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1.
Int J Mol Sci ; 23(23)2022 Nov 29.
Artigo em Inglês | MEDLINE | ID: mdl-36499252

RESUMO

In this study, a novel MXene (Ti3C2Tx)-based nanocarrier was developed for drug delivery. MXene nanosheets were functionalized with 3, 3'-diselanediyldipropionic acid (DSeDPA), followed by grafting doxorubicin (DOX) as a model drug to the surface of functionalized MXene nanosheets (MXene-Se-DOX). The nanosheets were characterized using scanning electron microscopy, atomic force microscopy (AFM), transmission electron microscopy, energy-dispersive X-ray spectroscopy (EDX), nuclear magnetic resonance spectroscopy, Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, X-ray diffraction, and zeta potential techniques. The drug-loading capacity (17.95%) and encapsulation efficiency (41.66%) were determined using ultraviolet-visible spectroscopy. The lateral size and thickness of the MXene nanosheets measured using AFM were 200 nm and 1.5 nm, respectively. The drug release behavior of the MXene-Se-DOX nanosheets was evaluated under different medium conditions, and the nanosheets demonstrated outstanding dual (reactive oxygen species (ROS)- and pH-) responsive properties. Furthermore, the MXene-Se-DOX nanosheets exhibited excellent antibacterial activity against both Gram-negative E. coli and Gram-positive B. subtilis.


Assuntos
Sistemas de Liberação de Medicamentos , Escherichia coli , Doxorrubicina/farmacologia , Doxorrubicina/química , Antibacterianos/farmacologia , Antibacterianos/química , Liberação Controlada de Fármacos , Espectroscopia de Infravermelho com Transformada de Fourier , Concentração de Íons de Hidrogênio
2.
Metab Eng ; 53: 48-58, 2019 05.
Artigo em Inglês | MEDLINE | ID: mdl-30738917

RESUMO

3-Hydroxypropionic acid (3-HP) is an important platform chemical, but its toxic effect at high concentrations (> 200 mM) is a serious challenge for commercial production. In this study, a highly 3-HP-tolerant strain of Escherichia coli W (tolerance concentration: 400 mM in M9 minimal medium and 800 mM when yeast extract was added) was developed by adaptive laboratory evolution (ALE) with glycerol as the carbon source. Genome analysis of the adapted strain (designated as E. coli WA) indicated the presence of mutations in 13 genes, including glpK (glycerol kinase) and yieP (a less-studied global regulator). The mutant GlpK (K67T) exhibited a higher activity than the wild-type enzyme, but it was not beneficial for 3-HP production due to its causing carbon overflow metabolism. Interestingly, among the other 12 genes, the mutation in yieP alone was almost fully responsible for the improved tolerance to 3-HP. When the mutant yieP was substituted with the wild-type counterpart, the adapted E. coli WA strain completely lost its tolerance to 3-HP, showing a tolerance similar to the wild-type W strain. Deletion of yieP conferred 3-HP tolerance to several other E. coli strains including K-12 W3110, K-12 MG1655, and B except BL21 (DE3). The E. coli WA with wild-type glpK showed, as compared with its parental strain, better 3-HP production, indicating that improved tolerance is beneficial for 3-HP production.


Assuntos
Tolerância a Medicamentos , Proteínas de Escherichia coli , Escherichia coli , Glicerol Quinase , Ácido Láctico/análogos & derivados , Mutação , Fatores de Transcrição , Escherichia coli/genética , Escherichia coli/metabolismo , Proteínas de Escherichia coli/genética , Proteínas de Escherichia coli/metabolismo , Glicerol Quinase/genética , Glicerol Quinase/metabolismo , Ácido Láctico/farmacologia , Fatores de Transcrição/genética , Fatores de Transcrição/metabolismo
3.
J Ind Microbiol Biotechnol ; 43(10): 1397-403, 2016 10.
Artigo em Inglês | MEDLINE | ID: mdl-27412724

RESUMO

Glycerol is an attractive feedstock for bioenergy and bioconversion processes but its use in microbial fuel cells (MFCs) for electrical energy recovery has not been investigated extensively. This study compared the glycerol uptake and electricity generation of a co-culture of Shewanella oneidensis MR-1 and Klebsiella pneumonia J2B in a MFC with that of a single species inoculated counterpart. Glycerol was metabolized successfully in the co-culture MFC (MFC-J&M) with simultaneous electricity production but it was not utilized in the MR-1 only MFC (MFC-M). A current density of 10 mA/m(2) was obtained while acidic byproducts (lactate and acetate) were consumed in the co-culture MFC, whereas they are accumulated in the J2B-only MFC (MFC-J). MR-1 was distributed mainly on the electrode in MFC-J&M, whereas most of the J2B was observed in the suspension in the MFC-J reactor, indicating that the co-culture of both strains provides an ecological driving force for glycerol utilization using the electrode as an electron acceptor. This suggests that a co-culture MFC can be applied to electrical energy recovery from glycerol, which was previously known as a refractory substrate in a bioelectrochemical system.


Assuntos
Fontes de Energia Bioelétrica , Glicerol/metabolismo , Klebsiella pneumoniae/fisiologia , Shewanella/fisiologia , Técnicas de Cocultura , Eletrodos , Shewanella/metabolismo
4.
Environ Technol ; 35(9-12): 1491-8, 2014.
Artigo em Inglês | MEDLINE | ID: mdl-24701948

RESUMO

A freshwater microalga Chlamydomonas mexicana was grown on municipal wastewater with different levels of salinity up to 400 mmol/L NaCl, and the biochemical properties were characterized after 10 days of cultivation. C. mexicana showed the higher specific growth rates for 100 and 200mmol/L NaCl. Nitrogen was completely removed within 10 days as a result of algal growth promoted by the addition of 200-400 mmol/L NaCl. Phosphorus removal increased from 77-84% as the concentration of NaCI increased from 100 to 400 mmol/L. The highest removal of total inorganic carbon (66%) was obtained with the addition of 200 mmol/L NaCl. The lipid content increased from 17% to 38% as the concentration of NaCl increased from 0 to 400mmol/L. The total fatty acid content and glycerol yield of C. mexicana increased 1.8- and 4-fold in wastewater amended with NaCl, respectively. Fatty acids accumulated in the algal biomass were mainly composed of palmitic (27-29%), y-linolenic (27-30%), and linolelaidic acids (16-18%). The optimal condition for fatty acids production in C. mexicana was observed when the municipal wastewater was amended with 100-200 mmol/L NaCl with a simultaneous removal of nutrients.


Assuntos
Biocombustíveis , Chlamydomonas/crescimento & desenvolvimento , Salinidade , Águas Residuárias/microbiologia , Biomassa , Chlamydomonas/metabolismo , Ácidos Graxos/metabolismo , Glicerol/metabolismo , Metabolismo dos Lipídeos , Cloreto de Sódio
5.
Front Microbiol ; 15: 1438758, 2024.
Artigo em Inglês | MEDLINE | ID: mdl-39268540

RESUMO

Fossil resources must be replaced by renewable resources in production systems to mitigate green-house gas emissions and combat climate change. Electro-fermentation utilizes a bioelectrochemical system (BES) to valorize industrial and municipal waste. Current electro-fermentation research is mainly focused on microbial electrosynthesis using CO2 for producing commodity chemicals and replacing petroleum-based infrastructures. However, slow production rates and low titers of metabolites during CO2-based microbial electrosynthesis impede its implementation to the real application in the near future. On the other hand, CO is a highly reactive gas and an abundant feedstock discharged from fossil fuel-based industry. Here, we investigated CO and CO2 electro-fermentation, using a CO-enriched culture. Fresh cow fecal waste was enriched under an atmosphere of 50% CO and 20% CO2 in N2 using serial cultivation. The CO-enriched culture was dominated by Clostridium autoethanogenum (≥89%) and showed electro-activity in a BES reactor with CO2 sparging. When 50% CO was included in the 20% CO2 gas with 10 mA applied current, acetate and ethanol were produced up to 12.9 ± 2.7 mM and 2.7 ± 1.1 mM, respectively. The coulombic efficiency was estimated to 148% ± 8% without an electron mediator. At 25 mA, the culture showed faster initial growth and acetate production but no ethanol production, and only at 86% ± 4% coulombic efficiency. The maximum optical density (OD) of 10 mA and 25 mA reactors were 0.29 ± 0.07 and 0.41 ± 0.03, respectively, whereas it was 0.77 ± 0.19 without electric current. These results show that CO electro-fermentation at low current can be an alternative way of valorizing industrial waste gas using a bioelectrochemical system.

6.
Bioresour Technol ; 393: 130157, 2024 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-38065517

RESUMO

Electrode-driven microbial electron transfer enables the conversion of CO2 into multi-carbon compounds. The electrosynthetic biofilms grow slowly on the surface and are highly susceptible to operational influences, such as hydrodynamic shear stress. In this study, a cylindrical roll-up carbon felt electrode was developed as a novel strategy to protect biofilms from shear stress within the reactor. The fabricated electrode allowed hydrogen bubble formation inside the structure, which enabled microbes to uptake hydrogen and convert CO2 to multi-carbon organic compounds. The roll-up electrode exhibited faster start-up and biofilm formation than the conventional linear shape carbon felt. The acetate yield and cathodic faradaic efficiency increased by 80% and 34%, respectively, and the bioelectrochemical stability was improved significantly. The roll-up structure increased biofilm development per unit electrode surface by three to five-fold. The roll-up configuration improved biofilm formation on the electrode, which enhanced the performance of microbial electrosynthesis-based CO2 valorization.


Assuntos
Dióxido de Carbono , Carbono , Dióxido de Carbono/química , Habitação , Fibra de Carbono , Hidrogênio , Eletrodos , Biofilmes
7.
J Hazard Mater ; 477: 135237, 2024 Sep 15.
Artigo em Inglês | MEDLINE | ID: mdl-39094305

RESUMO

This study presents a thorough investigation of the novel application of graphene oxide (GO) modified with melamine formaldehyde to fabricate granular three-dimensional GO (3D-GO), followed by the introduction of UiO-66 doping (3D-GO/U) for high uranium (U) adsorption. The U(VI) adsorption isotherms revealed that 3D-GO/U-10 with 10 % UiO-66 incorporation exhibited an impressive adsorption capacity of 375.5 mg g-1 and remained high U(VI) sorption performance in wide pH range. The introduction of UiO-66 to 3D-GO (3D-GO/U-10) led to the deagglomeration of the UiO-66 particles. The in situ surface-enhanced-Raman-spectroscopy-analysis and density-functional-theory simulations showed the symmetric metal center site Zr-O2 on UiO-66 was discovered to exhibit the highest adsorption energy (-3.21 eV) for U(VI) species due to the electrons transfer from the oxygen atom to U(VI) drives the covalent bonding between the symmetric metal center sites Zr-O2 and U(VI) on 3D-GO/U-10. The 3D-GO/U-10 was regenerated using a 0.1 M Na2CO3/0.01 M H2O2 solution and achieved up to 89.7 % U(VI) removal in the 5th cycle. The continuous flow column experiments results revealed 3D-GO/U-10 can regenerate and maintain a U(VI) removal capacity of ∼76 % for up to 4 cycles column experiments. Therefore, 3D-GO/U-10 exhibits great potential for removing U(VI) from water bodies.

8.
Chemosphere ; 361: 142330, 2024 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-38759805

RESUMO

Solar-driven artificial photosynthesis offers a promising avenue for hydrogen peroxide (H2O2) generation, an efficient and economical replacement for current methods. The efficiency and selectivity hurdles of the two-electron oxygen reduction reaction (ORR) in solar-to- H2O2 conversion are substantial barriers to large scale production. In this manuscript, a simple biomass-assisted synthesis was performed to produce oxygen-enriched carbon quantum dots (OE-CQDs) from spent coffee waste, acting as an efficient photocatalyst for solar-powered H2O2 production. OE-CQDs can stabilize and store light-generated electrons effectively, boosting charge separation and enhancing photocatalytic performance with longevity. The maximal photocatalytic H2O2 production was achieved viz the utilization of OE-CQDs with generation rate of 356.86 µmol g-1 h-1 by retaining 80% activity without any external sacrificial donors. The outstanding performance of synthesized OE-CQDs under light exposure at wavelength (λ) of 280 nm has been ensured by the quantum yield value of 9.4% upon H2O2 generation. The combinatorial benefits of OE-CQDs with their authentic crystalline structure and oxygen enrichment, is expected to be enhancing the ORR activity through accelerating charge transfer, and optimizing oxygen diffusion. Consequently, our eco-friendly method holds considerable promise for creating highly efficient, metal-free photocatalysts for artificial H2O2 production.


Assuntos
Carbono , Café , Peróxido de Hidrogênio , Oxigênio , Pontos Quânticos , Luz Solar , Pontos Quânticos/química , Oxigênio/química , Catálise , Peróxido de Hidrogênio/química , Carbono/química , Café/química , Oxirredução , Processos Fotoquímicos
9.
Foot Ankle Int ; 34(7): 990-4, 2013 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-23696188

RESUMO

BACKGROUND: The purpose of this study was to introduce our technique of arthroscopic excision of the os trigonum in the lateral decubitus position through anterolateral, centrolateral, and posterolateral portals and also to investigate the safety and clinical results of this technique. METHODS: Between May 2007 and May 2011, 23 ankles of 23 consecutive patients underwent subtalar arthroscopic removal of the os trigonum in a lateral decubitus position. Twenty patients were male and 3 were female. All patients injured their ankles during sports activities. Mean duration of postoperative follow-up was 18 months, and no patients were lost to follow-up. Clinical evaluations were performed using the American Orthopaedic Foot and Ankle Society (AOFAS) ankle-hindfoot score and the visual analog scale (VAS) for pain. The time to return to work and sports activities was assessed. RESULTS: Average AOFAS ankle-hindfoot score increased from 71.3 (range, 59-85) preoperatively to 94.7 (range, 90-100) postoperatively, and VAS for pain decreased from 6.7 (range, 3-10) to 1.5 (range, 0-3). Average plantarflexion of the ankle increased from 28.8 degrees (range, 15-40) preoperatively to 42.5 degrees (range, 25-50) postoperatively. Mean time to resumption of sports activities was 6.7 weeks (range, 5-12). There were no major complications in any patient. CONCLUSION: Arthroscopic excision of a symptomatic os trigonum using anterolateral, centrolateral, and posterolateral portals in the lateral decubitus position was a safe and effective technique. LEVEL OF EVIDENCE: Level IV, retrospective case series.


Assuntos
Traumatismos do Tornozelo/cirurgia , Artroscopia , Traumatismos em Atletas/cirurgia , Metatarsalgia/prevenção & controle , Posicionamento do Paciente , Tálus/cirurgia , Adulto , Traumatismos do Tornozelo/diagnóstico , Traumatismos do Tornozelo/etiologia , Traumatismos em Atletas/diagnóstico , Traumatismos em Atletas/etiologia , Estudos de Coortes , Feminino , Humanos , Masculino , Metatarsalgia/diagnóstico , Metatarsalgia/etiologia , Recuperação de Função Fisiológica , Resultado do Tratamento
10.
Int Orthop ; 37(9): 1863-9, 2013 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-23892518

RESUMO

PURPOSE: The purpose of this study was to evaluate the radiographic characteristics and structural configurations of a series of patients with a primary degenerative arthritis of the second metatarsophalangeal joint. METHODS: We studied 37 feet that had undergone surgical treatment for primary degenerative arthritis of the second metatarsophalangeal joint. The patients were compared with a randomly selected control group, without arthritis of the second metatarsophalangeal joint. The first, second, and fourth metatarsal lengths, and the size of the second metatarsal head were measured on weight-bearing anteroposterior radiographs. The patients were classified on the basis of joint-space narrowing, subchondral sclerosis, osteophyte formation, and subchondral cystic change. RESULTS: The average second metatarsal length was significantly longer in the study group (P = 0.01). The average length of the first metatarsal relative to the fourth metatarsal was significantly shorter (P = 0.02) in the study group, while the average length of the second metatarsal relative to the fourth metatarsal was significantly longer (P = 0.01) in the study group. The average diameter of the second metatarsal head was significantly larger in the study group (P = 0.00), and the average ratio of this diameter relative to the length of the fourth metatarsal was significantly higher in the study group (P = 0.00). A total of four feet were classified as grade 0, nine as grade 1, 17 as grade 2, and seven as grade 3. CONCLUSIONS: Second toe rigidus should be considered as a diagnosis in patients with painful limited dorsiflexion of the second metatarsophalangeal joint without evidence of Freiberg's infraction or trauma.


Assuntos
Articulação Metatarsofalângica/diagnóstico por imagem , Osteoartrite/diagnóstico por imagem , Adulto , Idoso , Feminino , Humanos , Masculino , Articulação Metatarsofalângica/cirurgia , Pessoa de Meia-Idade , Osteoartrite/cirurgia , Radiografia , Estudos Retrospectivos
11.
Bioresour Technol ; 372: 128662, 2023 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-36693505

RESUMO

Effects of limited dissolved oxygen (DO) on hydrogenotrophic denitrification at biocathode was investigated using bioelectrochemical system. It was found that total nitrogen removal increased by 5.9%, as DO reached about 0.24 mg/L with the cathodic chamber unplugged (group R_Exposure). With the presence of limited DO, not only the nitrogen metabolic pathway was influenced, but the composition of microbial communities of ammonia-oxidizing bacteria and nitrite-oxidizing bacteria were enriched accordingly. After metagenomic analysis, enriched genes in R_Exposure were found to be associated with nearly each of nitrogen removal steps as denitrification, nitrification, DNRA, nitrate assimilation and even nitrogen fixation. Moreover, genes encoding both Complexes III and IV constituted the electron transfer chain were significantly enriched, indicating that more electrons would be orientated to the reduction of NO2--N, NO-N and oxygen. Therefore, enhanced nitrogen removal could be attained through the co-respiration of nitrate and oxygen by means of NH4+-N oxidation.


Assuntos
Desnitrificação , Nitratos , Nitratos/metabolismo , Nitrogênio/metabolismo , Oxigênio , Reatores Biológicos , Nitrificação , Oxirredução
12.
ACS Omega ; 8(29): 26231-26242, 2023 Jul 25.
Artigo em Inglês | MEDLINE | ID: mdl-37521642

RESUMO

Acetate is an end-product of anaerobic biodegradation and one of the major metabolites of microbial fermentation and lingo-cellulosic hydrolysate. Recently, acetate has been highlighted as a feedstock to produce value-added chemicals. This study examined acetate conversion to succinate by citrate synthase (gltA)-overexpressed Pseudomonas putida under microaerobic conditions. The acetate metabolism is initiated with the gltA enzyme, which converts acetyl-CoA to citrate. gltA-overexpressing P. putida (gltA-KT) showed an ∼50% improvement in succinate production compared to the wild type. Under the optimal pH of 7.5, the accumulation of succinate (4.73 ± 0.6 mM in 36 h) was ∼400% higher than that of the wild type. Overall, gltA overexpression alone resulted in 9.5% of the maximum theoretical yield in a minimal medium with acetate as the sole carbon source. This result shows that citrate synthase is important in acetate conversion to succinate by P. putida under microaerobic conditions.

13.
Chemosphere ; 313: 137388, 2023 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-36455658

RESUMO

The interactions between the microbes and the surface of an anode play an important role in capturing the respiratory electrons from bacteria in a microbial fuel cell (MFC). The chemical and electrochemical characteristics of the carbon material affect biofilm growth and direct electron transfer in MFCs. This study examined the electrodeposition of polydopamine (PDA) and polypyrrole (PPY) on graphite felt electrode (GF). The MFC with the modified PDA/PPY-GF reached 920 mW/m2, which was 1.5, 1.17, and 1.18 times higher than those of the GF, PDA-GF, and PPY-GF, respectively. PDA has superior hydrophilicity and adhesive force biofilm formation, while PPY provides electrochemically active sites for microbial electron transfer. Raman spectroscopy, Fourier transform infrared spectroscopy, Brunauer-Emmett-Teller surface area measurements, and contact angle analysis revealed the enhanced physicochemical properties of the carbon electrode. These results show that co-doped PDA/PPY provides a strategy for electroactive biofilm development and improves the bioelectrochemical performance in realistic MFC reactors.


Assuntos
Fontes de Energia Bioelétrica , Grafite , Fontes de Energia Bioelétrica/microbiologia , Polímeros/química , Grafite/química , Pirróis/química , Bactérias , Carbono , Eletrodos
14.
Bioresour Technol ; 369: 128413, 2023 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-36462762

RESUMO

The inherent recalcitrance of lignocellulosic biomass is a significant barrier to efficient lignocellulosic biorefinery owing to its complex structure and the presence of inhibitory components, primarily lignin. Efficient biomass pretreatment strategies are crucial for fragmentation of lignocellulosic biocomponents, increasing the surface area and solubility of cellulose fibers, and removing or extracting lignin. Conventional pretreatment methods have several disadvantages, such as high operational costs, equipment corrosion, and the generation of toxic byproducts and effluents. In recent years, many emerging single-step, multi-step, and/or combined physicochemical pretreatment regimes have been developed, which are simpler in operation, more economical, and environmentally friendly. Furthermore, many of these combined physicochemical methods improve biomass bioaccessibility and effectively fractionate ∼96 % of lignocellulosic biocomponents into cellulose, hemicellulose, and lignin, thereby allowing for highly efficient lignocellulose bioconversion. This review critically discusses the emerging physicochemical pretreatment methods for efficient lignocellulose bioconversion for biofuel production to address the global energy crisis.


Assuntos
Biocombustíveis , Lignina , Lignina/química , Biomassa , Celulose , Hidrólise
15.
J Hazard Mater ; 452: 131197, 2023 06 15.
Artigo em Inglês | MEDLINE | ID: mdl-36989782

RESUMO

The aim of this study was to investigate the effects of hydrophilic sulfur-modified nanoscale zero-valent iron (S-nZVI) as a biocatalyst for denitrification. We found that the denitrifying bacteria Cupriavidus necator (C. necator) promoted Fe corrosion during biocatalytic denitrification, reducing surface passivation and sulfur species leaching from S-nZVI. As a result, S-nZVI exhibited a higher synergistic factor (fsyn = 2.43) for biocatalytic NO3- removal than nanoscale zero-valent iron (nZVI, fsyn = 0.65) at an initial nitrate concentration of 25 mg L-1-N. Based on kinetic profiles, SO42- was the preferred electron acceptor over NO3- when using C. necator and S-nZVI for biocatalytic denitrification. Up-flow column experiments demonstrated that biocatalytic denitrification using S-nZVI achieved a total nitrogen removal capacity of up to 2004 mg L-1 for 127 d. Notably, microbiome taxonomic profiling showed that the addition of S-nZVI to the groundwater promoted the growth of Geobacter, Desulfosporosinus, Streptomyces, and Simplicispira spp in the column experiments. Most of those microbes can reduce sulfate, promote denitrification, and match the batch kinetic profile obtained using C. necator. Our results not only discover the great potential of S-nZVI as a biocatalyst for enhancing denitrification via microbial activation but also provide a deep understanding of the complicated abiotic-biotic interaction.


Assuntos
Água Subterrânea , Poluentes Químicos da Água , Ferro , Desnitrificação , Nitratos , Bactérias , Nitrogênio
16.
Bioresour Technol ; 364: 128064, 2022 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-36195215

RESUMO

Acetate is a major byproduct of the bioconversion of the greenhouse gas carbon dioxide, pretreatment of lignocellulose biomass, and microbial fermentation. The utilization and valorization of acetate have been emphasized in transforming waste to clean energy and value-added platform chemicals, contributing to the development of a closed carbon loop toward a low-carbon circular bio-economy. Acetate has been used to produce several platform chemicals, including succinate, 3-hydroxypropionate, and itaconic acid, highlighting the potential of acetate to synthesize many biochemicals and biofuels. On the other hand, the yields and titers have not reached the theoretical maximum. Recently, recombinant strain development and pathway regulation have been suggested to overcome this limitation. This review provides insights into the important constraints limiting the yields and titers of the biochemical and metabolic pathways of bacteria capable of metabolizing acetate for acetate bioconversion. The current developments in recombinant strain engineering are also discussed.

17.
Polymers (Basel) ; 14(9)2022 May 02.
Artigo em Inglês | MEDLINE | ID: mdl-35567037

RESUMO

Translocation of cell-penetrating peptides is promoted by incorporated arginine or other guanidinium groups. However, relatively little research has considered the role of these functional groups on antimicrobial peptide activity. A series of cationic linear-, star- and multi-branched-poly(L-arginine-co-L-phenylalanine) have been synthesized via the ring-opening copolymerizations of corresponding N-carboxyanhydride monomers followed by further modifications using the N-heterocyclic carbene organocatalyst. All the polymers are characterized by the random coiled microstructure. Antibacterial efficacy, tested by the gram-positive B. subtilis bacteria and the gram-negative E. coli bacteria, was sensitive to the structure and relative composition of the copolymer and increased in the order of linear- < star- < multi-branched structure. The multi-branched-p[(L-arginine)23-co-(L-phenylalanine)7]8 polymer showed the best antibacterial property with the lowest minimum inhibitory concentration values of 48 µg mL−1 for E. coli and 32 µg mL−1 for B. subtilis. The efficacy was prominent for B. subtilis due to the anionic nature of its membrane. All of the resultant arginine moiety-containing polypeptides showed excellent blood compatibility. The antibiotic effect of the copolymers with arginine moieties was retained even in the environment bearing Ca2+, Mg2+, and Na+ ions similar to blood plasma. The cationic arginine-bearing copolypeptides were also effective for the sterilization of naturally occurring sources of water such as lakes, seas, rain, and sewage, showing a promising range of applicability.

18.
Bioresour Technol ; 363: 127983, 2022 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-36126849

RESUMO

Renewable electricity-based microbial electrosynthesis can upgrade CO2 into value-added chemicals and simultaneously increase the number of biocatalysts by cell growth, helping to achieve sustainable carbon-negative processes. In most studies, the main strategy for improving the MES performance was to enhance H2-based electron uptake by decreasing the overpotential and electrical conductivity of the electrode. Less is known about the electrode-based direct electron uptake for CO2 conversion in MES. In this study, a solid neutral red/Nafion conductive layer was developed on the carbon electrode surface using a feasible dip and dry method. The modified electrode showed higher HER overpotential and lower capacitance but enhanced redox capability and hydrophobicity, which increased direct electron transport to the bacteria rather than hydrogen-based indirect electron delivery. The Neutral red/Nafion-implemented MES showed faster start-up, higher acetate production, and energy efficiency than the non-modified electrode.


Assuntos
Dióxido de Carbono , Carbono , Acetatos/metabolismo , Dióxido de Carbono/metabolismo , Fibra de Carbono , Conservação de Recursos Energéticos , Condutividade Elétrica , Eletrodos , Polímeros de Fluorcarboneto , Hidrogênio , Vermelho Neutro
19.
Bioresour Technol ; 366: 128183, 2022 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-36307027

RESUMO

Chlorella is a promising microalga for CO2-neutral biorefinery that co-produces drop-in biofuels and multiple biochemicals. Cell disruption and selective lipid extraction steps are major technical bottlenecks in biorefinement because of the inherent robustness and complexity of algal cell walls. This review focuses on the state-of-the-art achievements in cell disruption and lipid extraction methods for Chlorella species within the last five years. Various chemical, physical, and biological approaches have been detailed theoretically, compared, and discussed in terms of the degree of cell wall disruption, lipid extractability, chemical toxicity, cost-effectiveness, energy use, scalability, customer preferences, environment friendliness, and synergistic combinations of different methods. Future challenges and prospects of environmental-friendly and efficient extraction technologies are also outlined for practical applications in sustainable Chlorella biorefineries. Given the diverse industrial applications of Chlorella, this review may provide useful information for downstream processing of the advanced biorefineries of other algae genera.


Assuntos
Chlorella , Microalgas , Biocombustíveis , Parede Celular , Lipídeos , Biomassa
20.
Bioelectrochemistry ; 146: 108136, 2022 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-35561642

RESUMO

Pseudomonas strains are a promising host cell in metabolic engineering for bioconversion, environmental remediation, and most recently for bioelectrochemical applications. This study isolated an electrochemically active Pseudomonas sp. from an anaerobic sludge using a colorimetric and electrochromic WO3 nanorod (WO3-NR) probe. A strategy was developed to determine the presence of electroactive species from enriched cultures. A mixed consortium was enriched using Pseudomonas isolation media containing betaine and triclosan as the carbon source and antibacterial reagent, respectively. A single blue colony was isolated using WO3-NR sandwiched agar plates. The isolate was sequenced by 16 s rRNA and designated Pseudomonas aeruginosa PBH03, producing phenazines and pyocyanin aerobically. The isolate exhibited clear electrochemical characteristics from cyclic voltammetry and linear sweep voltammetry and produced a current density of 9.01 µA cm-2 in a microbial fuel cell.


Assuntos
Nanotubos , Tungstênio , Colorimetria , Pseudomonas , Pseudomonas aeruginosa/metabolismo , Piocianina/metabolismo , Tungstênio/metabolismo
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