Electron Acceptor Research Articles

Degradation of pyrene at high concentrations in sediment and the implications for the microbiome in microbial electrochemical systems

The polycyclic aromatic hydrocarbons (PAHs) frequently accumulate in sediments, particularly those near industrial sites. The efficacy of microbial electrochemical systems (MESs) in electricity generation and PAHs degradation is intricately linked to the microbiome’s response to high contaminant levels. Metabolomics and metagenomics were applied to elucidate the impact of a high pyrene concentration on the functional structure and metabolic dynamics of sediment microbiomes within MES. In sediment with a high pyrene concentration, both the electrical output of MES and efficiency of their microbiomes in degrading organic substrates and pyrene were markedly reduced. These conditions were associated with the enrichment of PAH-degrading microorganisms, such as Hydrogenophaga and Flavobacterium. Analyses of metabolites and genetic profiles revealed that metabolic pathways were primarily influenced in MES exposed to low pyrene concentrations whereas fewer metabolic pathways were activated in MES exposed to high concentrations; instead, pathways representing functions critical for microbial survival and communication were activated as well. According to enzymatic analyses, low pyrene levels promoted carbohydrate metabolism by sediment microorganisms, whereas high levels had an inhibitory effect. An examination of electron transport enzymes revealed that intracellular electron transfer was facilitated by both low and high concentrations. However, high levels impeded enzymes associated with outer membrane electron transfer, hindering electron movement from intracellular to extracellular electron acceptors and thus negatively affecting the electrical output of MES. Our study provides crucial theoretical insight and mechanistic understanding for addressing the challenges that may be encountered when MES are used to treat pyrene-contaminated sediment near industrial sites.

Beyond denitrification: Alginate production by mucoid Pseudomonas aeruginosa using wastewater nitrate as electron acceptor

Microbial synthesis is an effective method for carbon and nitrogen recovery in the biological nitrogen removal process. The recycling of alginate-like exopolymers has attracted the attention of many researchers; however, the composition of the polymers and alginate differs. In this study, the capacity and mechanism of a mucoid Pseudomonas aeruginosa to remove nitrate and synthesize alginate were investigated. The results showed that the P. aeruginosa achieved higher nitrate removal efficiency (95.3 %) and alginate yield (298 mg/L) after 36 hours of microaerobic cultivation compare to aerobic condition. The optimal conditions for nitrogen removal and alginate recovery are 35 °C, pH 7 and C/N 15. The transcriptional activities of denitrifying genes in P. aeruginosa were upregulated at the low dissolved oxygen level. Although O2 may upregulate the expression of alginate synthesis key genes (algD, alg8 and alg44) by activating AlgZ-AlgR two-component signal transduction system, microaerobic condition facilitates P. aeruginosa proliferation and results in a higher alginate yield. Moreover, the P. aeruginosa strain was further coupled with an anoxic/aerobic reactor for deeper nitrogen removal, and the nitrate removal efficiency and alginate yield were maintained above 91 % and 100 mg/L, respectively. The conversion efficiency of sodium acetate to alginate reached 15 %. This work provides an economically and environmentally sustainable strategy for wastewater treatment and the recovery of high-value bioresource.

A novel strategy combining hydrogenotrophic methanogens' bioaugmentation and biochar biostimulation for simultaneous polycyclic aromatic hydrocarbon biodegradation and bioenergy recovery.

A novel strategy combining bioaugmentation using methanogenic archaea and biostimulation using biochar was proposed for the first time to obtain simultaneous improvement of mixed PAHs' anaerobic biodegradation and bioenergy production. The results showed that the addition of PHAs immediately resulted in inhibition in methane production and accumulation of VFA, indicating that PHAs are more toxic to methanogens than the acetogenic bacteria. The coupling of biochar with hydrogenotrophic methanogen alleviated the inhibitory effects of PAHs, allowing the anaerobic fermentation system to recover its methane production capability rapidly. Compared to the Fe3+ + bioaugmentation group, the biochar + bioaugmentation group exhibited a 7.5% higher restored cumulative methane production. This coupling strategy ultimately facilitated the degradation of most PAHs, achieving a removal rate of over 90%. Moreover, the coupled biochar and bioaugmentation induced significant changes in the archaeal community structure. Direct interspecies electron guilds (i.e., Streptococcus and Methanosarcina) were enriched in the presence of biochar and bioaugmentation, responsible for prominent PAH removal and methane recovery. This study demonstrated the feasibility of simultaneous PAH biodegradation and bioenergy production using electron acceptor and enriched microorganisms.

Enhanced Photocatalytic Degradation by the Preparation of a Stable La-Doped FeTiO3 Photocatalyst: Experimental and DFT Study.

The rapid photocarrier recombination limits the photocatalytic activity of iron titanate (FeTiO3) to be further improved. Developing novel approaches to inhibit the rapid recombination rate of the FeTiO3 photocatalysts is crucial for efficiently degrading pollutants in wastewater. Rare earth ions, with unique electron dispositions and large ion radii, could effectively inhibit photocarrier recombination. Herein, novel lanthanum (La)-doped FeTiO3 photocatalysts were designed and successfully synthesized. The photocatalytic performance of the 12 mol % La/FeTiO3 photocatalyst was superior in degrading tetracycline hydrochloride (TCH), methylene blue (MB), and brilliant blue (BB). These degradation rate constants (k) were 0.12358, 0.01357, and 0.03064 L mg-1 min-1, respectively, which were 12.83, 1.61, and 7.78 times that of pure FeTiO3. The photoelectronic tests and density functional theory (DFT) calculations revealed that the La 4f orbital forms an impurity energy level in the conduction band of FeTiO3. This level narrows the bandgap and acts as an electron acceptor, capturing photoexcited electrons and inhibiting the rapid recombination of photoexcited electron-hole pairs in FeTiO3. This work enhances the potential of FeTiO3 in the photocatalysis field and provides important insights into the efficient degradation of organic pollutants in wastewater.

Conducting Electrospun Poly(3-hexylthiophene-2,5-diyl) Nanofibers: New Strategies for Effective Chemical Doping and its Assessment Using Infrared Spectroscopy.

Vibrational spectroscopy allows the investigation of structural properties of pristine and doped poly(3-hexylthiophene-2,5-diyl) (P3HT) in highly anisotropic materials, such as electrospun micro- and nanofibers. Here, we compare several approaches for doping P3HT fibers. We have selected two different electron acceptor molecules as dopants, namely iodine and 2,3,5,6-tetrafluoro-7,7,8,8-tetracyanoquinodimethane (F4TCNQ). In the case of iodine, we have explored the doping of the fibers according to several different procedures, i.e., by sequential doping both in vapors and in solution, and with a novel promising one-step method, which exploits the mixing of the dopant to the electrospinning feed solution. Polarized infrared (IR) spectroscopy experiments prove the orientation of P3HT chains, with the polymer backbone mainly running parallel to the fiber axis. After doping, P3HT fibers show very strong and polarized doping-induced IR active vibrations (IRAVs), which are the spectroscopic signature of the structure relaxation induced by the charged defects (polarons), thus providing an unambiguous proof of the effective doping. Raman spectroscopy complements the IR evidence: The Raman spectrum shows a clearly recognizable shift of the main band, the so-called effective conjugation coordinate band, in the doped samples. A simple protocol, which quantifies the evolution of the IRAV bands with time, allows monitoring of the doping stability over time and confirms that F4TCNQ is by far superior to iodine.

Phosphorus and sulfur co-doped nickel molybdate with rich-oxygen vacancies for efficient water splitting

The rational design of high-performance electrocatalysts is essential for promoting the industrialization of electrocatalytic water-splitting technology. Herein, phosphorus and sulfur co-doped nickel molybdate with rich-oxygen vacancies (P, S-NiMoO4) was prepared as an efficient bifunctional self-supporting water-splitting catalyst from the perspective of enhancing the conductivity and optimizing the electronic configurations. The incorporation of P, S and oxygen vacancies greatly enhances the conductivity and charge-transfer efficiency of NiMoO4. Additionally, P and S can serve as proton carriers and electron acceptors to enhance the catalytic activity by accelerating proton activation and high-valent metal generation in the hydrogen evolution reaction (HER) and oxygen evolution reaction (OER). As expected, P, S-NiMoO4 demonstrates efficient bifunctional catalytic activity with an overpotential of only 31/206 mV at 10 mA cm−2 for HER/OER in 1 M KOH. Meantime, the electrolyzer assembled with P, S-NiMoO4 as electrodes requires a voltage of only 1.55 V to achieve a water-splitting current density of 50 mA cm−2 along with good stability over 110 h. This work puts forward a novel approach based on elemental doping and vacancy engineering for the design of effective and enduring catalysts for water splitting.

Aromaticity of tropylium derivatives: When and why might captodative structures be preferred over the isomeric push‐pull structures?

AbstractAn intriguing question in the general problem of aromaticity is whether captodative aromatic systems with the donor and acceptor substituents at the same carbon of the CC bond can be more stable than the π‐conjugated push‐pull counterparts? The analysis of electronic, magnetic, and structural criteria of aromaticity showed that for conventional organic substituents XO, TfN, (NC)2C, (NO2)2C, Tf2C, the push‐pull tropylidene derivatives [tropylium]+CHCHX− are expectedly more stable than their captodative isomers [tropylium]+C(X−)CH2, with the lowest ΔE for the most strong acceptor Tf2C. A different behavior is observed for XMHlg3 (MB, Al; HlgF, Cl). They are not only structurally and magnetically most aromatic in both series but show the inverse stability of the push‐pull and captodative isomers, the latter being more stable by up to 10 kcal/mol (in gas).The difference between the MHlg3 groups and conventional organic groups is that in the latter the electron density is transferred to the π‐system of the substituent, while the former can accept it only to the σ*(CM) orbital. Thus, when the electron donor and acceptor effects are separated between the σ and π systems, captodative isomers can be more stable than their push‐pull isomers with more extended conjugation.

Isolation of a methyl-reducing methanogen outside the Euryarchaeota.

Methanogenic archaea are main contributors to methane emissions, and have a crucial role in carbon cycling and global warming. Until recently, methanogens were confined to Euryarchaeota, but metagenomic studies revealed the presence of genes encoding the methyl coenzyme M reductase complex in other archaeal clades1-4, thereby opening up the premise that methanogenesis is taxonomically more widespread. Nevertheless, laboratory cultivation of these non-euryarchaeal methanogens was lacking to corroborate their potential methanogenic ability and physiology. Here we report the isolation of a thermophilic archaeon LWZ-6 from an oil field. This archaeon belongs to the class Methanosuratincolia (originally affiliated with 'Candidatus Verstraetearchaeota') in the phylum Thermoproteota. Methanosuratincola petrocarbonis LWZ-6 is a strict hydrogen-dependent methylotrophic methanogen. Although previous metagenomic studies speculated on the fermentative potential of Methanosuratincolia members, strain LWZ-6 does not ferment sugars, peptides or amino acids. Its energy metabolism is linked only to methanogenesis, with methanol and monomethylamine as electron acceptors and hydrogen as an electron donor. Comparative (meta)genome analysis confirmed that hydrogen-dependent methylotrophic methanogenesis is a widespread trait among Methanosuratincolia. Our findings confirm that the diversity of methanogens expands beyond the classical Euryarchaeota and imply the importance of hydrogen-dependent methylotrophic methanogenesis in global methane emissions and carbon cycle.

Custom-printed microfluidic chips using simultaneous ratiometric fluorescence with "Green" carbon dots for detection of multiple antibiotic residues in pork and water samples.

In the evolving field of food safety, rapid and precise detection of antibiotic residues is crucial. This study aimed to tackle this challenge by integrating advanced inkjet printing technology with sophisticated microfluidic paper-based analytical devices (µPADs). The µPAD design utilized "green" quantum dots synthesized via an eco-friendly hydrothermal method using green white mulberry leaves as the carbon source, serving as the key fluorescent detection material. The action mechanism involved a photoinduced electron transfer system using red carbon dots (CDs) as electron donors and blue CDs combined with two-dimensional layered molybdenum disulfide (MoS2) nanosheets as electron acceptors. This system could quickly detect antibiotics within 10min in pork and water samples, demonstrating high sensitivity and recovery rates: 6.5pmol/L at 99.75%-110% for sulfadimethoxine, 3.3pmol/L at 99%-105% for sulfamethoxazole, and 8.5pmol/L at 98.5%-105% for tetracycline. It achieved a relative standard deviation under 5%, ensuring reliability and reproducibility. The fabricated sensor offered a promising application for the rapid and efficient on-site detection of antibiotic residues in food.

Constructing Heavy-Atom-Free Photosensitizers for Hypoxic Tumor Phototherapy Based on Donor-Excited Photoinduced Electron-Transfer-Driven Type-I and Type-II Mechanisms.

The spin-orbit charge transfer intersystem crossing (SOCT-ISC) photophysical process has shown great potential for constructing heavy-atom-free photosensitizers (PSs) for photodynamic therapy (PDT) of tumors. However, for almost all such PSs reported to date, the SOCT-ISC is driven by the acceptor-excited photoinduced electron transfer (a-PeT). In this work, for the first time the donor-excited photoinduced electron transfer (d-PeT)-driven SOCT-ISC mechanism is utilized to construct the heavy-atom-free PSs for PDT of tumors by directly installing the electron-deficient N-alkylquinolinium unit (as an electron acceptor) into the meso-position of the near-infrared (NIR) distyryl Bodipy chromophore (as an electron donor). In the less polar environment, the PSs exist as the monomer and promote the production of singlet oxygen (1O2) (Type-II) relying on the d-PeT-driven population of the triplet excited state via SOCT-ISC, whereas in the aqueous environment, they exist as nanoaggregates and induce the generation of superoxides (O2-•) and hydroxyl radicals (HO•) (Type-I) via the d-PeT-driven formation of the delocalized charge-separated state. The PSs could rapidly be internalized into cancer cells and induce the simultaneous production of intracellular 1O2, O2-•, and HO• upon NIR light irradiation, endowing the PSs with superb photocytotoxicity with IC50 values up to submicromolar levels whether under normoxia or under hypoxia. Based on the PSs platform, a tumor-targetable PS is developed, and its abilities in killing cancer cells and in ablating tumors without damage to normal cells/tissues under NIR light irradiation are verified in vitro and in vivo. The study expands the design scope of PSs by introducing the d-PeT conception, thus being highly valuable for achieving novel PSs in the realm of tumor PDT.

Achieving High Efficiency and Stability in Organic Photovoltaics with a Nanometer-Scale Twin p-i-n Structured Active Layer.

In pursuing high stability and power conversion efficiency for organic photovoltaics (OPVs), a sequential deposition (SD) approach to fabricate active layers with p-i-n structures (where p, i, and n represent the electron donor, mixed donor:acceptor, and electron acceptor regions, respectively, distinctively different from the bulk heterojunction (BHJ) structure) has emerged. Here, we present a novel approach that by incorporating two polymer donors, PBDBT-DTBT and PTQ-2F, and one small-molecule acceptor, BTP-3-EH-4Cl, into the active layer with sequential deposition, we formed a device with nanometer-scale twin p-i-n structured active layer. The twin p-i-n PBDBT-DTBT:PTQ-2F/BTP-3-EH-4Cl device involved first depositing a PBDBT-DTBT:PTQ-2F blend under layer and then a BTP-3-EH-4Cl top layer and exhibited an improved power conversion efficiency (PCE) value of 18.6%, as compared to the 16.4% for the control BHJ PBDBT-DTBT:PTQ-2F:BTP-3-EH-4Cl device or 16.6% for the single p-i-n PBDBT-DTBT/BTP-3-EH-4Cl device. The PCE enhancement resulted mainly from the twin p-i-n active layer's multiple nanoscale charge carrier pathways that contributed to an improved fill factor and faster photocurrent generation based on transient absorption studies. The PBDBT-DTBT:PTQ-2F/BTP-3-EH-4Cl film possessed a vertical twin p-i-n morphology that was revealed through secondary ion mass spectrometry and synchrotron grazing-incidence small-angle X-ray scattering analyses. The thermal stability (T80) at 85 °C of the twin p-i-n PBDBT-DTBT:PTQ-2F/BTP-3-EH-4Cl device surpassed that of the single p-i-n PBDBT-DTBT/BTP-3-EH-4Cl devices (906 vs 196 h). This approach of providing a twin p-i-n structure in the active layer can lead to substantial enhancements in both the PCE and stability of organic photovoltaics, laying a solid foundation for future commercialization of the organic photovoltaics technology.

The resting cyst of dinoflagellate Scrippsiella acuminata host bacterial microbiomes with more diverse trophic strategies under conditions typically observed in marine sediments.

Variation in the condition of marine sediments provides selective preservation milieus, which act as a key determinant for the abundance and distribution of dinoflagellate resting cysts in natural sediments. Microbial degradation is an understudied biological factor of potential importance in the processes. However, gaps remain in our knowledge about the fundamental information of the bacterial consortia associated with dinoflagellate resting cysts both in laboratory cultures and in the field. Here we used Scrippsiella acuminata as a representative of cyst-producing dinoflagellates to delineate the diversity and composition of bacterial microbiomes co-existing with the laboratory-cultured resting cysts, and to explore possible impacts of low temperature, darkness, and anoxia (the mock conditions commonly observed in marine sediments) on the associated bacterial consortia. Bacterial microbiome with high diversity were revealed associated with S. acuminata at resting stage. The mock conditions could significantly shift bacterial community structure and exert notably inhibitory effects on growth-promoting bacteria. Resting cysts under conditions typically observed in marine sediments fostered bacterial microbiomes with more diverse trophic strategies, characteristic of prominently enriched anaerobic chemotrophic bacteria generating energy via respiration with several different terminal electron acceptors, which yielded more acidic milieu unfavorable for the preservation of calcareous resting cysts. Our findings suggest that there is complex and dynamic interaction between dinoflagellates resting cysts and the associated bacterial consortia in natural sediments. This intrinsic interaction may influence the maintenance and/or accumulation of dinoflagellate resting cysts with potential of germination and initiation blooms in the field.

Distribution and composition of redox-active species and dissolved organic carbon in Arctic lacustrine porewaters

ABSTRACT The interaction between redox-active species and dissolved organic carbon (DOC) is crucial in driving lacustrine benthic microbial processes. In lacustrine porewaters, many redox-active species exist in their reduced form, while DOC acts as a substrate and an electron acceptor. Understanding the types and abundance of redox-active species in porewaters along with their complementary DOC substrate is pivotal for gaining insights into benthic processes, particularly in regions susceptible to climate change. We report the in-situ measurement of redox-active species in sediment porewaters, alongside the ex-situ measurement of DOC extracted from cores collected from two Arctic lakes (Toolik and Fog 1). Fe2+ was abundantly detected below 4 cm of the sediment-water interface in all cores and was inversely related to dissolved O2. Additionally, two distinct Fe(III)-complexes were identified. DOC ranged in the order of 10s of mg/L and either remained stable or increased with depth. A comparison between Toolik and Fog 1 lakes revealed a higher accumulation of Fe2+ and DOC in the latter. This study marks the first of its kind to assess spatial distributions of redox-active species and DOC as a function of depth from multiple sites in Arctic lacustrine porewaters.

Unraveling the Photovoltage Formation Mechanism in Indium-Tin Oxide Branched Nanowires/Poly(3-Hexylthiophene) Photorechargeable Supercapacitors.

Photorechargeable supercapacitors are promising next-generation renewable energy storage devices. Previously, a hybrid structure consisting of indium-tin oxide branched nanowires (ITO BRs) and poly(3-hexylthiophene) (P3HT) was demonstrated as a photorechargeable supercapacitor. However, the formation mechanism of photovoltage has not been studied. Herein, we experimentally investigated the photovoltage-determining parameters in the ITO BRs/P3HT photorechargeable supercapacitor by inserting a polyethylenimine ethoxylated (PEIE) interlayer or adding a phenyl-C61-butyric acid methyl ester (PCBM) electron acceptor. Coating the PEIE interlayer on ITO BRs decreased the work function by 0.5 eV and hindered the hole extraction from P3HT to ITO BRs, leading to interfacial recombination and a decrease in photovoltage. On the other hand, the addition of PCBM promoted the charge transfer of the electrons from P3HT to PCBM, enhanced the redox reaction at the PCBM/electrolyte interface, and reduced the number of accumulated electrons, leading to a decreased photovoltage. From these results, we found that two key parameters determine the photovoltage and charge storage capability; one is the interfacial recombination at the ITO BRs/P3HT interface and the other is the redox reaction at the P3HT/electrolyte interface.

Revisiting the role of algal biocathodes in microbial fuel cells for bioremediation and value-addition

Algal-microbial fuel cells (A-MFC) offers a sustainable solution for wastewater treatment and energy recovery. The performance of a typical MFC is affected by the oxidative-reductive reactions occurring in it. The cathodic reduction is facilitated by electron acceptors such as oxygen and ferricyanide. However, higher operational cost is incurred from their application. Algae owing to its phototrophic metabolism, oxygenates the cathode photosynthetically and acts as a mediator for cathodic electron transfer. Mixotrophic metabolism of algae enable their adaptation and growth in pollutant-rich toxic environments, making them suitable for wastewater treatment and remediation. A-MFCs enable the generation of algal biomass, a rich source of carbohydrates, lipids, proteins, pigments, and many more for commercial applications. Algal-based CO2 sequestration, nutrient and heavy metal removal via assimilation and carbon capture pathways make A-MFC systems a promising approach for bioenergy generation and wastewater remediation. Hence, this review offers an overview on the principles and applications of A-MFC and their relevance in developing a waste-centered-circular economy.

Efficient methane oxidation to formaldehyde via photon–phonon cascade catalysis

The oxidation of methane to value-added chemicals provides an opportunity to use this abundant feedstock for sustainable petrochemistry. Unfortunately, such technologies remain insufficiently competitive due to a poor selectivity and a low yield rate for target products. Here we show a photon–phonon-driven cascade reaction that allows for methane conversion to formaldehyde with an unprecedented productivity of 401.5 μmol h−1 (or 40,150 μmol g−1 h−1) and a high selectivity of 90.4% at 150 °C. Specifically, with a ZnO catalyst decorated with single Ru atoms, methane first reacts with water to selectively produce methyl hydroperoxide via photocatalysis, followed by a thermodecomposition step yielding formaldehyde. Single Ru atoms, serving as electron acceptors, improve charge separation and promote oxygen reduction in photocatalysis. This reaction route with minimized energy consumption and high efficiency suggests a promising pathway for the sustainable transformation of light alkanes.

Dual–Acceptor Engineering in Pyrene‐Based Covalent Organic Frameworks for Boosting Photocatalytic Hydrogen Evolution

AbstractThe integration of electron donor (D) and acceptor (A) units into covalent organic frameworks (COFs) has received increasing interest due to its potential for efficient photocatalytic hydrogen (H2) evolution from water. Nevertheless, the advancement of D–A COFs is still constrained by the limited investigations on acceptor engineering, which enables the highly effective charge transfer pathways in COFs to deliver photoexcited electrons in a preferential orientation to enhance photocatalytic performance. Herein, two systems with D–A and D–A–A configurations based on the acceptor molecular engineering strategy are proposed to construct three distinct COFs. Specifically, TAPPy‐DBTDP‐COF merging one pyrene‐based donor and two benzothiadiazole acceptors realized an average H2 evolution rate of 12.7 mmol h−1 g−1 under visible light, among the highest ever reported for typical D–A‐type COF systems. The combination of experimental and theoretical analysis signifies the crucial role of the dual‐acceptor arrangement in promoting exciton dissociation and carrier migration. These findings underscore the significant potential of D–A–A structural design, which is conducive to the efficient separation of photoexcited electrons and holes resulting in superior photocatalytic activities.

PBAT is biodegradable but what about the toxicity of its biodegradation products?

ContextPoly(butylene adipate-co-terephthalate) (PBAT) is a biodegradable plastic. It was introduced to the plastics market in 1998 and since then has been widely used around the world. The main idea of this research is to perform quantum chemical calculations to study the potential toxicity of PBAT and its degradation products. We analyzed the electron transfer capacity to determine its potential toxicity. We found that biodegradable products formed with benzene rings are as good electron acceptors as PBAT and OOH•. Our results indicate that the biodegradation products are potentially as toxic as PBAT. This might explain why biodegradation products alter the photosynthetic system of plants and inhibit their growth. From this and other previous investigations, we can think that biodegradable plastics could represent a potential environmental risk.MethodsAll DFT computations were performed using the Gaussian16 at M062x/6–311 + g(2d,p) level of theory without symmetry constraints. Electro-donating (ω-) and electro-accepting (ω +) powers were used as response functions.

Precisely Regulating Intermolecular Interactions and Molecular Packing of Nonfused‐Ring Electron Acceptors via Halogen Transposition for High‐Performance Organic Solar Cells

AbstractThe structure of molecular aggregates is crucial for charge transport and photovoltaic performance in organic solar cells (OSCs). Herein, the intermolecular interactions and aggregated structures of nonfused‐ring electron acceptors (NFREAs) are precisely regulated through a halogen transposition strategy, resulting in a noteworthy transformation from a 2D‐layered structure to a 3D‐interconnected packing network. Based on the 3D electron transport pathway, the binary and ternary devices deliver outstanding power conversion efficiencies (PCEs) of 17.46 % and 18.24 %, respectively, marking the highest value for NFREA‐based OSCs.

Clostridioides difficile colonization is not mediated by bile salts and requires Stickland fermentation of proline in an in vitro model of infection.

Treatment with antibiotics is a major risk factor for Clostridioides difficile infection, likely due to depletion of the gastrointestinal microbiota. Two microbiota-mediated mechanisms thought to limit C. difficile colonization include conversion of conjugated primary bile salts into secondary bile salts toxic to C. difficile growth, and competition between the microbiota and C. difficile for limiting nutrients. Using a continuous flow model of the distal colon, we investigated how treatment with six clinically-used antibiotics influenced susceptibility to C. difficile infection in 12 different microbial communities cultivated from healthy individuals. Antibiotic treatment reduced microbial richness; disruption varied by antibiotic class and microbiota composition, but did not correlate with C. difficile susceptibility. Antibiotic treatment also disrupted microbial bile salt metabolism, increasing levels of the primary bile salt, cholate, and decreasing levels of the secondary bile salt, deoxycholate. However, decreased levels of deoxycholate did not correlate with increased C. difficile susceptibility. Further, bile salts were not required to inhibit C. difficile colonization. We tested whether amino acid fermentation contributed to persistence of C. difficile in antibiotic-treated communities. C. difficile mutants unable to use proline as an electron acceptor in Stickland fermentation due to disruption of proline reductase (ΔprdB) had significantly lower levels of colonization than wild-type strains in four of six antibiotic-treated communities tested. This data provides further support for the importance of bile salt-independent mechanisms in regulating colonization of C. difficile.