Unveiling the impacts of salts on halotolerant bacteria during filtration: A new perspective on membrane biofouling formation in MBR treating high-saline organic wastewater.

In recent decades, membrane bioreactor (MBR) has been prevalently employed to treat high-saline organic wastewater, where the halotolerant microorganisms should be intensively utilized. However, limited works were devoted to investigating the biofouling characteristics from the perspective of the relationship between halotolerant bacteria and salts. This work filled the knowledge gap by exploring the biofouling formation mechanisms affected by high salinity. The results showed that the amount of negative charge on halotolerant bacteria surface was significantly reduced by high content of NaCl, probably leading to the obvious cell agglomeration. Despite the normal proliferation, the halotolerant bacteria still produced substantial EPS triggered by high salinity. Compared with the case of control without salt addition, the enhanced biofouling development was observed under high-saline conditions, with the fouling mechanism dramatically transformed from cake filtration to intermediate blocking. It was inferred that the halotolerant bacteria initially adhered on membrane created an extra filter layer, which contributed to the subsequent NaCl retention, resulting in the simultaneous occurrences of pore blockage and cake layer formation because of NaCl deposition both on membrane pores as well as on biofilm layer. Under high-saline environment, remarkable salt crystallization occurred on the biofilm layer, with more protein secreted by the attached halotolerant bacteria. Consequently, the potential mechanisms for the enhanced biofouling formation influenced by high salinity were proposed, which should provide new insights and enlightenments on fouling control strategies for MBR operation when treating high-saline organic wastewater.

Bound Water Enhances the Ion Selectivity of Highly Charged Polymer Membranes.

Electrochemical technologies for water treatment, resource recovery, energy generation, and energy storage rely on charged polymer membranes to selectively transport ions. With the rise of applications involving hypersaline brines, such as management of desalination brine or the recovery of ions from brines, there is an urgent need for membranes that can sustain high conductivity and selectivity under such challenging conditions. Current membranes are constrained by an inherent trade-off between conductivity and selectivity, alongside concerns regarding their high costs. Moreover, a gap in the fundamental understanding of ion transport within charged membranes at high salinities prevents the development of membranes that could meet these stringent requirements efficiently. Here, we present the synthesis of scalable, highly charged membranes that demonstrate high conductivity and selectivity while contacting 1 and 5 molal NaCl solutions. A detailed analysis of the membrane transport properties reveals that the high proportion of bound water in the membranes, enabled by the high charge content and hydrophilic structure of the polymers, enhances both the ion partitioning and diffusion selectivities of the membranes. These structure/property relationships derived from this study offer valuable guidance for designing next-generation membranes that simultaneously achieve exceptional conductivity and selectivity in high-salinity conditions.

Study on the effect of volatile organic compounds on the treatment of high-salt wastewater by low-temperature evaporation.

High-salinity wastewater, owing to its intricate composition and challenging treatment requirements, poses a significant hurdle in water environmental governance. In this study, low-temperature evaporation technology is used to tackle wastewater containing the volatile organic compound such as N,N-dimethylacetamide (DMAC). Utilisation of comprehensive approaches involving experimental testing, mathematical modelling, and Aspen Plus software simulations, The influence of DMAC on evaporation efficiency is researched through the following factors which encompassing its effects on boiling point elevation, partial molar activation energy, and the formation of by-products. Additionally, the comparation of the impact of temperature, ionic strength, intermolecular interactions on the evaporation rate and the concentration of the volatile component DMAC in the condensate is also conducted in this study. After conducting a multiple linear regression analysis of evaporation efficiency using the Statistical Product and Service Solutions (SPSS) tool, it was discovered that temperature serves as the primary determinant influencing the evaporation rate. Additionally, ionic strength impacts solution viscosity, intermolecular interactions, and saturated vapour pressure by altering the intermolecular forces, thereby indirectly influencing both the evaporation rate and the quality of condensate water. The comparative analysis of single-effect and double-effect evaporation indicates that the optimal operating condition for double-effect evaporation yields an evaporation rate of 70%, with a remarkable 88% reduction in steam consumption compared to single one. Based on heat and mass balance principles, the mathematical model for double-effect evaporation is established to offer crucial data support for practical industrial applications.

Efficient bioremediation of multiple steroid hormones by halotolerant 17ß-hydroxysteroid dehydrogenase derived from moderately halophilic Pontibacillus chungwhensis HN14.

Steroid hormones exhibit potent endocrine disrupting activity and have been shown to disrupt the equilibrium of aquatic ecosystems and pose a threat to public health through their persistent and carcinogenic effects. Pontibacillus chungwhensis HN14, a moderately halophilic bacterium with the capacity to effectively degrade various polycyclic aromatic hydrocarbons and other organic pollutants, was previously isolated. Additionally, the strain HN14 showed strong environmental adaptability under various environmental stress conditions. In this study, the steroid degradation by strain HN14 was studied for the first time. We demonstrated that strain HN14 could degrade estradiol (E2) to maintain the growth of the strain and could convert E2 to estrone. Additionally, the efficient substrate degradation efficiency of P. chungwhensis HN14 under high salinity and high substrate concentration conditions was demonstrated. Furthermore, a 17ß-hydroxysteroid dehydrogenase, 17ß-HSD(HN14), was identified in strain HN14. Comparative analysis reveals that 17ß-HSD(HN14) shares approximately 38% sequence identity with 17ß-HSDx from Rhodococcus sp. P14. In addition, 100 µg of purified 17ß-HSD(HN14) could effectively convert about 40% of 0.25 mM of E2 within 1 h period, with an enzyme activity of 17.5 U/mg, and catalyze the dehydrogenation of E2 and testosterone at the C-17 position. The characterization of purified enzyme properties reveals that 17ß-HSD(HN14) exhibits exceptional structural robustness and enzymatic efficacy even under high salinity conditions of up to 20%. Overall, this study enhances our comprehension of steroid biodegradation in strain HN14 and contributes novel ideas and theoretical underpinnings for advancing bioremediation technologies targeting steroid pollution in high-saline environments.

Study on membrane fouling mechanisms and mitigation strategies in a pilot-scale anaerobic membrane bioreactor (P-AnMBR) treating digestate.

Anaerobic Membrane Bioreactor (AnMBR) are employed for solid-liquid separation in wastewater treatment, enhancing process efficiency of digestion systems treating digestate. However, membrane fouling remains a primary challenge. This study operated a pilot-scale AnMBR (P-AnMBR) to treat high-concentration organic digestate, investigating system performance and fouling mechanisms. P-AnMBR operation reduced acid-producing bacteria and increased methane-producing bacteria on the membrane, preventing acid accumulation and ensuring stable operation. The P-AnMBR effectively removed COD and VFA, achieving removal rates of 82.3 % and 92.0 %, respectively. Higher retention of organic nitrogen and lower retention of ammonia nitrogen were observed. The membrane fouling consisted of organic substances (20.3 %), predominantly polysaccharides, and inorganic substances (79.7 %), primarily Mg ions (10.1 %) and Ca ions (4.5 %). To reduce the increased transmembrane pressure (TMP) caused by fouling (a 10.6-fold increase in filtration resistance), backwash frequency experiment was conducted. It revealed a 30-min backwash frequency minimized membrane flux decline, facilitating recovery to higher flux levels. The water produced amounted to 70.3 m³ over 52 days. The research provided theoretical guidance and practical support for engineering applications, offering practical insights for scaling up P-AnMBR.

Metabolic pathway engineering of high-salinity-induced overproduction of L-proline improves high-salinity stress tolerance of an ectoine-deficient Halomonas elongata.

Halophilic bacteria have adapted to survive in high-salinity environments by accumulating amino acids and their derivatives as organic osmolytes. L-Proline (Pro) is one such osmolyte that is also being used as a feed stimulant in the aquaculture industry. Halomonas elongata OUT30018 is a moderately halophilic bacterium that accumulates ectoine (Ect), but not Pro, as an osmolyte. Due to its ability to utilize diverse biomass-derived carbon and nitrogen sources for growth, H. elongata OUT30018 is used in this work to create a strain that overproduces Pro, which could be used as a sustainable Pro-rich feed additive. To achieve this, we replaced the coding region of H. elongata OUT30018's Ect biosynthetic operon with the artificial self-cloned proBm1AC gene cluster that encodes the Pro biosynthetic enzymes: feedback-inhibition insensitive mutant γ-glutamate kinase (γ-GKD118N/D119N), γ-glutamyl phosphate reductase, and pyrroline-5-carboxylate reductase. Additionally, the putA gene, which encodes the key enzyme of Pro catabolism, was deleted from the genome to generate H. elongata HN6. While the Ect-deficient H. elongata KA1 could not grow in minimal media containing more than 4% NaCl, H. elongata HN6 thrived in the medium containing 8% NaCl by accumulating Pro in the cell instead of Ect, reaching a concentration of 353.1 ± 40.5 µmol/g cell fresh weight, comparable to the Ect accumulated in H. elongata OUT30018 in response to salt stress. With its genetic background, H. elongata HN6 has the potential to be developed into a Pro-rich cell factory for upcycling biomass waste into single-cell feed additives, contributing to a more sustainable aquaculture industry.IMPORTANCEWe report here the evidence for de novo biosynthesis of Pro to be used as a major osmolyte in an ectoine-deficient Halomonas elongata. Remarkably, the concentration of Pro accumulated in H. elongata HN6 (∆ectABC::mCherry-proBm1AC ∆putA) is comparable to that of ectoine accumulated in H. elongata OUT30018 in response to high-salinity stress. We also found that among the two γ-glutamate kinase mutants (γ-GKD118N/D119N and γ-GKD154A/E155A) designed to resemble the two known Escherichia coli feedback-inhibition insensitive γ-GKD107N and γ-GKE143A, the γ-GKD118N/D119N mutant is the only one that became insensitive to feedback inhibition by Pro in H. elongata. As Pro is one of the essential feed additives for the poultry and aquaculture industries, the genetic makeup of the engineered H. elongata HN6 would allow for the sustainable upcycling of high-salinity waste biomass into a Pro-rich single-cell eco-feed.

Expression of an engineered salt-inducible proline biosynthetic operon in a glutamic acid over-producing mutant, Halomonas elongata GOP, confers increased proline yield due to enhanced growth under high-salinity conditions.

L-Proline (Pro) is an essential amino acid additive in livestock and aquaculture feeds. Previously, we created a Pro overproducing Halomonas elongata HN6 by introducing an engineered salt-inducible Pro biosynthetic mCherry-proBm1AC operon and deleting a putA gene that encoded a Pro catabolic enzyme in the genome of H. elongata OUT30018. Here, we report a generation of a novel Pro overproducing H. elongata HN10 strain with improved salt tolerance and higher Pro yield by expressing the mCherry-proBm1AC operon and deleting the putA gene in the genome of a spontaneous mutant H. elongata Glutamic acid Over-Producing, which overproduces glutamic acid (Glu) that is a precursor for Pro biosynthesis. The optimal salt concentration for growth of H. elongata HN10 was found to be 7% to 8% w/v NaCl, and the average Pro yield of 166 mg/L was achieved when H. elongata HN10 was cultivated in M63 minimal medium containing 4% w/v glucose and 8% w/v NaCl.

Pore-scale investigation of low-salinity water flooding in a heterogeneous-wet porous medium.

Low-Salinity Water Flooding (LSWF) is a technique aimed at modifying the interactions between rock and fluids particularly altering wettability and reducing interfacial tension (IFT). However, there remains limited understanding of how heterogeneous wettability and the presence of Initial Water Saturation (Swi) can impact the effectiveness of LSWF. This study contributes to a deeper understanding of LSWF mechanisms in the context of heterogeneous wettability, while also considering Swi. The simulations were conducted using OpenFOAM, employing a non-reactive quasi-three-phase flow solver that accounts for wettability alteration and IFT reduction during the mixing of Low-Salinity (LSW) and High-Salinity Water (HSW). A heterogeneous pore geometry is designed, and four distinct scenarios are simulated, encompassing both heterogeneous and homogeneous wettability conditions while considering the presence of Swi. These scenarios included secondary High-Salinity Water Flooding (HSWF), tertiary and secondary LSWF. Notably, the simulations reveal that secondary LSWF consistently yields the highest oil recovery across all scenarios, achieving recovery rates of up to 96.98 %. Furthermore, the presence of Swi significantly influences the performance of LSWF in terms of oil recovery, particularly in heterogeneous wettability conditions where it boosts recovery by up to 3.5 %, but in homogeneous wettability, it decreases recovery by nearly 26 %. These simulations also underscore the pivotal role played by the distribution of oil and HSW phases in profoundly affecting the outcomes of LSWF.

Offshore produced water treatment by a biofilm reactor on the seabed: The effect of temperature and matrix characteristics.

In many industrial processes a large amount of water with high salinity is co-produced whose treatment poses considerable challenges to the available technologies. The produced water (PW) from offshore operations is currently being discharged to sea without treatment for dissolved pollutants due to space limitations. A biofilter on the seabed adjacent to a production platform would negate all size restrictions, thus reducing the environmental impact of oil and gas production offshore. The moving bed biofilm reactor (MBBR) was investigated for PW treatment from different oilfields in the North Sea at 10 °C and 40 °C, corresponding to the sea and PW temperature, respectively. The six PW samples in study were characterized by high salinity and chemical oxygen demand with ecotoxic effects on marine algae S. pseudocostatum (0.4%

Salt concentration in substrate modulates the composition of bacterial and yeast microbiomes of Drosophila melanogaster.

Aim: Microbiomes influence the physiology and behavior of multicellular organisms and contribute to their adaptation to changing environmental conditions. However, yeast and bacterial microbiota have usually been studied separately; therefore, the interaction between bacterial and yeast communities in the gut of Drosophila melanogaster (D. melanogaster) is often overlooked. In this study, we investigate the correlation between bacterial and yeast communities in the gut of D. melanogaster. Methods: We studied the shifts in the joint microbiome of Drosophila melanogaster, encompassing both yeasts and bacteria, during adaptation to substrate with varying salt concentrations (0%, 2%, 4%, and 7%) using plating for both yeasts and bacteria and NGS-sequencing of variable 16S rRNA gene regions for bacteria. Results: The microbiome of flies and their substrates was gradually altered at moderate NaCl concentrations (2% and 4% compared with the 0% control) and completely transformed at high salt concentrations (7%). The relative abundance of Acetobacter, potentially beneficial to D. melanogaster, decreased as NaCl concentration increased, whereas the relative abundance of the more halotolerant lactobacilli first increased, peaking at 4% NaCl, and then declined dramatically at 7%. At this salinity level, potentially pathogenic bacteria of the genera Leuconostoc and Providencia were dominant. The yeast microbiome of D. melanogaster also undergoes significant changes with an increase in salt concentration in the substrate. The total yeast abundance undergoes nonlinear changes: it is lowest at 0% salt concentration and highest at 2%-4%. At a 7% concentration, the yeast abundance in flies and their substrate is lower than at 2%-4% but significantly higher than at 0%. Conclusions: The abundance and diversity of bacteria that are potentially beneficial to the flies decreased, while the proportion of potential pathogens, Leuconostoc and Providencia, increased with an increase in salt concentration in the substrate. In samples with a relatively high abundance and/or diversity of yeasts, the corresponding indicators for bacteria were often lowered, and vice versa. This may be due to the greater halotolerance of yeasts compared to bacteria and may also indicate antagonism between these groups of microorganisms.

Analysis of Hyperosmotic Tolerance Mechanisms in Gracilariopsis lemaneiformis Based on Weighted Co-Expression Network Analysis.

We conducted transcriptome sequencing on salt-tolerant mutants X5 and X3, and a control (Ctr) strain of Gracilariopsis lemaneiformis after treatment with artificial seawater at varying salinities (30‱, 45‱, and 60‱) for 3 weeks. Differentially expressed genes were identified and a weighted co-expression network analysis was conducted. The blue, red, and tan modules were most closely associated with salinity, while the black, cyan, light cyan, and yellow modules showed a close correlation with strain attributes. KEGG enrichment of genes from the aforementioned modules revealed that the key enrichment pathways for salinity attributes included the proteasome and carbon fixation in photosynthesis, whereas the key pathways for strain attributes consisted of lipid metabolism, oxidative phosphorylation, soluble N-ethylmaleimide-sensitive factor-activating protein receptor (SNARE) interactions in vesicular transport, and porphyrin and chlorophyll metabolism. Gene expression for the proteasome and carbon fixation in photosynthesis was higher in all strains at 60‱. In addition, gene expression in the proteasome pathway was higher in the X5-60 than Ctr-60 and X3-60. Based on the above data and relevant literature, we speculated that mutant X5 likely copes with high salt stress by upregulating genes related to lysosome and carbon fixation in photosynthesis. The proteasome may be reset to adjust the organism's proteome composition to adapt to high-salt environments, while carbon fixation may aid in maintaining material and energy metabolism for normal life activities by enhancing carbon dioxide uptake via photosynthesis. The differences between the X5-30 and Ctr-30 expression of genes involved in the synthesis of secondary metabolites, oxidative phosphorylation, and SNARE interactions in vesicular transport suggested that the X5-30 may differ from Ctr-30 in lipid metabolism, energy metabolism, and vesicular transport. Finally, among the key pathways with good correlation with salinity and strain traits, the key genes with significant correlation with salinity and strain traits were identified by correlation analysis.

Enhanced separation of monovalent and divalent ions in high salinity wastewater by selective electrodialysis: Experimental investigation and performance prediction.

To fulfill the industrial requirements of salt fractionation and recovery from saline wastewater, a two-chamber selective electrodialysis (SED) stack incorporating commercial monovalent selective anion exchange membranes was employed and investigated in this study. Three different initial concentration ratios of NaCl/Na2SO4, namely 1:1 (10 g/L:10 g/L), 3:1 (30 g/L:10 g/L), and 5:1 (50 g/L:10 g/L) were examined to simulate various scenarios of saline wastewater. The influence of applied current density on membrane selectivity and overall system efficiency was further evaluated. The results indicated that an increase in the NaCl fraction within the feed solution directly correlates with enhanced concentration and purity of Na2SO4 in the product, achieving purities exceeding 92 %. A lower current density contributed to improved concentration and purity of Na2SO4, whereas higher current densities were conducive to augmenting the concentration and purity of NaCl. Additionally, a linear correlation was observed between the volumetric water transport and NaCl migration. Through numerical simulations, the concentrations of Na2SO4 and NaCl in the effluent were predicted, facilitating a comparative analysis with the salt fractionation efficiency of commercial nanofiltration membranes. Subsequent assessments of energy consumption and current efficiency revealed that the SED system ensured high product concentration and purity at reasonably low energy consumption (0.22-0.28 kWh per kg NaCl) alongside a high current efficiency (83-89 %). These findings offer critical insights into the optimization of salt fractionation process and highlight its economic and technical feasibility for the sustainable management of industrial saline wastewater.

Influence of Organic Impurities on Fractional Crystallization of NaCl and Na2SO4 from High-Salinity Coal Chemical Wastewater: Thermodynamics and Nucleation Kinetics Analysis.

It is a valid path to realize the zero discharge of coal chemical wastewater by using the fractional crystallization method to recycle the miscellaneous salt in high-salinity wastewater. In this study, the thermodynamics and nucleation kinetics of sodium chloride (NaCl) and sodium sulfate (Na2SO4) crystallization in coal chemical wastewater were systematically studied. Through analyses of solubility, metastable zone width, and induction period, it was found that the impurity dimethoxymethane would increase the solid-liquid interface energy and critical crystal size during the nucleation of Na2SO4. Ternary phase diagrams of the pseudo-ternary Na2SO4-NaCl-H2O systems in simulated wastewater were plotted in the temperature range of 303.15 to 333.15 K, indicating that a co-ionization effect existed between NaCl and Na2SO4, and NaCl had a strong salting out effect on Na2SO4. Finally, the nucleation rate and growth rate of Na2SO4 crystals under simulated wastewater conditions were determined by the intermittent dynamic method, and the crystallization kinetic models of Na2SO4 were established. The crystallization nucleation of Na2SO4 crystals was found to be secondary nucleation controlled by surface reactions. The basic theoretical research of crystallization in this study is expected to fundamentally promote the application of fractional crystallization to realize the resource utilization of high-salinity wastewater in the coal chemical industry.

Natural-inspired hierarchic double-Janus solar evaporator for stable clean water production from high-salinity emulsions.

Interfacial solar evaporation shows great potential in clean water production, emulsions separation, and high-salinity brine treatment. However, it remains challenging for the evaporators to maintain a high evaporation rate in the high-salinity emulsions due to the co-pollution of salt and oil. Herein, we first proposed a hierarchic double-Janus solar evaporator (HDJE) with a hydrophobic salt-rejecting top layer and oil-rejecting bottom layer. Compared to the traditional one, HDJE could treat industrial high-salinity oil-in-water emulsions stably for over 70 h, with a stable average evaporation rate of 1.73 kg m-2 h-1 and a high purification efficiency of up to 99.8 % for oil and ions. It was also verified that HDJE could be used for high-efficiency purification of oily concentrated seawater outdoor. An average water production rate of 3.59 kg m-2 d-1 and a TOC removal ratio of over 98 % was obtained. In conclusion, this study provides a novel way to effectively dispose of high-salinity oily wastewater.

One electron oxidation-induced degradation of brominated flame retardants in electroactive membrane filtration system: Vital role of dichlorine radical-mediated process.

Reactive chlorine species (RCS) are inevitably generated in electrochemical oxidation process for treating high-salinity industrial wastewater, thereby resulting in the competition with coexisting hydroxyl radicals (•OH) for oxidizing recalcitrant organic compounds. Due to the low redox potentials compared to •OH, the role of RCS has been often overlooked. In this work, we developed an electroactive membrane filtration (EMF) system that had a high removal efficiency (99.1 ± 0.5 %) for tetrabromobisphenol S (TBBPS) at low energy consumption (1.45 kWh m-3). Electron spin resonance spectroscopy and molecular probing tests indicated the predominance of Cl2•-, of which steady-state concentration (2.2 ×10-10 M) was extremely higher than those of ClO• (6.7 ×10-13 M), •OH (0.95 ×10-13 M), and Cl• (2.39 ×10-15 M). The density functional theory (DFT) and intermediate product analysis highlighted that Cl2•- radicals had a higher electrophilic attack efficacy than •OH radicals for inducing changes in the electron density of the carbon atoms around phenolic hydroxyl groups, thus leading to the generation of transition state intermediates and accelerating the degradation of TBBPS. Our work demonstrates the vital role of Cl2•- radicals for pollutant degradation, highlighting the potential of this technology for cost-effective removal of recalcitrant organic compounds from water and wastewater.

Low-voltage stimulated denitrification performance of high-salinity wastewater using halotolerant microorganisms.

Nitrate is a common contaminant in high-salinity wastewater, which has adverse effects on both the environment and human health. However, conventional biological treatment exhibits poor denitrification performance due to the high-salinity shock. In this study, an innovative approach using an electrostimulating microbial reactor (EMR) was explored to address this challenge. With a low-voltage input of 1.2 V, the EMR reached nitrate removal kinetic parameter (kNO3-N) of 0.0166-0.0808 h-1 under high-salinities (1.5 %-6.5 %), which was higher than that of the microbial reactor (MR) (0.0125-0.0478 h-1). The mechanisms analysis revealed that low-voltage significantly enhanced microbial salt-in strategy and promoted the secretion of extracellular polymeric substances. Halotolerant denitrification microorganisms (Pseudomonas and Nitratireductor) were also enriched in EMR. Moreover, the EMR achieved a NO3-N removal efficiency of 73.64 % in treating high-salinity wastewater (salinity 4.69 %) over 18-cycles, whereas the MR only reached 54.67 %. In summary, this study offers an innovative solution for denitrification of high-salinity wastewater.

Overexpression of a Fragaria vesca NAM, ATAF, and CUC (NAC) Transcription Factor Gene (FvNAC29) Increases Salt and Cold Tolerance in Arabidopsis thaliana.

The NAC (NAM, ATAF1/2, CUC2) family of transcription factors (TFs) is a vital transcription factor family of plants. It controls multiple parts of plant development, tissue formation, and abiotic stress response. We cloned the FvNAC29 gene from Fragaria vesca (a diploid strawberry) for this research. There is a conserved NAM structural domain in the FvNAC29 protein. The highest homology between FvNAC29 and PaNAC1 was found by phylogenetic tree analysis. Subcellular localization revealed that FvNAC29 is localized onto the nucleus. Compared to other tissues, the expression level of FvNAC29 was higher in young leaves and roots. In addition, Arabidopsis plants overexpressing FvNAC29 had higher cold and high-salinity tolerance than the wild type (WT) and unloaded line with empty vector (UL). The proline and chlorophyll contents of transgenic Arabidopsis plants, along with the activities of the antioxidant enzymes like catalase (CAT), peroxidase (POD), and superoxide dismutase (SOD) under 200 mM NaCl treatment or -8 °C treatment, were higher than those activities of the control. Meanwhile, malondialdehyde (MDA) and the reactive oxygen species (ROS) content were higher in the WT and UL lines. FvNAC29 improves transgenic plant resistance to cold and salt stress by regulating the expression levels of AtRD29a, AtCCA1, AtP5CS1, and AtSnRK2.4. It also improves the potential to tolerate cold stress by positively regulating the expression levels of AtCBF1, AtCBF4, AtCOR15a, and AtCOR47. These findings suggest that FvNAC29 may be related to the processes and the molecular mechanisms of F. vesca response to high-salinity stress and LT stress, providing a comprehensive understanding of the NAC TFs.

Internal Electric Field Facilitates Facet-Dependent Photocatalytic Cl- Utilization on BiOCl in High-Salinity Wastewater for Ammonium Removal.

High Cl- concentration in saline wastewater (e.g., landfill leachate) limits wastewater purification. Catalytic Cl- conversion into reactive chlorine species (RCS) arises as a sustainable strategy, making the salinity profitable for efficient wastewater treatment. Herein, aiming to reveal the structure-property relationship in Cl- utilization, bismuth oxychloride (BiOCl) photocatalysts with coexposed {001} and {110} facets are synthesized. With an increasing {001} ratio, the RCS production efficiency increases from 75.64 to 96.89 µg L-1 min-1. Mechanism investigation demonstrates the fast release of lattice Cl- as an RCS and the compensation of ambient Cl-. Correlation analysis between the internal electric field (IEF, parallel to [001]) and normalized efficiency on {110} (kRCS/S{110}, perpendicular to [001]) displays a coefficient of 0.86, validating that the promoted carrier dynamics eventually affects Cl- conversion on the open layered structure. The BiOCl photocatalyst is well behaved in ammonium (NH4+-N) degradation ranging from 20 to 800 mg N L-1 with different chlorinity (3-12 g L-1 NaCl). The sustainable Cl- conversion into RCS also realizes 85.4% of NH4+-N removal in the treatment of realistic landfill leachate (662 mg of N L-1 NH4+-N). The structure-property relationship provides insights into the design of efficient catalysts for environment remediation using ambient Cl-.

Glycine betaine modulates extracellular polymeric substances to enhance microbial salinity tolerance.

High salinity inhibits microbial activity in the bioremediation of saline wastewater. To alleviate osmotic stress, glycine betaine (GB), an osmoprotectant, is added to enhance the secretion of extracellular polymeric substances (EPS). These EPS are pivotal in withstanding environmental stressors, yet the intricate interplay between GB supplementation and microbial responses through EPS modifications-encompassing composition, molecular architecture, and electrochemical features-remains elusive in hypersaline conditions. Here we show microbial strategies for salinity endurance by investigating the impact of GB on the dynamic alterations of EPS properties. Our findings reveal that GB supplementation at 3.5% salinity elevates the total EPS (T-EPS) content from 12.50 ± 0.05 to 24.58 ± 0.96 mg per g dry cell weight. The observed shift in zeta potential from -28.95 to -6.25 mV at 0% and 3.5% salinity, respectively, with GB treatment, indicates a reduction in electrostatic repulsion and compaction. Notably, the EPS protein secondary structure transition from ß-sheet to α-helix, with GB addition, signifies a more compact protein configuration, less susceptible to salinity fluctuations. Electrochemical analyses, including cyclic voltammetry (CV) and differential pulse voltammetry (DPV), reveal GB's role in promoting the release of exogenous electron shuttles, such as flavins and c-type cytochromes (c-Cyts). The enhancement in DPV peak areas (QDPV) with GB addition implies an increase in available extracellular electron transfer sites. This investigation advances our comprehension of microbial adaptation mechanisms to salinity through EPS modifications facilitated by GB in saline habitats.