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1.
PLoS One ; 15(8): e0236226, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32866160

RESUMO

Amine oxidases (AOs) including copper containing amine oxidases (CuAOs) and FAD-dependent polyamine oxidases (PAOs) are associated with polyamine catabolism in the peroxisome, apoplast and cytoplasm and play an essential role in growth and developmental processes and response to biotic and abiotic stresses. Here, we identified PAO genes in common wheat (Triticum aestivum), T. urartu and Aegilops tauschii and reported the genome organization, evolutionary features and expression profiles of the wheat PAO genes (TaPAO). Expression analysis using publicly available RNASeq data showed that TaPAO genes are expressed redundantly in various tissues and developmental stages. A large percentage of TaPAOs respond significantly to abiotic stresses, especially temperature (i.e. heat and cold stress). Some TaPAOs were also involved in response to other stresses such as powdery mildew, stripe rust and Fusarium infection. Overall, TaPAOs may have various functions in stress tolerances responses, and play vital roles in different tissues and developmental stages. Our results provided a reference for further functional investigation of TaPAO proteins.


Assuntos
Resposta ao Choque Frio/genética , Oxirredutases atuantes sobre Doadores de Grupo CH-NH/genética , Proteínas de Plantas/genética , Termotolerância/genética , Triticum/genética , Aegilops/enzimologia , Aegilops/genética , Processamento Alternativo , Sequência de Aminoácidos , Conjuntos de Dados como Assunto , Evolução Molecular , Perfilação da Expressão Gênica , Regulação da Expressão Gênica no Desenvolvimento , Regulação da Expressão Gênica de Plantas , Genes de Plantas , Genoma de Planta , Estudo de Associação Genômica Ampla , Cadeias de Markov , Modelos Genéticos , Peso Molecular , Família Multigênica , Oxirredutases atuantes sobre Doadores de Grupo CH-NH/química , Oxirredutases atuantes sobre Doadores de Grupo CH-NH/metabolismo , Filogenia , Proteínas de Plantas/química , Proteínas de Plantas/metabolismo , Domínios Proteicos/genética , RNA-Seq , Alinhamento de Sequência , Triticum/enzimologia
2.
Mar Pollut Bull ; 159: 111480, 2020 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-32738639

RESUMO

Batch experiments were conducted to study the migration behavior of arsenic (As) and iron (bivalent, trivalent, and total Fe) of the presence of the low molecular weight organic acids (LMWOAs) citric acid, malic acid, and oxalic acid in As-enriched mangrove sediments. The results for supernatant As/Fe species were significant according to each LMWOA treatment. Significant non-linear correlations were found among As level, pH, and acid dose based on our predictive model. The capacity of LMWOAs to mobilize As/Fe species followed the order of citric acid > malic acid/oxalic acid. The supernatant As correlated positively with the LMWOAs dose and negatively correlated with the pH. As migration was affected by acid strength, the number of carboxyl groups, the pH and levels of Fe compounds in the sediments. The results indicate that LMWOAs can potentially attenuate As contamination from mangrove sediment, allowing for a better understanding of As/Fe behavior in the rhizosphere.


Assuntos
Arsênico , Disponibilidade Biológica , Concentração de Íons de Hidrogênio , Peso Molecular , Compostos Orgânicos , Ácido Oxálico
3.
PLoS One ; 15(8): e0236164, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32760085

RESUMO

Hyaluronan (HA) is a nonsulfated glycosaminoglycan that has been widely used for biomedical applications. Here, we have analyzed the effect of HA on the rescue of primary cells under stress as well as its potential to recover muscle atrophy and validated the developed model in vitro using primary muscle cells derived from rats. The potentials of different HAs were elucidated through comparative analyses using pharmaceutical grade a) high (HHA) and b) low molecular weight (LHA) hyaluronans, c) hybrid cooperative complexes (HCC) of HA in three experimental set-ups. The cells were characterized based on the expression of myogenin, a muscle-specific biomarker, and the proliferation was analyzed using Time-Lapse Video Microscopy (TLVM). Cell viability in response to H2O2 challenge was evaluated by 3-[4,5-dimethylthiazole-2-yl]-2,5-diphenyltetrazolium bromide (MTT) assay, and the expression of the superoxide dismutase enzyme (SOD-2) was assessed by western blotting. Additionally, in order to establish an in vitro model of atrophy, muscle cells were treated with tumor necrosis factor-alpha (TNF-α), along with hyaluronans. The expression of Atrogin, MuRF-1, nuclear factor kappa-light-chain-enhancer of activated B-cells (NF-kB), and Forkhead-box-(Fox)-O-3 (FoxO3a) was evaluated by western blotting to elucidate the molecular mechanism of atrophy. The results showed that HCC and HHA increased cell proliferation by 1.15 and 2.3 folds in comparison to un-treated cells (control), respectively. Moreover, both pre- and post-treatments of HAs restored the cell viability, and the SOD-2 expression was found to be reduced by 1.5 fold in HA-treated cells as compared to the stressed condition. Specifically in atrophic stressed cells, HCC revealed a noteworthy beneficial effect on the myogenic biomarkers indicating that it could be used as a promising platform for tissue regeneration with specific attention to muscle cell protection against stressful agents.


Assuntos
Ácido Hialurônico/farmacologia , Fibras Musculares Esqueléticas/efeitos dos fármacos , Atrofia Muscular/terapia , Medicina Regenerativa/métodos , Animais , Proliferação de Células/efeitos dos fármacos , Sobrevivência Celular/efeitos dos fármacos , Meios de Cultura/metabolismo , Géis , Humanos , Ácido Hialurônico/química , Peróxido de Hidrogênio/toxicidade , Microscopia Intravital , Peso Molecular , Fibras Musculares Esqueléticas/patologia , Atrofia Muscular/patologia , Miogenina/análise , Miogenina/metabolismo , Estresse Oxidativo/efeitos dos fármacos , Cultura Primária de Células , Ratos , Superóxido Dismutase/análise , Superóxido Dismutase/metabolismo , Imagem com Lapso de Tempo , Fator de Necrose Tumoral alfa/metabolismo
4.
PLoS One ; 15(8): e0236212, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32797100

RESUMO

Although an impact of processing on immunogenicity of food proteins has clearly been demonstrated, the underlying mechanisms are still unclear. We applied 3 different processing methods: wet heating (60 °C) and low- or high-temperature (50 °C or 130 °C, respectively) dry-heating in absence or presence of reducing sugars, to ß-lactoglobulin (BLG), lysozyme and thyroglobulin, which represent dietary proteins with different pI or molecular weight. Uptake of the soluble fraction of the samples was tested in two types of, genetically homogeneous, antigen-presenting cells (macrophages and dendritic cells derived from THP-1 monocytes). This revealed a strong correlation between the uptake of the different protein samples by macrophages and dendritic cells, and confirmed the key role of hydrophobicity, over aggregation, in determining the uptake. Several uptake routes were shown to contribute to the uptake of BLG by macrophages. However, cytokine responses following exposure of macrophages to BLG samples were not related to the levels of uptake. Together, our results demonstrate that heat-treatment-induced increased hydrophobicity is the prime driving factor in uptake, but not in cytokine production, by THP-1 macrophages.


Assuntos
Citocinas/metabolismo , Células Dendríticas/imunologia , Proteínas na Dieta/imunologia , Macrófagos/imunologia , Receptores de Superfície Celular/metabolismo , Culinária , Células Dendríticas/metabolismo , Proteínas na Dieta/química , Proteínas na Dieta/metabolismo , Temperatura Alta , Humanos , Interações Hidrofóbicas e Hidrofílicas , Macrófagos/metabolismo , Peso Molecular , Células THP-1
5.
J Phys Chem Lett ; 11(17): 7267-7272, 2020 Sep 03.
Artigo em Inglês | MEDLINE | ID: mdl-32787337

RESUMO

The coronavirus disease pandemic caused by infection with the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has affected the global healthcare system. As low-molecular-weight drugs have high potential to completely match interactions with essential SARS-CoV-2 targets, we propose a strategy to identify such drugs using the fragment-based approach. Herein, using ligand- and protein-observed fragment screening approaches, we identified niacin and hit 1 binding to the catalytic pocket of the main protease (Mpro) of SARS-CoV-2, thereby modestly inhibiting the enzymatic activity of Mpro. We further searched for low-molecular-weight drugs containing niacin or hit 1 pharmacophores with enhanced inhibiting activity, e.g., carmofur, bendamustine, triclabendazole, emedastine, and omeprazole, in which omeprazole is the only one binding to the C-terminal domain of SARS-CoV-2 Mpro. Our study demonstrates that the fragment-based approach is a feasible strategy for identifying low-molecular-weight drugs against the SARS-CoV-2 and other potential targets lacking specific drugs.


Assuntos
Antivirais/farmacologia , Betacoronavirus/efeitos dos fármacos , Reposicionamento de Medicamentos , Peptídeo Hidrolases/metabolismo , Relação Dose-Resposta a Droga , Modelos Moleculares , Peso Molecular , Peptídeo Hidrolases/química , Domínios Proteicos
6.
Sci Total Environ ; 737: 140287, 2020 Oct 01.
Artigo em Inglês | MEDLINE | ID: mdl-32783864

RESUMO

To gain greater insights into impacts of bio-carriers on the fate and characteristics of soluble microbial products (SMPs) for mariculture wastewater treatment, the hybrid membrane bioreactor (HMBR) and conventional membrane bioreactor (CMBR) were investigated. Both protein and polysaccharide exhibited lower level in HMBR (8.95 ± 0.28 mg/L and 20.49 ± 1.3 mg/L for anoxic stage, 5.16 ± 0.22 mg/L and 17.85 ± 0.92 mg/L for aerobic stage) than CMBR (14.6 ± 0.68 mg/L and 28.3 ± 2.99 mg/L for anoxic stage, 10.53 ± 0.68 and 26.04 ± 3.15 mg/L for aerobic stage). Three-dimensional fluorescence excitation emission matrix (EEM) revealed bio-carriers reduced the production of aromatic protein-like components in anoxic and aerobic supernatant and caused a blue-shift of soluble microbial product in aerobic stage. Molecular weight (Mw) distribution indicated that bio-carriers ameliorated the excretion of biopolymer (Mw > 500 kDa) in anoxic supernatant and intermediate Mw fractions (20-500 kDa) in aerobic supernatant. Moreover, little changes were observed in SMPs with Mw < 3 kDa down the whole treatment process of both systems. Gas chromatography-mass spectrometry (GC-MS) demonstrated that the major SMPs were long-chain alkanes and aromatics in all units of both systems and fewer aromatics were detected in HMBR. For anoxic stage, more peaks were identified in the HMBR (138) than CMBR (115), while for aerobic stage, more compounds were observed in the CMBR (94) than HMBR (70). Over 50% of the compounds in the anoxic supernatant for the HMBR were the same as in the CMBR. And 27 compounds were the same in aerobic supernatant for the HMBR and CMBR. Fewer compounds in the HMBR effluent (52) was observed, compared to CMBR effluent (80). Approximately 25.7% of compounds in the aerobic stage of the HMBR were rejected by membrane, while this value decreased to 14.9% in the CMBR.


Assuntos
Eliminação de Resíduos Líquidos , Águas Residuárias , Reatores Biológicos , Membranas Artificiais , Peso Molecular
7.
J Chromatogr A ; 1625: 461282, 2020 Aug 16.
Artigo em Inglês | MEDLINE | ID: mdl-32709333

RESUMO

In recent years, core-shell silica particles (CSSPs) have been increasingly used for highly efficient separation at fast flow rates and relatively low back pressures in high-performance liquid chromatography (HPLC). However, material synthesis techniques for producing CSSPs economically in batch processes remain elusive. In this report, a practical and straightforward method for the preparation of CSSPs is presented. By refluxing freshly prepared nonporous silica particles in ammonia-water solution in the presence of poly(diallyldimethylammonium chloride) at 70-100 °C, CSSPs with shell thicknesses of up to 300 nm and pore sizes from 8 to 25 nm were easily prepared. The effects of the synthetic conditions on the shell thickness, surface area, and pore size were investigated in detail, and the method reproducibility was evaluated in scale-up experiments. A mechanism of CSSP formation is also proposed. The CSSPs were characterized via scanning electron microscopy, transmission electron microscopy, laser particle size (dynamic light scattering) analysis, and nitrogen adsorption and desorption experiments. The synthesized 3.4-µm CSSPs were functionalized with dimethyloctadecylchlorosilane and used as an HPLC packing material, exhibiting excellent separation performance for both small molecules and large biomolecules. In summary, we report the simplest method developed thus far for the preparation of monodisperse core-shell silica particles suitable for HPLC column packing.


Assuntos
Cromatografia Líquida de Alta Pressão/métodos , Sílica Gel/química , Adsorção , Amônia/análise , Difusão Dinâmica da Luz , Microesferas , Peso Molecular , Nanopartículas/química , Nanopartículas/ultraestrutura , Tamanho da Partícula , Polietilenos/química , Porosidade , Compostos de Amônio Quaternário/química , Reprodutibilidade dos Testes , Temperatura , Fatores de Tempo
8.
J Chromatogr A ; 1625: 461285, 2020 Aug 16.
Artigo em Inglês | MEDLINE | ID: mdl-32709335

RESUMO

An experimental methodology for the determination of the obstruction factor in the expression for mesopore diffusion in Zorbax Eclipse Plus C18 reversed-phase particles is proposed. The method uses peak parking experiments conducted on particles that were previously stripped of their stationary phase by flushing the column with trifluoroacetic acid at a temperature of 60°C. Further using pure organic solvents as the mobile phase, any potential retention or surface diffusion effect is omitted. To avoid interference between the parked peaks and baseline disturbances typically occurring when switching on and off the flow, peak parking experiments were carried out in a set-up wherein two identical columns were used in parallel. This set-up allowed to maintain the flow through the detector at all times, by redirecting the flow from one column to the other during the peak parking experiments. Several tracer molecules (ionic and deuterated tracers) were compared and it was found that the use of deuterated molecules provides the best possible coverage of the accessible space of the mesopore volume. Interpreting the peak parking responses obtained with these tracers with a model based on the effective medium theory (EMT) subsequently provided an estimate of the value of the mesopore diffusion obstruction factor γmp. Taking the well-established pore hindrance factor F(λ) correction into account, the obtained experimental γmp-values are more in agreement with the tortuous and constricted diffusion paths one can expect in the void space within a structure resembling a monolithic skeleton with tetrahedral connectivity rather than in the void space formed by a packing of nanospheres. This is also more in line with the measured internal porosity values lying around εpz=0.5, whereas a packing of nanospheres would rather correspond to an Îµpz of 0.4. As such, the presented protocol provides a means to infer the internal mesopore structure of reversed-phase particles.


Assuntos
Cromatografia de Fase Reversa/métodos , Modelos Químicos , Cromatografia Líquida , Difusão , Peso Molecular , Porosidade , Solventes/química
9.
Ecotoxicol Environ Saf ; 203: 110983, 2020 Oct 15.
Artigo em Inglês | MEDLINE | ID: mdl-32678760

RESUMO

Chelating agents have been considered as an important phytoremediation strategy to enhance heavy metal extraction from contaminated soil. A pot experiment was conducted to explore the effects of low molecular weight organic acids (LMWOAs) on the phytoremediation efficiency of copper (Cu) by castor bean, and soil enzyme activities. Results indicated that the addition of all the three kinds of LMWOAs (citric, tartaric, oxalic acids) did not decrease the biomass of castor bean, despite the fact they reduced the concentration of chlorophyll-a in leaves compared to the control. The Cu concentrations in the roots and shoots significantly increased by 6-106% and 5-148%, respectively, in the LMWOAs treatments so that the total accumulation of Cu by whole plants in all the LMWOAs treatments increased by 21-189% in comparison with the control. The values of the translocation factor (TF) and bio-concentration factor (BCF) of Cu in castor bean also rose following the addition of LMWOAs, indicating that the LMWOAs enhanced the uptake and transportation of Cu. Moreover, the application of LMWOAs did not significantly change the soil pH but significantly increased the activity of soil enzymes (urease, catalase, and alkaline phosphatase). The addition of exogenous LMWOAs increased the available Cu significantly in the soil, thus promoted the phytoextraction efficiency of Cu by castor bean. These results will provide some new insights into the practical use of LMWOAs for the phytoremediation of heavy-metal-contaminated soil employing castor bean.


Assuntos
Bioacumulação , Semente de Rícino/metabolismo , Quelantes/química , Cobre/metabolismo , Compostos Orgânicos/química , Poluentes do Solo/metabolismo , Solo/química , Ácidos/administração & dosagem , Ácidos/química , Biodegradação Ambiental , Semente de Rícino/efeitos dos fármacos , Quelantes/administração & dosagem , Peso Molecular , Compostos Orgânicos/administração & dosagem
10.
Chemosphere ; 255: 127055, 2020 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-32679637

RESUMO

Nanofiltration concentrated landfill leachate (NCLL) is produced during the integration process of biodegradation and nanofiltration, containing a large amount of recalcitrant dissolved organic matter (DOM). In this work, electrocatalytic oxidation technology was employed to degrade DOM in NCLL and spectroscopic technology was applied to explore the structural changes. The results showed that under the optimal experimental condition (pH = 2.0, NaCl concentration = 0.7%, Fe2(SO4)3 concentration = 0.8%, the retention time = 6 h), the removal rates of COD, TOC, and UV254 were 99.0%, 57.4%, 99.3% respectively. Ultraviolet-Visible (UV-Vis) spectral analysis showed that aromatic CC can be effectively degraded by electrocatalytic oxidation, resulting in decreases of aromaticity and molecular weight in NCLL. Two fluorescent components (terrestrial humic-like substances and fulvic-like substances) were identified in NCLL by parallel factor analysis, which can be effectively removed by electrocatalytic oxidation with removal rates of 99.9% and 90.5%, respectively. In addition, through two-dimensional correlation spectroscopic analysis, the sequence of structural changes of the DOM in NCLL was confirmed: unsaturated double bonds → fulvic-like components/aromatic structures → terrestrial humic-like components. These spectral characterization techniques can provide a deep understanding of the degradation pathways of DOM and provide new insights for the treatment of NCLL.


Assuntos
Poluentes Químicos da Água/química , Biodegradação Ambiental , Substâncias Húmicas/análise , Peso Molecular , Oxirredução , Poluentes Químicos da Água/análise
11.
J Chromatogr A ; 1625: 461334, 2020 Aug 16.
Artigo em Inglês | MEDLINE | ID: mdl-32709359

RESUMO

A comprehensive study on the chiral separation of bupivacaine, mepivacaine, prilocaine and propanocaine with eight commercial polysaccharide-based chiral stationary phases (CSPs) in reversed phase conditions compatible with MS detection is performed. Methanol and acetonitrile are used as organic modifiers. Retention and resolution values obtained for each compound in the different CSPs and mobile phases are compared. The polysaccharide-based CSPs tested present different enantioselectivity towards the analytes. From the results, the experimental conditions for determining the enantiomers of bupivacaine, mepivacaine, prilocaine and propanocaine in saline aqueous samples using MS detection are used, for the first time, to perform an enantioselective biodegradability study.


Assuntos
Anestésicos Locais/isolamento & purificação , Cromatografia de Fase Reversa/métodos , Polissacarídeos/química , Acetonitrilos/química , Biodegradação Ambiental , Cromatografia Líquida de Alta Pressão , Metanol/química , Peso Molecular , Estereoisomerismo , Água/química
12.
Nat Protoc ; 15(8): 2728-2757, 2020 08.
Artigo em Inglês | MEDLINE | ID: mdl-32669637

RESUMO

Although organic nanomaterials and inorganic nanoparticles possess inherent flexibility, facilitating functional modification, increased intracellular uptake and controllable drug release, their underlying cytotoxicity and lack of specificity still cause safety concerns. Owing to their merits, which include natural biocompatibility, structural stability, unsurpassed programmability, ease of internalization and editable functionality, tetrahedral DNA nanostructures show promising potential as an alternative vehicle for drug delivery and biomedical treatment. Here, we describe the design, fabrication, purification, characterization and potential biomedical applications of a self-assembling tetrahedral DNA nanostructure (TDN)-based multifunctional delivery system. First, relying on Watson-Crick base pairing, four single DNA strands form a simple and typical pyramid structure via one hybridization step. Then, the protocol details four different modification approaches, including replacing a short sequence of a single DNA strand by an antisense peptide nucleic acid, appending an aptamer to the vertex, direct incubation with small-molecular-weight drugs such as paclitaxel and wogonin and coating with protective agents such as cationic polymers. These modified TDN-based complexes promote the intracellular uptake and biostability of the delivered molecules, and show promise in the fields of targeted therapy, antibacterial and anticancer treatment and tissue regeneration. The entire duration of assembly and characterization depends on the cargo type and modification method, which takes from 2 h to 3 d.


Assuntos
DNA/química , Portadores de Fármacos/química , Desenho de Fármacos , Nanoestruturas/química , Antibacterianos/química , Antibacterianos/farmacologia , Antineoplásicos/química , Antineoplásicos/farmacologia , DNA/farmacologia , Regeneração Tecidual Guiada , Humanos , Células MCF-7 , Peso Molecular , Polietilenoimina/química
13.
PLoS One ; 15(7): e0236190, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32702068

RESUMO

The quality of sourdough bread mainly depends on metabolic activities of lactic acid bacteria (LAB). The exopolysaccharides (EPS) produced by LAB affect positively the technological and nutritional properties of the bread, while phytases improve the bioavailability of the minerals by reducing its phytate content. In the present study, a pool of 152 cereal-sourced LAB were screened for production of phytases and EPS for potential use as sourdough starter cultures for the baking industry. There was large heterogeneity in the phytase activity observed among the screened isolates, with 95% showing the ability to degrade sodium phytate on plates containing Sourdough Simulation Medium (SSM). The isolates Lactobacillus brevis LD65 and Lactobacillus plantarum PB241 showed the highest enzymatic activity, while the isolates ascribed to Weissella confusa were characterized by low or no phytase activity. Only 18% of the screened LAB produced EPS, which were distinguished as ropy or mucoid phenotypes on SSM supplemented with sucrose. Almost all the EPS producers carried one or more genes (epsD/E and/or epsA) involved in the production of heteropolysaccharides (HePS), whereas the isolates ascribed to Leuconostoc citreum and W. confusa carried genes involved in the production of both HePS and homopolysaccharides (HoPS). Monosaccharide composition analysis of the EPS produced by a selected subset of isolates revealed that all the HePS included glucose, mannose, and galactose, though at different ratios. Furthermore, a few isolates ascribed to L. citreum and W. confusa and carrying the gtf gene produced ß-glucans after fermentation in an ad hoc formulated barley flour medium. Based on the overall results collected, a subset of candidate sourdough starter cultures for the baking industry was selected, including Lb. brevis LD66 and L. citreum PB220, which showed high phytase activity and positive EPS production.


Assuntos
Pão/microbiologia , Grão Comestível/microbiologia , Microbiologia de Alimentos , Indústrias , Lactobacillales/isolamento & purificação , 6-Fitase/metabolismo , Fermentação , Farinha , Genes Bacterianos , Hordeum , Lactobacillales/genética , Peso Molecular , Monossacarídeos/análise , Polissacarídeos Bacterianos/metabolismo , RNA Ribossômico 16S/genética , Especificidade da Espécie , beta-Glucanas/análise
14.
Chemosphere ; 260: 127535, 2020 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-32683026

RESUMO

Integrated ultrafiltration (UF) membrane technology has attracted extensive attention in drinking water treatment due to its excellent performance and small footprint. However, membrane modules normally are static in membrane tanks, which cause a gradual increase in the cake layer thickness over time, thus resulting in severe membrane fouling. To overcome this shortcoming, we report an effective strategy to regulate cake layer thickness by rotating the membrane module in the presence of flocs. The results showed that the cake layer thickness can be effectively reduced because of the floc looseness, resulting in the alleviation of membrane fouling. The higher the module rotation speed, the higher the flow velocity in the membrane tank and the larger the shearing force on the cake layer surface. As a result, the membrane fouling was considerably mitigated, and it was interesting that the pollutant removal efficiency was hardly influenced. With module rotation, we found that acid solutions displayed a better performance in removing pollutants (even low molecular weight pollutants) and alleviating membrane fouling compared to the alkaline conditions because of the smaller floc size, larger floc specific surface area, and higher floc positive charge. Additionally, an excellent UF membrane performance was also observed with the raw water taken from the South-North water in China. Collectively, this study demonstrated that floc-based cake layers can be effectively regulated with module rotation, which has a great potential in drinking water treatment application, particularly in small water plants.


Assuntos
Ultrafiltração/métodos , Purificação da Água/métodos , China , Membranas Artificiais , Peso Molecular
15.
Sci Total Environ ; 742: 140416, 2020 Nov 10.
Artigo em Inglês | MEDLINE | ID: mdl-32721714

RESUMO

A crucial mechanism for the application of biochar in soil improvement is the direct release of nutrients from biochar. Low molecular weight organic acids (LMWOAs) ubiquitously exist in soil. However, the mechanism of LMWOAs-mediated release of nutrients from biochars remains little known. Ten biochars with different mineral element stoichiometric ratio were produced, and four LMWOAs [acetic (HAc), glycolic (GA), tartaric (TA), and citric acids (CA)] were employed, to enunciate the influence mechanism of LMWOAs on the release of phosphorus and potassium from biochar. The results showed that HAc suppressed the release of P from biochars, while TA and CA facilitated the release of P from biochars with high ratios of polyvalent metals to P. A new mechanism was proposed that the deprotonated HAc combined with the dissolved HPO42- or H2PO4- to form a complex through hydrogen bond and cation bridging. The hydrophobic methyl group of HAc was exposed outside of the complex, which decreased the water-solubility of phosphate. Meanwhile, a high ratio of polyvalent metals to P benefited more P to combine with polyvalent metals, which decreased the water-solubility of P, but the deprotonated TA and CA are polyvalent anions that could substitute this part of P by anion exchange. Also, LMWOAs promoted the release of K from biochars with low K/(P + S) ratios, possibly due to unionized carboxyl of LMWOAs served as a hydrogen bond donor to displace K out of biochars. This study gives a deep understanding of the fate of biochar originated nutrients response to LMWOAs.


Assuntos
Fósforo , Poluentes do Solo/análise , Carvão Vegetal , Minerais , Peso Molecular , Potássio , Solo
16.
Sci Total Environ ; 742: 140535, 2020 Nov 10.
Artigo em Inglês | MEDLINE | ID: mdl-32721724

RESUMO

Many studies have shown that introducing N2-fixing trees (e.g. Acacia mangium) in eucalypt plantations can increase soil N availability as a result of biological N2 fixation and faster N cycling. Some studies have also shown improved eucalypt P nutrition. However, the effects of N2-fixing trees on P cycling in tropical soils remain poorly understood and site-dependent. Our study aimed to assess the effects of planting A. mangium trees in areas managed over several decades with eucalypt plantations on soil organic P (Po) forms and low molecular weight organic acids (LMWOAs). Soil samples were collected from two tropical sites, one in Brazil and one in the Congo. Five different treatments were sampled at each site: monospecific acacia, monospecific eucalypt, below acacias in mixed-species, below eucalypts in mixed-species as well as native vegetation. Po forms and LMWOAs were identified in sodium hydroxide soil extracts using ion chromatography and relationships between these data and available P were determined. At both sites, the concentrations of most Po forms and LMWOAs were different between native ecosystems and monospecific eucalypt and acacia plots. Also, patterns of Po and LMWOAs were clearly separated, with glucose-6-P found mainly under acacia and phytate and oxalate mainly under eucalypt. Despite the strongest changes occurred at site with a higher N2 fixation and root development, acacia introduction was able to change the profile of organic P and LMWOAs in <10 years. The variations between available Pi, Po and LMWOA forms showed that P cycling was dominated by different processes at each site, that are rather physicochemical (via Pi desorption after LMWOAs release) at Itatinga and biological (via organic P mineralization) at Kissoko. Specific patterns of Po and LMWOAs forms found in soil sampled under acacia or eucalypt would therefore explain the effect of acacia introduction in both sites.


Assuntos
Acacia , Árvores , Brasil , Ecossistema , Peso Molecular , Solo
17.
J Biosci Bioeng ; 130(3): 283-289, 2020 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-32507385

RESUMO

A novel exopolysaccharide (EPS) from Paenibacillus polymyxa PYQ1 was extracted, well purified and characterized. This EPS was homogeneous glucomannan-type polysaccharide with the average molecular weight of 4.38 × 106 Da. Structural characterization indicated that the monosaccharides of EPS were pyranoses connected by ß-glycosidic linkages. Furthermore, our results showed the protective benefits of EPS against UVC induced cytotoxicity in HaCaT cells through scavenging excessive reactive oxygen species, mitigating the decrease of mitochondrial membrane potential, improving catalase activity and maintaining membrane integrity. Taken together, this study qualified EPS from P. polymyxa PYQ1 was a promising natural polymer which worth further investigation as a skin-care agent.


Assuntos
Citoproteção/efeitos dos fármacos , Paenibacillus polymyxa/metabolismo , Polissacarídeos Bacterianos/isolamento & purificação , Polissacarídeos Bacterianos/farmacologia , Raios Ultravioleta/efeitos adversos , Catalase/metabolismo , Potencial da Membrana Mitocondrial/efeitos dos fármacos , Potencial da Membrana Mitocondrial/efeitos da radiação , Peso Molecular , Monossacarídeos/análise , Polissacarídeos Bacterianos/biossíntese , Polissacarídeos Bacterianos/química , Espécies Reativas de Oxigênio/metabolismo
18.
J Biosci Bioeng ; 130(3): 272-282, 2020 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-32546403

RESUMO

The industrially relevant biopolymer poly-γ-glutamic acid (γ-PGA) is commonly synthesized using glycerol, citrate, and glutamic acid as carbon sources. In this study, two strains capable of utilizing glucose as sole carbon source for γ-PGA synthesis were constructed. Efficient γ-PGA production was achieved with derivatives of the well-investigated laboratory strain Bacillus subtilis 168, by replacing the native promoter of the PGA synthetase operon with the strong constitutive promoter Pveg or with the xylose-inducible promoter Pxyl. The carbon yield for γ-PGA increased by 129% to 0.131 C-mol C-mol-1 when using glucose as the sole substrate compared to the conventional carbon source mixture glycerol, citrate, and glutamic acid. The characterization of the produced γ-PGA demonstrated a time-dependent molecular weight of 1180-1850 kDa and a d-glutamic acid monomer content of 49-62%. To elucidate the consequences of γ-PGA production, we characterized the engineered strain by metabolomics. While the metabolite concentrations in the TCA cycle leading up to 2-oxoglutarate decreased in γ-PGA producer strains, the glutamic acid concentration was constant, despite the drastic increase in glutamic acid demand. The results are discussed in the context of metabolic regulation and future metabolic engineering strategies to enhance precursor supply for γ-PGA synthesis from glucose.


Assuntos
Bacillus subtilis/metabolismo , Glucose/metabolismo , Metabolômica , Ácido Poliglutâmico/análogos & derivados , Bacillus subtilis/genética , Ciclo do Ácido Cítrico , Engenharia Metabólica , Peso Molecular , Óperon/genética , Ácido Poliglutâmico/biossíntese , Ácido Poliglutâmico/química
19.
Chemosphere ; 258: 127278, 2020 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-32554006

RESUMO

Syringe filters are widely used for sample pretreatments in laboratories. This study found that, surprisingly, these filters can leak dissolved organic carbon (DOC) that can potentially serve as precursors of disinfection by-products (DBPs). Nine common types of syringe filters were assessed. The results showed that the DOC of ultrapure water increased after syringe filtration. The DOC shed from filter membranes was characterized, whose spectra showed that the main compounds exhibited a low apparent molecular weight. Five classes of DBPs were investigated including trihalomethanes, haloacetaldehydes, haloacetonitriles, haloacetamides and halonitromethanes, among which trichloromethane (TCM), dichloroacetaldehyde (DCAL), trichloroacetaldehyde (TCAL), dichloroacetonitrile (DCAN), and trichloronitromethane (TCNM) were principally detected. The DBP formation was affected by chlorination time and membrane types. In general, the use of the poly vinylidene fluoride membrane resulted in the highest formation of TCM and TCAL, whereas nylon and mixed cellulose esters membranes contributed significantly to the formation of DCAN and TCNM, respectively. The shedding DOC and the formation of TCM, DCAL and TCAL from filter membranes were mitigated effectively by pre-washing; however, the contribution of membrane leakage to DCAN and TCNM formation was still notable, even with a pre-wash volume of 50 mL. When unwashed syringe filters were used for a real water sample, the DBP formation increased by up to 73.2% compared to the pre-washed ones; particularly for TCNM it was always over 15%. Therefore, for better quality control in laboratories, more attention should be paid to the syringe filters during sample pre-treatments, particularly when DBP formation is being investigated.


Assuntos
Desinfetantes/análise , Desinfetantes/química , Desinfecção/métodos , Membranas Artificiais , Acetonitrilos/análise , Acetonitrilos/química , Clorofórmio/análise , Clorofórmio/química , Cromatografia em Gel , Filtração/instrumentação , Filtração/métodos , Halogenação , Hidrocarbonetos Clorados/análise , Hidrocarbonetos Clorados/química , Peso Molecular , Trialometanos/análise , Trialometanos/química , Poluentes Químicos da Água/análise , Poluentes Químicos da Água/química , Purificação da Água/métodos
20.
PLoS One ; 15(6): e0234958, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32574185

RESUMO

Proteases play an essential role in living organisms and represent one of the largest groups of industrial enzymes. The aim of this work was recombinant production and characterization of a newly identified thermostable protease 1147 from thermophilum indigenous Cohnella sp. A01. Phylogenetic tree analysis showed that protease 1147 is closely related to the cysteine proteases from DJ-1/ThiJ/PfpI superfamily, with the conserved catalytic tetrad. Structural prediction using MODELLER 9v7 indicated that protease 1147 has an overall α/ß sandwich tertiary structure. The gene of protease 1147 was cloned and expressed in Escherichia coli (E. coli) BL21. The recombinant protease 1147 appeared as a homogenous band of 18 kDa in SDS-PAGE, which was verified by western blot and zymography. The recombinant protein was purified with a yield of approximately 88% in a single step using Ni-NTA affinity chromatography. Furthermore, a rapid one-step thermal shock procedure was successfully implemented to purify the protein with a yield of 73%. Using casein as the substrate, Km, and kcat, kcat/Km values of 13.72 mM, 3.143 × 10-3 (s-1), and 0.381 (M-1 S-1) were obtained, respectively. The maximum protease activity was detected at pH = 7 and 60°C with the inactivation rate constant (kin) of 2.10 × 10-3 (m-1), and half-life (t1/2) of 330.07 min. Protease 1147 exhibited excellent stability to organic solvent, metal ions, and 1% SDS. The protease activity was significantly enhanced by Tween 20 and Tween 80 and suppressed by cysteine protease specific inhibitors. Docking results and molecular dynamics (MD) simulation revealed that Tween 20 interacted with protease 1147 via hydrogen bonds and made the structure more stable. CD and fluorescence spectra indicated structural changes taking place at 100°C, very basic and acidic pH, and in the presence of Tween 20. These properties make this newly characterized protease a potential candidate for various biotechnological applications.


Assuntos
Bacillales/enzimologia , Proteínas de Bactérias/química , Peptídeo Hidrolases/química , Proteínas de Bactérias/isolamento & purificação , Proteínas de Bactérias/ultraestrutura , Clonagem Molecular , Ensaios Enzimáticos , Estabilidade Enzimática , Concentração de Íons de Hidrogênio , Simulação de Dinâmica Molecular , Peso Molecular , Peptídeo Hidrolases/isolamento & purificação , Peptídeo Hidrolases/ultraestrutura , Proteínas Recombinantes/química , Proteínas Recombinantes/isolamento & purificação , Proteínas Recombinantes/ultraestrutura , Especificidade por Substrato
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