Hydrolysis Of Polymers Research Articles

Solventless Dual-Cure Liquid Resins Via Circular Use of Phthalic Anhydride for Recyclable Composite Applications.

Fiber-reinforced composites (FRCs) possess a remarkable strength-to-weight ratio, making them ideal light-weighing alternative materials of metals used in automotive, aerospace, and outdoor equipment applications, but their recycling is challenging. Chemically recyclable thermoset polymers can enable fiber recovery and reuse; however, challenges remain in the separation and purification of depolymerized small molecules for efficient polymer recycling. To this end, a series of liquid resins for chemically recyclable polymer networks is designed based on phthalic anhydride, a widely produced and inexpensive chemical. The straightforward sublimation of phthalic anhydride is leveraged to enable a simple and efficient separation process for polymer recycling. To liquefy phthalic anhydride, five mono-acryloyl-phthalates are synthesized to obtain stable liquid resins together with phthalic diglycidyl ester. These liquid resins undergo dual-cure reactions that comprise photopolymerization of acrylate and, subsequently, heat-mediated epoxy-acid polymerization reactions. These liquid resins exhibit moderate viscosities (2600-6400 cP @ 22 °C), fast curing, and robust thermomechanical properties (Tgs from 71 to 116 °C). It is demonstrated that hydrolysis of the dual-cured polymers completes within 2 h at 80 °C, and direct sublimation produces phthalic anhydride with 82% yield. This resin system is expected to provide a cost-competitive, highly efficient platform for recyclable FRCs.

Exo- and Endo-1,5-α-L-Arabinanases and Prebiotic Arabino-Oligosaccharides Production.

There is growing interest in pentose-based prebiotic oligosaccharides as alternatives to traditional hexose-based prebiotics. Among these, arabino-oligosaccharides (AOS), derived from the enzymatic hydrolysis of arabinan polymers, have gained significant attention. AOS can selectively stimulate the growth of beneficial gut bacteria, including Bifidobacterium and Bacteroides species, and contribute to health-benefit functions such as blood sugar control, positioning AOS as a promising synbiotic candidate. For the industrial production of AOS, the development of efficient enzymatic processes is essential, with exo- and endo-1,5-α-L-arabinanases (exo- and endo-ABNs) playing a crucial catalytic role. Most ABNs belong to the glycoside hydrolase (GH) family 43, characterized by a five-bladed β-propeller fold structure. These enzymes hydrolyze internal α-1,5-L-arabinofuranosidic linkages, producing AOS with varying degrees of polymerization. Some ABNs GH43 were known to exhibit exo-type hydrolytic modes of action, producing specific AOS products such as arabinotriose. Additionally, exo-ABNs from GH93, which feature a six-bladed β-propeller fold, exclusively release arabinobiose through their exo-type catalytic mechanism. This review represents the first comprehensive analysis of exo- and endo-ABNs, offering scientific insights into their biotechnological potential for AOS production. It systematically compares enzyme classification, structural differences, catalytic mechanisms, paving the way for innovative applications in health, food, and pharmaceutical industries.

Antimicrobial biodegradable blown films from PBAT/TPS with Glucono-delta-lactone as acid regulator active packaging

Glucono-delta-lactone (GDL), an acid regulator commonly used in food preservation, was incorporated into biodegradable poly(butylene adipate-co-terephthalate) (PBAT)/thermoplastic starch (TPS) (60/40 and 70/30) blended films to evaluate its antimicrobial activity and its influence on film properties. The blends were characterized for chemical interactions, morphology, thermal, mechanical, and barrier properties. Antimicrobial activity against Staphylococcus aureus and Escherichia coli was also assessed. FTIR analysis revealed interactions between GDL and starch at the -OH regions, resulting in a decrease in melting temperature. Microstructural observations showed a fibrous structure and increased compaction in PBAT/TPS films with GDL incorporation. Thermal analysis indicated that GDL modified thermal properties, possibly due to its promotion of higher crystallinity in the blended films. The addition of GDL also improved mechanical strength in both blending ratios, potentially through cross-linking. However, excessive GDL use weakened mechanical properties, likely due to acid-induced polymer hydrolysis. GDL increased the water contact angle in both blending ratios, suggesting enhanced surface hydrophobicity. The introduction of GDL into the blended films improved barrier properties, especially oxygen barrier. Additionally, GDL's antimicrobial properties effectively limited the growth of S. aureus and E. coli, particularly in high-moisture environments. Therefore, biodegradable PBAT/TPS films incorporating GDL demonstrate potential as active packaging materials. A 2 wt% addition of GDL was found to offer optimal performance in terms of film properties and significantly influenced the chemical, morphological, and thermal properties of the PBAT/TPS biodegradable packaging.

Unclicking the Click: A Depolymerizable Clicked Polymer via Two Consecutive Single-Crystal-to-Single-Crystal Reactions.

We report here a clicked polymer that can be depolymerized by a declicking reaction. A designed dipeptide monomer, upon heating its crystals, underwent a single-crystal-to-single-crystal topochemical ene-azide cycloaddition polymerization to form a triazoline-linked polymer, which upon further heating, underwent a remarkable SCSC denitrogenation, resulting in an imine-linked polymer quantitatively. As both the TEAC polymerization and the denitrogenation occurred in SCSC fashion, the structures of the triazoline-linked polymer and the imine-linked polymer could be determined at atomic resolution by SCXRD. Acid hydrolysis of the imine-linked polymer leads to quantitative depolymerization, yielding a dipeptide, showcasing the degradability and depolymerizability of such polymers. This solid-state click polymerization and denitrogenation yielding depolymerizable polymer is attractive over the usual click polymers that cannot be unclicked.

Engineering water-shut-off operations: Application of rheological time-temperature superposition approach for organically-crosslinked polymer gel systems

Polymer-based gels have been extensively utilized in reservoirs to prevent excessive water production and improve oil recovery. In this study, a sulfonated-hydrolyzed polyacrylamide polymer (HPAM-S) and low-toxic organic crosslinkers (hydroquinone and hexamethylenetetramine) were mixed in brine at specified concentrations to formulate the polymer-crosslinker fluid system. The quantitative rheological analysis, along with the TTS (Time-Temperature Superposition) approach, was examined for the first time to achieve the water shut-off operations in high-temperature reservoirs (90 °C–150 °C). The TTS approach was defined as modelling of the viscosity vs. time data obtained at various temperatures using an appropriate empirical shift factor (at) such that a single master curve is established for the viscosity evolution of the given fluid system. This approach facilitates the prediction of the gelation behavior of polymer-crosslinker fluid systems as a function of time at varied reservoir temperatures especially over time scales that are not experimentally accessible. The time-dependent rheological evolution of the fluid system was experimentally investigated using batch-wise bottle testing methods as well as viscosity and viscoelastic measurements by employing an advanced rheometer. The TTS approach was applied to the obtained rheological data at varied temperatures. The model was validated for an unknown set of temperature vs. viscosity data. Based on the TTS approach, the term ‘gelation time’ was defined as the time required to reach a pre-specified viscosity to signify a transition from the liquid-like state to the solid-like state. The gelation time decreases with increasing temperatures. After the gelation time, at each temperature, a swift increase in the fluid viscosity was observed, indicating the initiation of the rapid crosslinking in the fluid systems. It was found that beyond the gelation time, the batch-wise bottle testing showed (G-I) gel strength (qualitative). Analogously, the visco-elasticity test demonstrated a rapid rise in elastic modulus (G′) beyond the gelation time. An underlying mechanism based on polymer hydrolysis was utilized to explain the evolution of distinct viscous and viscoelastic properties as a function of temperature. Moreover, the modeling predictions for the fluid systems were examined for in-situ rock plugging with the help of core-flood equipment. The core-flooding tests confirmed a 99% reduction in the rock permeability beyond the gelation time. The gelation time values obtained from both the batch-wise bottle testing method and rheological tests for the polymer-crosslinker fluid systems were found in agreement with each other, with a tolerance of (±5%).

Performance analysis and degradation mechanism of acrylamide co-polymer as rheology and filtrate reducers in different salt aqueous-based drilling mud systems at high-temperature conditions

To maintain performance of an aqueous-based drilling muds (ABDMs), it was imperative to understand the decay mechanism of the incorporated synthetic polymers, when exposed to the elevated temperatures. The understanding of the decay mechanism could provide a polymer replenishment strategy for the fluid to retain a specific rheology and filtrate control performance. In this context, thermal-degradation of various acrylamide co-polymers was investigated in different monovalent brines. The acrylamide co-polymers were custom synthesized, and their molecular weight and % sulfonic substitution was verified using the capillary viscometer and nuclear magnetic resonance spectroscopy techniques respectively. The co-polymer thermal degradation mechanism (i.e., polymer hydrolysis) in various monovalent brines (KCl, NaCl and NaBr) was quantified by novel titration for temperature range {121 °C, 177 °C}. The degradation response of the co-polymers was then correlated with their rheology and HPHT (high-pressure-high-temperature) filtrate performance; for instance, the titration studies showed that co-polymer degradation was 12–15% and 44–47% after sixteen hours aging at 121 °C and 177 °C respectively; correspondingly the co-polymer performance in ABDM, exhibited HPHT filtrate of 12–18 mL and 38–40 mL at those respective temperatures after sixteen hours of aging. The quantified understanding of the co-polymer thermal degradation was used to device a new approach for co-polymer replenishment strategy; it was illustrated that a 7% replenishment of the co-polymer for every eight hours, at 121 °C, enabled sustained HPHT filtrate of 12–18 mL for the studied evaluation period of thirty-two hours. The replenishment approach presented in the study would provide a valuable tool for drilling automation to ensure sustained fluid performance.

Agricultural light-converting anti-icing superhydrophobic coating for plant growth promotion

Agricultural coatings play a crucial role in addressing the global food crisis by significantly improving the plant growth environment, accelerating plant development, and enhancing the biological quality of plants. Nevertheless, there exist constraints in the form of limited sunlight utilization, decreased light transmission caused by surface icing leading to diminished plant photosynthesis, and high cost. In this study, a cost-effective and readily scalable superhydrophobic photothermal light-conversion coating is suggested as a means to improve the light conditions necessary for optimal plant growth. By employing in situ growth of carbon dots (CDs) on the surface and interlayers of montmorillonite (MMT) and hydrolytic polymerization of fluorinated alkyl silane (FAS) on the surface of MMT, light-converting superhydrophobic materials (CDs/MMT) with a micro-nano structure were synthesized. These materials demonstrated broad-spectrum fluorescence emission suitable for utilization by plant photosynthesis. They were dispersed into an epoxy resin (ER) matrix to obtain an agricultural superhydrophobic coating (ER-CDs/MMT). The “light absorption-capture-conversion” effect confers exceptional passive anti-icing and active de-icing properties upon the coating. Furthermore, outdoor planting experiments have demonstrated its capacity to substantially enhance the light environment and enhance the biological quality of soybean and morning glory by leveraging light scattering and conversion characteristics. This underscores its considerable potential for application in the next generation of facility agriculture.

Ultrasonic-assisted alkali hydrolysis of polyethylene terephthalate fabric and its effect on the microstructure and dyeing properties of fibers

Abstract In this study, ultrasound energy was applied to assist the alkali hydrolysis of polyethylene terephthalate (PET) fabric, and then, the results were compared with those of the mechanical oscillating method, which was used as the control. The effects of various factors such as the sodium hydroxide concentration, the dosage of dodecyl dimethyl benzyl ammonium chloride (DDBAC), and the frequency on the weight loss of the PET fabrics were systematically investigated. The surface appearance and microstructures of the treated fibers with different methods were analyzed using a scanning electron microscope and X-ray diffraction, respectively. The results showed that DDBAC played a prominent accelerating role in the hydrolysis of the PET polymer, and the frequency had a great influence on the weight loss of the PET fabric. Ultrasound with a frequency of 60 kHz showed a similar decomposition rate as the control, resulting in similar weight loss, which was the highest value among the three frequencies (20, 60, and 80 kHz). In addition, the application of ultrasonic energy led to more pits on the fiber surface, a smaller average grain size, and decreased crystallinity of the treated fibers, while the mechanical oscillating method resulted in slightly increased crystallinity. By comparing the K/S value of the dyed fabrics with two commercial disperse dyes, we found that the treatment method had no obvious correlation with the color depth of the treated fabric.

Phylogenomic evaluation of Mangrovimicrobium sediminis gen. nov. sp. nov., the first nitrogen fixing member of the family Halieaceae adapted to mangrove habitat and reclassification of Halioglobus pacificus to Pseudohaliglobus pacificus comb. nov.

The taxonomic position and genomic characteristics of a nitrogen fixing and polymer degrading marine bacterium, strain SAOS 164 isolated from a mangrove sediment sample was investigated. Sequence analysis based on 16S rRNA gene identified it as a member of family Halieaceae with closest similarity to Haliea salexigens DSM 19537T (96.3 %), H. alexandrii LZ-16-2T (96.2 %) and Parahaliea maris HSLHS9T (96.0 %) but was distantly related to the genera Haliea, Parahaliea and Halioglobus in phylogenetic trees. In order to ascertain the exact taxonomic position, phylogeny based on RpoBC proteins, whole genome, core and orthologous genes, and comparative analysis of metabolic potential retrieved the strain in an independent lineage clustering along with the genera Halioglobus, Pseudohalioglobus and Seongchinamella. Further, various genome based delimitation parameters represented by mol % GC content, percentage of conserved proteins (POCP), and amino acid identity (AAI) along with chemotaxonomic markers (i.e. fatty acids and polar lipids) supported the inferences of genome based phylogeny and indicated that the strain SAOS 164 belongs to a novel genus. The genome was mapped to 4.8 Mb in size with 65.1 % DNA mol% G + C content. In-silico genomic investigation and phenotyping revealed diverse metabolite genes/pathways related to polymer hydrolysis, nitrogen fixation, light induced growth, carbohydrate, sulfur, phosphorus and amino acid metabolism, virulence factors, defense mechanism, and stress-responsive elements facilitating survival in the mangrove habitat. Based on polyphasic taxonomic approach including genome analyses, a novel genus Mangrovimicrobium sediminis gen. nov. sp. nov. (=SAOS 164T = MTCC 12907T = KCTC 52755T = JCM 32136T) is proposed. Additionally, the reclassification of Halioglobus pacificus (=DSM 27932T = KCTC 23430T = S1–72T) to Pseudhalioglobus pacificus comb. nov. is also proposed.

Magnetic resonance insights into the heterogeneous, fractal-like kinetics of chemically recyclable polymers.

Moving toward a circular plastics economy is a vital aspect of global resource management. Chemical recycling of plastics ensures that high-value monomers can be recovered from depolymerized plastic waste, thus enabling circular manufacturing. However, to increase chemical recycling throughput in materials recovery facilities, the present understanding of polymer transport, diffusion, swelling, and heterogeneous deconstruction kinetics must be systematized to allow industrial-scale process design, spanning molecular to macroscopic regimes. To develop a framework for designing depolymerization processes, we examined acidolysis of circular polydiketoenamine elastomers. We used magnetic resonance to monitor spatially resolved observables in situ and then evaluated these data with a fractal method that treats nonlinear depolymerization kinetics. This approach delineated the roles played by network architecture and reaction medium on depolymerization outcomes, yielding parameters that facilitate comparisons between bulk processes. These streamlined methods to investigate polymer hydrolysis kinetics portend a general strategy for implementing chemical recycling on an industrial scale.

Hydrolysis of Cellulose Acetate Phthalate and Hydroxypropyl Methylcellulose Phthalate in Amorphous Solid Dispersions

The preparation of amorphous solid dispersions (ASDs) represents a promising strategy for addressing the solubility limitations of poorly soluble drugs, facilitating enhanced absorption. Acidic polymers such as cellulose acetate phthalate (CAP) and hydroxypropyl methylcellulose phthalate (HPMCP) have emerged as effective carriers for ASDs. Although the hydrolytic degradation of these polymers has been documented, its impact on the stability of ASDs has not been systematically investigated. This research aimed to explore the potential hydrolysis of CAP and HPMCP and how it influences the stability of ASDs containing ketoconazole (KTZ), at drug loadings of 10 % and 50 %. Our study utilized thermal analysis, infrared spectroscopy, and evaluations of physical and chemical stability. The results revealed that although KTZ remained physically stable in all ASDs over a 60-day period under various stability conditions, the emergence of crystalline phthalic acid (PA), a byproduct of polymer hydrolysis, was observed at elevated temperatures and relative humidity levels. The acidic microenvironment fostered by the release of PA further catalyzed drug chemical degradation. This study underscores the susceptibility of CAP and HPMCP to hydrolytic degradation, highlighting the inherent risk of PA-induced drug degradation, particularly for acid-labile compounds. These insights into the understanding of polymer hydrolysis in ASDs pave the way for the development of targeted approaches to safeguard drug stability and optimize pharmaceutical formulations for enhanced bioavailability, efficacy, and safety.

Adsorption performance and mechanism of TiO2/PVDF-based lithium-ion imprinted membrane in leaching solution of spent lithium-ion batteries

Efficient recycling of spent lithium-ion batteries (LIBs) is particularly important for the sustainable development of energy metal resources. A lithium ion-imprinted membranes (LIIMs) was synthesized by environmentally friendly hydrolysis polymerization. Its adsorption performance and mechanism in a simulated spent LIBs leaching solution was investigated. The Li+ adsorption of the LIIMs conformed to a pseudo-second-order kinetic model and occurred with a fast adsorption rate. The activation energy was associated with chemical adsorption. Thermodynamic results confirmed that Li+ adsorption was exhibited by the LIIMs as spontaneous exothermic behavior. The LIIMs showed a satisfactory affinity for lithium in simulated leaching solution (SLS), and the selective separation factors of Li+ for Fe2+, Cu2+, Ca2+, Zn2+, Mn2+, K+, and Na+ were 10.93, 19.30, 22.66, 23.49, 26.14, 27.57 and 39.00, respectively. The selective adsorption mechanism of LIIMs mainly occurred through coordination between Li+ and the oxygen on the crown ether at the surface active adsorption sites. The results proved that the LIIMs as a highly selective green adsorbent material has a broad application prospect in the recycling of spent LIBs. Importantly, the elucidation of the adsorption performance and the revelation of the adsorption mechanism provide the theoretical support for the future commercialization of LIIMs.

Hydrolyzable and biocompatible aliphatic polycarbonates with ether-functionalized side chains attached via amide linkers

Investigating polymer degradation mechanisms enables the establishment of controlled degradation techniques for the development of sustainable and recyclable materials. Hydration can play a crucial role in controlling the hydrolysis of polymers. Here, ether-functionalized aliphatic polycarbonates (APCs) susceptible to nonenzymatic hydrolysis were developed for application as biocompatible biomaterials. Among these polymers, those grafted with 2-methoxyethyl and 3-methoxypropyl side chains via an amide group were highly wettable, strongly interacted with water, and experienced almost complete hydrolysis in phosphate-buffered saline over 30 days, which was attributed to the hydrogen bonding between water and the amide/methoxy groups. In an alkaline medium, all amide-linked APCs were completely hydrolyzed within 30 days, regardless of the side-chain structure. In contrast, the nonamide-linked APCs and a representative aliphatic polycarbonate, poly(trimethylene carbonate), were minimally degraded in the buffer and experienced <31% degradation under alkaline conditions. The APC with the 3-methoxypropyl side chain exhibited platelet adhesion properties comparable to those of ether-functionalized APCs previously reported as blood-compatible polymers. Thus, our results demonstrate the effects of an amide linker on the hydration and hydrolytic properties of APCs and can help establish new design concepts for degradable polymers.

Исследование свойств гранулята форполимера полиамида-6

A technological process for low-temperature hydrolytic polymerization of caprolactam in a melt is being developed, which includes two stages: 1) prepolymer synthesis; 2) continuous combined drying–demonomerization of the granulate. The first stage of the process was carried out at a temperature of 210-220°C. The synthesized prepolymer samples were investigated for the content of low molecular weight compounds and relative viscosity.

Amine-enriched Ti/SiOx framework fabricated via one-step photochemical synthesis for carbon dioxide adsorption and separation applications

The coordination environment encompassing the amine sites governs the stability of the adsorbent. In this work, an amine-enriched Ti/SiOx framework (OP-ATSO) was constructed through a one-step hydrolytic polymerization induced under ultraviolet irradiation in order to increase the amine content. Characterization results as well as CO2 adsorption and separation performance evaluation show that compared with the amine-functionalized Ti/SiOx (HT-ATSO) synthesized through conventional hydrothermal means followed by post-synthetic impregnation, OP-ATSO possesses more abundant amine sites on the framework, which in turn exhibits enhanced CO2 adsorption capacity, two-fold increase in CO2/N2 separation coefficient, and outstanding cyclic adsorption stability. The one-step photochemical synthesis procedure dramatically reduces the time and operating steps of material synthesis, concurrently eliminating liquid waste. This work provides a novel concept of developing superior sorbents with high CO2 adsorption performance.

Preparation and Characterization of Thermoplastic Cassava and Sweet Potato Starches

Thermoplastics starches are plastics made from renewable resources like plants that are fully bio-based and biodegradable. The aim of this study was to produce and characterize thermoplastic using starches extracted from cassava and sweet potato. The effect of variable amounts of glycerol used as plasticizer and acetic acid used for hydrolysis of the starch polymer were investigated. The intermolecular interaction between the starch and glycerol was ascertained using FT-IR spectroscopy. The biodegradability test conducted on both cassava thermoplastic starch (TPSc) and potato thermoplastic starch (TPSp) were found to lose 36% and 23% respectively of their initial weights after seven days of soil burial. The result showed that as plasticizer concentration increased from 50 to 80%, there was an increase in both moisture and oil uptake but a decrease in water uptake. However, an increase in acetic acid concentration from 2.5% to 7.5% resulted in a decrease in oil uptake, water uptake and moisture uptake of the thermoplastics. Findings in this study reveal increase in the amount of glycerol plasticizer in both thermoplastics increases moisture contents retention however the observed oil uptake and biodegradability properties suggest the thermoplastic starches especially the potato thermoplastic starch is generally suitable for making eco-friendly thermoplastics.

Nanostructured SiOx/Si composite confined by carbon layer as anode materials for high-performance lithium-ion battery

Owing to its extremely high capacity, availability, and abundant resources, silicon anode is an excellent option for the future generation of high-energy-density lithium-ion batteries. Nevertheless, because of its significant volume expansion and low conductivity, it is less applicable in practical applications. Herein, we constructed a SiOx/Si with good dispersion obtained by hydrolytic polymerization and aluminothermic reduction, then the SiOx/Si/C (SSC) composite was prepared by carbon coating. The as-prepared samples have a thin layer of carbon which can improve electrical conductivity and buffer the volume expansion of Si. The optimized SSC-14 anode material has a high specific capacity and excellent cyclability (1355 mA h g−1 at 0.2 A g−1 after 350 cycles). Additionally, the SiOx/Si/C-14 composite has exceptional structural stability and may preserve 78.11 % of its original shape after 350 cycles. The SiOx/Si/C-14 composite material synthesized in this work might offer a new idea for design of future lithium-ion battery anode materials.

Coagulation effect of polyaluminum-titanium chloride coagulant and the effect of floc aging in fluoride removal: A mechanism analysis

Excessive discharge of fluoride can lead to environmental pollution and human hazards. Coagulation is a widely used process for the removal of fluoride. Existing research on the interaction between coagulants and fluoride has primarily concentrated on the removal of fluoride and the selection of coagulants, while studies on floc aging are lacking. Understanding the aging process of flocs can provide valuable insights into the mechanisms of interaction between coagulants and fluoride and further provide guidance for coagulation as well as sludge return processes. This study compares the fluoride removal efficiencies of two coagulants: polyaluminum-titanium chloride (PATC) and polyaluminum chloride (PACl), and examines the change patterns of fluoride ion during aging (0–120 h). Additionally, the study characterizes the impact of Ti or Al-Ti on the aging process using FTIR, XPS, XRD, and ESI-TOF-MS analyses. The results of the study demonstrate that the fluoride removal efficiency of PATC is 20.2% higher than that of PACl at a dosage of 0.8 mmol/L. The introduction of titanium provides additional binding sites for F−, resulting in a more intricate floc structure. Moreover, titanium promotes the hydrolytic polymerization of aluminum, increasing its positive charge and making it more attractive to F−. Upon the complete precipitation of the flocs, F− in the supernatant of PATC (0–6 h) and PACl (6–72 h) competes with -OH for binding sites, while F− attacks the Al-O or Al-O-Ti bond, leading to the disruption of the polymer. As time progresses, PATC flocs (6–120 h) are less affected by aging than PACl flocs (72–120 h). Throughout the aging process, PATC releases less F− at a slower rate, presumably because the introduction of titanium inhibited the dehydration and crystallization of the flocs to delay the release of F−.

Molecular characterization and in-depth genome analysis of Enterobacter sp. S-16.

Enterobacter species are considered to be an opportunistic human pathogen owing to the existence of antibiotic-resistant strains and drug resides; however, the detailed analysis of the antibiotic resistance and virulence features in environmental isolates is poorly characterized. Here, in the study, we characterized the biochemical characteristics, and genome, pan-genome, and comparative genome analyses of an environmental isolate Enterobacter sp. S-16. The strain was identified as Enterobacter spp. by using 16S rRNA gene sequencing. To unravel genomic features, whole genome of Enterobacter sp. S-16 was sequenced using a hybrid assembly approach and genome assembly was performed using the Unicycler tool. The assembled genome contained the single conting size 5.3 Mbp, GC content 55.43%, and 4500 protein-coding genes. The genome analysis revealed the various gene clusters associated with virulence, antibiotic resistance, type VI secretion system (T6SS), and many stress tolerant genes, which may provide important insight for adapting to changing environment conditions. Moreover, different metabolic pathways were identified that potentially contribute to environmental survival. Various hydrolytic enzymes and motility functions equipped the strain S-16 as an active colonizer. The genome analysis confirms the presence of carbohydrate-active enzymes (CAZymes), and non-enzymatic carbohydrate-binding modules (CBMs) involved in the hydrolysis of complex carbohydrate polymers. Moreover, the pan-genome analysis provides detailed information about the core genes and shared genes with the closest related Enterobacter species. The present study is the first report showing the presence of YdhE/NorM in Enterobacter spp. Thus, the elucidation of genome sequencing will increase our understanding of the pathogenic nature of environmental isolate, supporting the One Health Concept.

Insight into control mechanism of polymeric ferric titanium composite coagulant on membrane fouling: Role of natural organic matters

A series of polymerized ferric titanium coagulants (PFTC) with different basicity and Ti/Fe molar ratio were prepared, aiming to remove natural organic matters (NOM) as the main pollutants causing membrane fouling in water treatment process. The effects of basicity and Ti/Fe molar ratio on the structure of PFTC hydrolysates were preliminarily explored through the changes in peak intensity in Fourier transform infrared spectra and peak displacement in X-ray photoelectron spectroscopy spectra. The hydrolysis processes of Fe (III) and Ti (IV) were proposed based on hydrolysis polymerization curve and chemical distribution of PFTC. The coagulation results indicated that PFTC with low basicity and moderate Ti/Fe molar ratio could efficiently remove UV254, DOC and turbidity. When the amount of OH– or Ti (IV) was excessively high, the hydrolysates of PFTC transferred from oligomers to medium polymerized or colloidal species. PFTC could efficiently remove small hydrophilic substances through hydrogen bonding or sweeping effects of amorphous hydroxyl complexes, while PFTC with high basicity exhibited relatively low efficiency for UV254 and DOC removal. Finally, it was found that the control performance of PFTC on membrane fouling mainly depended on its efficiency in removing NOMs. This study will provide new insight into the development of composite coagulant and the precise control of membrane fouling.