFSI) to fabricate PE-PEO/NaTFSI SPE. The resulting SPE features a remarkable thickness of 25 µm, lightweight property (2.1 mg cm-2), superior mechanical strength (tensile strength = 100.3 MPa), and good flexibility. The SPE also shows an ionic conductivity of 9.4 × 10-5 S cm-1 at 60 °C and enhanced interfacial stability with a sodium metal anode. Benefiting from these advantages, the assembled Na-Na symmetric cells with PE-PEO/NaTFSI show a high critical current density (1 mA cm-2) and excellent long-term cycling stability (3000 h at 0.3 mA cm-2). The all-solid-state Na||PE-PEO/NaTFSI||Na3V2(PO4)3 coin cells exhibit a superior cycling performance, retaining 93% of the initial capacity for 190 cycles when matched with a 6 mg cm-2 cathode loading. Meanwhile, the pouch cell can work stably after abuse testing, proving its flexibility and safety. This work offers a promising strategy to simultaneously achieve thin, high-strength, and safe solid-state electrolytes for all-solid-state sodium metal batteries.

Effects of straw management and N levels on gross nitrogen transformations in fluvo-aquic soil of the North China Plain.

Straw incorporation with nitrogen (N) fertilization is crucial for enhancing soil fertility and minimizing negative environmental impacts by altering the magnitude and direction of soil N transformation processes. However, the response of soil N transformations to long-term carbon (C) and N inputs, and their primary driving factors, remain poorly understood. Thus, a 15N tracing study was conducted to investigate the effects of straw incorporation (AS) and straw removal (NS) with N levels of 0, 150 and 250 kg N ha-1 per season (N0, N150 and N250) on gross N transformation rates in the North China Plain after 6-year trial. Results indicated that at N0, AS significantly increased soil microbial immobilization of nitrate (NO3--N, INO3) and autotrophic nitrification rates (ONH4) compared to NS. With N fertilization, AS increased gross N immobilization (Itotal), ammonium-N immobilization (NH4+-N, INH4), net NH4+-N immobilization (InetNH4) and net NH4+-N absorption rates (AnetNH4). Specifically, at N150, AS significantly increased recalcitrant organic N mineralization rate (MNrec), while significantly reducing ONH4, labile organic N mineralization (MNlab), and gross N mineralization rates (Mtotal). At N250, AnetNH4, MNlab, MNrec and ONH4 under AS were significantly higher than under NS. Nitrogen application significantly increased ONH4, Itotal and INO3 under two straw management practices, and enhanced INH4 and InetNH4 under AS. Compared to N250, N150 significantly increased INH4 and InetNH4 under AS, while decreasing Mtotal. Opposite results were observed under NS. Meanwhile, NO3--N and dissolved organic carbon (DOC) were master factors controlling immobilization, total nitrogen (TN), hydrolysable NH4+-N (HNN) and stable organic N significantly affected AnetNH4, while labile organic N were the key environmental factors affecting MNrec, all of which positively influenced the rates of assimilation, mineralization and clay mineral adsorption. Overall, this study provides new insights into reducing N fertilization under straw incorporation by quantifying soil N transformation processes.

Direct transmission of severe fever with thrombocytopenia syndrome virus from farm-raised fur animals to workers in Weihai, China.

BACKGROUND: Severe fever with thrombocytopenia syndrome (SFTS) is an emerging infectious disease. SFTS virus (SFTSV) is transmitted by tick bites and contact with the blood or body fluids of SFTS patients. Animal-to-human transmission of SFTS has been reported in Japan, but not in China. In this study, the possible transmission route of two patients who fed and cared for farm-raised fur animals in a mink farm was explored. METHOD: An epidemiological investigation and a genetic analysis of patients, animals and working environment were carried out. RESULTS: It was found that two patients had not been bitten by ticks and had no contact with patients infected with SFTS virus, but both of them had skinned the dying animals. 54.55% (12/22) of the farm workers were positive for SFTS virus antibody. By analyzing the large, medium and small segments sequences, the viral sequences from the two patients, animals and environments showed 99.9% homology. CONCLUSION: It is suspected that the two patients may be directly infected by farm-raised animals, and that the virus may have been transmitted by aerosols when skinning dying animals. Transmission by direct blood contacts or animal bites cannot be ignored.

Integrated immunogenomic analysis of single-cell and bulk profiling reveals novel tumor antigens and subtype-specific therapeutic agents in lung adenocarcinoma.

Background: In recent years, mRNA-based vaccines with promising safety and functional characteristics have gained significant momentum in cancer immunotherapy. However, stable immunological molecular subtypes of lung adenocarcinoma (LUAD) and novel tumor antigens for LUAD mRNA vaccine development remain elusive. Therefore, a novel approach is urgently needed to identify suitable LUAD subtypes and potential tumor antigens. Methods: The Cancer Genome Atlas (TCGA), the Genotype Tissue Expression (GTEx), and Gene Expression Omnibus (GEO) databases were utilized to retrieve gene expression data. The LUAD Immunological Multi-Omics Classification (LIMOC) system was developed using seven machine learning (ML) algorithms by performing integrative immunogenomic analysis of single-cell and bulk tissue transcriptome profiling. Subsequently, a panel of approaches was applied to identify novel tumor antigens. Results: First, the LIMOC system was construct to identify three subtypes: LIMOC1, LIMOC2, and LIMOC3. Second, we identified CHIT1, LILRA4, and MEP1A as novel tumor antigens in LUAD; these genes were up-regulated, amplified, and mutated, and showed a positive association with APC infiltration, making them promising candidates for designing mRNA vaccines. Notably, the LIMOC2 subtype had the worst prognosis and could benefit most from mRNA immunization. Furthermore, we performed a comprehensive in silico screening of approximately 2000 compounds and identified Sorafenib and Azacitidine as potential subtype-specific therapeutic agents. Conclusions: Overall, our study established a robust LIMOC system and identified CHIT1, LILRA4, and MEP1A as promising tumor antigen candidates for development of anti-LUAD mRNA vaccines, particularly for the LIMOC2 subtype.

Ventilator-Associated Pneumonia Prediction Models Based on AI: Scoping Review.

Background: Ventilator-associated pneumonia (VAP) is a serious complication of mechanical ventilation therapy that affects patients' treatments and prognoses. Owing to its excellent data mining capabilities, artificial intelligence (AI) has been increasingly used to predict VAP. Objective: This paper reviews VAP prediction models that are based on AI, providing a reference for the early identification of high-risk groups in future clinical practice. Methods: A scoping review was conducted in accordance with the PRISMA-ScR (Preferred Reporting Items for Systematic Reviews and Meta-Analyses extension for Scoping Reviews) guidelines. The Wanfang database, the Chinese Biomedical Literature Database, Cochrane Library, Web of Science, PubMed, MEDLINE, and Embase were searched to identify relevant articles. Study selection and data extraction were independently conducted by 2 reviewers. The data extracted from the included studies were synthesized narratively. Results: Of the 137 publications retrieved, 11 were included in this scoping review. The included studies reported the use of AI for predicting VAP. All 11 studies predicted VAP occurrence, and studies on VAP prognosis were excluded. Further, these studies used text data, and none of them involved imaging data. Public databases were the primary sources of data for model building (studies: 6/11, 55%), and 5 studies had sample sizes of <1000. Machine learning was the primary algorithm for studying the VAP prediction models. However, deep learning and large language models were not used to construct VAP prediction models. The random forest model was the most commonly used model (studies: 5/11, 45%). All studies only performed internal validations, and none of them addressed how to implement and apply the final model in real-life clinical settings. Conclusions: This review presents an overview of studies that used AI to predict and diagnose VAP. AI models have better predictive performance than traditional methods and are expected to provide indispensable tools for VAP risk prediction in the future. However, the current research is in the model construction and validation stage, and the implementation of and guidance for clinical VAP prediction require further research.

Antimicrobial peptide cecropin B functions in pathogen resistance of Mythimna separata.

Mythimna separata (Lepidoptera: Noctuidae) is an omnivorous pest that poses a great threat to food security. Insect antimicrobial peptides (AMPs) are small peptides that are important effector molecules of innate immunity. Here, we investigated the role of the AMP cecropin B in the growth, development, and immunity of M. separata. The gene encoding M. separata cecropin B (MscecropinB) was cloned. The expression of MscecropinB was determined in different developmental stages and tissues of M. separata. It was highest in the prepupal stage, followed by the pupal stage. Among larval stages, the highest expression was observed in the fourth instar. Tissue expression analysis of fourth instar larvae showed that MscecropinB was highly expressed in the fat body and haemolymph. An increase in population density led to upregulation of MscecropinB expression. MscecropinB expression was also upregulated by the infection of third and fourth instar M. separata with Beauveria bassiana or Bacillus thuringiensis (Bt). RNA interference (RNAi) targeting MscecropinB inhibited the emergence rate and fecundity of M. separata, and resulted in an increased sensitivity to B. bassiana and Bt. The mortality of M. separata larvae was significantly higher in pathogen plus RNAi-treated M. separata than in controls treated with pathogens only. Our findings indicate that MscecropinB functions in the eclosion and fecundity of M. separata and plays an important role in resistance to infection by B. bassiana and Bt.

Soil recalcitrant but not labile organic nitrogen mineralization contributes to microbial nitrogen immobilization and plant nitrogen uptake.

Soil organic nitrogen (N) mineralization not only supports ecosystem productivity but also weakens carbon and N accumulation in soils. Recalcitrant (mainly mineral-associated organic matter) and labile (mainly particulate organic matter) organic materials differ dramatically in nature. Yet, the patterns and drivers of recalcitrant (MNrec) and labile (MNlab) organic N mineralization rates and their consequences on ecosystem N retention are still unclear. By collecting MNrec (299 observations) and MNlab (299 observations) from 57 15N tracing studies, we found that soil pH and total N were the master factors controlling MNrec and MNlab, respectively. This was consistent with the significantly higher rates of MNrec in alkaline soils and of MNlab in natural ecosystems. Interestingly, our analysis revealed that MNrec directly stimulated microbial N immobilization and plant N uptake, while MNlab stimulated the soil gross autotrophic nitrification which discouraged ammonium immobilization and accelerated nitrate production. We also noted that MNrec was more efficient at lower precipitation and higher temperatures due to increased soil pH. In contrast, MNlab was more efficient at higher precipitation and lower temperatures due to increased soil total N. Overall, we suggest that increasing MNrec may lead to a conservative N cycle, improving the ecosystem services and functions, while increasing MNlab may stimulate the potential risk of soil N loss.

Warming-Induced Stimulation of Soil N2O Emissions Counteracted by Elevated CO2 from Nine-Year Agroecosystem Temperature and Free Air Carbon Dioxide Enrichment.

Globally, agricultural soils account for approximately one-third of anthropogenic emissions of the potent greenhouse gas and stratospheric ozone-depleting substance nitrous oxide (N2O). Emissions of N2O from agricultural soils are affected by a number of global change factors, such as elevated air temperatures and elevated atmospheric carbon dioxide (CO2). Yet, a mechanistic understanding of how these climatic factors affect N2O emissions in agricultural soils remains largely unresolved. Here, we investigate the soil N2O emission pathway using a 15N tracing approach in a nine-year field experiment using a combined temperature and free air carbon dioxide enrichment (T-FACE). We show that the effect of CO2 enrichment completely counteracts warming-induced stimulation of both nitrification- and denitrification-derived N2O emissions. The elevated CO2 induced decrease in pH and labile organic nitrogen (N) masked the stimulation of organic carbon and N by warming. Unexpectedly, both elevated CO2 and warming had little effect on the abundances of the nitrifying and denitrifying genes. Overall, our study confirms the importance of multifactorial experiments to understand N2O emission pathways from agricultural soils under climate change. This better understanding is a prerequisite for more accurate models and the development of effective options to combat climate change.

Visualized detection of water by modified metal organic framework-199 and its portable test paper with reversible color change.

Herein, we fabricate a melamine modified metal organic framework-199 composite (MOF-199@melamine), of which the structure is affected by the dynamics of the guest H2O molecule with significant color change. It realizes the visualized quantitative detection of water in a variety of organic solvents within 30 s. Moreover, DMF restored the original structure by replacing H2O molecules, realizing the regeneration of the materials. On this basis, PTFE-MOF-199@melamine test paper is developed to portably detect water content in organic solvents (maximum 0 %-98 % (v/v) water content) and ambient relative humidity (11-85 %). The test paper can be recycled four times with a regeneration rate higher than 90 %. The results are expected to solve the problems of existed electrochemical or fluorescence strategy such as the complicated operation process and signal output/reading system.

Root rot destabilizes the Sanqi rhizosphere core fungal microbiome by reducing the negative connectivity of beneficial microbes.

The stability of microbial communities, especially among core taxa, is essential for supporting plant health. However, the impacts of disease infection on the stability of rhizosphere fungal core microbiome remain largely unexplored. In this study, we delved into the effects of root rot infestation on the community structure, function, network complexity, and stability of Sanqi fungal core microbiomes, employing amplicon sequencing combined with co-occurrence network and cohesion analyses. Our investigation revealed that root rot disease led to a decrease in the α-diversity but an increase in the ß-diversity of the Sanqi fungal core microbiomes in the rhizosphere. Notably, Ilyonectria, Plectosphaerella, and Fusarium emerged as indicator species in the rhizosphere core microbiome of root rot-infected Sanqi plants, while Mortierella predominated as the dominant biomarker taxa in healthy soils. Additionally, root rot diminished the complexity and modularity of the rhizosphere networks by reducing the metrics associated with nodes, edges, degrees, and modularity. Furthermore, root rot resulted in a reduction in the proportion of negative connections in the network and the negative/positive cohesion of the entire core fungal microbiome. Particularly noteworthy was the observation that root rot infection destabilized the rhizosphere core fungal microbiome by weakening the negative connectivity associated with beneficial agents. Collectively, these results highlight the significance of the negative connectivity of beneficial agents in ensuring the stability of core microbial community.IMPORTANCERoot rot disease has been reported as the most devastating disease in the production process of artificial cultivated Sanqi ginseng, which seriously threatens the Sanqi industry. This study provides valuable insights into how root rot influences microbial relationships within the community. These findings open up opportunities for disease prevention and the promotion of plant health by regulating microbial interactions. In summary, the research sheds light on the ecological consequences of root rot on rhizosphere fungal microbiomes and offers potential strategies for managing soil-borne diseases and enhancing plant health.

Land Use Change from Natural Tropical Forests to Managed Ecosystems Reduces Gross Nitrogen Production Rates and Increases the Soil Microbial Nitrogen Limitation.

Understanding the underlying mechanisms of soil microbial nitrogen (N) utilization under land use change is critical to evaluating soil N availability or limitation and its environmental consequences. A combination of soil gross N production and ecoenzymatic stoichiometry provides a promising avenue for nutrient limitation assessment in soil microbial metabolism. Gross N production via 15N tracing and ecoenzymatic stoichiometry through the vector and threshold element ratio (Vector-TER) model were quantified to evaluate the soil microbial N limitation in response to land use changes. We used tropical soil samples from a natural forest ecosystem and three managed ecosystems (paddy, rubber, and eucalyptus sites). Soil extracellular enzyme activities were significantly lower in managed ecosystems than in a natural forest. The Vector-TER model results indicated microbial carbon (C) and N limitations in the natural forest soil, and land use change from the natural forest to managed ecosystems increased the soil microbial N limitation. The soil microbial N limitation was positively related to gross N mineralization (GNM) and nitrification (GN) rates. The decrease in microbial biomass C and N as well as hydrolyzable ammonium N in managed ecosystems led to the decrease in N-acquiring enzymes, inhibiting GNM and GN rates and ultimately increasing the microbial N limitation. Soil GNM was also positively correlated with leucine aminopeptidase and ß-N-acetylglucosaminidase. The results highlight that converting tropical natural forests to managed ecosystems can increase the soil microbial N limitation through reducing the soil microbial biomass and gross N production.

Initial evidence on the effect of copper on global cropland nitrogen cycling: A meta-analysis.

Copper (Cu) is a key cofactor in ammonia monooxygenase functioning responsible for the first step of nitrification, but its excess availability impairs soil microbial functions and plant growth. Yet, the impact of Cu on nitrogen (N) cycling and process-related variables in cropland soils remains unexplored globally. Through a meta-analysis of 1209-paired and 319-single observations from 94 publications, we found that Cu (Cu addition or Cu-polluted soil) reduced soil potential nitrification by 33.8% and nitrite content by 73.5% due to reduced soil enzyme activities of nitrification and urease, microbial biomass content, and ammonia oxidizing archaea abundance. The response ratio of potential nitrification decreased with increasing Cu concentration, soil total N, and clay content. We further noted that soil potential nitrification inhibited by 46.5% only when Cu concentration was higher than 150 mg kg-1, while low Cu concentration (less than 150 mg kg-1) stimulated soil nitrate by 99.0%. Increasing initial soil Cu content stimulated gross N mineralization rate due to increased soil organic carbon and total N, but inhibited gross nitrification rate, which ultimately stimulated gross N immobilization rate as a result of increased the residence time of ammonium. This resulted in a lower ratio of gross nitrification rate to gross N immobilization rate, implying a lower potential risk of N loss as evidenced by decreased nitrous oxide emissions with increasing initial soil Cu content. Our analysis offers initial global evidence that Cu has an important role in controlling soil N availability and loss through its effect on N production and consumption.

Climate controls on nitrate dynamics and gross nitrogen cycling response to nitrogen deposition in global forest soils.

Understanding the patterns and controls regulating nitrogen (N) transformation and its response to N enrichment is critical to re-evaluating soil N limitation or availability and its environmental consequences. Nevertheless, how climatic conditions affect nitrate dynamics and the response of gross N cycling rates to N enrichment in forest soils is still only rudimentarily known. Through collecting and analyzing 4426-single and 769-paired observations from 231 15N labeling studies, we found that nitrification capacity [the ratio of gross autotrophic nitrification (GAN) to gross N mineralization (GNM)] was significantly lower in tropical/subtropical (19%) than in temperate (68%) forest soils, mainly due to the higher GNM and lower GAN in tropical/subtropical regions resulting from low C/N ratio and high precipitation, respectively. However, nitrate retention capacity [the ratio of dissimilatory nitrate reduction to ammonium (DNRA) plus gross nitrate immobilization (INO3) to gross nitrification] was significantly higher in tropical/subtropical (86%) than in temperate (54%) forest soils, mainly due to the higher precipitation and GNM of tropical/subtropical regions, which stimulated DNRA and INO3. As a result, the ratio of GAN to ammonium immobilization (INH4) was significantly higher in temperate than in tropical/subtropical soils. Climatic rather than edaphic factors control heterotrophic nitrification rate (GHN) in forest soils. GHN significantly increased with increasing temperature in temperate regions and with decreasing precipitation in tropical/subtropical regions. In temperate forest soils, gross N transformation rates were insensitive to N enrichment. In tropical/subtropical forests, however, N enrichment significantly stimulated GNM, GAN and GAN to INH4 ratio, but inhibited INH4 and INO3 due to reduced microbial biomass and pH. We propose that temperate forest soils have higher nitrification capacity and lower nitrate retention capacity, implying a higher potential risk of N losses. However, tropical/subtropical forest systems shift from a conservative to a leaky N-cycling system in response to N enrichment.