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1.
Small ; 20(12): e2307843, 2024 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-37948442

RESUMO

Covalent organic frameworks (COFs) with flexible periodic skeletons and ordered nanoporous structures have attracted much attention as potential candidate electrode materials for green energy storage and efficient seawater desalination. Further improving the intrinsic electronic conductivity and releasing porosity of COF-based materials is a necessary strategy to improve their electrochemical performance. Herein, the employed graphene as the conductive substrate to in situ grow 2D redox-active COF (TFPDQ-COF) with redox activity under solvent-free conditions to prepare TFPDQ-COF/graphene (TFPDQGO) nanohybrids and explores their application in both supercapacitor and hybrid capacitive deionization (HCDI). By optimizing the hybridization ratio, TFPDQGO exhibits a large specific capacitance of 429.0 F g-1 due to the synergistic effect of the charge transport highway provided by the graphene layers and the abundant redox-active centers contained in the COF skeleton, and the assembled TFPDQGO//activated carbon (AC) asymmetric supercapacitor possesses a high energy output of 59.4 Wh kg-1 at a power density of 950 W kg-1 and good cycling life. Furthermore, the maximum salt adsorption capacity (SAC) of 58.4 mg g-1 and stable regeneration performance is attained for TFPDQGO-based HCDI. This study highlights the new opportunities of COF-based hybrid materials acting as high-performance supercapacitor and HCDI electrode materials.

2.
Microb Ecol ; 85(2): 544-556, 2023 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-35316342

RESUMO

The single-celled eukaryote Euplotes aediculatus was chosen to test and compare the toxic effects of Cu and CuO nanoparticles (NPs). The antioxidant enzymatic activity, morphological changes, and functional groups on the membrane were determined using spectrophotometry, microscopy, and Fourier transform infrared spectroscopy after NPs treatment. The toxicity of the NPs to cells was dose-dependent, and the 24 h-LC50 values of the CuNPs and CuONPs were 0.46 µg/L and 1.24 × 103 µg/L, respectively. These NPs increased the activities of superoxide dismutase, glutathione peroxidase, and catalase and destroyed the cell structure; moreover, the CuNPs were more toxic than the CuONPs. In addition to the higher enzymatic activity, CuNPs also caused nucleoli disappearance, chromatin condensation, and mitochondrial and pellicle damage. The oxidization of the functional groups of the membrane (PO2 - , C-O-C, and δ(COH) of carbohydrates) also confirmed the severe damage caused by CuNPs. Our study showed that oxidative stress and organelle destruction played important roles in the toxic effects of these NPs on this protozoan. Compared with other aquatic organisms, E. aediculatus can be considered a potential indicator at the preliminary stage of environmental pollution.


Assuntos
Euplotes , Nanopartículas Metálicas , Nanopartículas , Nanopartículas Metálicas/toxicidade , Cobre , Estresse Oxidativo
3.
Microb Cell Fact ; 21(1): 270, 2022 Dec 24.
Artigo em Inglês | MEDLINE | ID: mdl-36566171

RESUMO

BACKGROUND: Resveratrol is a plant-derived phenylpropanoid with diverse biological activities and pharmacological applications. Plant-based extraction could not satisfy ever-increasing market demand, while chemical synthesis is impeded by the existence of toxic impurities. Microbial production of resveratrol offers a promising alternative to plant- and chemical-based processes. The non-conventional oleaginous yeast Rhodotorula toruloides is a potential workhorse for the production of resveratrol that endowed with an efficient and intrinsic bifunctional phenylalanine/tyrosine ammonia-lyase (RtPAL) and malonyl-CoA pool, which may facilitate the resveratrol synthesis when properly rewired. RESULTS: Resveratrol showed substantial stability and would not affect the R. toruloides growth during the yeast cultivation in flasks. The heterologus resveratrol biosynthesis pathway was established by introducing the 4-coumaroyl-CoA ligase (At4CL), and the stilbene synthase (VlSTS) from Arabidopsis thaliana and Vitis labrusca, respectively. Next, The resveratrol production was increased by 634% through employing the cinnamate-4-hydroxylase from A. thaliana (AtC4H), the fused protein At4CL::VlSTS, the cytochrome P450 reductase 2 from A. thaliana (AtATR2) and the endogenous cytochrome B5 of R. toruloides (RtCYB5). Then, the related endogenous pathways were optimized to affect a further 60% increase. Finally, the engineered strain produced a maximum titer of 125.2 mg/L resveratrol in YPD medium. CONCLUSION: The non-conventional oleaginous yeast R. toruloides was engineered for the first time to produce resveratrol. Protein fusion, co-factor channeling, and ARO4 and ARO7 overexpression were efficient for improving resveratrol production. The results demonstrated the potential of R. toruloides for resveratrol and other phenylpropanoids production.


Assuntos
Arabidopsis , Rhodotorula , Engenharia Metabólica/métodos , Resveratrol/metabolismo , Arabidopsis/genética , Rhodotorula/genética , Rhodotorula/metabolismo , Leveduras , Plantas
4.
Phys Chem Chem Phys ; 24(36): 21872-21885, 2022 Sep 21.
Artigo em Inglês | MEDLINE | ID: mdl-36065968

RESUMO

Prospects for the use of manganites in various areas of modern technologies require comprehensive studies of their physical and chemical properties. La0.9Mn1.1O3 (LMO) ceramics have been synthesized at an annealing temperature tann of 1150 °C with further post-annealing at 1250, 1350, and 1450 °C. As tann increases, the structure symmetry changes, and both the crystallite size and chemical defects increase. The post-annealing, on one hand, leads to a dramatic reduction of the magnetocaloric effect (MCE) |-ΔSmaxM| from 3.50 to 0.75 J (kg K)-1 at 2 T and a Curie temperature TC from 227 to 113 K with increasing tann. On the other hand, an external hydrostatic high-pressure P works oppositely enhancing ferromagnetic interactions. The saturation of -ΔSmaxM and TC is already achieved at a relatively low P of ≈ 0.4 GPa. LMO-1150 exhibits the best magnetocaloric characteristics compared with other studied samples. Moreover, the electrochemical characteristics of the LMO materials as electrocatalysts for overall water splitting (OER process) and features of their transformation in different 0.5 M K2SO4, 0.5 M K2HPO4, and 0.1 M K2B4O7 electrolytes have been studied thoroughly. After electrocatalysis of LMO, the magnetization M decreases and TC remains, which makes it possible to control the depletion of electrodes and predict their working time based on the magnetic measurements. All samples show the best OER activity in the 0.5 M K2HPO4 media. The obtained results demonstrate the ways for controlling the MCE of LMO under changing internal and external conditions, and an evaluation of the possibilities for their OER applications in electrocatalysts.

5.
Water Sci Technol ; 84(8): 2057-2067, 2021 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-34695030

RESUMO

Metal ions in sediment are inherent Ca and Fe sources for biochar modification. In this work, the effect of Ca2+ and Fe2+ released from sediment on biochar for phosphorus adsorption was evaluated. Results showed that raw peanut shell biochar (PSB) was poor in phosphorus adsorption (0.48 mg/g); sediment-triggered biochar (S-PSB) exhibited a P adsorption capacity of 1.32 mg/g in capping reactor and maximum adsorption capacity of 10.72 mg/g in the Langmuir model. Sediment released Ca2+ of 2.2-4.1 mg/L and Fe2+/Fe3+ of 0.2-9.0 mg/L. The metals loaded onto the biochar surface in the forms of Ca-O and Fe-O, with Ca and Fe content of 1.47 and 0.29%, respectively. Sediment metals made point of zero charge (pHpzc) of biochar shifted from 5.39 to 6.46. The mechanisms of enhanced P adsorption by S-PSB were surface complexation of CaHPO4 followed by precipitation of Ca3(PO4)2 and Ca5(PO4)3(OH). Sediment metals induced the modification of biochar and improvement of P adsorption, which was feasible to overcome the shortcomings of biochar on phosphorus control in sediment capping.


Assuntos
Carvão Vegetal , Fósforo , Adsorção , Metais
6.
Langmuir ; 36(2): 600-608, 2020 01 21.
Artigo em Inglês | MEDLINE | ID: mdl-31885276

RESUMO

Because of the unique optical properties of gold nanomaterials, the preparation of gold nanomaterials with excellent chirality has received extensive attention. In order to develop a simple fabrication method for three-dimensional chiral Au nanostructures with a size of several hundred nanometers, chiral gold nanoparticles were developed to transfer chirality of a peptide to gold nanoparticles. In this study, the controlled synthesis of asymmetric gold nanopolyhedrons was achieved. The asymmetric gold nanopolyhedrons prepared via peptide-directed growth can exhibit strong circular dichroism (∼±50 mdeg) couplets in the visible range (500-600 nm). Also, the morphology of chiral Au nanododecahedrons-peptide particles showed distorted and asymmetric properties. In order to prove that the size and spatial structure of gold nanopolyhedrons have an influence on their chiral optical properties, Au nanotrioctahedron-peptide particles were prepared by using Au nanotrioctahedrons with different morphologies. Au nanotrioctahedron-peptide particles also exhibited circular dichromatic couplets in the visible region.


Assuntos
Ouro/química , Nanopartículas Metálicas/química , Peptídeos/síntese química , Fenômenos Ópticos , Tamanho da Partícula , Peptídeos/química , Propriedades de Superfície
8.
Appl Microbiol Biotechnol ; 101(9): 3801-3809, 2017 May.
Artigo em Inglês | MEDLINE | ID: mdl-28168317

RESUMO

Lipid production by the red yeast Rhodosporidium toruloides was explored under nutrient limitation. To determine the compositional profiles of R. toruloides cells, samples were prepared using a continuous cultivation process under nutrient limitation and analyzed via several methods, including Fourier transform infrared spectroscopy and elemental analysis. Under nitrogen limitation, as the dilution rate increased, the cellular lipid content decreased but the carbohydrate and protein contents increased. Under carbon limitation, the cellular lipid, protein, and carbohydrate contents remained relatively constant at the different dilution rates. Moreover, the cellular elemental composition was essentially identical under nitrogen and carbon limitation at a high dilution rate of 0.20 h-1. We also analyzed the consumed carbon to nitrogen (C/N) under different nutrition conditions. The results indicated that the consumed C/N had a major influence on cell metabolism and product formation, which contributed to our understanding of the physiological characteristics of R. toruloides.


Assuntos
Meios de Cultura , Lipídeos/análise , Rhodotorula/química , Rhodotorula/crescimento & desenvolvimento , Carboidratos/análise , Carbono/análise , Elementos Químicos , Nitrogênio/análise , Proteínas/análise , Rhodotorula/metabolismo , Espectroscopia de Infravermelho com Transformada de Fourier
9.
Histopathology ; 68(2): 221-9, 2016 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-25980696

RESUMO

AIMS: The aim of the present study was to investigate the prognostic value of B-cell associated protein 31 (BAP31) in human primary hepatocellular carcinoma (HCC). METHODS AND RESULTS: BAP31 levels were evaluated by immunohistochemistry on tissue microarrays. The integral optical density, representing the expression level of BAP31 in each tissue sample, was calculated with image-pro plus. Immunohistochemical analysis of BAP31 levels in 74 paired HCC tissues and peritumoral non-cancerous tissues showed that BAP31 expression was significantly higher in HCC tumour tissues (P = 0.025). The prognostic value of BAP31 in HCC was evaluated in 234 cases in a training cohort and in 63 cases in a validation cohort. The expression level of BAP31 was significantly correlated with overall survival (OS) in both the training cohort and the validation cohort. The lower the level of BAP31 expression in HCC tissue, the poorer the prognosis. Univariate and multivariate analyses showed that the expression level of BAP31 in HCC was an independent prognostic factor for OS in both the training cohort and the validation cohort. CONCLUSIONS: BAP31 expression is an independent prognostic factor for OS of patients with postoperative HCC, and low expression levels of BAP31 in HCC may indicate poor outcomes of HCC patient after surgical resection.


Assuntos
Biomarcadores Tumorais/metabolismo , Carcinoma Hepatocelular/diagnóstico , Neoplasias Hepáticas/diagnóstico , Proteínas de Membrana/metabolismo , Adulto , Idoso , Linfócitos B/metabolismo , Linfócitos B/patologia , Carcinoma Hepatocelular/metabolismo , Carcinoma Hepatocelular/patologia , Feminino , Humanos , Imuno-Histoquímica , Estimativa de Kaplan-Meier , Neoplasias Hepáticas/metabolismo , Neoplasias Hepáticas/patologia , Masculino , Pessoa de Meia-Idade , Prognóstico , Análise Serial de Tecidos
10.
Tumour Biol ; 37(5): 5911-7, 2016 May.
Artigo em Inglês | MEDLINE | ID: mdl-26592251

RESUMO

Betaine homocysteine methyltransferase (BHMT) catalyzes the synthesis of methionine using betaine and homocysteine (Hcy), which is restricted to the liver and kidney. Impaired BHMT pathway has been associated with hepatocellular carcinogenesis in Bhmt-/- mice model, and decreased BHMT was observed in a small sample of human hepatocellular carcinoma (HCC) patients. However, the prognostic significance of BHMT in HCC has not been elucidated. This study aimed to examine the expression of BHMT in HCC and investigate the relationship between its expression and prognosis of HCC patients. BHMT expression was analyzed in 68 paired HCC samples (HCC tissues vs matched adjacent non-cancerous liver tissues), 115 paraffin-embedded HCC sections (primary cohort), and 65 paraffin-embedded HCC sections (validation cohort) using immunohistochemistry (IHC). The results of IHC analysis showed that BHMT was decreased in tumorous tissues in 85.2 % (58/68) of cases compared to the corresponding adjacent non-tumorous liver tissues. Further correlation analyses indicated that the decreased BHMT expression was closely correlated with serum α-fetoprotein (AFP) (p = 0.011), tumor size (p = 0.039), and vascular invasion (p = 0.017). Moreover, HCC patients with low BHMT expression had shorter overall survival (OS) and time to recurrence (TTR) than those with high BHMT expression in both primary cohort (p < 0.0001) and validation cohort (p < 0.05) assessed by the Kaplan-Meier method. In addition, multivariate analysis showed that BHMT was an independent prognostic factor for OS and TTR in the two cohorts (all p < 0.005). Collectively, our study demonstrated that BHMT could be served as a potential prognostic marker for HCC patients.


Assuntos
Betaína-Homocisteína S-Metiltransferase/genética , Betaína-Homocisteína S-Metiltransferase/metabolismo , Carcinoma Hepatocelular/metabolismo , Carcinoma Hepatocelular/mortalidade , Neoplasias Hepáticas/metabolismo , Neoplasias Hepáticas/mortalidade , Adulto , Idoso , Biomarcadores Tumorais , Carcinoma Hepatocelular/patologia , Regulação para Baixo , Feminino , Humanos , Imuno-Histoquímica , Estimativa de Kaplan-Meier , Neoplasias Hepáticas/patologia , Masculino , Pessoa de Meia-Idade , Invasividade Neoplásica , Estadiamento de Neoplasias , Prognóstico , Carga Tumoral
11.
Eukaryot Cell ; 14(3): 252-64, 2015 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-25576482

RESUMO

Lipid droplets (LDs) are ubiquitous organelles that serve as a neutral lipid reservoir and a hub for lipid metabolism. Manipulating LD formation, evolution, and mobilization in oleaginous species may lead to the production of fatty acid-derived biofuels and chemicals. However, key factors regulating LD dynamics remain poorly characterized. Here we purified the LDs and identified LD-associated proteins from cells of the lipid-producing yeast Rhodosporidium toruloides cultured under nutrient-rich, nitrogen-limited, and phosphorus-limited conditions. The LD proteome consisted of 226 proteins, many of which are involved in lipid metabolism and LD formation and evolution. Further analysis of our previous comparative transcriptome and proteome data sets indicated that the transcription level of 85 genes and protein abundance of 77 proteins changed under nutrient-limited conditions. Such changes were highly relevant to lipid accumulation and partially confirmed by reverse transcription-quantitative PCR. We demonstrated that the major LD structure protein Ldp1 is an LD marker protein being upregulated in lipid-rich cells. When overexpressed in Saccharomyces cerevisiae, Ldp1 localized on the LD surface and facilitated giant LD formation, suggesting that Ldp1 plays an important role in controlling LD dynamics. Our results significantly advance the understanding of the molecular basis of lipid overproduction and storage in oleaginous yeasts and will be valuable for the development of superior lipid producers.


Assuntos
Gotículas Lipídicas/metabolismo , Proteoma/metabolismo , Ustilaginales/metabolismo , Proteínas Fúngicas/genética , Proteínas Fúngicas/metabolismo , Metabolismo dos Lipídeos , Proteoma/genética , Ustilaginales/genética
12.
Bioresour Technol ; 395: 130366, 2024 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-38266783

RESUMO

Single cell oil (SCO) prepared from biodiesel-derived crude glycerol (BCG) and lignocellulosic biomass (LCB) via oleaginous yeasts is an intriguing alternative precursor of biodiesel. Here, a novel strategy combining alkaline BCG pretreated corn stover and dilute acid pretreated water hyacinth for SCO overproduction was developed. The mixed pretreatment liquors (MPLs) were naturally neutralized and adjusted to a proper carbon-to-nitrogen ratio beneficial for SCO overproduction by Cutaneotrichosporon oleaginosum. The toxicity of inhibitors was relieved by dilution detoxification. The enzymatic hydrolysate of solid fractions was suitable for SCO production either separately or simultaneously with MPLs. Fed-batch fermentation of the MPLs resulted in high cell mass, SCO content, and SCO titer of 80.7 g/L, 75.7 %, and 61.1 g/L, respectively. The fatty acid profiles of SCOs implied high-quality biodiesel characteristics. This study offers a novel BCG&LCB-to-SCO route integrating BCG-based pretreatment and BCG/LCB hydrolysates co-utilization, which provides a cost-effective technical route for micro-biodiesel production.


Assuntos
Basidiomycota , Eichhornia , Glicerol , Biocombustíveis , Zea mays , Lipídeos , Leveduras , Fermentação , Ácidos , Biomassa
13.
J Colloid Interface Sci ; 656: 289-296, 2024 Feb 15.
Artigo em Inglês | MEDLINE | ID: mdl-37995399

RESUMO

Currently, the development of economical and effective non-noble metal electrocatalysts is vital for advancing hydrogen evolution reaction (HER) and enabling its widespread applications. The customizable pore structure and enormous surface area of metal-organic frameworks (MOFs) have made them to become promising non-noble metal electrocatalysts for HER. However, MOFs have some challenges, including low conductivity and instability, which can result in them having high overpotentials and slow reaction kinetics in electrocatalytic processes. In this work, we present an innovative approach for synthesizing cost-effective and high-efficient Zr-MOF-derived pH-universal electrocatalysts for HER. It entails creating the interfaces of the electrocatalysts with suitable proportions of phosphide nanostructures. Zr-MOF/Ni2P@nickel foam (NF) electrodes with interface regulated by Ni2P nanostructures were successfully developed for high-efficient pH-universal HER electrocatalysts. The presence of Ni2P nanostructures with abundant active sites at the Zr-MOFs@NF interfaces boosted the electronic conductivity and local charge density of the hybrid electrocatalysts. This helped to improve their reaction kinetics and electrocatalytic activity. By optimizing the Ni2P amount, Zr-MOF/Ni2P@NF demonstrated impressive stability and superior HER activities, with a low overpotential of 149 mV (acidic electrolytes) and 143 mV (alkaline electrolytes) at 10 mA cm-2. The proven strategy in this work can be expanded to many types of MOF-based materials for wider practical applications.

14.
Front Bioeng Biotechnol ; 12: 1276795, 2024.
Artigo em Inglês | MEDLINE | ID: mdl-38449677

RESUMO

Dynamic assessment of cerebral blood flow (CBF) is crucial for guiding personalized management and treatment strategies, and improving the prognosis of stroke. However, a safe, reliable, and effective method for dynamic CBF evaluation is currently lacking in clinical practice. In this study, we developed a CBF monitoring system utilizing electromagnetic coupling sensing (ECS). This system detects variations in brain conductivity and dielectric constant by identifying the resonant frequency (RF) in an equivalent circuit containing both magnetic induction and electrical coupling. We evaluated the performance of the system using a self-made physical model of blood vessel pulsation to test pulsatile CBF. Additionally, we recruited 29 healthy volunteers to monitor cerebral oxygen (CO), cerebral blood flow velocity (CBFV) data and RF data before and after caffeine consumption. We analyzed RF and CBFV trends during immediate responses to abnormal intracranial blood supply, induced by changes in vascular stiffness, and compared them with CO data. Furthermore, we explored a method of dynamically assessing the overall level of CBF by leveraging image feature analysis. Experimental testing substantiates that this system provides a detection range and depth enhanced by three to four times compared to conventional electromagnetic detection techniques, thereby comprehensively covering the principal intracranial blood supply areas. And the system effectively captures CBF responses under different intravascular pressure stimulations. In healthy volunteers, as cerebral vascular stiffness increases and CO decreases due to caffeine intake, the RF pulsation amplitude diminishes progressively. Upon extraction and selection of image features, widely used machine learning algorithms exhibit commendable performance in classifying overall CBF levels. These results highlight that our proposed methodology, predicated on ECS and image feature analysis, enables the capture of immediate responses of abnormal intracranial blood supply triggered by alterations in vascular stiffness. Moreover, it provides an accurate diagnosis of the overall CBF level under varying physiological conditions.

15.
Bioresour Technol ; 382: 129218, 2023 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-37217142

RESUMO

Pretreatment is a prerequisite to tackle the issue of biomass recalcitrance, which is the major hindrance of lignocellulose-to-sugars routes. In the present study, a novel combination of dilute sulfuric acid (dilute-H2SO4) with Tween 80 pretreatment of corn stover (CS) was developed to significantly enhance the enzyme digestibility. Strong synergistic effects of H2SO4 and Tween 80 for simultaneously eliminating hemicellulose and lignin and significantly promoting saccharification yield were observed. A response surface optimization realized the maximum monomeric sugar yield of 95.06% at 120 °C for 1.4 h with 0.75 wt% of H2SO4 and 73.92 wt% of Tween 80. The excellent enzyme susceptibility of pretreated CS was explained by their physical and chemical characteristics via SEM, XRD, and FITR. The repeatedly recovered pretreatment liquor exerted highly-effective reusability in the subsequent pretreatments for at least four cycles. This strategy offers a highly-efficient and practical pretreatment strategy, which provides valuable information for the lignocellulose-to-sugars routes.


Assuntos
Lignina , Polissorbatos , Zea mays , Hidrólise , Açúcares
16.
Waste Manag ; 168: 221-229, 2023 Aug 01.
Artigo em Inglês | MEDLINE | ID: mdl-37311389

RESUMO

Spent biomass from agricultural and forestry industries are substantial low-cost carbon source for reducing the input of microbial lipid production. Herein, the components of the vineyard winter prunings (VWPs) from 40 grape cultivars were analyzed. The VWPs contained (w/w) cellulose ranged from 24.8% to 32.4%, hemicellulose 9.6% to 13.8%, lignin 23.7% to 32.4%. The VWPs from Cabernet Sauvignon was processed with the alkali-methanol pretreatment, and 95.8% of the sugars was released from the regenerated VWPs after enzymatic hydrolysis. The hydrolysates from the regenerated VWPs was suitable for lipid production without further treatment as a lipid content of 59% could be achieved with Cryptococcus curvatus. The regenerated VWPs was also used for lipid production via simultaneous saccharification and fermentation (SSF), which led to a lipid yield of 0.088 g/g raw VWPs, 0.126 g/g regenerated VWPs and 0.185 g/g from the reducing sugars. This work demonstrated that the VWPs can be explored for co-production of microbial lipids.


Assuntos
Cryptococcus , Lipídeos , Fazendas , Fermentação , Açúcares , Biomassa
17.
Sheng Wu Gong Cheng Xue Bao ; 38(2): 760-771, 2022 Feb 25.
Artigo em Zh | MEDLINE | ID: mdl-35234396

RESUMO

Fatty acids (FA) are widely used as feed stocks for the production of cosmetics, personal hygiene products, lubricants and biofuels. Ogataea polymorpha is considered as an ideal chassis for bio-manufacturing, due to its outstanding characteristics such as methylotroph, thermal-tolerance and wide substrate spectrum. In this study, we harnessed O. polymorpha for overproduction of fatty acids by engineering its fatty acid metabolism and optimizing the fermentation process. The engineered strain produced 1.86 g/L FAs under the optimized shake-flask conditions (37℃, pH 6.4, a C/N ratio of 120 and an OD600 of seed culture of 6-8). The fed-batch fermentation process was further optimized by using a dissolved oxygen (DO) control strategy. The C/N ratio of initial medium was 17.5, and the glucose medium with a C/N ratio of 120 was fed when the DO was higher than 30%. This operation resulted in a titer of 18.0 g/L FA, indicating the potential of using O. polymorpha as an efficient cell factory for the production of FA.


Assuntos
Ácidos Graxos , Saccharomycetales , Meios de Cultura , Fermentação , Engenharia Metabólica , Saccharomycetales/genética , Saccharomycetales/metabolismo
18.
Front Microbiol ; 13: 834208, 2022.
Artigo em Inglês | MEDLINE | ID: mdl-35401497

RESUMO

Although many reports have demonstrated that nanoparticles can have a negative effect on aquatic organisms, the toxic effects on symbiotic organisms remain poorly understood. The present study conducts ultrastructure, enzyme activity, and transcriptomics to assess the toxic effects to the Paramecium bursaria-Chlorella symbiotic system from exposure to copper nanoparticles (CuNPs) for 24 h. We found that in both the host and symbiotic algae, CuNP exposure induced high reactive oxygen species level, which leads to oxidative damage and energy metabolism disorder. Moreover, transmission electron micrographs (TEMs) showed that the symbiotic algae in the cytoplasm of P. bursaria were enveloped in the digestive vacuole and digested, and the level of acid phosphatase activity increased significantly within 24 h, which indicated that the stability of the symbiotic system was affected after CuNP exposure. We speculated that the increased energy demand in the host and symbiotic algae resulted from oxidative stress, precipitating the decrease of the photosynthetic products provided to the host, the digestion of the symbiont, and the destruction of the stable symbiotic relationship. The study provides the first insight into the mechanisms of nanoparticles' toxicity to the symbiotic relationship in the ecosystem, which may help to understand the environmental effects and toxicological mechanisms of nanoparticles.

19.
Appl Biochem Biotechnol ; 194(7): 2968-2979, 2022 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-35316474

RESUMO

Direct bioconversion of high concentration of volatile fatty acids (VFAs) into microbial lipid is challenging due to the aggravated cytotoxicity of VFAs at high loadings. Herein, a robust oleaginous yeast Trichosporon cutaneum was screened for lipogenesis from high concentration of VFAs using a regular batch culture. Biomass and lipid content of 8.9 g/L and 49.1%, respectively, were attained from 50 g/L acetic acid with 90.9% of which assimilated within 10 days. The blend of VFAs (50 g/L), with mass ratio of acetic, propionic, and butyric acids of 6:3:1, was found superior to acetic acid for lipogenesis. Biomass and lipid titer increased by 16.9% and 18.2%, respectively, with the three VFAs completely consumed within 8 days. Butyric acid was assimilated simultaneously with acetic acid at the beginning of the culture. Heptadecanoic acid (C17:0) and heptadecenoic acid (C17:1) were produced when propionic acid co-existed with acetic and butyric acids. The estimation of biodiesel properties indicated that lipid prepared from VFA blend showed superiority to acetic acid for high-quality biodiesel production. This study strongly supported that T. cutaneum permitted high concentration of VFA mixture for lipid production.


Assuntos
Biocombustíveis , Trichosporon , Ácido Acético , Basidiomycota , Ácido Butírico , Ácidos Graxos , Ácidos Graxos Voláteis , Lipídeos
20.
Bioresour Technol ; 346: 126624, 2022 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-34958908

RESUMO

This study is designed to investigate the roles of five key terminal electron acceptors (TEAs): O2, NO3-, Fe3+, SO42-, and CH2O, typically existing in the sludge on the degradation rates and pathways of three representative MPs: polylactic acid (PLA), polyvinyl chloride (PVC), and polyhydroxyalkanoate (PHA). The results revealed that approximately 51.46 âˆ¼ 52.70% of PHA was degraded within 43 days, despite PLA and PVC being degraded insignificantly. Different TEAs significantly affected the end-products of PHA. The production rate of acetate gradually decreased from 90.48, 42.67, 38.30, and 17.56 to 3.30% when the TEAs were tested with CH2O, O2, SO42-, NO3- and Fe3+, respectively. The main functional bacteria involved in the PHA degradation were hydrolysis bacteria Burkholderiaceae and homo-acetogenic bacteria Clostridiacea, which accounted for 0.83% and 18.91% of the microbes. The current investigation could help improve understanding of MPs degradation pathways and mechanisms and minimize their risks in practice.


Assuntos
Microbiota , Esgotos , Elétrons , Microplásticos , Plásticos
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