Search Results (244)

Global antibiotic use saturates ecosystems with selective pressure, driving mobile genetic element (MGE)-mediated antibiotic resistance gene (ARG) dissemination that destabilizes ecological integrity and breaches public health defenses. This review synthesizes the sources, environmental distribution, and ecological risks of antibiotics and ARGs, emphasizing the mechanisms of horizontal gene transfer (HGT) driven by MGEs such as plasmids, transposons, and integrons. We further conduct a comparative critical analysis of the effectiveness and limitations of antibiotics and ARGs remediation strategies for adsorption (biochar, activated carbon, carbon nanotubes), chemical degradation (advanced oxidation processes, Fenton-based systems), and biological treatment (microbial degradation, constructed wetlands). To effectively curb the spread of antimicrobial resistance and safeguard the sustainability of ecosystems, we propose an integrated “One Health” framework encompassing enhanced global surveillance (antibiotic residues and ARGs dissemination) as well as public education. Full article

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

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

Soy molasses, a byproduct of soy protein concentrate production, offers potential as a substrate for biotechnological applications due to its rich composition of carbohydrates, proteins, lipids, and bioactive compounds. Despite this, it remains underutilized, often relegated to low-value applications such as animal feed or waste, largely due to variability in its composition, the presence of microbial inhibitors, and limited industrial awareness of its potential. This review explores the biotechnological strategies for valorizing soy molasses, focusing on its chemical and physical properties, potential applications, and the challenges associated with its use. Its high carbohydrate content supports its utilization in producing biofuels, organic acids, and polyhydroxyalkanoates (PHA), addressing the global demand for sustainable energy and materials while costing approximately 20% of the value of conventional carbohydrate sources. Additionally, bioactive compounds have extended applications to nutraceuticals and cosmetics, while proteins and lipids enable enzyme and biosurfactant production. However, challenges such as variability in composition, the presence of inhibitory compounds, and scalability issues require innovative approaches, including pre-treatment methods and strain engineering. By integrating soy molasses into a circular bioeconomy framework, industries can reduce waste, lower their carbon footprint, valorize agro-industrial residues, and generate economic value. This review underscores the untapped potential of soy molasses as a versatile, sustainable resource, while highlighting the need for continued advancements to transform it into a key player in industrial biotechnology. Full article

The bioavailability of heavy metals is profoundly influenced by their interactions with active soil components (microorganisms, organic matter, and iron minerals). However, the effects of urease-producing bacteria combined with organo-Fe hydroxide coprecipitates (OFCs) on Cd accumulation in wheat, as well as the mechanisms underlying these effects, remain unclear. In this study, pot experiments integrated with high-throughput sequencing were employed to investigate the impacts of the urease-producing bacterial strain TJ6, ferrihydrite (Fh), and OFCs on Cd enrichment in wheat grains, alongside the underlying soil–microbial mechanisms. The results demonstrate that the strain TJ6-Fh/OFC consortium significantly (p < 0.05) reduced (50.1–66.7%) the bioavailable Cd content in rhizosphere soil while increasing residual Cd fractions, thereby decreasing (77.4%) Cd accumulation in grains. The combined amendments elevated rhizosphere pH (7.35), iron oxide content, and electrical conductivity while reducing (14.5–21.1%) dissolved organic carbon levels. These changes enhanced soil-colloid-mediated Cd immobilization and reduced Cd mobility. Notably, the NH₄⁺ content and NH₄⁺/NO₃⁻ ratio were significantly (p < 0.05) increased, attributed to the ureolytic activity of TJ6, which concurrently alkalinized the soil and inhibited Cd uptake via competitive ion channel interactions. Furthermore, the relative abundance of functional bacterial taxa (Proteobacteria, Gemmatimonadota, Enterobacter, Rhodanobacter, Massilia, Nocardioides, and Arthrobacter) was markedly increased in the rhizosphere soil. These microbes exhibited enhanced abilities to produce extracellular polymeric substances, induce phosphate precipitation, facilitate biosorption, and promote nutrient (C/N) cycling, synergizing with the amendments to immobilize Cd. This study for the first time analyzed the effect and soil science mechanism of urease-producing bacteria combined with OFCs in blocking wheat’s absorption of Cd. Moreover, this study provides foundational insights and a practical framework for the remediation of Cd-contaminated wheat fields through microbial–organic–mineral collaborative strategies. Full article

The use of service (cover) crops is widely practiced in soil agriculture due to their many benefits, including enhanced nutrient supply and improved soil health. Bacteria, as major decomposers of plant residues in the soil, play essential roles in nutrient cycling. This study examined the impact of various almond orchard management practices on the soil microbial community composition in a hyper-arid ecosystem. High-throughput sequencing was used to compare the microbial communities in two adjacent almond orchards managed with either organic (ORG) or regenerative agriculture (RA) practices, alongside an uncultivated (UC) site. Notably, little is known about the responses of soil bacterial communities in hyper-arid regions to intercrop mulch from service crops. This study may offer insights into the ecological limits of the benefits of service crops in promoting soil health under extreme conditions. Our findings demonstrate that RA management can alter soil organic carbon levels and reshape microbial communities by increasing overall bacterial abundance and enriching specific keystone taxa. These changes may have significant implications for nutrient cycling processes in hyper-arid agroecosystems. Full article

Cadmium (Cd) mobilization in paddy soils during redox fluctuations poses significant risks to rice safety. This study investigated the efficacy of nano-calcium carbonate (NCC), nano-hydroxyapatite (NHAP), and their composite (C+P) in immobilizing Cd under simulated flooding–drainage cycles. Soil treatments (0.5% and 1.0% w/w) were subjected to 40 day anaerobic and 20 day aerobic incubation. The results demonstrated that NCC and C+P elevated the soil pH by 1.35–1.39 and 0.72–1.01 units during the anaerobic and aerobic phases, respectively. These amendments suppressed Fe(II) and Mn(II) release by 41–75%, correlating with reduced Cd bioavailability. While nanomaterials minimally influenced Cd speciation during flooding, aerobic conditions triggered a marked shift: residual Cd fractions increased by 80.8–116.4% under NCC, driven by CdCO₃ precipitation and phosphate complexation. Cd release rates decreased by 53.6–66.8% in NCC and C+P treatments during oxidation. Microbial analysis revealed diminished bacterial diversity but enriched Firmicutes (up to 58.9%), which positively correlated with pH and residual Cd. Redundancy analysis identified pH and Fe/Mn dynamics as key regulators of the microbial community structure. NCC emerged as the most effective amendment. This study highlights the potential of NCC-based strategies for mitigating Cd risks in acidic paddy soils, particularly during post-flooding drainage. Full article

Although algae possess a high capacity for carbon sequestration, the recalcitrant multilayered cell wall structure and residual microcystin toxicity associated with Microcystis aeruginosa significantly hinder the efficient recovery of algal biomass resources. This study developed a synergistic ozone-ultrasonication (O₃-US) pretreatment strategy, systematically comparing its cell-disruption efficacy with standalone O₃ or US, using harvested algal biomass from natural aquatic systems dominated by Microcystis aeruginosa. The synergistic effects revealed were: (1) O₃-mediated oxidation of extracellular polymeric substances and cell wall matrices, (2) the release of ultrasound-induced cavitation-enhancing intracellular components, and (3) an improvement in the O₃ mass transfer by hydrodynamic shear forces. Through response surface methodology optimization, the O₃-US process achieved maximal performance at 0.14 gO₃/gTSS, with a 4 W/mL ultrasonic intensity, and a 20 min duration. Remarkably, the released protein was 289.2 mg/gTSS, which was 4.3-fold and 1.9-fold, respectively, more than that released in O₃ pretreatment and US pretreatment, while the polysaccharide was 87.5 mg/gTSS, increased by 2.4-fold and 3.1-fold respectively, compared to O₃ alone and US alone. The released solubilized chemical oxygen demand (SCOD) was 1037.1 mg/gTSS, increased by 43.3% and 216.1%, respectively, relative to O₃ alone and US alone. DNA quantification further validated the synergistic cell disruption caused by O₃-US. Fluorescence excitation-emission matrix (EEM) spectroscopy identified biodegradable aromatic proteins (Regions I-II) and soluble microbial byproducts (Region IV) as dominant organic fractions, demonstrating enhanced bioavailability. The hybrid process reduced energy consumption by 33.3% in ultrasonic intensity and 60% in duration versus US alone, while achieving 94.5% microcystin-LR (MC-LR) degradation, which showed a 96.6% risk reduction compared to ultrasonic treatment. This work establishes an efficient, low-energy, and safe pretreatment technology for algal resource recovery, synergistically enhancing intracellular resource release while mitigating cyanotoxin hazards in algal biomass valorization. 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

Water-capped tailings technology (WCTT) is a strategy where oil sand tailings are sequestered within a mined-out pit and overlayed with a layer of water in order to sequester tailings with the aim that the resulting pit lake will support aquatic plants and organisms over time. The Base Mine Lake Demonstration (BML) is the first full-scale demonstration of a pit lake in the Athabasca Oil Sands Region (AOSR). In the BML, the release of methane from the fluid tailings influences several key processes, including the flux of greenhouse gases, microbial oxygen consumption in the water column, and ebullition-facilitated transport of organics from the fluid tailings to the lake surface. It is hypothesized that the residual low molecular weight hydrocarbons (LMWHCs) derived from diluent naphtha used during bitumen extraction processes are the carbon sources fueling ongoing microbial methanogenesis within the BML. The aims of this study were to identify the LMWHCs in the BML fluid tailings, to elucidate their sources, and to assess the extent of biogeochemical cycling affecting them. A headspace GC/MS analysis identified 84, 44, and 56 LMWHCs (C4–C10) present in naphtha, unprocessed bitumen ore, and fluid tailings, respectively. Equilibrium mass balance assessment indicated that the vast majority (>95%) of LMWHCs were absorbed within residual bitumen rather than dissolving into tailings pore water. Such absorbed compounds would not be readily available to in situ microbial communities but would represent a long-term source for methanogenesis. Chromatographic analysis revealed that most biodegradable compounds (n-alkanes and BTEX) were present in the naphtha but not in fluid tailings or bitumen ore, implying they are sourced from the naphtha and have been preferentially biodegraded after being deposited. Among the LMWHCs observed in bitumen ore, naphtha, and fluid tailings, C2-cyclohexanes had the highest relative abundance in tailings samples, implying their relatively high recalcitrance to in situ biodegradation. Full article

Biodesulfurization (BDS) is a clean technology that uses microorganisms to efficiently remove sulfur from recalcitrant organosulfur compounds present in fuels (fossil fuels or new-generation fuels resulting from pyrolysis and hydrothermal liquefaction). One of the limitations of this technology is the low desulfurization rates. These result in the need for greater amounts of biocatalyst and lead to increased production costs. To mitigate this issue, several approaches have been pursued, such as the use of alternative carbon sources (C-sources) from agro-industrial waste streams or the co-production of high-added-value products by microorganisms. The main goal of this work is to assess the potential of strawberry tree fruit residue (STFr) as an alternative C-source for a BDS biorefinery using Gordonia alkanivorans strain 1B, a well-known desulfurizing bacterium with high biotechnological potential. Hence, the first step was to produce sugar-rich liquor from the STFr and employ it in shake-flask assays to evaluate the influence of different pretreatments (treatments with 1–4% activated charcoal for prior phenolics removal) on metabolic parameters and BDS rates. Afterwards, the liquor was used as the C-source in chemostat assays, compared to commercial sugars, to develop and optimize the use of STFr-liquor as a viable C-source towards cost-effective biocatalyst production. Moreover, the high-market-value bioproducts simultaneously produced during microbial growth were also evaluated. In this context, the best results, considering both the production of biocatalysts with BDS activity and simultaneous bioproduct production (carotenoids and gordofactin biosurfactant/bioemulsifier) were achieved when strain 1B was cultivated in a chemostat with untreated STFr-liquor (5.4 g/L fructose + glucose, 6:4 ratio) as the C-source and in a sulfur-free mineral-minimized culture medium at a dilution rate of 0.04 h⁻¹. Cells from this steady-state culture (STFr L1) achieved the highest desulfurization with 250 mM of dibenzothiophene as a reference organosulfur compound, producing a maximum of ≈213 mM of 2-hydroxibyphenil (2-HBP) with a corresponding specific rate (q_2-HBP) of 6.50 µmol/g(_DCW)/h (where DCW = dry cell weight). This demonstrates the potential of STFr as a sustainable alternative C-source for the production of cost-effective biocatalysts without compromising BDS ability. Additionally, cells grown in STFr L1 also presented the highest production of added-value products (338 ± 15 µg/g_(DCW) of carotenoids and 8 U/mL of gordofactin). These results open prospects for a future G. alkanivorans strain 1B biorefinery that integrates BDS, waste valorization, and the production of added-value products, contributing to the global economic viability of a BDS process and making BDS scale-up a reality in the near future. Full article

Soil organic carbon (SOC) plays a vital role in maintaining soil fertility and ecosystem sustainability, with crop residues serving as a key carbon input. However, how different maize residue components influence SOC stabilization across aggregate sizes and fertility levels remains poorly understood. This study investigated the effects of maize roots, stems, and leaves on SOC dynamics and aggregate-associated carbon under low- and high-fertility Brown Earth soils through a 360-day laboratory incubation. Results revealed that residue incorporation induced an initial increase in SOC, followed by a gradual decline due to microbial mineralization, yet maintained net carbon retention. In low-fertility soil, leaf residues led to the highest SOC content (12.08 g kg⁻¹), whereas root residues were most effective under high-fertility conditions (18.93 g kg⁻¹). Residue addition enhanced macroaggregate (>0.25 mm) formation while reducing microaggregate fractions, with differential patterns of SOC distribution across aggregate sizes. SOC initially accumulated in 0.25–2 mm aggregates but gradually shifted to >2 mm and <0.053 mm fractions over time. Root residues favored stabilization in high-fertility soils via mineral association, while stem and leaf residues promoted aggregate-level carbon protection in low-fertility soils. These findings highlight the interactive roles of residue type and soil fertility in regulating SOC sequestration pathways. Full article

The pyrolysis of sewage sludge into biochar, enhanced by incorporating agriculture waste rich in inorganic minerals and lignocellulosic compounds, provides an effective approach for achieving sludge-harmless treatment and resourceful utilization. In this study, sewage sludge and maize straw-based biochar (SMB) was prepared using the co-pyrolysis method, and the effects of different application ratios (0%, 1%, 3%, and 5%, w/w) of SMB on soil properties, ryegrass growth, microbial community structure, and Pb content and speciation in the contaminated soil of constructed wetlands were investigated. The results showed that SMB had a high carbon content (28.58%) and was rich in functional groups (e.g., -C-O, -C-N). The results indicated that increasing SMB dosage (0–5% w/w) in Pb-contaminated soil elevated soil pH from 6.40 to 7.93, cation-exchange capacity (CEC) from 30.59 to 79.03 cmol/kg (+158%), and organic carbon content by 65% (from 176.79 mg/kg to 107.3 mg/kg), while reducing available phosphorus and potassium by 20% and 30%, respectively, resulting in a 6% decline in ryegrass leaf length. SMB application enriched Pb-resistant bacteria (e.g., Sphingomonas abundance increased from 10.3% to 11.2%) and enhanced Pb immobilization. After 55 days, the total soil Pb increased by 33%, and the residual fraction Pb significantly increased by 7.3% to 21.7%, driven by functional group complexation, ion exchange, pH, and CEC improvements. Full article

The application of biochar is extensively recognized as an effective strategy to enhance soil ecosystem services. However, its combined effect with beneficial microorganisms, such as Trichoderma, still requires further investigation to understand its impact on soil microbiota and nutrient cycling processes. To address this gap, this study aimed to evaluate the effect of biochar produced from on-farm winery waste, specifically grape stalks (GSB) and grape fermentation residues (GFB), generated after wine production, when co-applied with Trichoderma aureoviride URM 5158 and Trichoderma hamatum URM 6656 in soil cultivated with Malbec grapevines. Our findings reveal that both types of biochar and Trichoderma promoted changes in soil properties. The application of GSB biochar combined with T. hamatum increased grape productivity, while GFB biochar enhanced soil enzymatic activities, particularly those expressed per unit of microbial biomass carbon. Additionally, biochar applications increased pH, phosphorus, potassium, organic carbon, and microbial biomass carbon of the soil. Soils treated with the GFB + T. hamatum treatment exhibited an increase of 569.23% in microbial biomass carbon compared to the control. The results of this study provide substantial evidence that biochar and Trichoderma can be used to improve the chemical and biological properties of vineyard soils, increasing nutrient availability, especially carbon. These effects may contribute to soil fertility by promoting a more favorable environment for microbiota development and grapevine growth. This is the first field study to investigate the impact of on-farm winery waste transformed into biochar, combined with Trichoderma isolates, on Malbec grapevines. 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