RESUMEN
Purpose: The current study aimed to investigate whether red blood cell distribution width (RDW) can predict the prognosis of patients with breast cancer (BC). Methods: We searched four databases, including PubMed, Embase, Cochrane Library databases, and CNKI, from inception to Jun 13, 2022. The primary outcome was overall survival (OS), and the secondary outcome was disease-free survival (DFS). A subgroup analysis was conducted based on different treatments. This meta-analysis was performed with RevMan 5.3 (The Cochrane Collaboration, London, United Kingdom). Results: A total of seven studies including 4,884 BC patients were identified. The high RDW group had a larger tumor size (OR = 2.12, 95% CI = 1.67 to 2.68, P < 0.01), higher proportions of advanced stage tumors (OR = 1.77, 95% CI = 1.38 to 2.27, P < 0.01), more lymph node metastases (OR = 2.00, 95% CI = 1.58 to 2.51, P < 0.01) and lower HER-2 expression (OR = 0.76, 95% CI = 0.61 to 0.95, P = 0.02). For prognosis, after pooling all the data, we found that the high RDW group was associated with worse OS (HR = 2.12, 95% CI = 1.47 to 3.08, P < 0.01) and DFS (HR = 1.77, 95% CI = 1.32 to 2.37, P < 0.01). The subgroup analysis found that RDW had prognostic significance but only for surgery-only patients (HR = 2.41, 95% CI = 1.67 to 3.49, P < 0.01). Conclusion: High RDW was associated with worse OS and DFS. Therefore, RDW was a simple predictive factor for the prognosis of BC patients.
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BACKGROUND: The aim of this meta-analysis was to compare the clinical outcomes of catheter-directed thrombolysis (CDT) plus anticoagulation with anticoagulation alone in patients with lower-extremity proximal deep vein thrombosis (DVT). PATIENTS AND METHODS: We systematically searched Pubmed, Embase, and the Cochrane Library from inception to October, 2014. All randomized controlled trials (RCTs) and non-randomized studies comparing the clinical outcomes between additional CDT and anticoagulation alone were included. The primary outcomes were postthrombotic syndrome and major bleeding complications. The secondary outcomes included the iliofemoral patency rate, deep venous function, mortality, pulmonary embolism, and recurrent DVT. RESULTS: Three RCTs and 3 non-randomized studies were included. Compared with standard anticoagulation treatment, additional CDT was associated with a significantly higher rate of complete lysis within 30 days (OR = 91; 95 % CI 19.28 to 429.46), a higher rate of 6-month patency (OR = 5.77; 95 % CI 1.99 to 16.73), a lower rate of postthrombotic syndrome (OR = 0.4; 95 % CI 0.19 to 0.96), and a lower rate of venous obstruction (OR = 0.20; 95 % CI 0.09 to 0.44). More major bleeding episodes occurred in the CDT group (Peto OR 2.0; 95 % CI 1.62 to 2.62). CDT was not found to reduce mortality, pulmonary embolism, or recurrent DVT. CONCLUSIONS: Additional CDT therapy appeared to be more effective than standard anticoagulation treatment in improving the venous patency and preventing venous obstruction and postthrombotic syndrome. Caution should be taken when performing CDT given the increased risk of major bleeding. However, no evidence supported benefits of CDT in reducing mortality, recurrent DVT, or pulmonary embolism.
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Anticoagulantes/uso terapéutico , Cateterismo , Fibrinolíticos/administración & dosificación , Extremidad Inferior/irrigación sanguínea , Terapia Trombolítica , Trombosis de la Vena/tratamiento farmacológico , Anticoagulantes/efectos adversos , Cateterismo/efectos adversos , Quimioterapia Combinada , Fibrinolíticos/efectos adversos , Hemorragia/inducido químicamente , Humanos , Oportunidad Relativa , Síndrome Postrombótico/etiología , Síndrome Postrombótico/prevención & control , Factores de Riesgo , Terapia Trombolítica/efectos adversos , Factores de Tiempo , Resultado del Tratamiento , Grado de Desobstrucción Vascular , Trombosis de la Vena/sangre , Trombosis de la Vena/diagnóstico , Trombosis de la Vena/fisiopatologíaRESUMEN
The microenvironmental manipulation of glutathione (GSH) on improving cold resistance of Lactobacillus sanfranciscensis DSM 20451(T) was investigated in this study. It was proved that GSH relieves the metabolic disorder of cells under cold stress, and prevents the decreased activities of related key enzymes such as pyruvate kinase (PK), glyceraldehyde-3-phosphate dehydrogenase (GAPDH) and lactate dehydrogenase (LDH) upon cold challenges. Higher intracellular ATP level was also found in cells with GSH under cold stress. Moreover, cells with imported GSH had significantly higher intracellular than the control during cold treatment. In addition, proteomics analysis showed more exciting findings that the protective function of GSH under cold stress was related to metabolic regulation and the multi-control against induced cross-stresses. These results broaden the knowledge about the physiological function of GSH, and suggest a practicable approach to improve the cold resistance of L. sanfranciscensis, a starter culture for sourdough, by the addition of GSH.
Asunto(s)
Glutatión/metabolismo , Lactobacillus/fisiología , Proteínas Bacterianas/genética , Proteínas Bacterianas/metabolismo , Frío , Gliceraldehído-3-Fosfato Deshidrogenasas/genética , Gliceraldehído-3-Fosfato Deshidrogenasas/metabolismo , L-Lactato Deshidrogenasa/genética , L-Lactato Deshidrogenasa/metabolismo , Lactobacillus/enzimología , Lactobacillus/genética , Piruvato Quinasa/genética , Piruvato Quinasa/metabolismo , Estrés FisiológicoRESUMEN
Homoacetogenesis is an important potential hydrogen sink in acetogenesis, in which hydrogen is used to reduce carbon dioxide to acetate. So far the acetate production from homoacetogenesis, especially its kinetics, has not been given sufficient attention. In this work, enhanced production of acetate from anaerobic conversion of glucose through coupling glucose fermentation and homoacetogenesis is investigated with both experimental and mathematical approaches. Experiments are conducted to explore elevated acetate production in a coupled anaerobic system. Acetate production could be achieved by homoacetogenesis with a relative high acetate yield under mixed fermentation conditions. With the experimental observations, a kinetic model is formulated to describe such a homoacetogenic process. The maximum homoacetogenic rate (k(m,homo)) is estimated to be 28.5 ± 1.7 kg COD kg⻹ COD day⻹ with an uptake affinity constant of 3.7 × 10â»5± 3.1 × 10â»6kg COD m⻳. The improved calculation of homoacetogenic kinetics by our approach could correct the underestimation of homoacetogenesis in anaerobic fermentation processes, as it often occurs in these systems supported by literature analysis. The model predictions match the experimental results in different cases well and provide insights into the dynamics of anaerobic glucose conversion and acetate production. Furthermore, acetate production via homoacetogenesis increases by about 40% through utilizing the fed-batch coupling system, attributed to a balance between the hydrogen production in the acetogenesis phase and the hydrogen consumption in the homoacetogenesis phase. This work provides an effective way for increased anaerobic acetate production, and gives us a better understanding about the homoacetogenic kinetics in the anaerobic fermentation process.
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Acetatos/metabolismo , Bacterias/metabolismo , Glucosa/metabolismo , Anaerobiosis , Dióxido de Carbono/metabolismo , Fermentación , Hidrógeno/metabolismo , Cinética , Modelos TeóricosRESUMEN
In this study, the correlations between sludge characteristics, amount of extracellular polymeric substances (EPS) and membrane fouling were investigated and analysed, using continuous sludge discharges from a membrane bioreactor (MBR). The results showed that continuous sludge discharges improved sludge settleability, but not always weakened membrane fouling. The changes in the EPS amount, caused by continuous sludge discharge from MBRs, could resolve this situation well. Soluble EPS concentration could be regulated, to some extent, by sludge discharges. But it was embarrassed to artificially adjust bound EPS amount because the MBRs included living microorganisms and their metabolites. After sludge had been discharged four times, the sludge volume index (SVI) was in the range of 50-60 mL x gSS(-1) with a VSS:SS ratio of about 0.8. Sludge settleability mainly depended on the bound EPS content. The bound EPS content and its components presented a closer relationship to sludge hydrophobicity than to the membrane flux. Soluble EPS dominated both the EPS content on the membrane surface and membrane fouling.
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Reactores Biológicos , Membranas Artificiales , Aguas del AlcantarilladoRESUMEN
Lactobacillus sanfranciscensis DSM20451 cells containing glutathione (GSH) displayed significantly higher resistance against cold stress induced by freeze-drying, freeze-thawing, and 4 degrees C cold treatment than those without GSH. Cells containing GSH were capable of maintaining their membrane structure intact when exposed to freeze-thawing. In addition, cells containing GSH showed a higher proportion of unsaturated fatty acids in cell membranes upon long-term cold treatment. Subsequent studies revealed that the protective role of GSH against cryodamage of the cell membrane is partly due to preventing peroxidation of membrane fatty acids and protecting Na(+),K(+)-ATPase. Intracellular accumulation of GSH enhanced the survival and the biotechnological performance of L. sanfranciscensis, suggesting that the robustness of starters for sourdough fermentation can be improved by selecting GSH-accumulating strains. Moreover, the results of this study may represent a further example of mechanisms for stress responses in lactic acid bacteria.
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Frío , Glutatión/metabolismo , Lactobacillus/metabolismo , Ácidos Grasos/metabolismo , Fermentación , Liofilización , Congelación , Lactobacillus/fisiología , Peroxidación de LípidoRESUMEN
The nature of amino acid residue 47 shows a clear discrimination between the different groups of cyclodextrin glycosyltransferase (CGTase). The effects of amino acid side chain at position 47 on cyclodextrin product specificity were investigated by replacing Lys47 in the CGTase from Paenibacillus macerans strain JFB05-01 with arginine, histidine, threonine, serine, or leucine. All of the mutations reduced alpha-cyclodextrin-forming activity, whereas significant increases in beta-cyclodextrin-forming activity were achieved. Especially, the mutations of Lys47 into threonine, serine, or leucine converted P. macerans CGTase from alpha-type to beta/alpha-type. As a result, all of the mutants displayed a shift in product specificity toward the production of beta-cyclodextrin. Thus, they were more suitable for the industrial production of beta-cyclodextrin than the wild-type enzyme. The enhancement of beta-cyclodextrin specificity might be due to weakening or removal of hydrogen-bonding interactions between the side chain of residue 47 and the bent intermediate specific for alpha-cyclodextrin formation.
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Glucosiltransferasas/química , Lisina/genética , Mutagénesis Sitio-Dirigida , Paenibacillus/enzimología , beta-Ciclodextrinas/metabolismo , Glucosiltransferasas/genética , Leucina/química , Lisina/química , Serina/química , Relación Estructura-Actividad , Especificidad por Sustrato , Treonina/química , alfa-Ciclodextrinas/metabolismoRESUMEN
Overexpression of recombinant genes in Escherichia coli and targeting recombinant proteins to the culture medium are highly desirable for the production of industrial enzymes. However, a major barrier is inadequate secretion of recombinant protein across the two membranes of E. coli cells. In the present study, we have attempted to circumvent this secretion problem of the recombinant alpha-cyclodextrin glycosyltransferase (alpha-CGTase) from Paenibacillus macerans strain JFB05-01. It was found that glycine, as a medium supplement, could enhance the extracellular secretion of recombinant alpha-CGTase in E. coli. In the culture with glycine at the optimal concentration of 150 mM, the alpha-CGTase activity in the culture medium reached 23.5 U/mL at 40 h of culture, which was 11-fold higher than that of the culture in regular TB medium. A 2.3-fold increase in the maximum extracellular productivity of recombinant alpha-CGTase was also observed. However, further analysis indicated that glycine supplementation exerted impaired cell growth as demonstrated by reduced cell number and viability, increased cell lysis, and damaged cell morphology, which prevented further improvement in overall enzyme productivity. Significantly, Ca(2+) could remedy cell growth inhibition induced by glycine, thereby leading to further increase in the glycine-enhanced extracellular secretion of recombinant alpha-CGTase. In the culture with 150 mM glycine and 20 mM Ca(2+), both extracellular activity and maximum productivity of recombinant enzyme were 1.5-fold higher than those in the culture with glycine alone. To the best of our knowledge, this is the first article about the synergistic promoting effects of glycine and Ca(2+) on the extracellular secretion of a recombinant protein in E. coli.
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Calcio/farmacología , Escherichia coli/efectos de los fármacos , Escherichia coli/metabolismo , Glucosiltransferasas/metabolismo , Glicina/farmacología , Proteínas Recombinantes/metabolismo , Bacterias/enzimología , Permeabilidad de la Membrana Celular/efectos de los fármacos , Sinergismo Farmacológico , Escherichia coli/crecimiento & desarrollo , Expresión Génica , Glucosiltransferasas/biosíntesis , Glucosiltransferasas/genética , Proteínas Recombinantes/biosíntesis , Proteínas Recombinantes/genéticaRESUMEN
The effect of initial pH values on acetate production was studied in the acidification-homoacetogenesis two-phase coupling system using glucose as the substrate and the heat-treated and activated anaerobic sludge as the inoculum. Substrate degradation, product yield and pH variation during fermentation were examined at various initial pH values (5, 6, 7, 8, 9, 10 and 11). The results show that initial pH values affect volatile fatty acids and ethanol production not only in the acidification phase itself but also in the homoacetogenesis phase. Ethanol-type fermentation mainly takes place at initial pH 5 while butyrate-type fermentation at initial pH 6 and 7. But acetate is the dominant product at initial pH 8-11. The optimal initial pH value is 10 for acetate production in the two-phase coupling system. At initial pH 8-11, ethanol concentration is highest at the beginning of acidification, but there is a subsequent decline as ethanol is converted to acetate as a result of further metabolism of the microbes.
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Acetatos/metabolismo , Bacterias Anaerobias/metabolismo , Reactores Biológicos/microbiología , Fermentación , Anaerobiosis , Biodegradación Ambiental , Glucosa/metabolismo , Concentración de Iones de Hidrógeno , Eliminación de Residuos LíquidosRESUMEN
Effect of CTAB addition on the accumulation of microbial transglutaminase (MTG) with Streptomyces hygroscopicus was investigated. The results showed that the addition of CTAB enhanced MTG accumulation, and the optimal addition time and concentration of CTAB were 32 h and 1%. The maximum MTG activity in the culture broth was 5.04 u/mL and increased by 21.8% compared with the control. With the addition of CTAB, pro-MTG was activated to become MTG. CTAB could enhance the production of pro-MTG by relieving the product inhibition, and the accumulation of MTG was improved.
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Proteínas Bacterianas/metabolismo , Compuestos de Cetrimonio/farmacología , Streptomyces/efectos de los fármacos , Transglutaminasas/metabolismo , Cetrimonio , Relación Dosis-Respuesta a Droga , Electroforesis en Gel de Poliacrilamida , Activación Enzimática/efectos de los fármacos , Precursores Enzimáticos/metabolismo , Microbiología Industrial/métodos , Streptomyces/enzimología , Streptomyces/metabolismo , Tensoactivos/farmacología , Factores de TiempoRESUMEN
The V2 region of the 16S ribosomal DNA of the ammonia-oxidizing bacteria (AOB) was amplified directly from the environmental sample by using the specific PCR primers. The purified PCR product was cloned into T-vector and was identified as 16S rDNA fragment of AOB by sequencing and Real-time PCR method. Then, the recombined plasmid was used as standard molecule sample in Real-time PCR for AOB quantification. The numbers of the AOB were monitored in samples of both aerobic granular sludge and activated sludge influenced by PCP by using Real-time PCR. The results showed that the numbers of AOB in aerobic granular sludge and activated sludge were 4.28 x 10(7) 5.44 x 10(6) cells/g dried sludge and 2.51 x 10(9) +/- 8.61 x 10(8) cells/g dried sludge without PCP in the reactors, respectively. With the increase of PCP concentration (from 0mg/L to 50mg/L), the numbers of AOB in both types of sludge had no obvious change( P > 0.05) . The numbers of AOB had no obvious correlation with ammonia removal ( P > 0.05) . The main effect of PCP on AOB in both types of sludge was to inhibit their metabolic activity.
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Amoníaco/metabolismo , Reactores Biológicos , Recuento de Colonia Microbiana , Pentaclorofenol/farmacología , Reacción en Cadena de la Polimerasa/métodos , Aguas del Alcantarillado/microbiología , Oxidación-Reducción , PlásmidosRESUMEN
A mutant of Thermobifida fusca ATCC 27730 was used for cutinase production. Acetate was the most suitable carbon source for cell growth and cutinase production compared with others. The pH was one of the most important factors affecting cutinase yield and productivity. Batch cutinase fermentations by mutant Thermobifida fusca WSH04 at various pH values ranging from 7.0 to 7.9 were studied. Based on the effects of different pH values on the specific cell growth rate and specific cutinase formation rate, a two-stage pH control strategy was developed, in which the pH was set at 7.3 for the first 20 h, and switched to 7.6 afterwards. By applying this two-stage pH control strategy for cutinase fermentation, the maximal cutinase activity reached 19.8 U/mL.
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Actinomycetales/enzimología , Hidrolasas de Éster Carboxílico/biosíntesis , Mutación , Actinomycetales/genética , Actinomycetales/metabolismo , Etanol/farmacología , Fermentación/efectos de los fármacos , Glucosa/farmacología , Concentración de Iones de Hidrógeno , Microbiología Industrial/métodos , Lípidos de la Membrana/metabolismo , Acetato de Sodio/farmacología , Almidón/farmacología , Sacarosa/farmacologíaRESUMEN
The gene encoding pectate lyase (PL) from Bacillus subtilis WSHB04-02 was amplified by PCR, fused with a periplasmic secretion signal peptide sequence, pelB, from pET22b(+), cloned and expressed in Escherichia coli cells using a temperature control vector, pHsh. The recombinant E. coil was grown in a 5 l fermentor. PL was secreted in broth at 22 U l(-1) after 20 h when temperature was increased from 30 degrees C to 42 degrees C. The recombinant enzyme was purified to homogeneity as judged by SDS-PAGE. It was optimally active at pH 9.4 and 50 degrees C over 30 min. Analysis of polygalacturonic acid (PGA) degradation products by electrospray ionization (ESI)-mass spectrometry (MS) indicated that PL produced a mixture of unsaturated oligo-galacturonides including unsaturated tri-galacturonic acid and unsaturated bi-galacturonic acid but not unsaturated mono-galacturonic acid.
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Bacillus subtilis/enzimología , Escherichia coli/enzimología , Polisacárido Liasas/biosíntesis , Polisacárido Liasas/química , Ingeniería de Proteínas/métodos , Bacillus subtilis/genética , Activación Enzimática , Estabilidad de Enzimas , Escherichia coli/genética , Regulación Bacteriana de la Expresión Génica/fisiología , Regulación Enzimológica de la Expresión Génica/fisiología , Mejoramiento Genético/métodos , Polisacárido Liasas/genética , Polisacárido Liasas/aislamiento & purificación , Proteínas Recombinantes/biosíntesis , Proteínas Recombinantes/químicaRESUMEN
Syntrophic acetogenic bacteria, an important functional one in anaerobic habitats, were detected and counted by fluorescence in situ hybridization (FISH) technology by using 16S rRNA-based oligonucleotide probes. For enumeration and quantification of the targeted bacteria, an attempt was made to optimize the hybridization conditions. The optimum conditions are as follows: a fixation time of 19h, a dehydrated time of 5 min, and a formamide concentration of 55% in hybridized solution. The abundance of syntrophic acetogenic bacteria of different environmental samples were quantified by FISH and the results showed that Upflow Anaerobic Sludge Reactor (UASB) treating STHZ high-concentration organic wastewater and the digestive tract of some animals were the main habitats of syntrophic acetogenic bacteria. The numbers of syntrophic acetogenic bacteria in UASB and cattle manure were 1.70 x 10(9) cells/mL sample and 6.50 x 10(8) cells/mL sample, respectively. Meanwhile, the sediments of rivers and lakes existed less of the bacteria and the contents of them were just about 1.20 x 10(8) cells/mL sample in Taihu lake.
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Acetatos/metabolismo , Bacterias Anaerobias/aislamiento & purificación , Hibridación Fluorescente in Situ/métodos , Bacterias Anaerobias/metabolismo , Sedimentos Geológicos/microbiología , Estiércol/microbiología , Ríos/microbiología , Aguas del Alcantarillado/microbiologíaRESUMEN
The structure gene PL from Bacillus subtilis WSHB04-02 encoding pectate lyase was amplified by PCR. The pET22b(+) vector, with leader sequence PelB, harboring PL gene was constructed. From pET22b(+) PL, the fragment of PL and leader sequence PelB was amplified by PCR together, which was transformed into E. coli JMI109. The expression of PL in E. coli JM109 was not evidently different from E. coli BL21DE3 (pET22b(+) PL) which promoter is T7. SDS-PAGE analysis showed that the molecular weight of expressed recombinant PL was about 43 kDa which was the same as calculated value. The results indicated the expression of pHsh PL in E. coli JM109, Hsh as a promoter, was satisfied and low-cost. It is significant for large-scale fermentation of pectate lyase.
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Bacillus subtilis/enzimología , Bacillus subtilis/genética , Polisacárido Liasas/metabolismo , Electroforesis en Gel de Poliacrilamida , Escherichia coli/genética , Escherichia coli/metabolismo , Modelos Genéticos , Peso Molecular , Reacción en Cadena de la Polimerasa , Polisacárido Liasas/genética , Regiones Promotoras Genéticas/genéticaRESUMEN
Metabolic pathway network of CoQ10 synthesis by R. radiobacter WSH2601 were instructed. The metabolic flux and its changes were determined under the conditions of changing DO concentration and addition of 1% CSL in the medium. The results illustrated that the Ru5P flux (r7) increased by 26.6 when increasing the DO concentration, r7 increased by 17.2 when addition of 1% CSL. The ratio of EMP and HMP flux as well as TCA flux decreased at these two conditions. DPP flux had a little change at these two conditions. Therefore, the CoQ10 accumulation is greatly determined by two key enzymes activities of condensation reaction between p-hydroxybenzoate acid (PHB) and decaprenyl diphosphate (DPP). The nodes of G6P, pyruvate and PEP are principal nodes in primary metabolism of CoQ10 fermentation. The flexibility of principal nodes was evaluated that the G6P node is elastic, while pyruvate node is weakly flexibility, at the condition of changing culture conditions. The increase of DCW is associated with the improvement of HMP pathway flux.
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Agrobacterium tumefaciens/metabolismo , Medios de Cultivo , Ubiquinona/análogos & derivados , Aminoácidos/metabolismo , Biomasa , Coenzimas , Fermentación , Oxígeno/metabolismo , Ubiquinona/biosíntesisRESUMEN
The green fluorescent protein (GFP) isolated from the jellyfish Aequorea victoria is a very useful reporter for real-time bioprocess sensing. GFP culture fluorescence is a composite signal that can be influenced by factors such as culture autofluorescence, inner filter effect (IFE), and photobleaching. These factors complicate accurate estimation of GFP concentrations from the culture fluorescence. IFE is especially problematic when using GFP in monitoring transgenic plant cell suspension cultures, due to the aggregated nature of the cells and the high biomass concentration in these culture systems. Reported approaches for online compensation of IFE in monitoring culture NADH fluorescence or bioluminescence require online measurement of biomass density or culture turbidity/optical density, in addition to fluorescence/bioluminescence measurement. In this study, culture GFP fluorescence was used successfully to estimate GFP concentration and other important states in bioreactor culture of transgenic tobacco cells, while the influences of IFE and culture autofluorescence were rectified without the need for an additional biomass sensor. This was achieved by setting up a novel model-based state observer. First, we developed an improved model for a backscatter fluorescence probe that takes into account the influence of IFE and autofluorescence on reporting culture GFP concentration from online fluorescence. The state observer was then established using the extended Kalman filter (EKF), based on the fluorescence probe model, a dynamic state model of the plant cell bioreactor, and online GFP fluorescence measurement. Several versions of the observer were introduced to address practical requirements associated with monitoring GFP fluorescence of plant cell cultures. The proposed approach offers an effective means for online compensation of IFE to enable quantitative interpretation of the culture fluorescence signals for accurate reporting of GFP or GFP-fusion protein expression.
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Algoritmos , Proteínas Fluorescentes Verdes/biosíntesis , Modelos Biológicos , Nicotiana/genética , Nicotiana/metabolismo , Plantas Modificadas Genéticamente/metabolismo , Espectrometría de Fluorescencia/métodos , Artefactos , Células Cultivadas , Simulación por Computador , Genes Reporteros , Proteínas Fluorescentes Verdes/análisis , Proteínas Fluorescentes Verdes/genética , Sistemas en Línea , Proteínas Recombinantes/análisis , Proteínas Recombinantes/biosíntesis , Espectrometría de Fluorescencia/instrumentaciónRESUMEN
An alkaline catalase has been purified and characterized from a slightly halophilic and alkaliphilic bacterium Bacillus sp. F26. The purification was performed with a four step procedure consisting of ammonium sulfate precipitation, ion exchange, gel filtration and hydrophobic interaction chromatography, and finally achieved a 58.5-fold-purifying over the crude extract. The purified catalase was composed of two identical subunits with a native molecular mass of 140 kD. The native enzyme showed the typical Soret band appearing at 408 nm. The pyridine hemochrome spectrum indicated the presence of protoheme IX as the prosthetic group. The apparent Km value for enzyme activity on H2O2 was calculated to be 32.5 mmol/L. The activity of this catalase was not reduced by dithionite but was strongly inhibited by cyanide, azide, and 3-amino-1,2,4-triazole (the specific inhibitor of monofunctional catalase). No peroxidase activity of this enzyme was detected when using o-dianisidine, diaminobenzidine (DAB) and p-phenylenediamine as electron donor. Moreover, the N-terminal sequence of this catalase exhibited substantial similarity to the monofunctional catalase subgroup rather than catalase-peroxidase or Mn-catalase one. Therefore, we characterize the purified catalase as a monofunctional catalase. Besides, this monofunctional catalase was thermosensitive and its activity exhibited pH-independent over pH 5-9 but showed a sharp maximum at pH 11. An activity half-life of approximately 49 h was measured when the enzyme was incubated at 20 degrees C and pH 11. To our knowledge, pH 11 is the most alkaline condition for optimum catalysis and enzyme stability among the catalases reported up to now. Furthermore, this monofunctional catalase also showed excellent halo-alkali-stability with a half-life of approximately 90 h at 0.5 mol/L NaCl and pH 10.5. On the other hand, so far as we know, the characterized catalase is the first dimeric monofunctional catalase from alkaliphiles and is also the first monofunctional catalase derived from a natural soda lake, which could partially reflect the oxidative stress response in the corresponding environment.
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Bacillus/enzimología , Proteínas Bacterianas/química , Proteínas Bacterianas/aislamiento & purificación , Catalasa/química , Catalasa/aislamiento & purificación , Estabilidad de Enzimas , Concentración de Iones de Hidrógeno , TemperaturaRESUMEN
The influence of effluent discharging modes on membrane fouling in a submerged membrane bioreactor was evaluated, and the feasibility of the characterization of membrane fouling using Flundlich isothermal adsorption equation was also explored in this paper. Under the same operation conditions, the adsorption equations of three discharging modes of vacuum pump drawing combined with air back-blowing, vacuum pump drawing and suck pump drawing were 2.59ce1/0.957, 7.415ce1/1.369 and 7.10ce1/1.015. Experiment results showed that the effluent-discharging mode had a significant influence on membrane fouling in the submerged membrane bioreactor. Among three discharging modes, the membrane fouling degree in the mode of vacuum pump drawing combined with air back-blowing was the lightest. The experimental results also indicated that Flundlich isothermal adsorption equation is applicable in the characterization of membrane fouling.
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Reactores Biológicos , Purificación del Agua/métodos , Adsorción , Membranas ArtificialesRESUMEN
The capability of utilizing the intermediates of TCA-cycle as the sole carbon source by the multi-vitamin auxotrophic yeast Torulopsis glabrata CCTCC M202019 under the conditions of vitamins limitation was demonstrated. Furthermore, the colony numbers grown on medium supplemented with glucose, acetate and one of the intermediates of TCA-cycle was higher than that of medium used glucose and acetate or medium used one of the intermediates of TCA-cycle carbon source. Among the intermediates of TCA-cycle used in this study, oxaloacetate was the best carbon source for the yeast and it was found that its presence stimulated the conversion of acetate to acetyl-CoA. In batch fermentation with glucose medium, the addition of 10 g/L of oxaloacetate improved the dry cell weight from 11.8 g/L to 13.6 g/L, and the productivity of pyruvate from 0.96 g x L(-1) x h(-1) to 1.19 g x L(-1) x h(-1), a 24% increase after 56 h growth. The yield of pyruvate on glucose was also improved as well, from 0.63 g/g to 0.66 g/g.