Search Results (3,132)

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

The aim of the study was to evaluate the biotechnological potential of thermophilic microorganisms isolated from chernozem soil during composting of poultry manure. The efficiency of the strains was determined by their effect on organic matter degradation, humification intensity, and nitrogen accumulation. The correlation between the quality indicators of the composting process was assessed with the gross values, taking into account the proportion of compost fractions. The strains were identified as: Aeribacillus pallidus KCTC 3564^T (cellulolytic), Neobacillus sedimentimangrovi FJAT-2464^T, Aeribacillus composti N.8^T, Caldifermentibacillus hisashii N-11^T (nitrogen fixers), Acinetobacter pittii CIP 70.29^T, and Pseudomonas plecoglossicida NBRC 103162^T (nitrifies). It was found that all the bacteria increase the proportion of small fractions by 19.0–19.9%. The gross content of humic acids increases under the influence of nitrifiers (15.5%) and nitrogen fixers (5.5%). The total nitrogen content increases under cellulolytics (13.8%) and nitrogen fixers (20.2%). The smallest fraction (≤0.25 mm) in nitrogen fixers and nitrifying variants has the greatest bioreclamation properties, by 16.4% (p < 0.001) and 12.9% (p < 0.001). Targeted microbial strains provide the direction of the transformation processes during biocomposting. It can also be concluded that assessing the quality of composting based on the fraction distribution can be a promising element of the biofermentation process monitoring. Full article

The increasing adoption of biopolymeric and nanostructured coatings for horticultural produce has emerged as a sustainable strategy to mitigate postharvest losses and extend shelf life. However, while their technological performance has been extensively documented, comprehensive and integrative assessments of biosafety, potential human health implications, and environmental risks profiles are still insufficiently explored. This review critically analyzes recent advances in polysaccharide, protein, and lipid-based coatings, including nanoenabled systems incorporating metallic nanoparticles and bioactive agents. The mechanisms underlying gas barrier properties, antimicrobial activity, and preservation efficacy are discussed alongside degradation pathways in composting, soil, and aquatic environments. Particular attention is given to nanoparticle release, migration potential, gastrointestinal fate, and toxicological endpoints such as oxidative stress, genotoxicity, endocrine disruption, and immunomodulation. Ecotoxicological evidence across trophic levels, from microorganisms and invertebrates to fish and amphibians, is examined, highlighting sublethal and mechanistic biomarkers relevant to environmental risk assessment. Regulatory frameworks from major agencies are also compared to contextualize current safety standards and limitations. Overall, although biopolymeric coatings represent promising alternatives to conventional plastics, their life-cycle impacts, transformation products, and nano-related uncertainties require comprehensive, multilevel risk evaluation to ensure truly sustainable and safe postharvest applications. Full article

Biosurfactant-producing microorganisms play an important ecological role in soils impacted by hydrophobic contaminants by enhancing substrate bioavailability and influencing microbial interactions. In this study, we critically evaluated the reliability of commonly used screening methods for biosurfactant detection. A total of 71 microbial isolates (16 bacteria and 55 fungi) were obtained from vegetable oil-contaminated soil and screened using a multi-step approach combining enzymatic assays (lipolytic and hemolytic activity) and physicochemical methods, including drop-collapse, oil spreading, emulsification index (E₂₄), and surface tension reduction. Although 21 isolates exhibited lipolytic activity and 9 showed hemolysis, inconsistent responses among assays revealed significant limitations of individual screening methods. Only two bacterial isolates consistently tested positive across all criteria. When cultivated in mineral salt medium supplemented with hydrophobic substrates, both isolates produced stable emulsions and significantly reduced surface tension (from 54.26 mN/m to 31.46 mN/m). Substrate-dependent variation was observed for isolate C3, which showed reduced surface tension (39.63 mN/m) when grown with biodiesel. These findings highlight the risk of relying on single assays and emphasize the need for integrated screening strategies to ensure reliable detection of biosurfactant-producing microorganisms. Full article

Invasion by Spartina alterniflora has detrimental effects on existing ecosystems. Studies have shown that microorganisms can control plant growth and development. However, the root-associated community structures of bacteria, archaea, and fungi of S. alterniflora have rarely been investigated. Here, we applied metagenomics to reveal the bacterial, archaeal, and fungal communities across four root compartments, including the bulk soil, rhizosphere, rhizoplane, and endosphere. Our findings revealed the variation in different community structures. The bacterial and fungal communities exhibited greater potential environmental flexibility than the archaeal community. The endosphere environment had the simplest microbial networks and highest stability. Additionally, we identified root-exuded metabolites from S. alterniflora, which may influence microbial community assembly. Our results indicate that the rhizoplane plays a crucial role in controlling microbial entry into the root, selectively recruiting beneficial microbes for plant growth and colonization, thereby impacting nutrient cycling and plant health. This study provides insights into microbial diversity and function within the S. alterniflora root zone and suggests potential microbial-based strategies for managing this invasive species. Full article

To assess food safety conditions among family farmers supplying the National School Feeding Program (PNAE) in the Federal District, Brazil. This exploratory mixed-methods study was subdivided into two main phases: (i) samples of fruits, vegetables, water, soil, and farmers’ feces were analyzed microbiologically and/or parasitologically across nine properties; (ii) sociodemographic and Good Agricultural Practices (GAP) questionnaires were administered, followed by semi-structured interviews to evaluate their perceptions of food safety. Participants were males (100%), of mixed race (88.9%), aged 41–50 years (44.4%), with secondary education (33.3%), and an income between USD 1000 and USD 2000 (33.3%). Samples from food (n = 162), water (n = 18), soil (n = 90), and feces (n = 6) were analyzed. All fruit and vegetable samples, and 83.3% of water samples exceeded acceptable limits for at least one of the microorganisms analyzed. 86.7% of the soil samples showed high levels of contamination. Parasitic contamination was detected in 50.6% of the fruit and vegetable samples, in 63.3% of the soil samples, and in none of the water samples. Most farms used deep or artesian wells (77.7%) and non-connected septic pits (77.7%). Organic fertilization predominated (88.8%), with chemical fertilizers occasionally used (11.2%). Farmers demonstrated strong environmental awareness but limited technical knowledge of food safety. Results indicate persistent vulnerability despite ethical and ecological commitment. Continuous training and stronger public policies are essential to enhance GAP adherence, ensure food microbiological safety, and sustain PNAE objectives. Full article

The soil microbiome is a complex assemblage of microorganisms that are important in restoring and maintaining soil function, ecosystem stability, and sustainable agroecosystem development. However, soil microbial responses to environmental or land-use gradients in agroecosystems and the consequent implications for soil functional integrity and sustainable agroecosystem development remain poorly understood. In this review, we present the current state of the science on: (1) shifts in microbial community composition in response to environmental or land-use gradients within conventional dryland small grains farms, temperate evergreen forests, and riparian areas in the inland Pacific Northwest (iPNW) where the precipitation regime is considered mediterranean, and (2) microbial traits link to soil function as a response to soil health management. Upon conclusion of this review, the lack of information is still apparent in terms of understanding how to intentionally manage the soil microbiome after land-use conversions, especially given that soil health and ecosystem services are driven by the soil microbiome. This review, therefore, motivates future research into the primary land management regimes to better link specific microbial taxa to soil microbial and ecosystem processes across land-use gradients. Full article

Castanopsis hystrix (C. hystrix) is one of the most dominant and ecologically important species in subtropical evergreen broad-leaved forests of China. Interactions between its root and rhizosphere microorganisms play a pivotal role in nutrient acquisition and in mediating plant response s to environmental stresses. In this study, high-throughput 16S ribosomal RNA (16S rRNA) sequencing combined with untargeted metabolomics was employed to systematically characterize the rhizosphere microbial community and root exudates in C. hystrix. The results showed that, compared with non-rhizosphere soil, bacterial diversity in the rhizosphere of C. hystrix was significantly reduced, while several specialized and potentially efficient taxa were selectively enriched, particularly Candidatus_Solibacter, Candidatus_Xiphinematobacter, and Candidatus_Koribacter, thereby reshaping a distinct rhizosphere-specific community structure. Metabolomic analyses further revealed that 129 metabolites were significantly enriched in the rhizosphere, including four major classes of compounds associated with plant stress resistance: lipids and lipid-like molecules, organoheterocyclic compounds, organic acids and derivatives, and phenylpropanoids and polyketides. The enrichment of these metabolites likely contributes substantially to stress tolerance in C. hystrix. Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment analysis identified six defense-related metabolic pathways, including pyrimidine metabolism, steroid biosynthesis, nucleotide metabolism, plant hormone signal transduction, ATP-binding cassette transporter (ABC transporters), and the biosynthesis of various plant secondary metabolites. Further correlation analysis and co-occurrence network analysis suggested that C. hystrix may potentially influence the enrichment of beneficial microorganisms through rhizosphere metabolites selectively, which could reduce the reliance on external nutrient acquisition and enhance the stress resilience of C. hystrix. Our study provides a comprehensive perspective for elucidating rhizosphere interaction networks and their ecological functions in C. hystrix, thereby enhancing our understanding of the environmental adaptability of dominant tree species in subtropical forests. Full article