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1.
Science ; 369(6508): 1160-1161, 2020 09 04.
Artigo em Inglês | MEDLINE | ID: mdl-32883846
2.
J Environ Sci (China) ; 96: 171-177, 2020 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-32819691

RESUMO

Microbial fuel cells (MFC) utilize microbes as catalysts to convert chemical energy to electricity. Inocula used for MFC operation must therefore contain active microbial population. The dye reduction-based electron-transfer activity monitoring (DREAM) assay was employed to evaluate different inocula used in MFCs for their microbial bioelectrical activity. The assay utilizes the redox property of Methylene Blue to undergo color change from blue to colorless state upon microbial reduction. The extent of Methylene Blue reduction was denoted as the DREAM assay coefficient. DREAM assay was initially performed on a microbial culture along with the growth curve and estimation of colony forming units (CFUs). DREAM coefficient correlated to the CFU/mL obtained over time as growth progressed. The assay was then extended to water samples (domestic sewage, lake and a man-made pond) serving as inocula in MFCs. Domestic wastewater gave the highest DREAM coefficient (0.300 ± 0.05), followed by pond (0.224 ± 0.07) and lake (0.157 ± 0.04) water samples. Power density obtained conformed to the DREAM coefficient values, with the three samples generating power densities of 46.45 ± 5.1, 36.12 ± 3.2 and 25.08 ± 4.3 mW/m2 respectively. We have also studied the role of addition of various carbon sources and their concentrations towards improving the sensitivity of the assay. The DREAM assay is a rapid, easy-to-perform and cost-effective method to assess inocula for their suitability as anolytes in terms of electron transfer potential in MFCs.


Assuntos
Fontes de Energia Bioelétrica , Corantes , Eletricidade , Eletrodos , Elétrons , Oxirredução , Águas Residuárias
3.
J Assoc Physicians India ; 68(8): 93, 2020 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-32738850
5.
Science ; 369(6502): 375-376, 2020 07 24.
Artigo em Inglês | MEDLINE | ID: mdl-32703865
6.
Nature ; 583(7814): 35-36, 2020 07.
Artigo em Inglês | MEDLINE | ID: mdl-32612219
7.
Bioresour Technol ; 315: 123818, 2020 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-32688253

RESUMO

Chlorate has been described as an emerging pollutant that compromises water sources. In this study, bioelectrochemical reactors (BERs) using Dechloromonas agitata CKB, were evaluated as a sustainable alternative for chlorate removal. BERs were operated under flow-recirculation and batch modes with an applied cell-voltage of 0.44 V over a resistance of 1 kΩ. Results show chlorate removal up to 607.288 mg/L. After 115 days, scanning electron microscopy showed biofilm development over the electrodes, and electrochemical impedance spectroscopy confirmed the biocatalytic effect of CKB. The theoretical chlorate bioreduction potential (ε° = 0.792 V) was proven, and a kinetic study indicated that 6 electrons were involved in the reduction mechanism. Finally, a hypothetical bioelectrochemical mechanism for chlorate reduction in a BER was proposed. This research expands upon current knowledge of novel electrochemically active microorganisms and widens the scope of BER applications for chlorate removal.


Assuntos
Cloratos , Elétrons , Betaproteobacteria , Eletrodos , Oxirredução
8.
Sci Total Environ ; 741: 140365, 2020 Nov 01.
Artigo em Inglês | MEDLINE | ID: mdl-32610234

RESUMO

Geobacter sulfurreducens biofilms have promising applications in renewable energy, pollutant bioremediation, and bioelectronic applications. Genetically manipulating G. sulfurreducens biofilms is an effective strategy to improve the capacity of extracellular electron transfer (EET). Extracellular polysaccharide, a sticky component surrounding microbes, plays an important role in EET. Herein, we constructed a mutant of G. sulfurreducens strain PCA overexpressing the gene GSU1501 (part of the ATP-dependent exporter of the polysaccharide biosynthesis gene operon), designated strain PCA-1501, to increase EET capacity. Experimental results showed that the overexpression of GSU1501 increased extracellular polysaccharide secretion by 25.5%, which promoted the formation of biofilm with higher thickness and viability, as well as the content of extracellular c-type cytochromes. Compared with the control strain, the mutant showed a higher capacity of Fe(III) oxide reduction and current generation (increased by 20.4% and 22.2%, respectively). Interestingly, the overexpression of GSU1501 hindered the pili formation by reducing the transcription level of pilA; a compensatory relationship between extracellular polysaccharide and pili in promoting biofilm formation deserves further investigation. This study provides a feasible method to promote the EET capacity of G. sulfurreducens biofilms, which benefit their bioelectrochemical applications.


Assuntos
Geobacter , Biofilmes , Elétrons , Compostos Férricos , Oxirredução , Polissacarídeos
9.
J Chromatogr A ; 1624: 461218, 2020 Aug 02.
Artigo em Inglês | MEDLINE | ID: mdl-32540066

RESUMO

In this study, amylose- and cellulose-phenylcarbamate-based chiral columns with different chiral-selector (CS) chemistries were compared to each other for the separation of enantiomers of basic chiral analytes in acetonitrile and aqueous-acetonitrile mobile phases in HPLC. For two chemistries the amylose-based columns with coated and immobilized CSs were also compared. The comparison of CSs containing only electron-donating or electron-withdrawing substituents with those containing both electron-donating and electron-withdrawing substituents showed opposite results for the studied set of chiral analytes in the case of amylose and cellulose derivatives. Along with the chemistry of CS the focus was on the behavior of polysaccharide phenylcarbamates in acetonitrile versus aqueous acetonitrile as eluents. In agreement with earlier results, it was found that in contrast to the commonly accepted view, polysaccharide phenylcarbamates do not behave as typical reversed-phase materials for basic analytes either. In the range of water content in the mobile phase of up to 20-30% v/v the behavior of these CSs is similar to hydrophilic interaction liquid chromatography (HILIC)-type adsorbents. This means that with increasing water content in the mobile phase up to 20-30% v/v, the retention of analytes mostly decreases. The important finding of this study is that the separation efficiency improves for most analytes when switching from pure acetonitrile to aqueous acetonitrile. Therefore, in spite of reduced retention, the separation of enantiomers improves and thus, the HILIC-range of mobile phase composition, offering shorter analysis time and better peak resolution, is advantageous over pure polar-organic solvent mode. Interesting examples of enantiomer elution order (EEO) reversal were observed for some analytes based on the content of water in the mobile phase on Lux Cellulose-1 and Lux Amylose-2 columns.


Assuntos
Amilose/química , Celulose/química , Cromatografia Líquida de Alta Pressão/métodos , Preparações Farmacêuticas/isolamento & purificação , Fenilcarbamatos/química , Acetonitrilos/química , Elétrons , Etanolaminas/análise , Etanolaminas/isolamento & purificação , Preparações Farmacêuticas/análise , Propanolaminas/análise , Propanolaminas/isolamento & purificação , Propranolol/análise , Propranolol/isolamento & purificação , Estereoisomerismo , Água/química
11.
Water Sci Technol ; 81(6): 1209-1220, 2020 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-32597407

RESUMO

It has been proved that the nitrogen can be removed from the sediment in a sediment microbial fuel cell system (SMFCs), but the competition between nitrate and oxygen for electrons would be a key factor that would affect the removal efficiency, and its mechanism is not clear. Based on organic sediment fuel, an SMFC was constructed, and the influence of dissolved oxygen (DO) on nitrogen transformation and cathodic microbial communities was investigated. The results showed that the best total nitrogen removal efficiency of 60.55% was achieved at DO level of 3 mg/L. High DO concentration affected the removal efficiency through the electrons' competition with nitrate, while low DO concentration suppressed the nitrification. Comamonas, Diaphorobacter and Brevundimonas were the three dominant genera responsible for denitrification at DO concentration of 3 mg/L in this study. The establishment of SMFCs for nitrogen removal by regulating DO level would offer a promising method for sediment treatment.


Assuntos
Fontes de Energia Bioelétrica , Desnitrificação , Elétrons , Nitrificação , Nitrogênio , Oxigênio
12.
Chemosphere ; 257: 127269, 2020 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-32531490

RESUMO

Various sole and mixed electron donors were tested to promote the denitrification rate and nitrate removal efficiency in biofilter systems with high phosphate and ammonia removal efficiency (92.6% and 95.3% respectively). Compared to sole electron donors, complex organic carbon (bits of wood and straw) substantially improved the denitrification rate and nitrate removal efficiency (from 6.3%-18.5% to35.4%) by shifting the denitrifying microbial community composition, even though the relative abundance of functional genes mediating denitrification decreased. The mixed electron donor combining complex organic carbon with sulfur, iron and CH4 further promoted nitrate removal efficiency by 37.2%. The significantly higher abundance and diversity of bacteria mediating organic carbon decomposition in the treatments with complex organic carbon indicated the continuous production of organic carbon with small molecular weights, which provided sustainable and effective electron donor for denitrification. However, sole sulfur or iron did not effectively promote the denitrification rate and nitrogen removal efficiency, even though the related microbial community had been formed.


Assuntos
Reatores Biológicos/microbiologia , Desnitrificação/fisiologia , Microbiota , Bactérias , Carbono , Elétrons , Metagenoma , Nitratos , Nitrogênio , Óxidos de Nitrogênio , Enxofre
13.
Int J Nanomedicine ; 15: 3669-3680, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32547021

RESUMO

Introduction: The exhaustion and poor homing of activated lymphocytes are critical obstacles in adoptive cell immunotherapy for solid tumors. In order to effectively deliver immune cells into tumors, we encapsulated interferon-α2b (IFN-α2b) into macroporous hydrogels as an enhancement factor and utilized low-dose irradiation (LDI) as a tumoral attractor of T cells. Methods: Hydroxypropyl cellulose hydrogels were prepared by irradiation techniques, and the cross-sectional microstructure was characterized by scanning electron microscopy. The synergistic antitumor mechanism of combination of IFN-α2b and CIK cells was evaluated by detecting the expression of activation marker CD69 on CIK cell surface and IFN-γ production by CIK cells. The in vivo antitumor activity of IFN-α2b-incorporated hydroxypropyl cellulose hydrogels combined with CIK and radiation was evaluated in an MKN-45 xenografted nude mice model. Results: The bioactivity of IFN-α2b was well maintained in ultraviolet-reactive, rapidly cross-linkable hydroxypropyl cellulose hydrogels. In vitro studies demonstrated IFN-α2b-activated T cells, as evidenced by upregulating early activation marker CD69 and secretion inflammatory cytokine IFN-γ. In vivo real-time image showed our hydrogels kept a higher amount of drug delivery at the tumor site for a long time compared with free drug injection. Low-dose irradiation promoted T cell accumulation and infiltration in subcutaneous tumors. Combination of IFN-α2b-loaded hydrogels (Gel-IFN) with T cells and LDI exhibited higher efficacy to eradicate human gastric cancer xenograted tumors with less proliferating cells and more necrotic regions compared with IFN-α2b or T cells alone. Discussion: HPC hydrogels kept the activity of IFN-α2b and stably release of IFN-α2b to stimulate T cells for a long time. At the same time, low-dose radiation recruits T cells into tumors. This innovative integration mode of IFN-α2b-loaded hydrogels and radiotherapy offers a potent strategy to improve the therapeutic outcome of T cell therapy.


Assuntos
Antineoplásicos/uso terapêutico , Reagentes para Ligações Cruzadas/química , Hidrogéis/química , Interferon-alfa/uso terapêutico , Luz , Neoplasias Gástricas/tratamento farmacológico , Neoplasias Gástricas/radioterapia , Linfócitos T/imunologia , Animais , Antineoplásicos/farmacologia , Linhagem Celular Tumoral , Proliferação de Células/efeitos dos fármacos , Celulose/análogos & derivados , Celulose/química , Relação Dose-Resposta à Radiação , Elétrons , Humanos , Interferon-alfa/farmacologia , Masculino , Camundongos Endogâmicos BALB C , Camundongos Nus , Linfócitos T/efeitos dos fármacos , Ensaios Antitumorais Modelo de Xenoenxerto
14.
PLoS Biol ; 18(6): e3000741, 2020 06.
Artigo em Inglês | MEDLINE | ID: mdl-32520929

RESUMO

Mitochondrial metabolic remodeling is a hallmark of the Trypanosoma brucei digenetic life cycle because the insect stage utilizes a cost-effective oxidative phosphorylation (OxPhos) to generate ATP, while bloodstream cells switch to aerobic glycolysis. Due to difficulties in acquiring enough parasites from the tsetse fly vector, the dynamics of the parasite's metabolic rewiring in the vector have remained obscure. Here, we took advantage of in vitro-induced differentiation to follow changes at the RNA, protein, and metabolite levels. This multi-omics and cell-based profiling showed an immediate redirection of electron flow from the cytochrome-mediated pathway to an alternative oxidase (AOX), an increase in proline consumption, elevated activity of complex II, and certain tricarboxylic acid (TCA) cycle enzymes, which led to mitochondrial membrane hyperpolarization and increased reactive oxygen species (ROS) levels. Interestingly, these ROS molecules appear to act as signaling molecules driving developmental progression because ectopic expression of catalase, a ROS scavenger, halted the in vitro-induced differentiation. Our results provide insights into the mechanisms of the parasite's mitochondrial rewiring and reinforce the emerging concept that mitochondria act as signaling organelles through release of ROS to drive cellular differentiation.


Assuntos
Metabolômica , Mitocôndrias/metabolismo , Trypanosoma brucei brucei/crescimento & desenvolvimento , Trypanosoma brucei brucei/metabolismo , Trifosfato de Adenosina/biossíntese , Diferenciação Celular/efeitos dos fármacos , Linhagem Celular , Respiração Celular/efeitos dos fármacos , Transporte de Elétrons/efeitos dos fármacos , Elétrons , Glucose/farmacologia , Potencial da Membrana Mitocondrial/efeitos dos fármacos , Redes e Vias Metabólicas/efeitos dos fármacos , Mitocôndrias/efeitos dos fármacos , Proteínas Mitocondriais/metabolismo , Oxirredução , Oxirredutases/metabolismo , Proteínas de Plantas/metabolismo , Prolina/metabolismo , Proteoma/metabolismo , Proteínas de Protozoários/metabolismo , Espécies Reativas de Oxigênio/metabolismo , Transdução de Sinais , Transcriptoma/genética , Trypanosoma brucei brucei/efeitos dos fármacos , Trypanosoma brucei brucei/genética
15.
Bioresour Technol ; 313: 123648, 2020 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-32563791

RESUMO

High-solid anaerobic digestion (AD) faces the problems of easy acidification and low methane production efficiency. In this study, activated carbon (AC)-enhanced direct interspecies electron transfer (DIET) was investigated to overcome such problems. Results showed the conversion of volatile fatty acids (VFAs) into methane rate was increased with AC addition, which led improved methane production efficiency. The methane yields from the early AD stage improved by 124.0-146.3% with AC addition. The T80 shortened by 8-9 days with AC addition. The relative abundances of Geobacter, Syntrophomonas and Methanosaeta that associated with DIET improved for 63.65%, 256.3% and 4.35% by AC addition, which reflected the enhanced DIET with AC addition. The redox activity of AC might be responsible for the enhanced DIET. This study would advance the understanding of DIET and provide a potential solution to the problems existed in high-solid AD.


Assuntos
Carvão Vegetal , Esgotos , Anaerobiose , Reatores Biológicos , Elétrons , Metano
18.
Nature ; 583(7815): 314-318, 2020 07.
Artigo em Inglês | MEDLINE | ID: mdl-32499654

RESUMO

Light-driven sodium pumps actively transport small cations across cellular membranes1. These pumps are used by microorganisms to convert light into membrane potential and have become useful optogenetic tools with applications in neuroscience. Although the resting state structures of the prototypical sodium pump Krokinobacter eikastus rhodopsin 2 (KR2) have been solved2,3, it is unclear how structural alterations over time allow sodium to be translocated against a concentration gradient. Here, using the Swiss X-ray Free Electron Laser4, we have collected serial crystallographic data at ten pump-probe delays from femtoseconds to milliseconds. High-resolution structural snapshots throughout the KR2 photocycle show how retinal isomerization is completed on the femtosecond timescale and changes the local structure of the binding pocket in the early nanoseconds. Subsequent rearrangements and deprotonation of the retinal Schiff base open an electrostatic gate in microseconds. Structural and spectroscopic data, in combination with quantum chemical calculations, indicate that a sodium ion binds transiently close to the retinal within one millisecond. In the last structural intermediate, at 20 milliseconds after activation, we identified a potential second sodium-binding site close to the extracellular exit. These results provide direct molecular insight into the dynamics of active cation transport across biological membranes.


Assuntos
Flavobacteriaceae/química , Rodopsinas Microbianas/química , Rodopsinas Microbianas/efeitos da radiação , ATPase Trocadora de Sódio-Potássio/química , ATPase Trocadora de Sódio-Potássio/efeitos da radiação , Sítios de Ligação , Cristalografia , Elétrons , Transporte de Íons , Isomerismo , Lasers , Prótons , Teoria Quântica , Retinaldeído/química , Retinaldeído/metabolismo , Bases de Schiff/química , Sódio/metabolismo , Análise Espectral , Eletricidade Estática , Fatores de Tempo
19.
Nat Commun ; 11(1): 2773, 2020 06 02.
Artigo em Inglês | MEDLINE | ID: mdl-32487987

RESUMO

Cryo-electron microscopy is an essential tool for high-resolution structural studies of biological systems. This method relies on the use of phase contrast imaging at high defocus to improve information transfer at low spatial frequencies at the expense of higher spatial frequencies. Here we demonstrate that electron ptychography can recover the phase of the specimen with continuous information transfer across a wide range of the spatial frequency spectrum, with improved transfer at lower spatial frequencies, and as such is more efficient for phase recovery than conventional phase contrast imaging. We further show that the method can be used to study frozen-hydrated specimens of rotavirus double-layered particles and HIV-1 virus-like particles under low-dose conditions (5.7 e/Å2) and heterogeneous objects in an Adenovirus-infected cell over large fields of view (1.14 × 1.14 µm), thus making it suitable for studies of many biologically important structures.


Assuntos
Microscopia Crioeletrônica/métodos , Processamento de Imagem Assistida por Computador/métodos , Microscopia Crioeletrônica/instrumentação , Elétrons , HIV-1 , Microscopia Eletrônica de Transmissão/métodos , Microscopia de Contraste de Fase/métodos , Modelos Teóricos , Vírion/ultraestrutura
20.
Nat Commun ; 11(1): 2827, 2020 06 04.
Artigo em Inglês | MEDLINE | ID: mdl-32499507

RESUMO

Understanding the connection between the motion of the nuclei in a molecule and the rearrangement of its electrons lies at the heart of chemistry. While many experimental methods have been developed to probe either the electronic or the nuclear structure on the timescale of atomic motion, very few have been able to capture both these changes in concert. Here, we use time-resolved photoelectron imaging to probe the isomerisation coordinate on the excited state of an isolated model chromophore anion of the photoactive yellow protein. By probing both the electronic structure changes as well as nuclear dynamics, we are able to uniquely measure isomerisation about a specific bond. Our results demonstrate that the photoelectron signal dispersed in time, energy and angle combined with calculations can track the evolution of both electronic and geometric structure along the adiabatic state, which in turn defines that chemical transformation.


Assuntos
Proteínas de Bactérias/química , Elétrons , Fotorreceptores Microbianos/química , Anisotropia , Isomerismo , Fatores de Tempo
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