Search Results (164)

Pyrochar has been identified as a favorable soil conditioner that can effectively ameliorate soil acidification. Hydrochar is considered a more affordable carbon material than pyrochar, but its effect on the process of soil acidification has yet to be investigated. An indoor incubation and a soil column experiment were conducted to study the effect of rice straw hydrochar application on nitrification and NO₃⁻-N leaching in acidic red soil. Compared to the control and pyrochar treatments, respectively, hydrochar addition mitigated the net nitrification rate by 3.75–48.75% and 57.92–78.19%, in the early stage of urea fertilization. This occurred mainly because a greater amount of dissolved organic carbon (DOC) was released from hydrochar than the other treatments, which stimulated microbial nitrogen immobilization. The abundances of ammonia-oxidizing archaea and ammonia-oxidizing bacteria were dramatically elevated by 25.62–153.19% and 12.38–22.39%, respectively, in the hydrochar treatments because of DOC-driven stimulation. The cumulative leaching loss of NO₃⁻-N in soils amended with hydrochar was markedly reduced by 43.78–59.91% and 61.70–72.82% compared with that in the control and pyrochar treatments, respectively, because hydrochar promoted the soil water holding capacity by 2.70–9.04% and reduced the residual NO₃⁻-N content. Hydrochar application can dramatically diminish total H⁺ production from soil nitrification and NO₃⁻-N leaching. Thus, it could be considered an economical soil amendment for ameliorating soil acidification. Full article

This study evaluated the effects of different types and rates of locally produced organic residues on soil organic matter (SOM) and soil health in highly degraded loamy soils of olive orchards in arid southern Tunisia. Three residues were tested: poultry manure, raw date palm waste, and composted date palm waste mixed with manure. A randomised field trial was conducted over three years. Two years after application, soil samples were analysed for physical and chemical properties, basal respiration, nitrogen mineralisation, microbial biomass, enzyme activities (dehydrogenase, phosphomonoesterase, β-glucosidase, urease, arylsulphatase), and community-level physiological profiles. All residues increased SOM and available phosphorus (Pi), with dose-dependent effects sustained over time, though significant increases were only observed at the highest application rates. The most notable improvements occurred in soils amended with composted date palm waste. In contrast, biological and biochemical parameters showed little response, even after remoistening to stimulate microbial activity. This limited response was attributed to the absence of vegetation and, consequently, of root exudates and plant residues. This will be further investigated by assessing changes in the same biological and biochemical properties following the implementation of an intercropping system, which is expected to enhance both SOM content and microbial activity in these soils. Full article

The increasing resistance of pathogenic microorganisms to antimicrobials has driven the search for safe and sustainable alternatives. In this context, microbial biosurfactants have gained prominence due to their antimicrobial activity, low toxicity, and high stability under extreme conditions. This study presents the production and characterization of a biosurfactant with antimicrobial potential, obtained from Bacillus subtilis isolated from soil, for application in the control of resistant strains. Bacterial identification was performed using mass spectrometry (MALDI-TOF), confirming it as Bacillus subtilis. The strain B. subtilis UCP 1533 was cultivated using different carbon sources (glucose, soybean oil, residual frying oil, and molasses) and nitrogen sources (ammonium chloride, sodium nitrate, urea, and peptone), with evaluations at 72, 96, and 120 h. The best condition involved a mineral medium supplemented with 2% soybean oil and 0.12% corn steep liquor, resulting in the production of 16 g·L⁻¹ of biosurfactant, with a critical micelle concentration (CMC) of 0.3 g·L⁻¹ and a reduction in water surface tension to 25 mN·m⁻¹. The biosurfactant showed an emulsification index of 100% for used motor oil and ranged from 50% to 100% for different vegetable oils, maintaining stability across a wide range of pH, salinity, and temperature. FT-IR and NMR analyses confirmed its lipopeptide nature and anionic charge. Toxicity tests with Tenebrio molitor larvae showed 100% survival at all the tested concentrations. In phytotoxicity assays, seed germination rates above 90% were recorded for Solanum lycopersicum and Lactuca sativa. Antimicrobial tests revealed inhibitory activity against resistant strains of Escherichia coli and Pseudomonas aeruginosa, as well as against species of the genus Candida (C. glabrata, C. lipolytica, C. bombicola, and C. guilliermondii), highlighting the biosurfactant as a promising alternative in combating antimicrobial resistance (AMR). These results indicate the potential application of this biosurfactant in the development of antimicrobial agents for pharmaceutical formulations and sustainable strategies for phytopathogen control in agriculture. Full article

This study systematically evaluated the residual behavior of fluxapyroxad (FXP) and mefentrifluconazole (MFZ) in rice–soil systems, alongside their soil and metabolic impacts. Analytical methods validated via linear regression (0.0001–0.05 mg/L) complied with EU guidelines, demonstrating recoveries of 71.97–114.96%, RSDs ≤ 12.12%, and effective mitigation of matrix effects (−85.08% to −76.97%) using matrix-matched calibration. Residual dissipation followed first-order kinetics, with half-lives (T_1/2) spanning 10.83–21.00 d (FXP) and 23.10–57.76 d (MFZ). Notably, MFZ exhibited prolonged persistence in brown rice (T_1/2 = 57.76 d), though final residues (0.031 ± 0.001 μg/g FXP; 0.011 ± 0.0003 μg/g MFZ) remained below regulatory limits (China: 1 mg/kg; CAC: 5 mg/kg). Microbial analysis revealed transient diversity loss in rhizosphere communities (Chao1 index, p < 0.05), recovering by 21 d, while endophytes displayed resilience linked to plant metabolites. Enrichment of degraders (e.g., Sphingomonas) contrasted with suppression of nitrogen-fixing Bradyrhizobium, indicating functional trade-offs. Metabolomic profiling identified 3512 metabolites, with 332 and 173 differentially expressed metabolites at 7 d (S) and 21 d (T), dominated by lipids, benzenoids, and phenylpropanoids. Key metabolic shifts included a 2.11-fold increase in coumarin and elevated L-aspartic acid, highlighting adaptive responses via phenylalanine and TCA cycle pathways. Correlation analyses linked stress-tolerant endophytes (Azorhizobium) to defense-related metabolites (e.g., coumarin), suggesting microbial modulation of plant resilience. These findings emphasize the need for integrated strategies combining residue monitoring, microbial management, and metabolic insights to mitigate agrochemical risks in sustainable agriculture. Full article

Treelines are advancing upward on mountain slopes due to climate warming and reduced grazing intensity. However, the effects of initial vegetation changes on soil C, N, and P retention, microbial biomass, and catabolic diversity in the subalpine meadows during the early stages of treeline shifts remain poorly understood. This research aimed to better understand the direction and drivers of microbial processes related to C, N, and P cycles in the soil of subalpine natural and grazed meadows, with treatments involving meadow grasses alone (GR, control) and as a mixture with forest litter, specifically birch leaves (BLs), in a one-year microcosm experiment. The addition of BLs with GR resulted in a 12–67% decrease in the retention of C, N, and P in soil microbial biomass, but an 8–9% increase in catabolic diversity compared to the control. The most pronounced effect was observed in the N content of the soil microbial biomass (MBN) for both land uses. The increased proportion of recalcitrant plant residue fractions (acid-insoluble and non-polar extractables) contributed to the decrease in soil MBN content. This shift also reduced the microbial metabolic response to carbohydrates in total substrate-induced respiration, leading to a more balanced and catabolically diverse microbial community. These results improve our understanding of the early response of C, N, and P cycling in mountain soils to treeline shifts mediated by climate warming. Full article

Recirculation in vanadium mining enhances resource efficiency but risks ammonia nitrogen (NH₃-N) accumulation, severely compromising leaching yields. To address this bottleneck, we developed a bioaugmentation strategy using Pseudomonas sp. S.P-1 acclimated to vanadium stress. Under optimized conditions (sodium citrate as a carbon source, C/N = 5, 5% inoculum, and pH = 8), the strain achieved exceptional NH₃-N (2000 mg·L⁻¹) removal (>99.25% within 16 days; residual NH₄⁺ < 15 mg·L⁻¹), 12.7% higher than the original bacteria. Mechanistic studies revealed that vanadium exposure triggered dual adaptive responses: enhanced biosorption via the stimulated synthesis of extracellular polymeric substances (EPS) enriched with negatively charged functional groups (C=O, -COOH-, and C-N), improving NH₄⁺ adsorption capacity, and metabolic activation via an elevated transmembrane electrochemical potential and an accelerated substrate uptake due to cell membrane permeability, while up-regulation of ammonia monooxygenase (AMO) activity (123.11%) facilitated efficient NH₄⁺→NH₂OH conversions. Crucially, this bio-process enabled simultaneous NH₃-N degradation (89.2% efficiency) and vanadium recovery, demonstrating its dual role in pollution control and critical metal recycling. By integrating microbial resilience with circular economy principles, our strategy offers a scalable prototype for sustainable vanadium extraction, aligning with low-carbon metallurgy demands in clean energy transitions. This study investigated the ability of vanadium stress to enhance microbial ammonia nitrogen metabolism, and by acclimatizing S.P-1 to vanadium-containing solutions, we aimed to address the dual problems of NH₃-N accumulation and vanadium toxicity in wastewater recirculation. Full article

Global water scarcity and antimicrobial resistance (AMR) represent two escalating crises that urgently demand integrated and effective solutions. While wastewater reuse is increasingly promoted as a strategy to alleviate water scarcity, conventional treatment processes often fail to eliminate persistent contaminants and antibiotic-resistant microorganisms. Cold plasma (CP), a non-thermal advanced oxidation process, has demonstrated the strong potential to simultaneously inactivate pathogens and degrade micropollutants. CP generates a diverse mix of reactive oxygen and nitrogen species (ROS and RNS), as well as UV photons and charged particles, capable of breaking down complex contaminants and inducing irreversible damage to microbial cells. Laboratory studies have reported bacterial log reductions ranging from 1 to >8–9 log₁₀, with Gram-negative species such as E. coli and Pseudomonas aeruginosa showing higher susceptibility than Gram-positive bacteria. The inactivation of endospores and mixed-species biofilms has also been achieved under optimized CP conditions. Viral inactivation studies, including MS2 bacteriophage and norovirus surrogates, have demonstrated reductions >99.99%, with exposure times as short as 0.12 s. CP has further shown the capacity to degrade antibiotic residues such as ciprofloxacin and sulfamethoxazole by >90% and to reduce ARGs (e.g., bla, sul, and tet) in hospital wastewater. This perspective critically examines the mechanisms and current applications of CP in wastewater treatment, identifies the operational and scalability challenges, and outlines a research agenda for integrating CP into future water reuse frameworks targeting AMR mitigation and sustainable water management. Full article

This study reveals how microbial diversity relates to soil properties in Auricularia heimuer residue–chicken manure composting, presenting sustainable waste recycling solutions. These microbial-straw strategies are adaptable to various agroecological regions, offering flexible residue valorization approaches for local conditions, crops, and resources. This study examined the effects of composting Auricularia heimuer residue and chicken manure at three ratios (6:4, 7:3, 8:2) on soil properties, lignocellulose content, enzyme activity, microbial diversity, and maize growth. The compost was mixed into potting soil at different proportions (0:10 to 10:0). During composting, the temperature remained above 50 °C for more than 14 days, meeting safety and sanitation requirements. The composting process resulted in a pH range of 7–8, a stable moisture content of 60%, a color change from brown to gray-brown, the elimination of unpleasant odors, and the formation of loose aggregates. Lignocellulose content steadily decreased, while lignocellulosic enzyme activity and actinomycete abundance increased, indicating suitability for field application. Compared with the control (CK), total nitrogen, total phosphorus, and total potassium in the soil increased by 57.81–77.91%, 4.5–19.28%, and 301.09–577.2%, respectively. Lignin, cellulose, and hemicellulose increased 50.6–83.49%, 59.6–340.33%, and 150.86–310.5%, respectively. The activities of lignin peroxidase, cellulase, and hemicellulase increased by 9.05–36.31%, 6.7–36.66%, and 37.39–52.16%, respectively. Maize root weight, plant biomass, and root number increased by 120.87–138.59%, 117.83–152.86%, and 29.03–75.81%, respectively. In addition, composting increased the relative abundance of actinomycetes while decreasing the abundance of ascomycetes and ascomycetes. The relative abundance of Sphingomonas and Gemmatimonas increased, whereas pathogenic fungi such as Cladosporium and Fusarium decreased. Compost application also enhanced bacterial and fungal diversity, with bacterial diversity indices ranging from 6.744 to 9.491 (B1), 5.122 to 9.420 (B2), 8.221 to 9.552 (B3), and 6.970 to 9.273 (CK). Fungal diversity indices ranged from 4.811 to 8.583 (B1), 1.964 to 9.160 (B2), 5.170 to 9.022 (B3), and 5.893 to 7.583 (CK). Correlation analysis of soil physicochemical properties, lignocellulose content, enzymes, microbial community composition, and diversity revealed that total nitrogen, total phosphorus, total potassium, and lignocellulose content were the primary drivers of rhizosphere microbial community dynamics. These factors exhibited significant correlations with the dominant bacterial and fungal taxa. Additionally, bacterial and fungal diversity increased with the incorporation of Auricularia heimuer residue. In conclusion, this study elucidates the relationships between microbial diversity and soil properties across different proportions of Auricularia heimuer residue and chicken manure composting, offering alternative strategies for waste recycling and sustainable agricultural development. At present, the production of biobiotics using waste culture microorganisms is still in the laboratory research stage, and no expanded experiments have been carried out. Therefore, how to apply waste bacterial bran to the production of biocontrol biotics on a large scale needs further research. Full article

Auricularia auricula (L.) is a widely cultivated edible mushroom, and the resource utilization of its residues offers significant opportunities for sustainable waste management and nutrient recovery. This study investigated the effects of substrate composition on nutrient dynamics and microbial diversity during the aerobic composting of Auricularia auricula (L.) residues. Two treatments were established: composting of Auricularia auricula (L.) residues alone (CR) and composting supplemented with green grass (CRG) over a 49-day period. The results showed that both treatments achieved compost maturity, characterized by a slightly alkaline pH, a germination index (GI) above 80%, and an electrical conductivity below 4 mS/cm. Both composts were odorless, insect-free, and dark brown. Compared to CR, the CRG treatment exhibited higher total organic carbon (TOC) degradation, cumulative total phosphorus (TP) and potassium (TK) levels, as well as enhanced urease, cellulase, and β-glucosidase activities. In contrast, CR retained higher total nitrogen (TN), humic carbon (HEC), fulvic acid carbon (FAC), humic acid carbon (HAC), and a greater humic-to-fulvic acid (HA/FA) ratio. Microbial community analysis revealed diverse bacterial and fungal taxa, with certain species positively correlated with nutrient cycling. Notably, specific substrate compositions promoted beneficial microbial proliferation, essential for efficient composting and nutrient mineralization. These findings not only provide a scientific basis for optimizing composting strategies of mushroom residues but also offer a practical pathway to convert agricultural waste into high-quality organic fertilizers. By enhancing soil fertility, reducing reliance on synthetic fertilizers, and promoting circular bioeconomy practices, this study contributes directly to sustainable agricultural development. CR and CRG treatments, respectively, support either nutrient retention or release, allowing tailored application based on crop demand and soil condition. This study underscores the potential of Auricularia auricula (L.) residues in composting systems, contributing to waste reduction and soil fertility enhancement through tailored substrate management, and offers practical insights into optimizing composting strategies for Auricularia farming by-products. Full article

The organic carbon content of soil (SOC) is considered a key factor for soil health and plays an important role in climate change. Conservation tillage systems promote carbon sequestration and reduce greenhouse gas emissions. A long-term field experiment with different soil tillage practices (conventional tillage—CT; reduced tillage—RT; and no tillage—NT) has been conducted in Prague-Ruzyně (Czech Republic) since 1995. The soil’s organic carbon content, microbial biomass (C_mic), and enzymatic characteristics were evaluated in four-year crop rotation periods from 2005 to 2024. The crop rotation was as follows: winter oil seed rape, winter wheat, pea, and winter wheat. The following soil layers were studied: 0–10, 10–20, and 20–30 cm. Crop residues remained in the field and were incorporated into the soil according to the used tillage—completely under CT, partly under RT, and the remaining mulch under NT. Under RT and NT, the SOC, C_mic, and enzymatic activity were concentrated in the top soil layer and decreased in deeper layers, whereas all these characteristics were evenly distributed across the soil layers under the CT practice. The SOC content increased gradually in the whole soil profile (0–30 cm) from 51.0 t ha⁻¹ on average in 2005–2008 to 56.0 t ha⁻¹ in 2021–2024 under CT. An SOC increase from 57.4 to 63.1 t ha⁻¹ under RT and from 61.1 to 65.7 t ha⁻¹ under NT was noted in 2017–2020, after which the stagnation in SOC content was observed in the years of 2021–2024. Similarly, a lower C_mic and enzymatic activity were found in the same period. The highest C sequestration was found under NT; an increase of 571 kg C ha⁻¹ year⁻¹ was recorded from the establishment of the experiment in 1995 to 2024. This was followed by the RT and CT practices (462 and 221 kg C ha⁻¹ year⁻¹, respectively). The average winter wheat yields and nitrogen content in grain were higher under CT (8.67 t ha⁻¹, 2.16% N) and RT (8.97 t ha⁻¹, 2.13% N) than under NT (8.23 t ha⁻¹, 2.03% N). The weather conditions during the year (abundance of precipitation) influenced crop yields significantly more than the tillage practices. Conservation tillage practices increase the organic carbon and microbial activity in soils, but climate change associated with higher average temperatures can affect these processes. Full article

Vitamin C industrial residue after evaporation (RAE) acts as both a rapid-release carbon source and a microbial activity promoter. A two-year maize field experiment assessed the effectiveness of RAE in improving soil quality in degraded semi-arid regions. The RAE formulation was applied via drip irrigation during the sixth true leaf unfolded (BBCH 24), fourteenth true leaf unfolded (BBCH 38), and middle of grain filling (BBCH 66) stages, which consisted of three treatments: (1) untreated control (CK), (2) low RAE rate (LR: 150 L/ha), and (3) high RAE rate (HR: 300 L/ha). Soil physicochemical properties, enzyme activities, maize nutrient accumulations, and yields were comprehensively analyzed at the maize maturity stage. RAE application significantly improved the following soil nutrients: dissolved organic carbon (10.40–25.92%), ammonium nitrogen (14.04–70.67%), nitrate nitrogen (14.80–78.63%), and available phosphorus (11.79–42.55%). Soil enzyme activities also increased: sucrase (12.38–30.25%), amidase (1.95–25.69%), peptidase (0.56–48.79%), β-1,4-N-acetylglucosaminidase (3.11–9.48%), protease (17.41–226.29%), and acid phosphatase (8.73–60.04%). These changes enhanced maize nitrogen (17.63–40.73%) and phosphorus (20.09–42.11%) uptake, increasing yield by 7.12–13.46%. Statistical analysis showed strong correlations between yields and nutrient accumulations (r = 0.82, p < 0.01), particularly phosphorus (r = 0.91, p < 0.001). RAE enhances crop productivity in degraded agricultural systems by improving soil nutrient availability and plant assimilation, making it a viable alternative to conventional fertilizers. Full article

This review summarizes recent findings on the diverse roles of bacterial sialidases in microbial biology. Bacterial sialidases, also known as neuraminidases, are exog α-lycosidases that cleave terminal sialic acid residues from a number of complex compounds designated as sialoglycoconjugates (glycoproteins, glycolipids and oligosaccharides). Metabolically, they are involved in sialic acid catabolism, providing energy, carbon and nitrogen sources. Catabolic degradation of sialic acids is a physiological feature that can be considered an important virulence factor in pathogenic microorganisms. Sialidases play a pivotal role in host–pathogen interactions and promotion of bacterial colonization. The activity of these enzymes enables bacterial adhesion, biofilm formation, tissue invasion, and also provides immune evasion by exposing cryptic receptors and modifying immune components. Many different perspectives are being developed for the potential application of sialidases. In the field of medicine, they are being explored as appropriate targets for antimicrobials, vaccines, diagnostic preparations and in tumor immunotherapy. In the field of enzymatic synthesis, they are used for the regioselective production of oligosaccharide analogs, enzymatic separation of isoenzymes and as a tool for structural analysis of sialylated glycans, among other applications. Full article

Under the concept of green and low-carbon development, efficient and environmentally friendly biochar preparation methods have attracted much attention. This study assessed a novel sodium carbonate activator combined with acid modification for sludge-based biochar (SB) production and its adsorption of organics in wool scouring wastewater. Under 600 °C, the optimal carbonization temperature, the residual weight percentage of biochar carbonized material increases from 27% to 73% after Na₂CO₃ activation compared to ZnCl₂ activation. Compared to HCl-modified ZnCl₂-activated biochar (Zn-Cl-SB), HCl-H₂SO₄-modified Na₂CO₃-activated biochar (Na-Cl/S-SB) had a specific surface area of 509.3 m²/g, and the average mesopore size was 7.896 nm, with micropore volume and specific surface area increasing by 83.3% and 79.8%, respectively. Meanwhile, the C-O oxygen-containing functional groups and pyrrole nitrogen-containing functional groups were significantly increased. Na-Cl/S-SB exhibited an excellent adsorption performance for organic matter in wool scouring wastewater, with a maximum adsorption capacity of 168.3 mg/g. Furthermore, the adsorption process followed the pseudo-second-order kinetic model. Three-dimensional fluorescence spectrum analysis showed that Na-Cl/S-SB had a strong adsorption capacity for aromatic protein analogs, proteins containing benzene rings, and dissolved microbial by-products in wool scouring wastewater. This study will serve as a guideline for the green synthesis of SB while improving its ability to adsorb pollutants. Full article

Soil microbes are critical in regulating the growth and function of eucalyptus plantations. The mechanisms underlying soil microbial communities’ response to different eucalyptus plantation management practices remain elusive. In this study, we compiled datasets containing 2744 observations across global eucalyptus-planted regions and analyzed the effects of five management practices (i.e., burning, residual removal, fertilization, mixed planting, and controlling planting years) on soil microbial biomass, diversity, and structures. Our results showed that fungal community alpha diversity responds more sensitively to management practices than bacterial community alpha diversity on eucalyptus plantations. Although the implementation of management practices significantly increased the content of most soil nutrients and microbial biomass elements (excluding burning), these practices did not necessarily improve soil microbial biomass and diversity, particularly among fungal communities. Burning, fertilization, and mixing eucalyptus with nitrogen-fixing species significantly decreased the diversity of fungal communities, which were mainly impacted by soil organic carbon and total potassium content. Compared to the four other management practices, mixing eucalyptus with nitrogen-fixing species favored the growth of bacterial communities and the storage of microbial biomass nitrogen, making it the most effective management practice. However, attention should also be paid to the protection of fungal communities. In addition, these management practices significantly changed microbial community structures, which were positively correlated with the microbial biomass elements carbon and nitrogen and, to a lesser extent, soil microbial alpha diversity. Our results highlight the importance of prioritizing mixing eucalyptus with nitrogen-fixing species as a management practice and safeguarding fungal community diversity during its implementation and suggest that microbial diversity development associated with soil organic carbon and potassium contents should be given priority in eucalyptus plantation management. Full article

Microbial necromass carbon (MNC) is crucial for soil carbon sequestration in bamboo (Phyllostachys edulis) forests. However, the response of MNC to bamboo-sourced organic fertilizers (BSOF) prepared by composting bamboo plant growth-promoting microorganisms and bamboo residues remains unclear. This study examined MNC and its contribution to soil organic carbon (SOC) in Moso bamboo plantations under four BSOF treatments: control (CK, 0 t·hm⁻²), low fertilizer application (LF, 7.5 t·hm⁻²), medium fertilizer application (MF, 15 t·hm⁻²), and high fertilizer application (HF, 30 t·hm⁻²) across 0–20 cm and 20–40 cm soil layers. In these two layers, HF and MF significantly (p < 0.05) increased the total MNC, fungal necromass carbon (FNC), and their contributions to SOC compared to CK, and HF led to higher (p < 0.05) bacterial necromass carbon (BNC) levels and SOC contributions than LF and CK. Soil depth and BSOF treatment were found to interact significantly. A random forest model showed that in the 0–20 cm layer, SOC was the best predictor of total MNC and FNC, whereas available potassium was optimal for BNC. Nitrate-nitrogen (NO₃⁻-N) was the top predictor for total MNC, BNC, and FNC in the 20–40 cm layer. Partial least squares path modeling indicated that available soil nutrients directly influenced BNC and FNC, affecting SOC accumulation. These findings suggest a new method for enhancing soil carbon sequestration in bamboo forests. Full article