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1.
Environ Res ; 236(Pt 2): 116801, 2023 11 01.
Artigo em Inglês | MEDLINE | ID: mdl-37558112

RESUMO

A novel and first electrochemical biosensor based on Deoxyribonucleic acid (DNA) as a biological component to measure an antimigraine drug, rizatriptan benzoate (RZB) for patients under treatment in biological samples was developed. A carbon paste electrode (CPE) was modified by calf thymus (CT) double-stranded (ds)-DNA, nickel ferrite magnetic nanoparticles (NiFe2O4NPs), and gold nanoparticles (AuNPs). The morphology of the CT-DNA/NiFe2O4NPs/AuNPs/CPE was characterized by Field emission scanning electron microscope (FESEM). The presence of NiFe2O4NPs and AuNPs was confirmed by energy-dispersive X-ray spectroscopy (EDS) image of the NiFe2O4NPs/AuNPs/CPE surface. Electrochemical impedance spectroscopy (EIS) and cyclic voltammetry (CV) were used to determine the structure and electrochemical characteristics of the CT-DNA/NiFe2O4NPs/AuNPs/CPE. Differential pulse voltammetry (DPV) was used to investigate the electrochemical behavior of RZB. Chronoamperometry (CA) was applied to study the effect of CT-DNA immobilization time on the peak oxidation current of RZB accumulated on the surface of the CT-DNA/NiFe2O4NPs/AuNPs/CPE. The results showed that, under optimum conditions, the prepared electrode responded linearly to RZB concentrations between 0.01 and 2.0 µM, with a 0.0033 µM detection limit (LOD) and 0.01 µM limit of quantification (LOQ). The parameters influencing the biosensor performance (temperature, CT-DNA immobilization time, and RZB/CT-DNA accumulation time) were optimized. DPV showed the displacement of the peak potential towards positive values and the reduction of its current, indicating that the drug could intercalate between the guanine base pairs of CT-DNA. Our biosensor was successfully applied for RZB measurement in human urine, blood serum, plasma samples, and tablets. The presented biosensor was fast response, sensitive, selective, cost-effective, and easy-to-use for RZB determination in pharmaceutical formulations and biological samples.


Assuntos
Técnicas Biossensoriais , Nanopartículas Metálicas , Humanos , Carbono/química , Ouro/química , Nanopartículas Metálicas/química , Técnicas Eletroquímicas/métodos , Limite de Detecção , DNA , Preparações Farmacêuticas , Eletrodos , Técnicas Biossensoriais/métodos , Tomografia Computadorizada por Raios X
2.
Mikrochim Acta ; 187(6): 315, 2020 05 07.
Artigo em Inglês | MEDLINE | ID: mdl-32383071

RESUMO

Nickel-ferrite nanoparticles (NiFe2O4) were synthesized by a hydrothermal method. They were used to modify a carbon paste electrode (CPE) and to prepare an electrochemical sensor for simultaneous determination of rizatriptan benzoate (RZB) and acetaminophen (AC). The structure and morphology of the bare CPE and modified CPE were studied using field emission scanning electron microscopy, while the structural characterization of NiFe2O4 was performed via X-ray diffraction. In the potential range 0.2-1.2 V, AC and RZB were detected at potentials of 0.5 V and 0.88 V (vs. Ag/AgCl saturated KCl 3 M), respectively. Both calibration plots are linear in the 1 to 90 µM concentration range. The limits of detection (at 3σ) of AC and RZB are 0.49 and 0.44 µM, respectively. The performance of the modified CPE was evaluated by quantifying the two drugs in spiked urine and in tablets. Graphical abstract The modified electrode consist of Nickel-ferrite and graphite by differential pulse voltammetry methods are schematically presented for simultaneous detection of acetaminophen (a painkiller drug) and rizatriptan benzoate (an antimigraine drug) in human urine and tablet samples.


Assuntos
Acetaminofen/urina , Técnicas Eletroquímicas/métodos , Compostos Férricos/química , Nanopartículas Metálicas/química , Níquel/química , Triazóis/urina , Triptaminas/urina , Acetaminofen/química , Carbono/química , Técnicas Eletroquímicas/instrumentação , Eletrodos , Humanos , Limite de Detecção , Oxirredução , Comprimidos/análise , Triazóis/química , Triptaminas/química
3.
Bioprocess Biosyst Eng ; 41(4): 519-530, 2018 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-29299676

RESUMO

Cultivation of microalgae in wastewater is a promising and cost-effective approach for both CO2 biofixation and wastewater remediation. In this study, a new strain of Coelastrum sp. was isolated from cattle manure leachate. The isolated microalgae were then cultivated in wastewater. Effects of different sCOD concentrations (600, 750, 900, 1050 mg L-1) and light intensities (1000, 2300, 4600, 6900 and 10000 Lux) on biomass production, CO2 consumption rate and nutrient removal from wastewater were investigated. The results showed that maximum cell growth and CO2 consumption rate were 2.71 g L-1 and 53.12 mg L-1 day-1, respectively, which were obtained in the wastewater with 750 mg L-1 sCOD and under the light intensity of 6900 Lux. The microalgae were able to completely consume all CO2 after incubation period of 4 days. The highest sCOD, total Kjeldahl nitrogen (TKN), nitrate and total phosphorous (TP) removal at such conditions were 53.45, 91.18, 87.51 and 100%, respectively. The lipid content of microalgal biomass was also measured under different light intensities; maximum amount of lipid was determined to be 50.77% under illumination of 2300 Lux. Finally, the CO2 consumption rate and biomass productivity of microalgae in semi-batch culture with continuous gas flow (CO2 6%:N2 94%) were investigated. The rate of CO2 consumption and biomass productivity were 0.528 and 0.281 g L-1 day-1, respectively. The TKN, nitrate, TP and sCOD removal rate of microalgae were 83.51, 80.91, 100, 41.4%, respectively.


Assuntos
Dióxido de Carbono/metabolismo , Clorófitas/crescimento & desenvolvimento , Lipídeos/biossíntese , Microalgas/crescimento & desenvolvimento , Águas Residuárias/microbiologia , Microbiologia da Água , Microalgas/isolamento & purificação , Purificação da Água/métodos
4.
Chirality ; 29(6): 304-314, 2017 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-28422452

RESUMO

S-naproxen by enantioselective hydrolysis of racemic naproxen methyl ester was produced using immobilized lipase. The lipase enzyme was immobilized on chitosan beads, activated chitosan beads by glutaraldehyde, and Amberlite XAD7. In order to find an appropriate support for the hydrolysis reaction of racemic naproxen methyl ester, the conversion and enantioselectivity for all carriers were compared. In addition, effects of the volumetric ratio of two phases in different organic solvents, addition of cosolvent and surfactant, optimum pH and temperature, reusability, and inhibitory effect of methanol were investigated. The optimum volumetric ratio of two phases was defined as 3:2 of aqueous phase to organic phase. Various water miscible and water immiscible solvents were examined. Finally, isooctane was chosen as an organic solvent, while 2-ethoxyethanol was added as a cosolvent in the organic phase of the reaction mixture. The optimum reaction conditions were determined to be 35 °C, pH 7, and 24 h. Addition of Tween-80 in the organic phase increased the accessibility of immobilized enzyme to the reactant. The optimum organic phase compositions using a volumetric ratio of 2-ethoxyethanol, isooctane and Tween-80 were 3:7 and 0.1% (v/v/v), respectively. The best conversion and enantioselectivity of immobilized enzyme using chitosan beads activated by glutaraldehyde were 0.45 and 185, respectively.


Assuntos
Quitosana/química , Enzimas Imobilizadas/química , Enzimas Imobilizadas/metabolismo , Lipase/química , Lipase/metabolismo , Naproxeno/química , Naproxeno/síntese química , Candida/enzimologia , Técnicas de Química Sintética , Enzimas Imobilizadas/antagonistas & inibidores , Concentração de Íons de Hidrogênio , Hidrólise , Lipase/antagonistas & inibidores , Metanol/farmacologia , Solventes/química , Estereoisomerismo , Tensoativos/química , Temperatura
5.
Compr Rev Food Sci Food Saf ; 16(1): 124-140, 2017 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-33371546

RESUMO

Piperine is the major bio-active component of pepper, which imparts pungency and biting taste to it. This naturally occurring alkaloid has numerous demonstrated health effects and beneficial therapeutic properties; nevertheless, its biological applications are limited due to its poor solubility in aqueous environments. This emphasizes an implementation of advanced extraction approaches which could enhance the extraction yield of piperine from pepper and also the development of new formulations containing piperine to improve its in vivo bioavailability. This paper presents a review on the therapeutic and medicinal effects of piperine, its isolation from pepper fruit and the development of new formulations for its medicinal (pharmaceutical) applications. A thorough review on conventional and advanced separation techniques for the extraction of piperine from pepper is presented and an outline of the most significant conditions to improve the extraction yield is provided and discussed. Different methods used to measure and quantify the isolated piperine are also reviewed. An overview of biotechnological advancements for nanoparticle formulations of piperine or its incorporation in lipid formulations, which could enhance its bioavailability, is also presented.

6.
Bioprocess Biosyst Eng ; 39(9): 1341-9, 2016 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-27126500

RESUMO

Cheese whey fermentation to ethanol using immobilized Kluyveromyces marxianus cells was investigated in batch and continuous operation. In batch fermentation, the yeast cells were immobilized in carboxymethyl cellulose (CMC) polymer and also synthesized graft copolymer of CMC with N-vinyl-2-pyrrolidone, denoted as CMC-g-PVP, and the efficiency of the two developed cell entrapped beads for lactose fermentation to ethanol was examined. The yeast cells immobilized in CMC-g-PVP performed slightly better than CMC with ethanol production yields of 0.52 and 0.49 g ethanol/g lactose, respectively. The effect of supplementation of cheese whey with lactose (42, 70, 100 and 150 g/l) on fermentative performance of K. marxianus immobilized in CMC beads was considered and the results were used for kinetic studies. The first order reaction model was suitable to describe the kinetics of substrate utilization and modified Gompertz model was quite successful to predict the ethanol production. For continuous ethanol fermentation, a packed-bed immobilized cell reactor (ICR) was operated at several hydraulic retention times; HRTs of 11, 15 and 30 h. At the HRT of 30 h, the ethanol production yield using CMC beads was 0.49 g/g which implies that 91.07 % of the theoretical yield was achieved.


Assuntos
Carboximetilcelulose Sódica/química , Queijo , Etanol/metabolismo , Kluyveromyces/metabolismo , Soro do Leite/metabolismo , Fermentação , Cinética , Lactose/metabolismo , Microscopia Eletrônica de Varredura , Especificidade por Substrato
7.
Bioprocess Biosyst Eng ; 37(5): 923-30, 2014 May.
Artigo em Inglês | MEDLINE | ID: mdl-24078148

RESUMO

Biohydrogen production through water­gas shift (WGS) reaction by a biocatalyst was conducted in batch fermentation. The isolated photosynthetic bacterium Rhodopseudomonas palustris PT was able to utilize carbon monoxide and simultaneously produce hydrogen. Light exposure was provided as an indispensable requirement for the first stage of bacterial growth, but throughout the hydrogen production stage, the energy requirement was met through the WGS reaction. At ambient pressure and temperature, the effect of various sodium acetate concentrations in presence of CO-rich syngas on cell growth, carbon monoxide consumption, and biohydrogen production was also investigated. Maximal efficiency of hydrogen production in response to carbon monoxide consumption was recorded at 86 % and the highest concentration of hydrogen at 33.5 mmol/l was achieved with sodium acetate concentration of 1.5 g/l. The obtained results proved that the local isolate; R. palustris PT, was able to utilize CO-rich syngas and generate biohydrogen via WGS reaction.


Assuntos
Monóxido de Carbono/metabolismo , Hidrogênio/metabolismo , Rodopseudomonas/crescimento & desenvolvimento , Rodopseudomonas/metabolismo
8.
ScientificWorldJournal ; 2014: 910590, 2014.
Artigo em Inglês | MEDLINE | ID: mdl-24672390

RESUMO

The intrinsic growth, substrate uptake, and product formation biokinetic parameters were obtained for the anaerobic bacterium, Clostridium ljungdahlii, grown on synthesis gas in various pressurized batch bioreactors. A dual-substrate growth kinetic model using Luong for CO and Monod for H2 was used to describe the growth kinetics of the bacterium on these substrates. The maximum specific growth rate (µ(max) = 0.195 h(-1)) and Monod constants for CO (K s,CO = 0.855 atm) and H2 (K(s,H2) = 0.412 atm) were obtained. This model also accommodated the CO inhibitory effects on cell growth at high CO partial pressures, where no growth was apparent at high dissolved CO tensions (P(CO)(∗) > 0.743 atm). The Volterra model, Andrews, and modified Gompertz were, respectively, adopted to describe the cell growth, substrate uptake rate, and product formation. The maximum specific CO uptake rate (q(max) = 34.364 mmol/g cell/h), CO inhibition constant (K(I) = 0.601 atm), and maximum rate of ethanol (R(max) = 0.172 mmol/L/h at P(CO) = 0.598 atm) and acetate (R(max) = 0.096 mmol/L/h at P(CO) = 0.539 atm) production were determined from the applied models.


Assuntos
Biocombustíveis , Clostridium/metabolismo , Fermentação , Gases/metabolismo , Cinética
9.
Int J Microbiol ; 2022: 4386268, 2022.
Artigo em Inglês | MEDLINE | ID: mdl-35990767

RESUMO

Background and Aims: Microalgae are known as a promising source for food, pharmaceutical, and biofuel production while providing environmental advantages. The present study evaluates some newly isolated microalgal strains from north and southwest of Iran as a potential source for high-value products. Methods: Primitive screening was carried out regarding growth parameters. The molecular and morphological identifications of the selected strains were performed using 18S rRNA gene sequencing. After phylogenic and evolutionary studies, the selected microalgal strains were characterized in terms of protein and pigment content, in addition to the fatty acid profile content. Besides, the CO2 fixation rate was determined to assess capability for various environmental applications. Results: All of the selected strains were predominantly belonging to Scenedesmus sp. and Desmodesmus sp. The isolated Scenedesmus sp. VN 009 possessed the highest productivity content and CO2 fixation rate of 0.054 g·L-1d-1 and 0.1 g·L-1d-1, respectively. Moreover, data from GC/MS analysis demonstrated the high robustness of this strain to produce several valuable fatty acids including α-linolenic acid and linoleic acid in 45% and 20% of total fatty acids. Conclusions: The identified strains have a great but different potential for SCP, ß-carotene, and ω-3 production, as well as CO2 fixation for environmental purposes. In this study, considering the wide range of microalgal strains in different habitats of Iran, the potential applications of native microalgae for various pharmaceutical, food, and biotechnology purposes were investigated.

10.
Environ Technol ; 33(15-16): 1835-41, 2011 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-22439571

RESUMO

Biodegradation of phenol with pure culture of Pseudomonas putida was investigated. P. putida (PTCC 1694) was grown in facultative anaerobic condition at 27 degrees C and media pH value of 7. The effect of initial phenol concentration on the biodegradation rate was studied. The initial concentrations of phenol varied from 300 to 1000 mg/l. Experiments were performed for the duration of seven days while daily samples were withdrawn. The initial rate of biodegradation of phenol increased with initial concentration of 300-500 mg/l. Further increase in phenol concentration resulted in a slight decrease in the rate of biodegradation due to phenol inhibition. It was observed that by increasing the concentration of phenol, the lag phase was prolonged. Phenol is known to be an inhibitory substrate, thus Monod, Haldane and logistic kinetic models were applied to evaluate the growth kinetic parameters. The Monod model was unable to present the growth parameters over the defined concentration range. However, Haldane and logistic models perfectly fitted with the experimental data. The yield coefficients for the growth on phenol at concentrations of 300, 500, 700 and 1000 mg/l were 0.177, 0.062, 0.035 and 0.012 mg/mg, respectively.


Assuntos
Modelos Biológicos , Fenol/metabolismo , Pseudomonas putida/metabolismo , Biodegradação Ambiental , Proliferação de Células , Pseudomonas putida/crescimento & desenvolvimento
11.
Turk J Chem ; 45(5): 1454-1462, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-34849059

RESUMO

The present study aimed to synthesize ursolic acid-loaded chitosan nanoparticles (UA-Ch-NPs) as an antiinfective agent against 21 Staphylococcus aureus isolates. The UA-Ch-NPs were synthesized by a simple method and then characterized by TEM, FTIR, DLS-zeta potential, and XRD analyses. According to the characterization results, highly dispersed spherical nanoparticles with a mean diameter of 258 nm and a zeta potential of + 40.1 mV were developed. The antibacterial properties of UA-Ch-NPs were investigated and their inhibitory effect on biofilm formation was demonstrated by AFM. Finally, the expression levels of icaA and icaD were measured using real-time PCR. Results indicated that the minimum inhibitory concentration (MIC) of UA and UA-Ch-NPs against S. aureus was 64 and 32 µg/mL, respectively. The treatment of bacterial cells with UA-Ch-NPs significantly decreased the expression of icaA and icaD genes which are engaged in biofilm formation. Our results indicated that UA-Ch-NPs could be a promising material for antibacterial and antibiofilm applications.

12.
ACS Biomater Sci Eng ; 5(5): 2595-2609, 2019 May 13.
Artigo em Inglês | MEDLINE | ID: mdl-33405765

RESUMO

Nanodrug delivery systems are considered as promising therapeutic platforms to convey drugs to tumor cells. In this study, a single layer of carboxymethylcellulose (CMC) and poly N-vinylpyrrolidone (PVP) was cross-linked through disulfide bond and deposited on graphene oxide nanoparticles (GO NPs) using layer-by-layer technique. Overexpression of folate receptors on tumor cells is a great hallmark for drug delivery systems; though the NPs were functionalized by monoclonal folic acid antibody (FA) using polyethylene glycol (PEG) as linker. The mean diameter of synthesized nanoparticles was 60 nm. Curcumin was encapsulated within CMC layer with high encapsulation capacity of 94%. In vitro investigation showed 87% curcumin release at simulated tumor environment. Curcumin loaded FA modified CMC/PVP GO NPs showed high inhibition of 76 and 81% against Saos2 and MCF7 cell lines in vitro. In vivo investigations on 4T1 bearing breast cancer mice model exhibited 76% antitumor efficiency via active targeting mechanism of folate mediated transport without any significant side effect. Immunohistochemistry and immunofluorescence analyses showed enhanced antiangiogenesis, apoptosis and tumor growth inhibition.

13.
Carbohydr Polym ; 226: 115284, 2019 Dec 15.
Artigo em Inglês | MEDLINE | ID: mdl-31582083

RESUMO

Cellulose based microcarriers can be used in biomedical science as supports for cell adhesion and proliferation. However, to facilitate cell attachment to their surface, they require appropriate functional surface charge. Cell function such as adhesion and growth is increased on the modified surfaces with cationic and anionic groups. In this research, diethylaminoethyl cellulose was carboxymethylated to produce soluble multifunctional cellulose with simultaneous presence of cationic and anionic functional groups. Then, carboxymethylated diethylaminoethyl cellulose (CM-DEAEC) were produced by ionic crosslinking. Various instrumental techniques were applied to characterize the microcarriers. Biological tests were also performed to determine cell seeding efficiency, proliferation and attachment on microcarriers. Fabricated CM-DEAEC microcarriers had 1500-1800 µm diameter, +26.0 surface potential, 376% swelling behavior and 233 °C glass transition temperature respectively. The findings showed that CM-DEAEC microcarriers support cellular attachment and proliferation very well and hence are promising materials for cell therapy and tissue engineering applications.


Assuntos
Técnicas de Cultura de Células/métodos , DEAE-Celulose/análogos & derivados , Fibroblastos/citologia , Engenharia Tecidual/métodos , Adesão Celular , Proliferação de Células , Células Cultivadas , Humanos
14.
Bioresour Technol ; 99(7): 2612-9, 2008 May.
Artigo em Inglês | MEDLINE | ID: mdl-17582763

RESUMO

Hydrogen may be considered a potential fuel for the future since it is carbon-free and oxidized to water as a combustion product. Bioconversion of synthesis gas (syngas) to hydrogen was demonstrated in continuous stirred tank bioreactor (CSTBR) utilizing acetate as a carbon source. An anaerobic photosynthetic bacterium, Rhodospirillum rubrum catalyzed water-gas shift reaction which was applied for the bioconversion of syngas to hydrogen. The continuous fermentation of syngas in the bioreactor was continuously operated at various gas flow rates and agitation speeds, for the period of two months. The gas flow rates were varied from 5 to 14 ml/min. The agitation speeds were increasingly altered in the range of 150-500 rpm. The pH and temperature of the bioreactor was set at 6.5 and 30 degrees C. The liquid flow rate was kept constant at 0.65 ml/min for the duration of 60 days. The inlet acetate concentration was fed at 4 g/l into the bioreactor. The hydrogen production rate and yield were 16+/-1.1 mmol g(-1)cell h(-1) and 87+/-2.4% at fixed agitation speed of 500 rpm and syngas flow rate of 14 ml/min, respectively. The mass transfer coefficient (KLa) at this condition was approximately 72.8h(-1). This new approach, using a biocatalyst was considered as an alternative method of conventional Fischer-Tropsch synthetic reactions, which were able to convert syngas into hydrogen.


Assuntos
Anaerobiose , Reatores Biológicos , Hidrogênio/metabolismo , Rhodospirillum rubrum/metabolismo , Meios de Cultura
15.
Environ Sci Pollut Res Int ; 25(30): 30139-30150, 2018 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-30151786

RESUMO

Microalgae cultivation is a promising approach to remove ambient CO2 via photosynthesis process. This paper investigates the impact of high CO2 concentrations (6, 12, and 16%) on algae growth, CO2 biofixation, lipid and carbohydrate contents, and nutrient removal of newly isolated microalgae, Coelastrum sp. SM. In addition, the ability of microalgae to produce biodiesel at optimal condition was studied. The microalgae were cultivated in wastewater using an airlift photobioreactor. Under 12% CO2, the maximum biomass productivity and CO2 fixation rate were 0.267 g L-1 day-1 and 0.302 g L-1 h-1, respectively. Total Kjeldahl nitrogen (TKN), total phosphorous (TP), nitrate, and sCOD removal efficiency were 84.01, 100, 86.811, and 73.084%, respectively. Under 12% CO2 and at the same condition for cell growth, the highest lipid and carbohydrate contents were 3 7.91 and 58.45%, respectively. The composition of fatty acids methyl ester (FAME) of the microalga lipid was defined. Based on the obtained results and FAME profile, Coelastrum sp. SM was a suitable feedstock for biodiesel production and also, the organism had a great potential for CO2 biofixation, which is also more suitable than any other reported strains in other related studies.


Assuntos
Biocombustíveis/análise , Dióxido de Carbono/metabolismo , Clorofíceas/metabolismo , Microalgas/metabolismo , Biomassa , Metabolismo dos Carboidratos , Carboidratos/química , Clorofíceas/química , Clorofíceas/crescimento & desenvolvimento , Ácidos Graxos/química , Ácidos Graxos/metabolismo , Lipídeos/química , Microalgas/química , Microalgas/crescimento & desenvolvimento , Nitrogênio/análise , Fósforo/análise , Fósforo/metabolismo , Fotobiorreatores , Águas Residuárias/química
16.
Braz J Microbiol ; 48(2): 251-258, 2017.
Artigo em Inglês | MEDLINE | ID: mdl-28089612

RESUMO

Kinetic behaviors of five Lactobacillus strains were investigated with Contois and Exponential models. Awareness of kinetic behavior of microorganisms is essential for their industrial process design and scale up. The consistency of experimental data was evaluated using Excel software. L. bulgaricus was introduced as the most efficient strain with the highest biomass and lactic acid yield of 0.119 and 0.602gg-1 consumed lactose, respectively. The biomass and carbohydrate yield of L. fermentum and L. lactis were slightly less and close to L. bulgaricus. Biomass and lactic acid production yield of 0.117 and 0.358 for L. fermentum and 0.114 and 0.437gg-1 for L.actobacillus lactis were obtained. L. casei and L. delbrueckii had the less biomass yield, nearly 11.8 and 22.7% less than L. bulgaricus, respectively. L. bulgaricus (R2=0.9500 and 0.9156) and L. casei (R2=0.9552 and 0.8401) showed acceptable consistency with both models. The investigation revealed that the above mentioned models are not suitable to describe the kinetic behavior of L. fermentum (R2=0.9367 and 0.6991), L. delbrueckii (R2=0.9493 and 0.7724) and L. lactis (R2=0.8730 and 0.6451). Contois rate equation is a suitable model to describe the kinetic of Lactobacilli. Specific cell growth rate for L. bulgaricus, L. casei, L. fermentum, L. delbrueckii and L. lactis with Contois model in order 3.2, 3.9, 67.6, 10.4 and 9.8-fold of Exponential model.


Assuntos
Lactobacillus/crescimento & desenvolvimento , Lactobacillus/metabolismo , Lactose/metabolismo , Modelos Teóricos , Biomassa , Fermentação , Ácido Láctico/metabolismo , Edulcorantes/metabolismo
17.
Int J Biol Macromol ; 101: 1029-1040, 2017 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-28385521

RESUMO

The brown seaweed Sargassum sp. was used as a feedstock to produce polyhydroxybutyarte (PHB) using Cupriavidus necator PTCC 1615. In order to release monomeric sugars, dilute acid hydrolysis of Sargassum sp. biomass was followed by enzymatic saccharification. In addition, the effect of different nitrogen sources was evaluated for PHB production. The fermentation of hydrolysate with the ammonium sulfate as selected nitrogen source resulted PHB yield of 0.54±0.01g/g reducing sugar. Then, NaCl was used as external stress factor which was added to the media. Addition of 8g/L NaCl had a positive impact on high PHB yield of 0.74±0.01g/g reducing sugar. Increasing trend of NaCl concentration to 16g/L was found to inhibit the production of PHB. Based on obtained results using 20g/L of reducing sugar, at desired condition the highest cell dry weight and PHB concentrations were 5.36±0.22 and 3.93±0.24g/L, respectively. The findings of this study reveal that Sargassum sp. is a promising feedstock for biopolymer production. The characteristics of produced PHB were analyzed by FTIR, differential scanning calorimetry and 1H NMR.


Assuntos
Celulase/metabolismo , Cupriavidus necator/metabolismo , Poliésteres/metabolismo , Alga Marinha/química , Açúcares/metabolismo , Biomassa , Biotecnologia , Cupriavidus necator/efeitos dos fármacos , Concentração de Íons de Hidrogênio , Hidrólise/efeitos dos fármacos , Cloreto de Sódio/farmacologia
18.
Bioresour Technol ; 212: 62-71, 2016 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-27085147

RESUMO

In this paper, genetic algorithm was used to investigate mathematical modeling of ethanol fermentation in a continuous conventional bioreactor (CCBR) and a continuous membrane bioreactor (CMBR) by ethanol permselective polydimethylsiloxane (PDMS) membrane. A lab scale CMBR with medium glucose concentration of 100gL(-1) and Saccharomyces cerevisiae microorganism was designed and fabricated. At dilution rate of 0.14h(-1), maximum specific cell growth rate and productivity of 0.27h(-1) and 6.49gL(-1)h(-1) were respectively found in CMBR. However, at very high dilution rate, the performance of CMBR was quite similar to conventional fermentation on account of insufficient incubation time. In both systems, genetic algorithm modeling of cell growth, ethanol production and glucose concentration were conducted based on Monod and Moser kinetic models during each retention time at unsteady condition. The results showed that Moser kinetic model was more satisfactory and desirable than Monod model.


Assuntos
Reatores Biológicos , Etanol/metabolismo , Modelos Teóricos , Saccharomyces cerevisiae/metabolismo , Algoritmos , Dimetilpolisiloxanos , Fermentação , Glucose/química , Cinética , Membranas Artificiais , Saccharomyces cerevisiae/crescimento & desenvolvimento
19.
Bioresour Technol ; 86(1): 91-4, 2003 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-12421015

RESUMO

Kinetic studies of the enzymatic hydrolysis of molasses were conducted using glucoamylase. Central Sugar Refinery SDN BHD contains 13-20% glucose. The molasses was diluted and the kinetic experiments were conducted at 67 degrees C with 100-1000 mg/l of glucoamylase. The glucose contents of the molasses were enhanced after hydrolysis of molasses solution with 1000 mg/l glucoamylase. A Lineweaver-Burk plot was obtained based on enzyme kinetic data. The rate constant, Km and maximum reaction rate, Vmax for 500 mg/l of glucoamylase were 100 mmol/l (18 g/l) and 5 mmol/l min (0.9 g/l min), respectively. The maximum reaction rate, Vmax for 1000 mg/l of glucoamylase was doubled, to 100 mmol/l (18 g/l) and the rate constant, Km was the same for 500 mg/l of glucoamylase. The substrate inhibition model was noncompetitive based on the resulting Lineweaver-Burk plot for enzyme concentration of 500 and 1000 mg/l.


Assuntos
Glucana 1,4-alfa-Glucosidase/metabolismo , Melaço , Cor , Hidrólise , Cinética , Melaço/análise , Água/análise
20.
Bioresour Technol ; 92(3): 251-60, 2004 May.
Artigo em Inglês | MEDLINE | ID: mdl-14766158

RESUMO

Fermentation of sugar by Saccharomyces cerevisiae, for production of ethanol in an immobilized cell reactor (ICR) was successfully carried out to improve the performance of the fermentation process. The fermentation set-up was comprised of a column packed with beads of immobilized cells. The immobilization of S. cerevisiae was simply performed by the enriched cells cultured media harvested at exponential growth phase. The fixed cell loaded ICR was carried out at initial stage of operation and the cell was entrapped by calcium alginate. The production of ethanol was steady after 24 h of operation. The concentration of ethanol was affected by the media flow rates and residence time distribution from 2 to 7 h. In addition, batch fermentation was carried out with 50 g/l glucose concentration. Subsequently, the ethanol productions and the reactor productivities of batch fermentation and immobilized cells were compared. In batch fermentation, sugar consumption and ethanol production obtained were 99.6% and 12.5% v/v after 27 h while in the ICR, 88.2% and 16.7% v/v were obtained with 6 h retention time. Nearly 5% ethanol production was achieved with high glucose concentration (150 g/l) at 6 h retention time. A yield of 38% was obtained with 150 g/l glucose. The yield was improved approximately 27% on ICR and a 24 h fermentation time was reduced to 7 h. The cell growth rate was based on the Monod rate equation. The kinetic constants (K(s) and mu(m)) of batch fermentation were 2.3 g/l and 0.35 g/lh, respectively. The maximum yield of biomass on substrate (Y(X-S)) and the maximum yield of product on substrate (Y(P-S)) in batch fermentations were 50.8% and 31.2% respectively. Productivity of the ICR were 1.3, 2.3, and 2.8 g/lh for 25, 35, 50 g/l of glucose concentration, respectively. The productivity of ethanol in batch fermentation with 50 g/l glucose was calculated as 0.29 g/lh. Maximum production of ethanol in ICR when compared to batch reactor has shown to increase approximately 10-fold. The performance of the two reactors was compared and a respective rate model was proposed. The present research has shown that high sugar concentration (150 g/l) in the ICR column was successfully converted to ethanol. The achieved results in ICR with high substrate concentration are promising for scale up operation. The proposed model can be used to design a lager scale ICR column for production of high ethanol concentration.


Assuntos
Reatores Biológicos , Etanol/metabolismo , Glucose/metabolismo , Saccharomyces cerevisiae/metabolismo , Fermentação , Cinética , Microscopia Eletrônica de Varredura , Modelos Biológicos , Saccharomyces cerevisiae/ultraestrutura , Fatores de Tempo
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