Effect of gradual increase of salt on performance and microbial community during granulation process.

Salinity was considered to have effects on the characteristics, performance microbial communities of aerobic granular sludge. This study investigated granulation process with gradual increase of salt under different gradients. Two identical sequencing batch reactors were operated, while the influent of Ra and Rb was subjected to stepwise increments of NaCl concentrations (0-4 g/L and 0-10 g/L). The presence of filamentous bacteria may contribute to granules formed under lower salinity conditions, potentially leading to granules fragmentation. Excellent removal efficiency achieved in both reactors although there was a small accumulation of nitrite in Rb at later stages. The removal efficiencies of chemical oxygen demand (COD), total nitrogen (TN), and total phosphorus (TP) in Ra were 95.31%, 93.70% and 88.66%, while the corresponding removal efficiencies in Rb were 94.19%, 89.79% and 80.74%. Salinity stimulated extracellular polymeric substances (EPS) secretion and enriched EPS producing bacteria to help maintain the integrity and stability of the aerobic granules. Heterotrophic nitrifying bacteria were responsible for NH4+-N and NO2--N oxidation of salinity systems and large number of denitrifying bacteria were detected, which ensure the high removal efficiency of TN in the systems.

Comprehensive comparison of water quality risk and microbial ecology between new and old cast iron pipe distribution systems.

The effects of cast iron pipe corrosion on water quality risk and microbial ecology in drinking water distribution systems (DWDSs) were investigated. It was found that trihalomethane (THMs) concentration and antibiotic resistance genes (ARGs) increased sharply in the old DWDSs. Under the same residual chlorine concentration conditions, the adenosine triphosphate concentration in the effluent of old DWDSs (Eff-old) was significantly higher than that in the effluent of new DWDSs. Moreover, stronger bioflocculation ability and weaker hydrophobicity coexisted in the extracellular polymeric substances of Eff-old, meanwhile, iron particles could be well inserted into the structure of the biofilms to enhance the mechanical strength and stability of the biofilms, hence enhancing the formation of THMs. Old DWDSs significantly influenced the microbial community of bulk water and triggered stronger microbial antioxidant systems response, resulting in higher ARGs abundance. Corroded cast iron pipes induced a unique interaction system of biofilms, chlorine, and corrosion products. Therefore, as the age of cast iron pipes increases, the fluctuation of water quality and microbial ecology should be paid more attention to maintain the safety of tap water.

Preferential adsorption of medium molecular weight proteins in extracellular polymeric substance alleviates toxicity of small-sized microplastics to Skeletonema costatum.

Extracellular polymeric substances (EPS) secreted by organisms tend to encapsulate microplastics (MPs), forming an EPS-corona that affects the fate of MPs in marine ecosystems. However, the impact of the EPS-corona on the biotoxicity of MPs to marine organisms remains poorly understood. Herein, the effect of the EPS-corona on the toxicity of polystyrene (PS) MPs of different sizes (0.1 and 1 µm) to Skeletonema costatum (S. costatum) was investigated. The preferential adsorption of medium molecule weight (∼55 kDa) proteins onto PS MPs mainly contributed to the EPS-corona formation, decreasing the surface charge negativity of small-sized PS MPs (0.1 µm) by 72.4 %. Nitrogen (N) and oxygen (O) moieties in polysaccharides and proteins were identified as the preferential adsorption sites in the EPS-PS MPs interaction. Density functional theory (DFT) calculations confirmed the nuclear magnetic resonance spectroscopy (NMR) results, revealing that the binding mode between EPS and PS MPs was mainly hydrogen bonding. In addition, EPS-corona increased the cell density of S. costatum by 35.5-36.0 % when exposed to small-sized PS MPs (0.1 µm, 25-50 mg/L). These findings provide new insights into how EPS-corona affects the environmental fate and ecological risks associated with micro- and nano-sized plastics in marine ecosystems.

Cyanobacterial and microalgae polymers: antiviral activity and applications.

At the end of 2019, the world witnessed the beginning of the COVID-19 pandemic. As an aggressive viral infection, the entire world remained attentive to new discoveries about the SARS-CoV-2 virus and its effects in the human body. The search for new antivirals capable of preventing and/or controlling the infection became one of the main goals of research during this time. New biocompounds from marine sources, especially microalgae and cyanobacteria, with pharmacological benefits, such as anticoagulant, anti-inflammatory and antiviral attracted particular interest. Polysaccharides (PS) and extracellular polymeric substances (EPS), especially those containing sulfated groups in their structure, have potential antiviral activity against several types of viruses including HIV-1, herpes simplex virus type 1, and SARS-CoV-2. We review the main characteristics of PS and EPS with antiviral activity, the mechanisms of action, and the different extraction methodologies from microalgae and cyanobacteria biomass.

Evaluating the role of dissolved silica for dolomite formation in evaporitic environments: Insights from prolonged laboratory experiments.

The mineral Dolomite CaMg(CO3)2 is a common constituent of sedimentary rocks. Despite centuries of research, the mechanism of its formation remains elusive and debated. Recent studies have shown the presence of silica in solution promote the incorporation of Mg into the carbonate mineral, forming crystal phases that may be precursors to dolomite. The goal of this study was to evaluate with laboratory experiments whether dissolved silica may play a role for dolomite formation in sabkha (i.e., salt flats) environments. Several models for dolomite formation are based on the studies of sabkhas, which are often cited as modern analogue for ancient dolomite-rich sedimentary sequences. We performed long-incubation time (i.e., up to 600 days) laboratory precipitation experiments at 30 °C with solution mimicking the sabkha pore waters (characterized by a salinity of 23 % and Mg: Ca ratio of 15) to which we added different concentrations of Si. Our results revealed a positive of 24 h (p-value <0.001) between Si concentration in solution and the mol% Mg of the carbonate minerals forming in the experiment. With 2 mM of Si, the bulk precipitate was comprised of 90 % stoichiometric dolomite with possible signs or ordering. Moreover, the rhombohedral morphology of the crystals is analogue to that of natural dolomite previously described from sabkha sediments. Our results suggest that dissolved Si may play an important role for dolomite formation in evaporitic environments.

Attitudes of community pharmacists towards extending their professional roles in Oman.

Background: Over the last few decades, the pharmacy profession has witnessed a substantial evolution accompanied by the developing role of community pharmacists (CPs). Evidence indicates that extending the role of CPs contributes to fostering public health outcomes. However, in many countries, their role is still underused. To extend the role of CPs in Oman, it is crucial to understand their perception and determine the influences. Aim: This study determines the willingness of CPs in Oman to extend their role and assess their perception towards barriers. Method: A cross-sectional study was conducted across Oman using an online self-administered survey targeting CPs working in the private sector. Result: Generally, respondents welcomed broadening their professional role. However, among the top perceived barriers were shortage of staff, insufficient training, lack of interconnection between CPs and physicians, and regulation constraints. Different socio-demographic characteristics of respondents showed a noticeable impact on their responses. Conclusion: CPs welcomed extending their role. However, several obstacles were raised that need to be tackled to enable CPs to advance their role.

Reduction of benztropine use duration in acute psychiatry: A quality improvement initiative.

DISCLAIMER: In an effort to expedite the publication of articles, AJHP is posting manuscripts online as soon as possible after acceptance. Accepted manuscripts have been peer-reviewed and copyedited, but are posted online before technical formatting and author proofing. These manuscripts are not the final version of record and will be replaced with the final article (formatted per AJHP style and proofed by the authors) at a later time. PURPOSE: Secondary to the risk of antipsychotic-induced acute dystonia, prophylactic use of benztropine is occasionally warranted but is recommended for no longer than 7 days after initiating an antipsychotic, correlating to the period of highest dystonia risk. Despite the associated increased anticholinergic burden, many clinicians continue to order benztropine for periods exceeding the recommended prophylactic duration. We investigated the reduction of benztropine use duration subsequent to implementation of truncated electronic entry orders to improve benztropine prescribing within an acute psychiatric facility. METHODS: Data were collected for psychiatric inpatients admitted between January and June 2020 who were prescribed scheduled benztropine. In a quality improvement initiative implemented in April 2022, electronic orders for benztropine were modified from a 180-day to a 7-day duration, with subsequent postintervention data collection. The primary outcomes included a change in the duration of benztropine use for any indication in the hospital, and a change in the percentage of patients meeting predetermined "unnecessary use" criteria. Secondary analyses included the percentage of patients with discharge prescriptions for scheduled benztropine (either for prophylaxis or for other indications) in the pre- and postintervention periods. RESULTS: 73 pre- and 77 postintervention individual patients/encounters were included. Following the intervention, in-hospital duration of benztropine use for any indication decreased from a median of 14 days to a median of 7.5 days (P < 0.05), and appropriate use increased by 92.9%. The percentage of patients with prescriptions for scheduled benztropine decreased from 67.1% in the preintervention group to 29.9% in the postintervention group. CONCLUSION: Decreased benztropine use duration, by means of truncated order entry sentences, during inpatient psychiatric admissions, appears feasible regardless of dual antipsychotic or first-generation antipsychotic use, and may reduce the rates of benztropine prescriptions written for discharge.

Development of "Intelligent particles" for the treatment of dental caries.

Dental caries is one of the most prevalent non-communicable diseases worldwide, mediated by a multispecies biofilm that consists of high levels of acidogenic bacteria which ferment sugar to acid and cause teeth demineralization. Current treatment practice remains insufficient in addressing 1) rapid clearance of therapeutic agents from the oral environment 2) destroying bacteria that contribute to the healthy oral microbiome. In addition, increasing concerns over antibiotic resistance calls for innovative alternatives. In this study, we developed a pH responsive nano-carrier for delivery of polycationic silver nanoparticles. Branched-PEI capped silver nanoparticles (BPEI-AgNPs) were encapsulated in a tannic acid - Fe (III) complex-modified poly(D,L-lactic-co-glycolic acid) (PLGA) particle (Fe(III)-TA/PLGA@BPEI-AgNPs) to enhance binding to the plaque biofilm and demonstrate "intelligence" by releasing BPEI-AgNPs under acidic conditions that promote dental caries The constructed Fe(III)-TA/PLGA@BPEI-AgNPs (intelligent particles - IPs) exhibited significant binding to an axenic S. mutans biofilm grown on hydroxyapatite. Ag+ ions were released faster from the IPs at pH 4.0 (cariogenic pH) compared to pH 7.4. The antibiofilm results indicated that IPs can significantly reduce S. mutans biofilm volume and viability under acidic conditions. Cytotoxicity on differentiated Caco-2 cells and human gingival fibroblasts indicated that IPs were not cytotoxic. These findings demonstrate great potential of IPs in the treatment of dental caries.

Deciphering Fe@C amendment on long-term anaerobic digestion of sulfate and propionate rich wastewater: Driving microbial community succession and propionate metabolism.

This study evaluated the reflection of long-term anaerobic system exposed to sulfate and propionate. Fe@C was found to efficiently mitigate anaerobic sulfate inhibition and enhance propionate degradation. With influent propionate of 12000mgCOD/L and COD/SO42- ratio of 3.0, methane productivity and sulfate removal were only 0.06 ± 0.02L/gCOD and 63 %, respectively. Fe@C helped recover methane productivity to 0.23 ± 0.03L/gCOD, and remove sulfate completely. After alleviating sulfate stress, less organic substrate was utilized to form extracellular polymeric substances for self-protection, which enhanced mass transfer in anaerobic sludge. Microbial community succession, especially for alteration of key sulfate-reducing bacteria and propionate-oxidizing bacteria, was driven by Fe@C, thus enhancing sulfate reduction and propionate degradation. Acetotrophic Methanothrix and hydrogenotrophic unclassified_f_Methanoregulaceae were enriched to promote methanogenesis. Regarding propionate metabolism, inhibited methylmalonyl-CoA degradation was a limiting step under sulfate stress, and was mitigated by Fe@C. Overall, this study provides perspective on Fe@C's future application on sulfate and propionate rich wastewater treatment.

Identification of microbial communities and multi-species biofilms contamination in seafood processing environments with different hygiene conditions.

Biofilms formed by spoilage and pathogenic bacteria increase microbial persistence, causing an adverse influence on the quality of seafood. The mono-species biofilms are widely reported, however, the contamination of multi-species biofilms and their matrix in food environments are still not fully understood. Here, we assessed the contamination of multi-species biofilms in three seafood processing environments with different hygiene levels by detecting bacterial number and three biofilm matrix components (carbohydrates, extracellular DNA (eDNA), and proteins). Samples comprising seven food matrix surfaces and eight food processing equipment surfaces were collected from two seafood processing plants (XY and XC) and one seafood market (CC). The results showed that the bacterial counts ranged from 1.89 to 4.91 CFU/cm2 and 5.68 to 9.15 BCE/cm2 in these surfaces by cultivation and real-time PCR, respectively. Six biofilm hotspots were identified, including four in CC and two in XY. Among the three processing environments, the amplicon sequence variants (ASVs) of Proteobacteria, Bacteroidetes, and Actinobacteria decreased with improved processing hygiene, while Firmicutes showed a decrease in the four most abundant phyla. The most prevalent bacteria belonged to genera Psychrobacter, Acinetobacter, and Pseudomonas, demonstrating the significant differences and alteration in bacterial community composition during different environments. From the biofilm hotspots, 15 isolates with strong biofilm forming ability were identified, including 7 Pseudomonas, 7 Acinetobacter, and 1 Psychrobacter. The Pseudomonas isolates exhibited the highest production of EPS components and three strong motilities, whose characteristics were positively correlated. Thus, this study verified the presence of multi-species biofilms in seafood processing environments, offering preliminary insights into the diversity of microbial communities during processing. It highlights potential contamination sources and emphasizes the importance of understanding biofilms composition to control biofilms formation in seafood processing environments.

Hand, foot, and mouth disease: could EPs® 7630 be a treatment option? A prospective randomized open-label multicenter clinical study.

Purpose: Hand, foot and mouth disease (HFMD) is a viral contagious disease of children caused by human enteroviruses (EVs) and coxsackieviruses (CVs). There is no specific treatment option for HFMD. EPs® 7630's anti-infective and immunomodulatory properties have previously been demonstrated in several in vitro and in vivo studies; however, the use of this herbal medicine in children with HFMD has not previously been investigated. Methods: This prospective randomized multicenter clinical study included 208 children with HFMD. The diagnosis was made by pediatricians. The patients who were within the first 48 h of symptom onset (according to the first onset of fever and skin findings) were enrolled. The study participants were assigned into 2 groups as EPs® 7630 and control groups. All patients were followed up twice more, 48 h after the first admission and on the 5th-7th day. Another phone evaluation was conducted for those with continued complaints from the previous visit. Results: The median age was 27 (12-112) months. The male-female ratio was 0.98. One hundred thirty one (63%) of 190 patients had no history of household contact. EPs® 7630 group included 94 and control group included 96 patients. A significant difference was found between the groups in terms of complaint scores at the visits made at the 48th h of the treatment and on days 5-7 (p < 0.001). The mean ± SD disease duration of EPs® 7630 users was significantly shorter 6.07 ± 0.70 days (95% CI: 5.92-6.21)] than the control group [8.58 ± 0.94 days (95% CI: 8.39-8.77)] (p < 0.001). Besides, the hospitalization rate among the EPs® 7630 users were significantly lower (p = 0.019). No side effects were observed, except for unpleasant taste, which was reported in 5 patients (EPs® 7630 group). Conclusion: Considering its efficacy and safety profile EPs® 7630 may represent a feasible herbal-based treatment option for children with HFMD. Clinical Trial Registration: ClinicalTrials.gov, identifier (NCT06353477).

A trans-acting sRNA SaaS targeting hilD, cheA and csgA to inhibit biofilm formation of S. Enteritidis.

INTRODUCTION: Salmonella Enteritidis has brought great harm to public health, animal production and food safety worldwide. The biofilm formed by Salmonella Enteritidis plays a critical role in microbial cross-contamination. Small non-coding RNAs (sRNAs) have been demonstrated to be responsible for regulating the formation of biofilm. The sRNA SaaS has been identified previously, that promotes pathogenicity by regulating invasion and virulence factors. However, whether the SaaS is implicated in regulating biofilm formation in abiotic surfaces remains unclear. OBJECTIVES: This study aimed to clarify the effect of SaaS in Salmonella Enteritidis and explore the modulatory mechanism on the biofilm formation. METHODS: Motility characteristics and total biomass of biofilm of test strains were investigated by the phenotypes in three soft agar plates and crystal violet staining in polystyrene microplates. Studies of microscopic structure and extracellular polymeric substances (EPS) of biofilm on solid surfaces were carried out using confocal laser scanning microscope (CLSM) and Raman spectra. Transcriptomics and proteomics were applied to analyze the changes of gene expression and EPS component. The RNA-protein pull-down and promoter-reporter ß-galactosidase activity assays were employed to analyze RNA binding proteins and identify target mRNAs, respectively. RESULTS: SaaS inhibits biofilm formation by repressing the adhesion potential and the secretion of EPS components. Integration of transcriptomics and proteomics analysis revealed that SaaS strengthened the expression of the flagellar synthesis system and downregulated the expression of curli amyloid fibers. Furthermore, RNA-protein pull-down interactome datasets indicated that SaaS binds to Hfq (an RNA molecular chaperone protein, known as a host factor for phage Qbeta RNA replication) uniquely among 193 candidate proteins, and promoter-reporter ß-galactosidase activity assay confirmed target mRNAs including hilD, cheA, and csgA. CONCLUSION: SaaS inhibits the properties of bacterial mobility, perturbs the secretion of EPS, and contributes to the inhibition of biofilm formation by interacting with target mRNA (hilD, cheA, and csgA) through the Hfq-mediated pathway.

4-Ethylphenyl Sulfate Detection by an Electrochemical Sensor Based on a MoS2 Nanosheet-Modified Molecularly Imprinted Biopolymer.

One of the gut-derived uremic toxins 4-ethylphenyl sulfate (4-EPS) exhibits significantly elevated plasma levels in chronic kidney diseases and autism, and its early quantification in bodily fluids is important. Therefore, the development of rapid and sensitive technologies for 4-EPS detection is of significant importance for clinical diagnosis. In the current work, the synthesis of a molecularly imprinted biopolymer (MIBP) carrying 4-EPS specific cavities only using the biopolymer polydopamine (PDA) and molybdenum disulfide (MoS2) nanosheets has been reported. The fabricated electrode was prepared using screen-printed carbon electrodes on a polyvinyl chloride substrate. The synthesized material was characterized using several techniques, and electrochemical studies were performed using cyclic voltammetry (CV) and differential pulse voltammetry (DPV) techniques. The DPV technique for the electrochemical sensing of 4-EPS using the fabricated sensor (PDA@MoS2-MIBP) determined a sensitivity of 0.012 µA/ng mL/cm2 and a limit of detection of 30 ng/mL in a broad linear range of 1-2200 ng/mL. Also, the interferent study was performed to evaluate the selectivity of the fabricated sensor along with the control and stability study. Moreover, the performance of the sensor was evaluated in the spiked urine sample, and a comparison was made with the data obtained by ultraperformance liquid chromatography-tandem mass spectroscopy.

Bacterial surface properties and transport behavior actively respond to an extracellular polymeric substance gradient in saturated porous media.

The transport and retention of bacteria in porous media, such as aquifer, are governed by the solid-liquid interface characteristics and bacterial mobility. The secretion of extracellular polymeric substance (EPS) by bacteria modifies their surface property, and thereby has effects on their adhesion to surface. The role of EPS in bacterial mobility within saturated quartz sand media is uncertain, as both promoting and inhibitory effects have been reported, and underlying mechanisms remain unclear. In this study, the effects of EPS on bacterial transport behavior and possible underlying mechanism were investigated at 4 concentrations (0 mg L-1, 50 mg L-1, 200 mg L-1 and 1000 mg L-1) using laboratory simulation experiments in conjunction with Extend Derjaguin-Landau-Verweu-Overbeek (XDLVO) modeling. The results showed that EPS facilitated bacterial mobility at all tested concentrations. It could be partially explained by the increased energy barrier between bacterial cells and quartz sand surface in the presence of EPS. The XDLVO sphere-plate model predicted that EPS induced a higher electrostatic double layer (EDL) repulsive force, Lewis acid-base (AB) and steric stabilization (ST), as well as a lower Lifshitz-van der Waals (LW) attractive force. However, at the highest EPS concentration (1000 mg L-1), the promotion of EPS on bacterial mobility weakened as a result of lower repulsive interactions between cells, which was supported by observed enhanced bacterial aggregation. Consequently, the increased aggregation led to greater bio-colloidal straining and ripening in the sand column, weakening the positive impact of EPS on bacterial transport. These findings suggested that EPS exhibited concentration-dependent effects on bacterial surface properties and transport behavior and revealed non-intuitive dual effects of EPS on those processes.

Identification of Oil-Loving Cupriavidus necator BM3-1 for Polyhydroxyalkanoate Production and Assessing Contribution of Exopolysaccharide for Vegetable Oil Utilization.

Polyhydroxyalkanoates (PHA) have received attention owing to their biodegradability and biocompatibility, with studies exploring PHA-producing bacterial strains. As vegetable oil provides carbon and monomer precursors for poly(3-hydroxybutyrate-co-3-hydroxyhexanoate) (P(3HB-co-3HHx)), oil-utilizing strains may facilitate PHA production. Herein, Cupriavidus necator BM3-1, which produces 11.1 g/L of PHB with 5% vegetable oil, was selected among various novel Cupriavidus necator strains. This strain exhibited higher preference for vegetable oils over sugars, with soybean oil and tryptone determined to be optimal sources for PHA production. BM3-1 produced 33.9 g/L of exopolysaccharides (EPS), which was three-fold higher than the amount produced by H16 (10.1 g/L). EPS exhibited 59.7% of emulsification activity (EI24), higher than that of SDS and of EPS from H16 with soybean oil. To evaluate P(3HB-co-3HHx) production from soybean oil, BM3-1 was engineered with P(3HB-co-3HHx) biosynthetic genes (phaCRa, phaARe, and phaJPa). BM3-1/pPhaCJ produced 3.5 mol% of 3HHx and 37.1 g/L PHA. BM3-1/pCB81 (phaCAJ) produced 32.8 g/L PHA, including 5.9 mol% 3HHx. Physical and thermal analyses revealed that P(3HB-co-5.9 mol% 3HHx) was better than PHB. Collectively, we identified a novel strain with high vegetable oil utilization capacity for the production of EPS, with the option to engineer the strain for P(3HB-co-3HHx).

Microalgal extracellular polymeric substances (EPS) and their roles in cultivation, biomass harvesting, and bioproducts extraction.

Microalgae extracellular polymeric substances (EPS) are complex high-molecular-weight polymers and the physicochemical properties of EPS strongly affect the core features of microalgae cultivation and resource utilization. Revealing the key roles of EPS in microalgae life-cycle processes in an interesting and novelty topic to achieve energy-efficient practical application of microalgae. This review found that EPS showed positive effect in non-gas uptake, extracellular electron transfer, toxicity resistance and heterotrophic symbiosis, but negative impact in gas transfer and light utilization during microalgae cultivation. For biomass harvesting, EPS favored biomass flocculation and large-size cell self-flocculation, but unfavored small size microalgae self-flocculation, membrane filtration, charge neutralization and biomass dewatering. During bioproducts extraction, EPS exhibited positive impact in extractant uptake, but the opposite effect in cellular membrane permeability and cell rupture. Future research on microalgal EPS were also identified, which offer suggestions for comprehensive understanding of microalgal EPS roles in various scenarios.

Characterization of the redox-active extracellular polymeric substances in an anaerobic methanotrophic consortium.

Anaerobic oxidation of methane (AOM) is a microbial process of importance in the global carbon cycle. AOM is predominantly mediated by anaerobic methanotrophic archaea (ANME), the physiology of which is still poorly understood. Here we present a new addition to the current physiological understanding of ANME by examining, for the first time, the biochemical and redox-active properties of the extracellular polymeric substances (EPS) of an ANME enrichment culture. Using a 'Candidatus Methanoperedens nitroreducens'-dominated methanotrophic consortium as the representative, we found it can produce an EPS matrix featuring a high protein-to-polysaccharide ratio of ∼8. Characterization of EPS using FTIR revealed the dominance of protein-associated amide I and amide II bands in the EPS. XPS characterization revealed the functional group of C-(O/N) from proteins accounted for 63.7% of total carbon. Heme-reactive staining and spectroscopic characterization confirmed the distribution of c-type cytochromes in this protein-dominated EPS, which potentially enabled its electroactive characteristic. Redox-active c-type cytochromes in EPS mediated the EET of 'Ca. M. nitroreducens' for the reduction of Ag+ to metallic Ag, which was confirmed by both ex-situ experiments with extracted soluble EPS and in-situ experiments with pristine EPS matrix surrounding cells. The formation of nanoparticles in the EPS matrix during in-situ extracellular Ag + reduction resulted in a relatively lower intracellular Ag distribution fraction, beneficial for alleviating the Ag toxicity to cells. The results of this study provide the first biochemical information on EPS of anaerobic methanotrophic consortia and a new insight into its physiological role in AOM process.

Iron(III) cross-linked hydrogels based on Alteromonas macleodii Mo 169 exopolysaccharide.

Recently, polysaccharide-based hydrogels crosslinked with the trivalent iron cation have attracted interest due to their remarkable properties that include high mechanical stability, stimuli-responsiveness, and enhanced absorptivity. In this study, a Fe3+ crosslinked hydrogel was prepared using the biocompatible extracellular polysaccharide (EPS) secreted by the marine bacterium Alteromonas macleodii Mo169. Hydrogels with mechanical strengths (G') ranging from 0.3 kPa to 44.5 kPa were obtained as a result of the combination of different Fe3+ (0.05-9.95 g L-1) and EPS (0.3-1.7 %) concentrations. All the hydrogels had a water content above 98 %. Three different hydrogels, named HA, HB, and HC, were chosen for further characterization. With strength values (G') of 3.2, 28.9, and 44.5 kPa, respectively, these hydrogels might meet the strength requirements for several specific applications. Their mechanical resistance increased as higher Fe3+ and polymer concentrations were used in their preparation (the compressive hardness increased from 8.7 to 192.1 kPa for hydrogel HA and HC, respectively). In addition, a tighter mesh was noticed for HC, which was correlated to its lower swelling ratio value compared to HA and HB. Overall, this preliminary study highlighted the potential of these hydrogels for tissue engineering, drug delivery, or wound healing applications.

New insights into algal-bacterial sludge granulation based on the tightly-bound extracellular polymeric substances regulation in response to N-Methylpyrrolidone.

Algal-bacterial granular sludge (ABGS) system is promising in wastewater treatment for its potential in energy-neutrality and carbon-neutrality. However, traditional cultivation of ABGS poses significant challenges attributable to its long start-up period and high energy consumption. Extracellular polymeric substances (EPS), which could be stimulated as a self-defense strategy in cells under toxic contaminants stress, has been considered to contribute to the ABGS granulation process. In this study, photogranulation of ABGS by EPS regulation in response to varying loading rates of N-Methylpyrrolidone (NMP) was investigated for the first time. The results indicated the formation of ABGS with a maximum average diameter of ∼3.3 mm and an exceptionally low SVI5 value of 67 ± 2 mL g-1 under an NMP loading rate of 125 mg L-1 d-1, thereby demonstrating outstanding settleability. Besides, almost complete removal of 300 mg L-1 NMP could be achieved at hydraulic retention time of 48 h, accompanied by chemical oxygen demand (COD) and total nitrogen (TN) removal efficiencies higher than 90 % and 70 %, respectively. Moreover, possible degradation pathway and metabolism mechanism in the ABGS system for enhanced removal of NMP and nitrogen were proposed. In this ABGS system, the mycelium with network structure constituted by filamentous microorganisms was a prerequisite for photogranulation, instead of necessarily leading to granulation. Stress of 100-150 mg L-1 d-1 NMP loading rate stimulated tightly-bound EPS (TB-EPS) variation, resulting in rapid photogranulation. The crucial role of TB-EPS was revealed with the involved mechanisms being clarified. This study provides a novel insight into ABGS development based on the TB-EPS regulation by NMP, which is significant for achieving the manipulation of photogranules.

The deciphering of microplastics-derived fluorescent dissolved organic matter in urban lakes, canals, and rivers using parallel factor analysis modeling and mimic experiment.

The aim of the study is to investigate the leaching of fluorescent dissolved organic matter (fDOM) from microplastics. In addition, this study identifies the connection between fDOM and microplastics in the aquatic environment. Three-dimensional excitation-emission matrix identified five fluorophores, that is, peak A, M, T, Tuv, and Wuv, and the parallel factor analysis modeling identified five components, that is, tryptophan-like, p-hydroxy acetophenone, humic acid (C-like), detergent-like, and fulvic acid (M-like) in the urban surface water. Mimic experiments using commonly used synthetic plastic (like microplastics) in Mili-Q water under solar radiation and dark environments demonstrate the release of fDOM from plastic. Two fluorophore peaks were observed at Ex/Em = 250/302 nm and Ex/Em = 260/333 nm for the expanded polystyrene plastic polymer and one fluorophore peak at Ex/Em = 260/333 nm for the low-density polyethylene. Fluorophore and component intensity exhibited notable associations with microplastics in the aquatic environment. These findings indicated that the characteristics and dynamics of fDOM in urban surface water are influenced by microplastics. PRACTITIONER POINTS: Fluorescent dissolved organic matters were identified in urban surface waters. Expanded polystyrene (EPS) had shown two fluorophores at Em/Ex = 250/302 and Em/Ex = 260/333. Low-density polyethylene (LDPE) had one fluorophore at Em/Ex = 260/333. Fluorophore and component intensity in the aquatic settings exhibited associations with microplastics.