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Environmental Science & Technology Aug 2023Bioelectrochemical systems (BESs) are considered to be energy-efficient to convert ammonium, which is present in wastewater. The application of BESs as a technology to...
Bioelectrochemical systems (BESs) are considered to be energy-efficient to convert ammonium, which is present in wastewater. The application of BESs as a technology to treat wastewater on an industrial scale is hindered by the slow removal rate and lack of understanding of the underlying ammonium conversion pathways. This study shows ammonium oxidation rates up to 228 ± 0.4 g-N m d under microoxic conditions (dissolved oxygen at 0.02-0.2 mg-O/L), which is a significant improvement compared to anoxic conditions (120 ± 21 g-N m d). We found that this enhancement was related to the formation of hydroxylamine (NHOH), which is rate limiting in ammonium oxidation by ammonia-oxidizing microorganisms. NHOH was intermediate in both the absence and presence of oxygen. The dominant end-product of ammonium oxidation was dinitrogen gas, with about 75% conversion efficiency in the presence of a microoxic level of dissolved oxygen and 100% conversion efficiency in the absence of oxygen. This work elucidates the dominant pathways under microoxic and anoxic conditions which is a step toward the application of BESs for ammonium removal in wastewater treatment.
Topics: Ammonium Compounds; Wastewater; Bioreactors; Oxidation-Reduction; Oxygen; Nitrogen
PubMed: 37498945
DOI: 10.1021/acs.est.3c02227 -
Current Opinion in Chemical Biology Apr 2017The most abundant transition metal in biological systems is iron. It is incorporated into protein cofactors and serves either catalytic, redox or regulatory purposes.... (Review)
Review
The most abundant transition metal in biological systems is iron. It is incorporated into protein cofactors and serves either catalytic, redox or regulatory purposes. Anaerobic ammonium oxidizing (anammox) bacteria rely heavily on iron-containing proteins - especially cytochromes - for their energy conservation, which occurs within a unique organelle, the anammoxosome. Both their anaerobic lifestyle and the presence of an additional cellular compartment challenge our understanding of iron processing. Here, we combine existing concepts of iron uptake, utilization and metabolism, and cellular fate with genomic and still limited biochemical and physiological data on anammox bacteria to propose pathways these bacteria may employ.
Topics: Ammonium Compounds; Bacteria, Anaerobic; Biological Transport; Coenzymes; Iron; Oxidation-Reduction
PubMed: 28364725
DOI: 10.1016/j.cbpa.2017.03.009 -
Journal of Exposure Science &... Sep 2022Quaternary ammonium compounds (QACs), commonly used in cleaning, disinfecting, and personal care products, have recently gained worldwide attention due to the massive...
BACKGROUND
Quaternary ammonium compounds (QACs), commonly used in cleaning, disinfecting, and personal care products, have recently gained worldwide attention due to the massive use of disinfectants during the COVID-19 pandemic. However, despite extensive use of these chemicals, no studies have focused on the analysis of QACs in human milk, a major route of exposure for infants.
OBJECTIVE
Our objectives were to identify and measure QACs in breast milk and evaluate early-life exposure to this group of compounds for nursing infants.
METHODS
Eighteen QACs, including 6 benzylalkyldimethyl ammonium compounds (BACs, with alkyl chain lengths of C8-C18), 6 dialkyldimethyl ammonium compounds (DDACs, C8-C18), and 6 alkyltrimethyl ammonium compounds (ATMACs, C8-C18), were measured in breast milk samples collected from U.S. mothers. Daily lactational intake was estimated based on the determined concentrations for 0-12 month old nursing infants.
RESULTS
Thirteen of the 18 QACs were detected in breast milk and 7 of them were found in more than half of the samples. The total QAC concentrations (ΣQAC) ranged from 0.33 to 7.4 ng/mL (median 1.5 ng/mL). The most abundant QAC was C14-BAC with a median concentration of 0.45 ng/mL. The highest median ΣQAC estimated daily intake (EDI) was determined for <1-month old infants based on the average (using the median concentration) and high (using the 95 percentile concentration) exposure scenarios (230 and 750 ng/kg body weight/day, respectively).
SIGNIFICANCE
Our findings provide the first evidence of the detection of several QACs in breast milk and identify breastfeeding as an exposure pathway to QACs for nursing infants.
IMPACT STATEMENT
Our findings provide the first evidence of QAC occurrence in breast milk and identify breastfeeding as one of the exposure pathways to QACs for nursing infants.
Topics: Ammonium Compounds; COVID-19; Disinfectants; Female; Humans; Infant; Infant, Newborn; Milk, Human; Pandemics; Quaternary Ammonium Compounds
PubMed: 35437305
DOI: 10.1038/s41370-022-00439-4 -
Science Advances Jun 2024Unlike aquaporins or potassium channels, ammonium transporters (Amts) uniquely discriminate ammonium from potassium and water. This feature has certainly contributed to...
Unlike aquaporins or potassium channels, ammonium transporters (Amts) uniquely discriminate ammonium from potassium and water. This feature has certainly contributed to their repurposing as ammonium receptors during evolution. Here, we describe the ammonium receptor Sd-Amt1, where an Amt module connects to a cytoplasmic diguanylate cyclase transducer module via an HAMP domain. Structures of the protein with and without bound ammonium were determined to 1.7- and 1.9-Ångstrom resolution, depicting the ON and OFF states of the receptor and confirming the presence of a binding site for two ammonium cations that is pivotal for signal perception and receptor activation. The transducer domain was disordered in the crystals, and an AlphaFold2 prediction suggests that the helices linking both domains are flexible. While the sensor domain retains the trimeric fold formed by all Amt family members, the HAMP domains interact as pairs and serve to dimerize the transducer domain upon activation.
Topics: Ammonium Compounds; Cation Transport Proteins; Signal Transduction; Models, Molecular; Binding Sites; Crystallography, X-Ray; Protein Domains; Protein Binding; Amino Acid Sequence
PubMed: 38838143
DOI: 10.1126/sciadv.adm9441 -
The Science of the Total Environment Aug 2023During the pandemic of COVID-19, the amounts of quaternary ammonium compounds (QACs) used to inactivate the virus in public facilities, hospitals and households...
During the pandemic of COVID-19, the amounts of quaternary ammonium compounds (QACs) used to inactivate the virus in public facilities, hospitals and households increased, which raised concerns about the evolution and transmission of antimicrobial resistance (AMR). Although QACs may play an important role in the propagation of antibiotic resistance gene (ARGs), the potential contribution and mechanism remains unclear. Here, the results showed that benzyl dodecyl dimethyl ammonium chloride (DDBAC) and didecyl dimethyl ammonium chloride (DDAC) significantly promoted plasmid RP4-mediated ARGs transfer within and across genera at environmental relevant concentrations (0.0004-0.4 mg/L). Low concentrations of QACs did not contribute to the permeability of the cell plasma membrane, but significantly increased the permeability of the cell outer membrane due to the decrease in content of lipopolysaccharides. QACs altered the composition and content of extracellular polymeric substances (EPS) and were positively correlated with the conjugation frequency. Furthermore, transcriptional expression levels of genes encode for mating pairing formation (trbB), DNA replication and translocation (trfA), and global regulators (korA, korB, trbA) are regulated by QACs. And we demonstrate for the first time that QACs decreased the concentration of extracellular AI-2 signals, which was verified to be involved in regulating conjugative transfer genes (trbB, trfA). Collectively, our findings underscore the risk of increased disinfectant concentrations of QACs on the ARGs transfer and provide new mechanisms of plasmid conjugation.
Topics: Humans; Quaternary Ammonium Compounds; Ammonium Chloride; COVID-19; Drug Resistance, Microbial; Anti-Bacterial Agents; Genes, Bacterial; Plasmids
PubMed: 37149193
DOI: 10.1016/j.scitotenv.2023.163781 -
Journal of the American Chemical Society May 2021The site-specific oxidation of strong C(sp)-H bonds is of uncontested utility in organic synthesis. From simplifying access to metabolites and late-stage diversification...
The site-specific oxidation of strong C(sp)-H bonds is of uncontested utility in organic synthesis. From simplifying access to metabolites and late-stage diversification of lead compounds to truncating retrosynthetic plans, there is a growing need for new reagents and methods for achieving such a transformation in both academic and industrial circles. One main drawback of current chemical reagents is the lack of diversity with regard to structure and reactivity that prevents a combinatorial approach for rapid screening to be employed. In that regard, directed evolution still holds the greatest promise for achieving complex C-H oxidations in a variety of complex settings. Herein we present a rationally designed platform that provides a step toward this challenge using -ammonium ylides as electrochemically driven oxidants for site-specific, chemoselective C(sp)-H oxidation. By taking a first-principles approach guided by computation, these new mediators were identified and rapidly expanded into a library using ubiquitous building blocks and trivial synthesis techniques. The ylide-based approach to C-H oxidation exhibits tunable selectivity that is often exclusive to this class of oxidants and can be applied to real-world problems in the agricultural and pharmaceutical sectors.
Topics: Ammonium Compounds; Electrochemical Techniques; Molecular Structure; Oxidation-Reduction
PubMed: 33983721
DOI: 10.1021/jacs.1c03780 -
Molecules (Basel, Switzerland) Apr 2019Methacrylate analogs of quaternary ammonium salts functionalized with carboxylic (AMadh1 68.8% yield, AMadh2 53.2% yield) and methoxysilane (AMsil1 94.8% yield, AMsil2...
Methacrylate analogs of quaternary ammonium salts functionalized with carboxylic (AMadh1 68.8% yield, AMadh2 53.2% yield) and methoxysilane (AMsil1 94.8% yield, AMsil2 36.0% yield) groups were synthesized via Menschutkin reaction. Fourier-transform infrared spectroscopy (FTIR), nuclear magnetic resonance spectroscopy (H, C and 2D H-C heteronuclear single quantum coherence (HSQC) NMR), mass spectrometry, thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC) were utilized to validate structures and characterize thermal properties of the novel multifunctional quaternary ammonium salts synthesized. The potential adhesive, coupling and antimicrobial properties of these multifunctional monomers encourage their further comprehensive evaluation in conventional and experimental copolymers and composites.
Topics: Anti-Bacterial Agents; Methacrylates; Polymerization; Quaternary Ammonium Compounds
PubMed: 31013893
DOI: 10.3390/molecules24081464 -
International Journal of Molecular... Dec 2023Antibacterial resistance poses a critical public health threat, challenging the prevention and treatment of bacterial infections. The search for innovative antibacterial...
Antibacterial resistance poses a critical public health threat, challenging the prevention and treatment of bacterial infections. The search for innovative antibacterial agents has spurred significant interest in quaternary heteronium salts (QHSs), such as quaternary ammonium and phosphonium compounds as potential candidates. In this study, a library of 49 structurally related QHSs was synthesized, varying the cation type and alkyl chain length. Their antibacterial activities against , including antibiotic-resistant strains, were evaluated by determining minimum inhibitory/bactericidal concentrations (MIC/MBC) ≤ 64 µg/mL. Structure-activity relationship analyses highlighted alkyl-triphenylphosphonium and alkyl-methylimidazolium salts as the most effective against CECT 976. The length of the alkyl side chain significantly influenced the antibacterial activity, with optimal chain lengths observed between C and C. Dose-response relationships were assessed for selected QHSs, showing dose-dependent antibacterial activity following a non-linear pattern. Survival curves indicated effective eradication of CECT 976 by QHSs at low concentrations, particularly compounds , , and . Moreover, in vitro human cellular data indicated that compounds , , and showed favourable safety profiles at concentrations ≤ 2 µg/mL. These findings highlight the potential of these QHSs as effective agents against susceptible and resistant bacterial strains, providing valuable insights for the rational design of bioactive QHSs.
Topics: Humans; Ammonium Compounds; Methicillin-Resistant Staphylococcus aureus; Salts; Staphylococcus aureus; Staphylococcal Infections; Anti-Bacterial Agents; Cations; Organophosphorus Compounds; Quaternary Ammonium Compounds
PubMed: 38203676
DOI: 10.3390/ijms25010504 -
International Journal of Molecular... Apr 2024This review provides a comprehensive overview of recent advancements in the design and synthesis of biologically active quaternary ammonium compounds (QACs). The covered... (Review)
Review
This review provides a comprehensive overview of recent advancements in the design and synthesis of biologically active quaternary ammonium compounds (QACs). The covered scope extends beyond commonly reviewed antimicrobial derivatives to include synthetic agents with antifungal, anticancer, and antiviral properties. Additionally, this review highlights examples of quaternary ammonium compounds exhibiting activity against protozoa and herbicidal effects, as well as analgesic and anesthetic derivatives. The article also embraces the quaternary-ammonium-containing cholinesterase inhibitors and muscle relaxants. QACs, marked by their inherent permanent charge, also find widespread usage across diverse domains such as fabric softeners, hair conditioners, detergents, and disinfectants. The effectiveness of QACs hinges greatly on finding the right equilibrium between hydrophilicity and lipophilicity. The ideal length of the alkyl chain varies according to the unique structure of each QAC and its biological settings. It is expected that this review will provide comprehensive data for medicinal and industrial chemists to design and develop novel QAC-based products.
Topics: Quaternary Ammonium Compounds; Humans; Animals; Anti-Infective Agents; Cholinesterase Inhibitors
PubMed: 38731869
DOI: 10.3390/ijms25094649 -
PloS One 2020Alkyltrimethylammonium compounds (ATMACs), dialkyldimethylammonium compounds (DADMACs) and benzylalkyldimethylethylammonium compounds (BACs) are quaternary alkylammonium...
Alkyltrimethylammonium compounds (ATMACs), dialkyldimethylammonium compounds (DADMACs) and benzylalkyldimethylethylammonium compounds (BACs) are quaternary alkylammonium compounds (QAAC), which are released into the environment in large quantities after their use in cleaning agents and disinfectants. Despite their potential role as selective agents promoting resistance against QAACs as well as antibiotics, there is a lack of data for QAACs in soil due to the lack of sensitive analytical methods. Therefore, we present a robust and fast method for the extraction and quantification of concentrations of these compounds in soil and sewage sludge. The method is based on ultrasonic extraction (USE) with a mixture of acetonitrile and HCl followed by a solid phase extraction (SPE) cleaning step and a subsequent quantification of concentrations with high performance liquid chromatography with mass spectrometry (HPLC-MS/MS) in multi mass reaction mode (MRM). The proposed method is suitable for the quantification of ATMACs (chain length C-8 to C-16), BACs (C-8 to C-18) and DADMACs (C-8 to C-16). The achieved limits of quantification (LOQ) range from 0.1 μg kg-1 to 2.1 μg kg-1. The recovery rates of spiked soil samples for non-deuterated homologues were between 47% and 57%. The analysis of sewage sludge samples and soil samples revealed that BAC-C12 was the most abundant QAAC with concentrations up to 38600 μg kg-1 in sewage sludge and up to 81 μg kg-1 in a Mexican soil that was irrigated with wastewater. Overall, the presented methods open perspectives for effectively studying fate and effects of QAACs in soils.
Topics: Chromatography, High Pressure Liquid; Quaternary Ammonium Compounds; Sewage; Soil; Tandem Mass Spectrometry
PubMed: 32750078
DOI: 10.1371/journal.pone.0237020