Anion Concentration Research Articles

Staphylococcus aureus counters organic acid anion-mediated inhibition of peptidoglycan cross-linking through robust alanine racemase activity.

Weak organic acids are commonly found in host niches colonized by bacteria, and they can inhibit bacterial growth as the environment becomes acidic. This inhibition is often attributed to the toxicity resulting from the accumulation of high concentrations of organic anions in the cytosol, which disrupts cellular homeostasis. However, the precise cellular targets that organic anions poison and the mechanisms used to counter organic anion intoxication in bacteria have not been elucidated. Here, we utilize acetic acid, a weak organic acid abundantly found in the gut to investigate its impact on the growth of Staphylococcus aureus. We demonstrate that acetate anions bind to and inhibit d-alanyl-d-alanine ligase (Ddl) activity in S. aureus. Ddl inhibition reduces intracellular d-alanyl-d-alanine (d-Ala-d-Ala) levels, compromising staphylococcal peptidoglycan cross-linking and cell wall integrity. To overcome the effects of acetate-mediated Ddl inhibition, S. aureus maintains a substantial intracellular d-Ala pool through alanine racemase (Alr1) activity and additionally limits the flux of d-Ala to d-glutamate by controlling d-alanine aminotransferase (Dat) activity. Surprisingly, the modus operandi of acetate intoxication in S. aureus is common to multiple biologically relevant weak organic acids indicating that Ddl is a conserved target of small organic anions. These findings suggest that S. aureus may have evolved to maintain high intracellular d-Ala concentrations, partly to counter organic anion intoxication.

Oxidative weathering of pyrite in acidic environments: Data-driven experimental evaluation coupled with Raman hyperspectral imaging

This study deals with the identification of the factors that affect pyrite oxidation in acid mine drainage conditions. For this scope, weathering experiments have been carried at laboratory scale based on the design of experiments methodology to evaluate the effect of factors such as major ion concentrations, crystal size, and humic acids presence over the amount of elemental sulfur produced due to the involved weathering reactions. In particular, metal and anionic concentrations in solution were quantified by inductively coupled plasma-atomic emission spectroscopy and ion-chromatography techniques, respectively, whereas the amount of elemental sulfur was quantified with a high-performance liquid chromatography with diode-array detection technique after proper extraction procedure. A partial least squares regression was calculated to establish a quantitative relationship between the considered factors and the amount of elemental sulfur. After evaluation of the model, ferric iron, crystal size and the presence of humic acids were identified as the relevant factors for pyrite oxidation under acidic conditions. In addition, the surface of the samples was characterized by Raman imaging spectroscopy and subsequently analyzed by explorative hyperspectral analysis methods to assess the spatial distribution of the elemental sulfur as the main weathering product, resulting in a homogenous distribution.

Weakening the Space Charge Layer Effect Through Tethered Anion Electrolyte and Piezoelectric Effect Toward Ultra-Stable Zinc Anode.

The space charge layer (SCL) dilemma, caused by mobile anion concentration gradient and the rapid consumption of cations, is the fundamental reason for the generation of zinc dendrites, especially under high-rate discharge conditions. To address the issue, a physical (PbTiO3)/chemical (AMPS-Zn) barrier is designed to construct stable zinc ion flow and disrupt the gradient of anion concentration by coupling the ferroelectric effect with tethered anion electrolyte. The ferroelectric materials PbTiO3 with extreme-high piezoelectric constant can spontaneously generate an internal electric field to accelerate the movement of zinc ions, and the polyanionic polymer AMPS-Zn can repel mobile anions and disrupt the anions concentration gradient by tethering anions. Through numerical simulations and analyses, it is discovered that a high Zn2+ transference number can effectively weaken the SCL, thus suppressing the occurrence of zinc dendrites and parasitic side reactions. Consequently, an asymmetric cell using the PbTiO3@Zn demonstrates a reversible plating/stripping performance for 2900h, and an asymmetric cell reaches a state-of-the-art runtime of 3450h with a high average Coulombic efficiency of 99.98%. Furthermore, the PbTiO3@Zn/I2 battery demonstrated an impressive capacity retention rate of 84.0% over 65000 cycles by employing a slender Zn anode.

Transition Metal Complexes with Appended Benzimidazole Groups for Sensing Dihydrogenphosphate.

Four new complexes [Ru(bpy)2(bbib)](PF6)2, [Ru(phen)2(bbib)](PF6)2, [Re(CO)3(bbib)(py)](PF6) and [Ir(ppy)2(bbib)](PF6) [where bbib=4,4'-bis(benzimidazol-2-yl)-2,2'-bipyridine] have been prepared and their photophysical properties determined. Their behaviour has been studied with a variety of anions in acetonitrile, DMSO and 10 % aquated DMSO. Acetate and dihydrogenphosphate demonstrate a redshift in the bbib ligand associated absorptions suggesting that the ligand is strongly interacting with these anions. The 3MLCT emissive state is sensitive to the introduction of small quantities of anion (sub-stoichiometric quantities) and significant quenching is typically observed with acetate, although this is less pronounced in the presence of water. The emissive behaviour with dihydrogenphosphate is variable, showing systematic changes as anion concentration increases with several distinct interactions evident. 1H- and 31P-NMR titrations in a 10 % D2O-DMSO-D6 mixture suggest that with dihydrogenphosphate, the imidazole group is able to act as both a proton acceptor and donor. It appears that all four complexes can form a {[complex]2-H2PO4} "dimer", a one-to-one species (which the X-ray crystallography study suggests is dimeric in the solid-state), and a complex with a combined bis(dihydrogenphosphate) complex anion. The speciation relies on complex equilibria dependent on several factors including the complex charge, the hydrophobicity of the associated ligands, and the solvent.

Anionic vacancy filled-up mechanism in (Ti0.2V0.2Nb0.2Ta0.2W0.2)Cx high-entropy carbide

Carbothermic reduction for high-entropy carbide preparation has it’s promising potential for industrialization application and the relevant basic theory for formation process required to clarify urgently. This research reports the anionic vacancy filled-up (AVF) mechanism during the formation of (Ti0.2V0.2Nb0.2Ta0.2W0.2)Cx high-entropy carbide powder by predictions of first-principles calculations, thermodynamic phase diagram calculations and verification by experimental preparation and characterization. The mechanism demonstrated that the rock-salt carbide matrix with superfluous anionic vacancy was formed firstly and the residual carbon substance continuously occupied the vacancies to an equilibrium state. The origin of the equilibrium anionic vacancy concentration was revealed from the perspective of the energy variation.

CuMgAl-layered double hydroxide activating peroxydisulfate for efficient degradation of norfloxacin in sludge anaerobic digestion liquor

Norfloxacin (NOFX) in the sludge anaerobic digestion liquor (ADL) should be removed before returning to the mainstream wastewater biological treatment system. In this study, CuMgAl-layered double hydroxide (LDH) activating peroxydisulfate (PDS) for NOFX degradation was conducted. Research results indicated that reaction temperature, CuMgAl-LDH dosage and inorganic anions content in the wastewater all showed significant influences on NOFX degradation. Mechanisms analysis confirmed that Cu(I)-Cu(II) redox cycle led to PDS activation, and SO4−, OH as well as 1O2 made primary contribution to NOFX degradation. CuMgAl-LDH stability and reusability as well as possible degradation pathway of NOFX were systematically investigated. In view of ADL characteristic, the optimal condition for NOFX degradation was determined as initial pH of 7, 35 °C, 0.5 g/L CuMgAl-LDH, 0.5 mmol/L PDS and removing carbonate and phosphate from ADL, which could achieve 67 % of degradation rate within 10 h. What's more, the ecotoxicity of NOFX and its main degradation products was assessed by ECOSAR prediction. This study provided primary guideline of copper-based LDH/PDS system for antibiotics removal in real wastewater matrixes.

Membrane transport of rare earth metal ions N, N’-bisdioctylphosphorylmethyl-1,4-diaminobutane by the active transport mechanism

The method of membrane extraction for rare earth elements (REE) using the carrier N, N’-bisdioctylphosphorylmethyl-1,4-diaminobutane (DPDA-8) ions, leveraging an active transport mechanism, has been optimized. The distribution of DPDA-8 within the membrane pores was confirmed using scanning electron microscopy (SEM). Both light and heavy REE extractions from a simulated solution using DPDA-8 and trioctylphosphine oxide (TOPO) in 1,2-dichlorobenzene were explored. The influence of feed solution pH, carrier and anion concentration, supported liquid membrane (SLM) type and stability, and cell temperature, among other parameters, were meticulously examined. The results indicate a decrease in permeability with a decrease in feed solution pH attributed to competitive acid transport through the membrane. Additionally, the formation of H-complexes between carriers and perchloric or phosphoric acids was investigated using Fourier Transform Infrared (FTIR) spectroscopy and X-ray diffraction (XRD) techniques. Changes in the stretching bands of amino and phosphine oxide groups in DPDA-8 were monitored and characterized. XRD analysis of the crystal structures of salts DPDA-6·ClO4 and DPDA-12·H2PO4 revealed a two-dimensional layered supramolecular organization with varying anion positions relative to hydrophobic fragments. The DPDA-8 carrier demonstrated significantly higher permeability values compared to TOPO, with differences in permeability exceeding twofold for certain metals. FTIR spectroscopy identified the main coordination centers of DPDA-8 during the liquid–liquid extraction of specific REEs.

МИКРОВОДОРОСЛИ ХЛОРЕЛЛА ДЛЯ ОЧИСТКИ СТОКОВ В СЕЛЬСКОМ ХОЗЯЙСТВЕ

A promising way to solve current problems of energy saving and reducing environmental pollution may be the use of microalgae. These simple microorganisms are capable of purifying contaminated wastewater in agriculture. Wastewater contains nitrogen, phosphorus, sulfate and other contaminants. In order to optimize the technology of obtaining biodiesel fuel from lipid components in the conditions of small agricultural producers, the possibility of using Chlorella vulgaris in cleaning from ammonium ions and phosphate ions was studied. Chlorella was cultivated in a photobioreactor on a standard Tamiya medium and wastewater for 10 days at a temperature of 30 ° C and an illumination of 14 kLx in the red (620-740 nm), blue (430-500 nm) and green (500-565 nm) wavelength ranges. The filtrate of the microalgae suspension was collected over several days and assessed for the content of phosphate and nitrate ions using a photometric method. The greatest increase was observed with illumination in the red range (2 times higher), the minimum value in the green. The studies found that cell growth occurs both in synthetic, standard nutrient media and in wastewater, the latter being more costeffective. It was found that when adding chlorella to wastewater, the maximum decrease in the content of ammonium ions and phosphate anions is observed on the 6-7th day (by 19-59% and 5-29%, respectively), which is most likely due to the use of these elements by microalgae for nutrition and maintenance of life. A scheme for growing Chlorella vulgaris on wastewater for further production of lipid components of biodiesel fuel is proposed.

Photo-assisted oxygen-rich vacancy copper oxide catalyst to activate peroxymonosulfate (PMS) for efficient degradation of fulvic acid

In this study, novel copper oxide particles-activated peroxymonosulfate (CuO-S/PMS/UV) were employed to degrade fulvic acid(FA). Under the optimal treatment condition, the FA removal of the CuO-S/PMS/UV process was up to 97.74%. The removal rates of SUVA254, UVA365 UVA280 UVA463 and TOC within 40 min in the UV/CuO-S/PMS process were 23.4%, 95.6%, 63.2%, 100% and 40.8% respectively. The three-dimensional fluorescence spectrum analysis of FA during the degradation process revealed the disappearance of FA-associated functional structures. Furthermore, the impact of common anions in the water matrix on the degradation process was investigated, demonstrating that the system remains effective containing low concentrations of anions. Subsequently, mechanism studying showed that SO4•−, 1O2, h+, and •OH species were primarily involved in the degradation of FA, while O2•− has a limited effect in the degradation process. This study can provide valuable insights for the degradation of humic pollutants in the water environment.

The role of carboxyl and cationic groups in low-level cationised cellulose fibres investigated by zeta potential and sorption studies

The anionic nature of both cellulose fibres and reactive dyes prevents substantial exhaustion of dye from the dyebath, which is at neutral pH before alkali is added to initiate dye fixation. Conventionally, salt is added to minimize the electrostatic repulsions that interfere with dye sorption, but that increases salt loads in effluents. An alternative is to affix cationic agents on the cellulose to overcome the inherent anionic charge, but that has generally been observed to result in uneven dye sorption. The focus of investigations in this work is to examine the influence of the ratio of charges on cellulose (of affixed cationic charges to inherent anionic charges) on the extents and evenness of dye sorption. The cationisation agent 3-chloro-2-hydroxypropyl-N,N,N-trimethylammonium chloride (CHPTAC) was grafted on loose viscose fibres to yield 12 to 185 mmol kg−1 cationic group content on the fibre that exhibited an inherent carboxyl group content of 68 mmol kg−1. Three different dyes (of varying molecular sizes and anionic group content) were employed for examination of sorption profiles. The results from both zeta potential measurements and dye sorption profiles showed evidence of limited dye uptake until the cationic group content in fibres exceeded that of the inherent carboxyl groups. Thereafter, an uptick in dye sorption was observed, with dye sorption levels increasing with rise in degree of cationisation. There were differences between the dyes in their degrees of sorption, which appear correlated with their molecular sizes.

Assessment of the environmental impacts of utilizing coal ashes and OPC for soil stabilization applications: Leachate analysis in response to rainfall interaction

The construction industry is a leading sector for coal ashes utilization, including in cement manufacturing and soil stabilization applications. In soil stabilization, coal ashes, alongside Ordinary Portland Cement (OPC), are the most commonly used materials. However, the environmental impact of coal ashes, particularly the leaching of heavy metals from stabilized soil when exposed to rainfall, remains underexplored. There is a notable gap in assessing the environmental impacts of this utilization, particularly when the stabilized soil interacts with rainfall in real-world scenarios. Therefore, this study aimed to contribute to filling this gap. Accordingly, in this study, peat soil was stabilized by using fly ash, bottom ash, and OPC. The characterization of soil mixture materials, including physicochemical and engineering properties, was established and studied first. Following the environmental impact, simulations were conducted using a column to study soil leachate under different conditions and seasons (dry and wet) in response to its interaction with rainfall. The leachate was analyzed using Inductively Coupled Plasma Mass Spectrometry (ICP-MS) to measure the concentrations of heavy metals, including copper (Cu), aluminum (Al), manganese (Mn), iron (Fe), and zinc (Zn). Additionally, Ion Chromatography (IC) was employed to determine the concentrations of major anions, including fluoride (F⁻), chloride (Cl⁻), nitrate (NO₃⁻), phosphate (PO₄³⁻), and sulfate (SO₄²⁻). The findings revealed the complex interaction of the chemical stabilization processes and environmental factors with the leaching behavior of heavy metals and anions, highlighting the significant impact of stabilization on leaching patterns. To conclude, this study provides a valuable contribution to understanding the environmental and engineering implications of utilizing coal ashes in soil stabilization.

Multiple Roles of Anions on the Degradation Efficiency and Mineralization Pathway of Recalcitrant Acetaldehyde by Vacuum Ultraviolet (185 nm) Oxidation.

Vacuum-UV (185 nm, VUV) is widely applied to polish reverse osmosis permeate (ROP), such as the production of electronics-grade ultrapure water. In this study, the VUV oxidation of acetaldehyde, a common carbonyl in ROP, was found to be influenced by anions even at low concentrations. Interestingly, the influencing extent and mechanism varied depending on the anions. Bicarbonate minimally affected the VUV-photon absorption and •OH consumption, but at 5000 μg-C·L-1, it decreased the degradation of acetaldehyde by 58.7% possibly by scavenging organic radicals or other radical chain reactions. Nitrate strongly competed for VUV-photon absorption and •OH scavenging through the formation of nitrite, and at 500 μg-N·L-1, it decreased the removal rate of acetaldehyde degradation by 71.2% and the mineralization rate of dissolved organic carbon by 53.4%. Chloride competed for VUV-photon absorption and also generated reactive chlorine species, which did not affect acetaldehyde degradation but influenced the formation of organic byproducts. The radical chain reactions or activation of anions under VUV irradiation could compensate for the decrease in oxidation performance and need further investigation. In real ROPs, the VUV oxidation of acetaldehyde remained efficient, but mineralization was hindered due to nitrate and chloride anions. This study deepens the understanding of the photochemistry and feasibility of VUV in water with low concentrations of anions.

Catalyst-Free Transformation of Carbon Dioxide to Small Organic Compounds in Water Microdroplets Nebulized by Different Gases.

A straightforward nebulized spray system is designed to explore the hydrogenation of carbon dioxide (CO2) within water microdroplets surrounded by different gases such as carbon dioxide, nitrogen, oxygen, and compressed air. The collected droplets are analyzed using water-suppressed nuclear magnetic resonance (NMR). Formate anion (HCOO-), acetate anion (CH3COO-), ethylene glycol (HOCH2CH2OH), and methane (CH4) are detected when water is nebulized. This pattern persisted when the water is saturated with CO2, indicating that CO2 in the nebulizing gas triggers the formation of these small organics. In a pure CO2 atmosphere, the formate anion concentration is determined to be ≈70µm, referenced to dimethyl sulfoxide, which has been introduced as an internal standard in the collected water droplets. This study highlights the power of water microdroplets to initiate unexpected chemistry for the transformation of CO2 to small organic compounds.

Chloride Adsorption on Au (111) Electrodes

There are still numerous open questions with regards to adsorption phenomena and partial charge transfer at electrode interfaces. The dynamic nature electrode structure and adsorbate ordering makes an analysis solely based on thermodynamic considerations limited. Here we present recently collected data with such an analysis, using different concentrations of chloride anions in both acidic and neutral electrolytes, for well-defined Au (111) electrodes. Cyclic voltammograms and charge density data is obtained. Then the electrocapillary equation: "-dγ = σMdE + ΓCl-RTdln(cKCl)" is used to get the relative interfacial tension plot and later the electrosorption valency. In the future we will improve on this by more accurately placing the PZC of charge density measurements, using laser induced temperature jump transients and combining our interpretation with state-of-the-art molecular-dynamics using ground state machine learned potentials. Figure 1

Salicylic acid improves chilling tolerance via CsNPR1-CsICE1 interaction in grafted cucumbers.

Salicylic acid (SA) plays a role in the regulation of grafting-induced cold tolerance. However, the molecular mechanism behind it is still unknown. Here, we established that the phenylalanine ammonia-lyase (PAL) pathway-dependent elevate in SA content in grafted cucumber leaves was not only synthesized in the leaves but also transported from the roots under chilling stress. RNAi-CsPAL with low SA content as rootstock reduced SA accumulation in grafted seedling leaves while decreasing rootstock-induced cold tolerance, as evidenced by higher electrolyte leakage (EL), hydrogen peroxide (H2O2), and superoxide anion (O2 ·-) contents and lower expression of cold-responsive genes (CsICE1, CsDREB1A, CsDREB1B, and CsCOR47), whereas OE-CsPAL with high SA content as rootstock improved the cold tolerance of grafted plants in comparison with the wild type (WT). In addition, CsNPR1 was significantly upregulated in grafted cucumber under chilling stress, with exogenous and endogenous overexpressed SA inducing its transcriptional expression and protein stability, which exhibited higher expression in grafted plants than in self-root plants. While CsNPR1-overexpression (OE-CsNPR1) seedlings as scions were more tolerant to chilling stress than WT seedlings, CsNPR1-suppression (Anti-CsNPR1) seedlings as scions were more vulnerable to chilling stress. Notably, CsNPR1-CsICE1 interactions alleviated ROS accumulation and activated the expression of CsDREB1A, CsDREB1B, CsCOR47, CsCOR15, CsCOR413, and CsKIN1 to enhance SA-mediated chilling tolerance in grafted cucumber. Overall, our findings reveal that SA enhances chilling tolerance in grafted cucumbers via the model of the CsNPR1-CsICE1 transcriptional regulatory cascade.

Efficient photocatalytic degradation of diclofenac drug using the Zn1-x-yPrxAlyO photocatalyst under UV light irradiation.

Herein, we report the efficient photocatalytic degradation of the diclofenac drug using the Zn1-x-yPrxAlyO photocatalyst [x, y] = (0.00, 0.00), (0.03, 0.01), (0.03,0.03) under UV light irradiation. The analysis of the structure reveals that the Pr3+ and Al3+ cations insertion into the ZnO lattice leads to a decrease in the lattice constant (a and c), Zn-O bond length, strain lattice, and crystallite size. These alterations are linked to the high degree of atomic disorder triggered by the dopants, which produce stress and strain in the ZnO structure. The Raman measurements confirmed the structural phase and showed changes in the position and intensity of the E2High mode, associated with oxygen vibrations and material crystallinity. The presence of the dopants reduces the concentration of VZn and VO++ type defects while increasing the levels of VO, VO+, and Oi defects, as observed from the fitting of the Photoluminescence spectra. Furthermore, it was noted that de Pr3+ and Al3+ cations insertion into ZnO increases the optical band gap, which is associated with the Moss-Burstein effect. The micrograph images show that dopants transform the morphology from quasi-spherical particles to irregular cluster structures. The textural analysis indicated that an increase in the concentration of Al3+ in the ZnO lattice led to a higher surface area, likely enhancing photocatalytic activity. The sample containing 3% Pr3+ and 3% Al3+ showed the highest photocatalytic activity and degraded up to 71.42% of diclofenac. In addition, experiments with scavengers revealed that hydroxyl radicals are the main species involved in the drug's photodegradation mechanism. Finally, the Zn1-x-yPrxAlyO compound is highly recyclable and stable.

Melatonin Priming Promotes Crop Seed Germination and Seedling Establishment Under Flooding Stress by Mediating ABA, GA, and ROS Cascades.

Both seed germination and subsequent seedling establishment are key checkpoints during the life cycle of seed plants, yet flooding stress markedly inhibits both processes, leading to economic losses from agricultural production. Here, we report that melatonin (MT) seed priming treatment enhances the performance of seeds from several crops, including soybean, wheat, maize, and alfalfa, under flooding stress. Transcriptome analysis revealed that MT priming promotes seed germination and seedling establishment associated with changes in abscisic acid (ABA), gibberellin (GA), and reactive oxygen species (ROS) biosynthesis and signaling pathways. Real-time quantitative RT-PCR (qRT-PCR) analysis confirmed that MT priming increases the expression levels of GA biosynthesis genes, ABA catabolism genes, and ROS biosynthesis genes while decreasing the expression of positive ABA regulatory genes. Further, measurements of ABA and GA concentrations are consistent with these trends. Following MT priming, quantification of ROS metabolism-related enzyme activities and the concentrations of H2O2 and superoxide anions (O2 -) after MT priming were consistent with the results of transcriptome analysis and qRT-PCR. Finally, exogenous application of GA, fluridone (an ABA biosynthesis inhibitor), or H2O2 partially rescued the poor germination of non-primed seeds under flooding stress. Collectively, this study uncovers the application and molecular mechanisms underlying MT priming in modulating crop seed vigor under flooding stress.

Assessment of metals and anions in tap, river, wastewater, and sludge: comparison of hotplate- and microwave-assisted digestion

In this study, the analysis of metals in tap, river, wastewater, and sludge samples was conducted using ICP−OES after hotplate- or microwave-assisted digestion. Both digestion methods produced a good degree of accuracy, indicating their suitability for the analysis of the studied metals in water samples. From method development studies, 100 mL of HNO3 was found to be the optimum sample volume and acid type for digestion. The average concentrations obtained ranged from 4.9–410.8 µg/L, 5.9–465.0 µg/L, 3.6–425.4 µg/L, 16.1–647 µg/L and 9.7–784 µg/L in tap water, river, influent, effluent, and sludge samples, respectively. All metals were below their maximum permissible limits, with the exception of Mn in all sludge samples and Pb in all tap water, Umhlathuzana River, and Northern Works influent samples. Comparable recoveries and metal concentrations were obtained by microwave and hotplate methods, suggesting that the cheaper hotplate method can be used as an effective digestion method for daily analysis. Common anion concentrations obtained ranged from 0.03–23.5 mg/L, 0.02–3 064.67 mg/L, and 0.32–175.67 mg/L for tap, river, and wastewater samples, respectively. The anion concentrations were found to be below the maximum acceptable limits indicating no negative health effect on human and aquatic life, with the exception of Cl− and SO42− in Amanzimtoti and Northern River water, respectively.

Added Anions to Zirconia as a Ceramic Material

Abstract: Anodic polarization of zircaloy-4 has been studied at a constant current density of 8 mA.cm2 and at room temperature. Thickness estimates were made from capacitance and faradaic data. Anodic polarized coloured zirconia film was observed by the addition of millimolar concentration of anions (Cl¯). By the addition of chloride ions to the oxalic acid dihydrate was better improvement in the anodization rate, faradaic efficiency field strength zirconia ceramic is recorded for exhibiting enhanced mechanical properties for manufacture of medical devices as well as biocompatability and have biological properties also. In future research needed to validate zirconia ceramic applications

The application of PAHs-Degrading Pseudomonas aeruginosa to mitigate the phytotoxic impact of pyrene on barley (Hordeum vulgare L.) and broad bean (Vicia faba L.) plants

Mitigating the negative impacts of polycyclic aromatic hydrocarbons (PAHs) is an urgent need due to their toxicity and persistence in the environment. This study investigated the use of Pseudomonas aeruginosa ASU-B6 to detoxify pyrene (PY). The bacterium P. aeruginosa ASU-B6 is capable of degrading PY by 92% as a sole carbon source after 15 days of incubation with phthalate being the major metabolic product. In this regard, the impact of pyrene (PY), P. aeruginosa ASU-B6 (ASU-B6), the bacterial strain combined with pyrene (ASU-B6/PY) and the metabolites produced after pyrene degradation (PY-metabolites) on the germination and physiological attributes of Hordeum vulgare and Vicia faba seedlings were studied. A single application of PY or ASU-B6 showed a toxic effect on the germination of both tested seeds. Interestingly, broad bean seedlings exhibited less sensitivity to PY stress in terms of growth and metabolism compared to barley. Notably, ASU-B6 inhibited fresh and dry weight of shoots and roots of barley and, to a lesser extent, reduced the germination of broad beans compared to the control. However, the combined PY-metabolites and ASU-B6/PY showed a mutual ameliorative effect on seedlings growth, alleviating the phytotoxic impact of each component. Pyrene reduced the virulence of ASU-B6 by inhibiting the production of pyocyanin pigment, while bacteria ameliorated pyrene toxicity through its degradation. Heatmap and principal component analyses highlighted that increasing the contents of hydrogen peroxide, superoxide anion, hydroxyl radical, and lipid peroxidation positively correlated to the toxicity of PY or ASU-B6. However, improving the antioxidant system which buffers the oxidative stress induced by different combinations of PY and ASU-B6 enhanced the growth of germinated seedlings corresponding to PY or ASU-B6. This study reflected the role of ASU-B6 in ameliorating PY-phytotoxicity. In addition, the application of ASU-B6 strain is recommended as a prospective candidate for remediation of PAHs-contaminated environment with a positive impact on the plant growth and metabolic products.