Search Results (3,139)

Phosphorus (P) limitation is prevalent in terrestrial ecosystems. Plants can improve soil P availability through the exudation of organic acids and symbiotic interactions with microorganisms. However, associations between different plant functional groups and phosphorus cycling in P limited karst ecosystems remain poorly understood. To investigate this, the exudation rates of oxalic, citric and acetic acids from fine roots, the contents of carbon, nitrogen, and P in leaves and fine roots, and the contents of oxalic, citric and acetic acids, total P, available P (AP), and microbial biomass P in rhizosphere soils were measured across different plant functional groups in a karst ecosystem in southwestern China. Additionally, the activities of acid and alkaline phosphatases were also analyzed, as well as the relative abundance, community structure, diversity, and co-occurrence network patterns of arbuscular mycorrhizal fungi (AMF) and alkaline phosphatase-encoding (phoD) gene-harboring bacteria. The results showed that both the exudation rates and the contents of organic acids and AP were highest in the tree group, followed by the shrub and grass groups. The AP content of the legume group was significantly higher than that of the non-legume group. The exudation rates of oxalic acid were significantly greater than those of citric and acetic acids. AMF diversities were highest in the shrub and legume groups. The diversities of phoD-harboring bacteria decreased from the tree group to the shrub group and then to the grass group, yet there were no significant differences between the legume and non-legume groups. The communities of both AMF and phoD-harboring bacteria exhibited significant differences among these plant functional groups. The prevalent genera of phoD-harboring bacteria across all groups were Pseudomonas and Halomonas, with Halomonas being particularly prevalent in the legume group. The AMF community was dominated by Glomus, which attained its highest relative abundance in the tree and legume groups. Furthermore, the increased exudation rate and content of oxalic acid were associated with higher relative abundances of Glomus in AMF and Pseudomonas and Bacillus among phoD-harboring bacteria. Structural Equation Model (SEM) analysis demonstrated that plant-exuded organic acids, especially oxalic acid, were positively associated with P availability indirectly through their linkages with the diversity and abundance of AMF and phoD-harboring bacteria. The crucial role of oxalic acid was particularly prominent in the tree and legume groups. Our findings suggest that screening AMF and phoD-harboring bacteria with highly efficient P transformation activity and inoculating them into the rhizosphere of plants with high oxalic acid exudation could help improve plant resilience to P limitation and support sustainable restoration in karst ecosystems. Full article

Protected cultivation of pepper in southern China’s red soil region often leads to soil degradation and continuous cropping obstacles. To investigate whether biochar can alleviate these problems by regulating the soil microenvironment, pot and incubation experiments were conducted from 2021 to 2023 with biochar application rates of 0~10% (w/w). The results showed that appropriate biochar application significantly improved pepper yield and soil quality. Under the 6% biochar treatment, pepper yield and dry matter accumulation increased by 89.05% and 36.79%, respectively, compared to the control. Soil bacterial and fungal abundances increased by 346.61% and 107.37%, and their OTU numbers rose by 64.13% and 35.15%, respectively. Biochar application also elevated soil pH, organic matter, available potassium, and total nitrogen contents, improved aggregate stability, and enhanced the activities of urease, catalase, sucrase, and acid phosphatase. Furthermore, biochar altered the rhizosphere microbial community structure and increased bacterial diversity. These findings demonstrate that biochar can promote pepper growth by improving soil physicochemical properties, enzyme activities, and microbial community structure, providing a viable strategy for mitigating continuous cropping obstacles in protected cultivation. Full article

Increasing freshwater scarcity alongside growing irrigation demand poses a major challenge for agricultural production. One potential response is the use of drought adaptation amendments: materials of natural or synthetic origin that, when applied to soil or crops, either increase water availability or improve plant performance under water stress. Because these amendments range from minerals and microorganisms to polymers and plant-derived compounds, they are often studied in separate disciplinary literatures rather than as a single category of inputs. Here, we review drought adaptation amendments for agricultural use and evaluate them along three dimensions: effectiveness in mitigating drought stress, economic feasibility, and environmental and human-health implications. Across amendment classes, effectiveness is achieved through several recurring pathways, including reduced soil evaporation, altered canopy energy balance, improved infiltration and soil water retention, improved rhizosphere and root access to retained water, and enhanced physiological tolerance to water deficit. No single amendment consistently performs best across all three criteria. Materials that strongly modify soil water dynamics can be effective but may be costly or environmentally risky, while lower-risk options often have smaller or more context-dependent effects. Among the most promising lower-risk options identified in this review are microbial inoculants, certain mineral amendments, and water-based plant extracts, though their effectiveness remains context-dependent. Future research should prioritize amendments that combine drought-mitigating effects with economic feasibility and minimal environmental or health risks. Full article

Antarctica’s extreme cryospheric conditions impose severe thermodynamic constraints on the natural attenuation of hydrocarbon pollutants. Despite the Antarctic Treaty System’s protections, the footprint of human logistics has left persistent reservoirs of petroleum hydrocarbons that threaten endemic biodiversity. This review critically synthesizes the state-of-the-art in Antarctic bioremediation, moving beyond traditional culture-dependent studies to integrate recent multi-omics breakthroughs (2020–2025). We analyze the molecular mechanisms limiting bioavailability in frozen soils and highlight the adaptive strategies of psychrophilic consortia, including the modification of membrane fluidity and the expression of cold-active enzymes (e.g., RHDs, AlkB). Notably, we discuss emerging findings on novel long-chain alkane degradation genes (almA, ladA) identified in 2025, which challenge previous assumptions about recalcitrance. Furthermore, the review evaluates the engineering bottlenecks of in situ versus ex situ strategies, emphasizing the synergistic potential of bacterial–fungal co-cultures and the ecological necessity of “climate-smart” remediation to mitigate methane emissions from thawing permafrost. By bridging the gap between fundamental microbial genetics and applied field engineering, we propose a roadmap for the next generation of biotechnological solutions in the warming polar environment. Full article

Soil health is critical for the sustainability of tropical plantation ecosystems, However, the ecological factors driving productivity gradients remain inadequately understood. This study investigated rubber plantations on Hainan Island with varying yield levels to assess soil health and its underlying ecological mechanisms using a minimum data set (MDS) approach. Twenty-seven soil physical, chemical, and biological indicators were analyzed at two depths (0–20 cm and 20–40 cm). Principal component analysis identified seven key indicators for the MDS: soil organic matter (OM), alkaline-hydrolyzable nitrogen (AN), cation exchange capacity (CEC), dissolved organic carbon (DOC), microbial biomass phosphorus (MBP), acid phosphatase activity (ACP), and microbial diversity (Shannon-Wiener index, SHDI). The soil health indices derived from the MDS showed strong correlations with those generated from the total data set (TDS) (p < 0.001), confirming the reliability of the MDS framework. Overall, soil health levels were rated low to moderate with no significant differences across low-yield plantations (≤900 kg·ha⁻¹), medium-yield plantations (900–1200 kg·ha⁻¹), and high-yield plantations (≥1200 kg·ha⁻¹)., suggesting a decoupling of soil health and rubber productivity under uniform management practices. Random forest analysis identified microbial-driven phosphorus cycling, particularly MBP and ACP, as the primary determinant of soil health across soil layers, with DOC and SHDI also contributing significantly. These findings highlight the critical role of microbial-mediated nutrient cycling in maintaining soil health in rubber plantations and suggest that current management practices prioritize short-term yields over long-term soil ecological stability. Enhancing microbial activity and increasing organic matter inputs may be essential for improving soil health and ensuring the sustainability of rubber production in tropical agroecosystems. Full article

Ledum palustre (L. palustre) is widely used in drug development because of its antibacterial and analgesic effects. However, wild L. palustre is often affected by wildfires, resulting in unstable yields. Forest fires represent a major disturbance in northern forest ecosystems and profoundly affect shrub vegetation and its associated rhizosphere microbial communities. In this study, we investigated a fire chronosequence (1991, 2004, 2012, 2017, and 2020) to systematically examine the morphological traits of L. palustre, rhizosphere soil physicochemical properties, and microbial community characteristics and to identify the key drivers underlying these patterns. The results revealed that postfire recovery time significantly influenced the morphological traits of L. palustre. The biomass, branch number, basal diameter, and plant height of the shrubs at the 1991 burned site increased by 270.49%, 36.11%, 79.32%, and 191.36%, respectively (p < 0.05). From unburned soils, 29 bacterial and 29 fungal isolates were obtained, with Bacillus sp. and Oidiodendron sp. being the dominant culturable bacterial and fungal taxa, respectively. With increasing postfire recovery time, soil moisture, total nitrogen, ammonium, nitrate, soil organic carbon, acid phosphatase (AP) and N-acetyl-β-D-glucosaminidase (NAG) activity significantly decreased. Early fire disturbance markedly altered soil microbial abundance and community composition, leading to an overall decrease in bacterial α diversity. The bacterial community structure at the 2020 burn site and the fungal community structure at the 2012 burn site significantly differed. Mantel tests revealed significant positive correlations between branch number and basal diameter (p < 0.01) and significant negative correlations between plant height and stem density (p < 0.001). Soil carbon and hydrolysable nitrogen were significantly positively correlated with AP and NAG activities (p < 0.001). Moreover, soil physicochemical properties significantly shaped soil microbial community structures, with bacterial communities in early postfire sites driven by total carbon and nitrogen (p < 0.05), whereas fungal communities in the 2012 burned site were influenced primarily by β-N-acetylglucosaminidase (BG) activity (p < 0.05). Fire disturbance drives successional changes in the rhizosphere microbial community structure and function by altering the soil nutrient status and enzyme activity, which in turn influences the morphological traits of L. palustre. This study provides a theoretical basis for improving the yield of L. palustre by exploring the variation in rhizosphere microorganisms. Full article

Astragalus membranaceus is an important perennial medicinal plant whose roots constitute its primary medicinal organ; however, its cultivation is severely constrained by root rot caused by Fusarium oxysporum. This study aimed to characterize differences in the rhizosphere microbiome between healthy and diseased plants, identify antagonistic microorganisms from healthy rhizosphere soils, and investigate their suppressive effects on F. oxysporum and the associated host metabolic responses. High-throughput sequencing was used to compare bacterial and fungal communities in the rhizospheres of healthy and diseased plants. Microorganisms were isolated from healthy rhizosphere soils and screened for antagonistic activity against F. oxysporum, followed by validation in pot experiments. Metabolomic analysis was further conducted to assess host metabolic responses to microbial treatment. Root rot disease significantly altered the dominant composition of rhizosphere microbial communities and was associated with reduced fungal diversity and lower bacterial richness in diseased soils. Co-occurrence network analysis revealed increased complexity in bacterial networks and strengthened positive correlations among fungal taxa under diseased conditions. A total of 81 microbial strains were isolated from healthy rhizosphere soils, among which Penicillium halotolerans exhibited the strongest inhibitory activity against the mycelial growth of F. oxysporum. Pot experiments further supported its suppressive effect on Astragalus root rot. Metabolomic analysis indicated that P. halotolerans treatment was associated with changes in host metabolic profiles related to energy metabolism, defense-associated protein synthesis, and nutrient uptake. Overall, this study identified P. halotolerans as a fungal strain with antagonistic activity against F. oxysporum and provided initial evidence for its association with the suppression of Astragalus root rot. These findings offer candidate microbial resources and mechanistic insights for understanding rhizosphere-associated disease suppression in Astragalus membranaceus. Full article

Plant fungal diseases, such as apple tree canker caused by Valsa mali, have caused severe losses in agricultural production. Traditional chemical fungicides induce drug resistance in pathogens and cause environmental pollution. Therefore, it is of substantial importance to screen efficient and environmentally friendly bacterial strains as potential biocontrol agents. The tea rhizosphere harbors abundant microbial resources, and previous research has identified microorganisms with antifungal activity existing in this environment. Therefore, in this study, we isolated antagonistic bacteria with broad-spectrum biocontrol potential from tea rhizosphere soil. In this study, a strain with strong antagonistic activity against V. mali was isolated from tea rhizosphere soil. Based on morphological characteristics, 16S rRNA gene sequencing, and whole-genome analysis, the isolated strain was identified as Bacillus velezensis and designated as LW-66. This strain demonstrated broad-spectrum antifungal activity against various plant pathogenic fungi, including Valsa mali, Fusarium graminearum, Bipolaris sorokinianum, Alternaria solani, and Exserohilum turcicum. The active extract of B. velezensis maintained strong stability across a wide range of temperatures (25–90 °C) and pH values (2–8), with stability decreasing only when the temperature reached 100 °C or pH ≥ 10. In a preventive assay using detached apple branches inoculated with V. mali, the control efficacy of LW-66 against apple tree canker reached more than 90%. Additionally, in a therapeutic assay using V. mali-infected potted apple seedlings, the LW-66 bone-glue bacterial agent achieved a survival rate of up to 90%. Whole-genome analysis revealed that the genome of LW-66 contains 13 predicted secondary metabolite biosynthetic gene clusters, seven of which showed high homology (≥92% similarity) with known antimicrobial gene clusters, including surfactin, bacillaene, macrolactin H, fengycin, difficidin, bacillibactin, and bacilysin. These gene clusters may be connected to the broad-spectrum antifungal activity of B. velezensis, as well as its ability to disrupt hyphal morphology. The volatile organic compounds produced by LW-66 inhibited V. mali growth by 91.70%. Collectively, these findings demonstrate that B. velezensis LW-66 has a wide antimicrobial range and strong antagonistic effects against multiple plant pathogenic fungi. Therefore, B. velezensis shows promise as a biocontrol agent for managing fungal diseases in plants, providing a basis for developing LW-66-derived biocontrol products aimed at controlling diseases such as apple tree canker. Full article

A three-year field experiment (2021–2023) in southeast Spain evaluated whether reduced mineral fertilization, with or without plant-growth-promoting microorganisms, could maintain crop productivity and modify selected soil indicators in a Mediterranean vegetable rotation. Four treatments were compared: conventional fertilization (T1), reduced fertilization (T2; −30% or −50%), reduced fertilization plus bacterial inoculants (T3), and reduced fertilization plus bacterial–fungal inoculants (T4). Crop yields were not significantly affected by fertilization strategy. Potato yields ranged from 55,661 to 60,741 kg ha⁻¹, those of broccoli from 14,928 to 16,797 kg ha⁻¹, and those of melon from 30,815 to 33,423 kg ha⁻¹. Inoculated treatments were associated with some quality responses, including higher potato tuber firmness in T4 (16.0 vs. 13.2 kg cm⁻² in T1), whereas melon soluble solids tended to be slightly lower. Soil analyses showed changes in some nutrient-related indicators, including a 217% increase in NH₄⁺ in T4 and a 0.75% decrease in pH in T3. Reduced fertilization lowered production costs by about 9%. Under the conditions of this field trial, reduced fertilization maintained yield and gross margin relative to conventional fertilization, and inoculated treatments under reduced fertilization showed differences in selected soil indicators. Full article

Intercropping maize with legume cover crops has been shown to increase soil organic carbon (SOC) and alter soil microbial communities, potentially affecting soil aggregate stability. However, whether different legume cover crop varieties vary in their effects on SOC enhancement and aggregate stability improvement, and whether such variation is associated with their capacity to enhance distinct microbial taxa, remains unclear. Here, we conducted a five-year field experiment comprising maize monoculture (MM) and six intercropping systems in which maize was grown with different legume cover crop varieties. We aimed to assess the role of bacterial, non-AMF, and arbuscular mycorrhizal fungal (AMF) community composition in influencing SOC and aggregate stability, measured as mean weight diameter (MWD). On average, the six intercropping systems significantly increased SOC by 28% compared with MM, with no significant differences among legume varieties. However, MWD varied significantly depending on the specific legume used. Specifically, intercropping with red clover or sesbania resulted in MWD values similar to MM, whereas intercropping with soybean, hairy vetch, common vetch, or yellow sweet clover led to significantly higher MWD. Notably, MWD was positively correlated with the proportion of C within macroaggregates (>0.25 mm), and this effect was linked to the enrichment of specific microbial taxa—including the bacterium RB41, the non-AMF Trichoderma, and AMF (unclassified Glomerales, Glomus2, and Glomus3)—in systems with high MWD. These findings indicate that while SOC accrual under intercropping is robust across legume varieties, aggregate stability is contingent upon the identity of the legume and its associated microbiota. Selecting legume varieties with a greater ability to increase the abundance of specific microorganisms that enhance C allocation into macroaggregates can simultaneously improve both SOC accumulation and aggregate stability in maize-based intercropping systems. Full article

Clarifying the responses of microbial communities in distinct microhabitats like roots, the soil, and litter layers to secondary succession is critical for predicting the effects of global climate change on ecosystem functions. We investigated the microbial activities, compositions, and networks in these microhabitats of Fagus lucida forests ranging from 40 to 200 years. The results showed that soil physicochemical properties decreased with forest succession, except for NH₄⁺-N and available phosphorus, which decreased at the early stage. All vector angles of extracellular enzyme stoichiometry that were greater than 45° indicated that phosphorus was the key limiting element for microorganisms. The microbial community shifted from r- to K-strategists with forest succession, displaying the replacement of most bacterial phyla by Proteobacteria and Acidobacteriota, and an increase in the Acidobacteriota: Proteobacteria ratio, especially in the soil and litter layers. Soil properties, particularly NH₄⁺-N and pH, significantly affected the bacterial diversity and structure. Moreover, the bacterial network complexity increased with succession, particularly in the litter layer, and the topological properties of bacterial networks showed a stronger influence on microbial activities compared with those of fungal networks. The richness of keystone taxa in the litter layer was higher than in the soil layer and roots. However, the fungal community dominated by symbiotrophs showed lower sensitivity to soil nutrient changes and greater resilience to forest succession, displaying stable diversity and decreased network complexity, particularly in the roots. Ectomycorrhizal fungi (e.g., Russula) dominated the fungal guilds, and their abundance increased with forest succession, accompanied by a decrease in pathogenic fungi. Plant roots with significantly higher phosphatase activities played a stronger role than soils in structuring the litter microbial community, as reflected by similar carbon- and nitrogen-acquiring enzyme activities, microbial compositions, a greater share of taxa, and closer community distance. Our results revealed the increasingly important role of plant roots with forest succession in structuring the microbial community and nutrient cycling in the soil and litter layers. Full article

Soil contamination by heavy metals and organic pollutants presents significant challenges to the global environment and public health. However, a lack of micro-scale understanding of the pollution process hinders efforts to remediate and enhance soil quality. Synchrotron-based X-ray imaging and spectroscopy techniques are powerful tools in revealing complex interactions within heterogeneous soil systems. This review systematically explores recent advances in soil research that deepen our knowledge on the chemical states, spatial distribution, and dynamic interactions of heavy metals and organic contaminants via synchrotron-based techniques (e.g., micro-XRF imaging, FTIR, SR-μCT). It highlights the potential of these methods to characterize composition, aggregate structure, and microbial activity within soil matrices with high spatial and temporal resolution, in situ, and with element-specific analysis. Additionally, a forward-looking perspective outlines key research directions to leverage these advantages and develop more effective and sustainable soil restoration strategies. We hope this work emphasizes the role of synchrotron science in field-scale soil applications and inspires future, mechanism-driven, evidence-based soil remediation efforts. Full article

Mercury (Hg) is a ubiquitous element in the environment that may pose a threat to human health due to its toxicity, high mobility through the food chain, and long-lasting persistence. Organic Hg compounds, particularly methylmercury, are more toxic than inorganic mercury due to their easy absorption and persistent retention within the organism. Although natural attenuation can occur in soil through various processes, excessive levels of Hg cause pollution that can adversely affect agricultural soil, making remediation necessary to either remove or stabilize Hg within the soil. This review primarily aims to summarize key remediation strategies—chemical, biological, and physical—developed in recent years for agricultural soil remediation. It discusses the influencing factors, advantages, limitations, mechanisms, and practical applications of these soil remediation technologies. The published literature focuses on identifying plant species and microorganisms capable of remediating Hg-contaminated soils. Emerging amendments, such as biochar and nanomaterials, have been tested for treating mercury (Hg)-polluted soils primarily by immobilizing mercury and reducing its bioavailability and methylation. Ex situ remediation technologies are effective for Hg-contaminated soils but are often costly, labor-intensive, detrimental to soil quality, and generate hazardous secondary waste. In contrast, in situ technologies treat Hg directly within the soil, preserving the soil matrix and its biota. According to the literature, remediation of Hg-contaminated agricultural soils can be compatible with food crop production only if the bioavailable Hg fraction is sufficiently reduced and crop uptake remains below food safety limits. The gap between laboratory trials and actual field applications in Hg-contaminated soil remediation mainly arises from differences in scale, complexity, and the uncertainty of real-world conditions, which often reduce the efficiency and predictability of treatments. This review aims to provide a practical reference for improving the effective remediation of Hg-contaminated soils in the future. Full article

The textile industry wastewater contaminated by azo dyes usually contains a certain amount of salinity. Therefore, screening for microorganisms capable of degrading azo dyes in saline environments is of great significance. In this study, the decolorizing activity of azo dye methyl red (MR) by Klebsiella aerogenes WH2 (WH2), newly isolated from soil, was evaluated. WH2 was able to decolorize 92.4% and 86.0% of MR at concentrations of 200 mg/L and 300 mg/L within 24 h, respectively. Given that WH2 exhibited enhanced growth and superior degradation capacity in the presence of 2.5% NaCl compared to salt-free conditions, it can be classified as a slight halophile. Approximately 87.7% of MR was removed by WH2 in the presence of 10.0% NaCl within 24 h. Azoreductase activity assays indicated that WH2 retained higher enzyme activity in the presence of NaCl concentrations not exceeding 7.5%. The degradation products and putative metabolic pathways for MR degradation by WH2 were analyzed using FTIR and LC-MS. Phytotoxicity analysis based on seed germination of Vigna radiata indicated that the degradation products of MR exhibited less toxicity than the parent compound. The high degradation efficiency of MR under high salt concentrations makes WH2 a promising candidate for the treatment of saline textile wastewater. Full article

The salinization of natural grasslands is a growing global concern. The Songnen Plain in northeastern China represents a typical soda–saline grassland region, yet an integrated understanding of how salinization reshapes plant, soil, and microbial components in this ecosystem remains limited. In this study, we investigated plant community characteristics, soil physicochemical properties, and soil microbial communities across a salinity gradient (from non-saline to extremely severe saline) using field surveys, laboratory analyses, and structural equation modeling (SEM). Our results showed that vegetation species diversity, the Shannon–Wiener index, and Simpson’s index all decreased from mild to severe salinization. Soil nutrient indicators, including total nitrogen (TN), total phosphorus (TP), and total potassium (TK), significantly decreased with increasing salinity. SEM revealed that plant community diversity had a significant positive effect on soil microorganisms, whereas soil properties, particularly available potassium (AK) and electrical conductivity (EC), exerted significant negative effects on microbial diversity. Together, these results provide an integrated view of how salinization restructures plant–soil–microbe interactions across the Songnen Plain grasslands. These findings improve understanding of saline–alkali grassland degradation from a plant–soil–microbe perspective and provide a theoretical basis for ecosystem restoration in this region. Full article