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1.
In Vitro Cell Dev Biol Anim ; 44(8-9): 330-8, 2008.
Artículo en Inglés | MEDLINE | ID: mdl-18661193

RESUMEN

The symbiotic octocoral Sinularia flexibilis is a producer of potential pharmaceuticals. Sustainable mass production of these corals as a source of such compounds demands innovative approaches, including coral cell culture. We studied various cell dissociation methodologies and the feasibility of cultivation of S. flexibilis cells on different media and cell dissociation methodologies. Mechanical dissociation of coral tissue always yielded the highest number of cells and allowed subsequent cellular growth in all treatments. The best results from chemical dissociation reagents were found with trypsin-ethylene diamine tetraacetic acid. Coral cells obtained from spontaneous dissociation did not grow. Light intensity was found to be important for coral cell culture showing an enduring symbiosis between the cultured cells and their intracellular algae. The Grace's insect medium and Grace's modified insect medium were found to be superior substrates. To confirm the similarity of the cultured cells and those in the coral tissue, a molecular test with Internal Transcribed Spacer primers was performed. Thereby, the presence of similar cells of both the coral cells and zooxanthella in different culture media was confirmed.


Asunto(s)
Antozoos/citología , Técnicas de Cultivo de Célula/métodos , Animales , Antozoos/química , Antozoos/crecimiento & desarrollo , ADN Intergénico/metabolismo , Simbiosis/fisiología
2.
Trends Biotechnol ; 25(1): 16-23, 2007 Jan.
Artículo en Inglés | MEDLINE | ID: mdl-17113174

RESUMEN

The combination of web technology, knowledge of bioprocess engineering, and theories on learning and instruction might yield innovative learning material for bioprocess engineering. In this article, an overview of the characteristics of web-based learning material is given, as well as guidelines for the design of learning material from theories of learning and instruction and from the bioprocess engineering domain. A diverse body of learning material is presented, which illustrates the application of these guidelines; this material has been developed during the past six years for different courses, mostly at undergraduate level, and it illustrates how web-based learning material can enable various different approaches to learning objectives that might improve overall learning. Such learning material has been used for several years in education, it has been evaluated with positive results, and is now part of the regular learning material for bioprocess engineering at Wageningen University.


Asunto(s)
Ingeniería Biomédica/educación , Redes de Comunicación de Computadores , Educación a Distancia/métodos , Educación a Distancia/normas
3.
Biotechnol Adv ; 25(2): 137-47, 2007.
Artículo en Inglés | MEDLINE | ID: mdl-17196783

RESUMEN

Multiple phenomena are involved in conversions by immobilized biocatalysts. A paradox is identified between analytical desires on one hand and analytical boundary conditions on the other: while the study of interdependent phenomena would call for their simultaneous analysis in an integrated context, the available experimental options may impose a series of separate and dedicated analyses. From this analysis, bottlenecks in particle performance may be identified, if possible supported by a mechanistic model and performance criteria. Subsequently, a strategy for further biocatalyst development may be chosen. Finally, possibilities for future improvement of biocatalysts are discussed for various fields of research. Some examples of recent developments in enzyme and matrix characteristics, reactor operation, and micro-technology are discussed.


Asunto(s)
Biotecnología/métodos , Enzimas Inmovilizadas/química , Enzimas Inmovilizadas/metabolismo , Reactores Biológicos , Biotecnología/instrumentación , Catálisis , Presión Hidrostática , Cinética
4.
J Biotechnol ; 119(4): 400-15, 2005 Oct 10.
Artículo en Inglés | MEDLINE | ID: mdl-15927297

RESUMEN

In a study of Assemblase, an industrial immobilized penicillin-G acylase, various electron microscopic techniques were used to relate intra-particle enzyme heterogeneity with the morphological heterogeneity of the support material at various levels of detail. Transmission electron microscopy was used for the study of intra-particle penicillin-G acylase distribution in Assemblase particles of various sizes; it revealed an abrupt increase in enzyme loading at the particle surface (1.4-fold) and in the areas (designated halo's) surrounding internal macro-voids (7.7-fold). Cryogenic field-emission scanning electron microscopy related these abrupt local enzyme heterogeneities to local heterogeneity of the support material by revealing the presence of dense top layers surrounding both the particle exterior and the internal macro-voids. Furthermore, it showed a very distinct morphological appearance of the halo. Most probably, all these regions contained relatively more chitosan than gelatin (the polymers Assemblase was constructed of), which suggested local polymer demixing during particle production. A basic thermodynamic line of reasoning suggested that a difference in hydrophilicity between the two polymers induced local demixing. In the future, thermodynamic knowledge on such polymer interactions resulting in matrix heterogeneity may be used as a tool for biocatalyst design.


Asunto(s)
Nanotubos/química , Nanotubos/ultraestructura , Penicilina Amidasa/química , Penicilina Amidasa/ultraestructura , Sitios de Unión , Catálisis , Microscopía por Crioelectrón , Enzimas Inmovilizadas/análisis , Enzimas Inmovilizadas/química , Enzimas Inmovilizadas/ultraestructura , Ensayo de Materiales , Microscopía Electrónica de Rastreo , Nanotubos/análisis , Tamaño de la Partícula , Penicilina Amidasa/análisis , Unión Proteica , Conformación Proteica , Propiedades de Superficie
5.
Scanning ; 27(4): 181-9, 2005.
Artículo en Inglés | MEDLINE | ID: mdl-16089302

RESUMEN

Field-emission scanning electron microscopy (FESEM) was used in a technical feasibility study to obtain insight into the internal morphology and the intraparticle enzyme distribution of Assemblase, an industrial biocatalytic particle containing immobilized penicillin-G acylase. The results were compared with previous studies based on light and transmission electron microscopic techniques. The integrated FESEM approach yielded the same quantitative results as the microscopic techniques used previously. Given this technical equivalence, the integrated approach offers several advantages. First, the single preparation method and detection system avoids interpretation discrepancies between corresponding areas that were examined for different properties with different detection techniques in different samples. Second, the specimen size suitable for whole particle study is virtually unlimited, which simplifies sectioning and puts less stringent demands on the embedding technique. Furthermore, the sensitivity toward enzyme presence and distribution increases because the epitopes inside thick sections become available for labeling. Quick and unambiguous analysis of the relation between particle morphology and enzyme distribution is important because this information may be used in the future for the design of enzyme distributions in which the particle morphology can be used as a control parameter.


Asunto(s)
Industria Farmacéutica/instrumentación , Enzimas Inmovilizadas/análisis , Microscopía Electrónica de Rastreo , Penicilina Amidasa/análisis , Enzimas Inmovilizadas/química , Tamaño de la Partícula , Penicilina Amidasa/química
6.
J Biotechnol ; 79(1): 13-26, 2000 Apr 14.
Artículo en Inglés | MEDLINE | ID: mdl-10817338

RESUMEN

For the development of a continuous process for the production of solid D-malate from a Ca-maleate suspension by permeabilized Pseudomonas pseudoalcaligenes, it is important to understand the effect of appropriate process parameters on the stability and activity of the biocatalyst. Previously, we quantified the effect of product (D-malate2 -) concentration on both the first-order biocatalyst inactivation rate and on the biocatalytic conversion rate. The effects of the remaining process parameters (ionic strength, and substrate and Ca2 + concentration) on biocatalyst activity are reported here. At (common) ionic strengths below 2 M, biocatalyst activity was unaffected. At high substrate concentrations, inhibition occurred. Ca2+ concentration did not affect biocatalyst activity. The kinetic parameters (both for conversion and inactivation) were determined as a function of temperature by fitting the complete kinetic model, featuring substrate inhibition, competitive product inhibition and first-order irreversible biocatalyst inactivation, at different temperatures simultaneously through three extended data sets of substrate concentration versus time. Temperature affected both the conversion and inactivation parameters. The final model was used to calculate the substrate and biocatalyst costs per mmol of product in a continuous system with biocatalyst replenishment and biocatalyst recycling. Despite the effect of temperature on each kinetic parameter separately, the overall effect of temperature on the costs was found to be negligible (between 293 and 308 K). Within pertinent ranges, the sum of the substrate and biocatalyst costs per mmol of product was calculated to decrease with the influent substrate concentration and the residence time. The sum of the costs showed a minimum as a function of the influent biocatalyst concentration.


Asunto(s)
Hidroliasas/metabolismo , Malatos/metabolismo , Pseudomonas/enzimología , Calcio/metabolismo , Calcio/farmacología , Catálisis , Permeabilidad de la Membrana Celular , Costos y Análisis de Costo , Concentración de Iones de Hidrógeno , Isomerismo , Cinética , Malatos/química , Concentración Osmolar , Temperatura
7.
J Biotechnol ; 62(2): 105-18, 1998 Jun 30.
Artículo en Inglés | MEDLINE | ID: mdl-9706703

RESUMEN

Hydrophobic pollutants in waste gases are difficult to remove with the conventional biological treatment techniques because of the slow gas/water mass transfer rate. A two-stage system with a water-immiscible solvent as intermediate liquid was developed. This system consisted of a packed absorber for transfer of the model pollutant, ethene, from gas to solvent and a stirred-tank reactor (mixer) for solvent/water transfer and subsequent degradation by Mycobacterium parafortuitum. The solvent FC40, a perfluorocarbon, was recycled between these two compartments. The stability of the system was shown during a run of 10 days. The elimination efficiency was found to be a function of the solvent flow: 9% and 15% elimination were obtained at solvent flows of 6 x 10(-8) m3.s-1 and 11.3 x 10(-8) m3.s-1, respectively. Ethene removal remained constant at increasing solvent hold-ups up to 50% (v/v). In spite of the low elimination efficiencies caused by an inefficient use of the column, the feasibility of the system to remove ethene has been demonstrated. The system's performance was described by a steady-state mathematical model. Simulated ethene removal efficiencies agreed well with the experimental data. Based on this, the model was used to optimise the dimensions and operating conditions. Furthermore, the model was used to compare the performance of the combined system (PA/MS) with the performance of a similar system without solvent. It was found that the use of solvent as intermediate liquid can improve substantially the removal efficiency of hydrophobic gaseous pollutants compared with the system without solvent. This is dependent however, on the solubility of the pollutant in the solvent, on the dimensions of the system and on the operating conditions.


Asunto(s)
Reactores Biológicos , Contaminantes Ambientales , Etilenos/aislamiento & purificación , Gases/química , Solventes , Administración de Residuos/métodos , Absorción , Mycobacterium , Solubilidad , Residuos , Agua
8.
Enzyme Microb Technol ; 15(9): 722-9, 1993 Sep.
Artículo en Inglés | MEDLINE | ID: mdl-7764006

RESUMEN

The application of two liquid phases that are poorly miscible is a fascinating research topic for biocatalytical conversions because of the promising results. Motives for application include an increase of productivity and achievement of continuous processing, but new limitations arise, e.g., interfacial effects such as biocatalyst accumulation and loss of activity, medium component accumulation, and slow coalescence. Centrifuges, membranes, and immobilization are tools that can overcome part of the problems, but more fundamental knowledge about interfaces and coalescence is still necessary for successful application. For scaleup and further development of processes based on the obtained results, a choice must be made for the configuration of the experimental setup of a bioreactor. Aspects like aeration, shear stress, batch or continuous processing, and immobilization can play an important role. This review article describes these aspects and the proposals that have been made in recent years concerning two-liquid-phase bioreactors. It shows some adaptations to existing bioreactors, such as loop reactors and stirred-tank reactors.


Asunto(s)
Biodegradación Ambiental , Microbiología Industrial/instrumentación , Fluorocarburos/metabolismo , Solventes
9.
Mar Biotechnol (NY) ; 13(6): 1092-8, 2011 Dec.
Artículo en Inglés | MEDLINE | ID: mdl-21537947

RESUMEN

The zooxanthellate octocoral Sinularia flexibilis is a producer of potential pharmaceutically important metabolites such as antimicrobial and cytotoxic substances. Controlled rearing of the coral, as an alternative for commercial exploitation of these compounds, requires the study of species-specific growth requirements. In this study, phototrophic vs. heterotrophic daily energy demands of S. flexibilis was investigated through light and Artemia feeding trials in the laboratory. Rate of photosynthetic oxygen by zooxanthellae in light (≈200 µmol quanta m⁻² s⁻¹) was measured for the coral colonies with and without feeding on Artemia nauplii. Respiratory oxygen was measured in the dark, again with and without Artemia nauplii. Photosynthesis-irradiance curve at light intensities of 0, 50, 100, 200, and 400 µmol quanta m⁻² s⁻¹ showed an increase in photosynthetic oxygen production up to a light intensity between 100 and 200 µmol quanta m⁻² s⁻¹. The photosynthesis to respiration ratio (P/R > 1) confirmed phototrophy of S. flexibilis. Both fed and non-fed colonies in the light showed high carbon contribution by zooxanthellae to animal (host) respiration values of 111-127%. Carbon energy equivalents allocated to the coral growth averaged 6-12% of total photosynthesis energy (mg C g⁻¹ buoyant weight day⁻¹ and about 0.02% of the total daily radiant energy. "Light utilization efficiency (ε)" estimated an average ε value of 75% 12 h⁻¹ for coral practical energetics. This study shows that besides a fundamental role of phototrophy vs. heterotrophy in daily energy budget of S. flexibilis, an efficient fraction of irradiance is converted to useable energy.


Asunto(s)
Antozoos/microbiología , Antozoos/fisiología , Artemia , Dieta , Metabolismo Energético/fisiología , Luz , Fotosíntesis/fisiología , Animales , Antozoos/crecimiento & desarrollo , Oxígeno/metabolismo
10.
Mar Biotechnol (NY) ; 11(4): 488-94, 2009.
Artículo en Inglés | MEDLINE | ID: mdl-19048343

RESUMEN

The branching zooxanthellate soft coral Sinularia flexibillis releases antimicrobial and toxic compounds with potential pharmaceutical importance. As photosynthesis by the symbiotic algae is vital to the host, the light-dependency of the coral, including its specific growth rate (micro day(-1)) and the physiological response to a range of light intensities (10-1,000 micromol quanta m(-2) s(-1)) was studied for 12 weeks. Although a range of irradiances from 100 to 400 micromol quanta m(-2) s(-1) was favorable for S. flexibilis, based on chlorophyll content, a light intensity around 100 micromol quanta m(-2) s(-1) was found to be optimal. The contents of both zooxanthellae and chlorophyll a were highest at 100 micromol quanta m(-2) s(-1). The specific budding rate showed almost the same pattern as the specific growth rate. The concentration of the terpene flexibilide, produced by this species, increased at high light intensities (200-600 micromol quanta m(-2) s(-1)).


Asunto(s)
Antozoos/crecimiento & desarrollo , Antozoos/metabolismo , Dinoflagelados/metabolismo , Lactonas/metabolismo , Procesos Fototróficos , Animales , Clorofila/metabolismo , Clorofila A , Simbiosis
11.
Appl Microbiol Biotechnol ; 72(2): 263-78, 2006 Sep.
Artículo en Inglés | MEDLINE | ID: mdl-16397772

RESUMEN

A physical model was derived for the synthesis of the antibiotic cephalexin with an industrial immobilized penicillin G acylase, called Assemblase. In reactions catalyzed by Assemblase, less product and more by-product are formed in comparison with a free-enzyme catalyzed reaction. The model incorporates reaction with a heterogeneous enzyme distribution, electrostatically coupled transport, and pH-dependent dissociation behavior of reactants and is used to obtain insight in the complex interplay between these individual processes leading to the suboptimal conversion. The model was successfully validated with synthesis experiments for conditions ranging from heavily diffusion limited to hardly diffusion limited, including substrate concentrations from 50 to 600 mM, temperatures between 273 and 303 K, and pH values between 6 and 9. During the conversion of the substrates into cephalexin, severe pH gradients inside the biocatalytic particle, which were previously measured by others, were predicted. Physical insight in such intraparticle process dynamics may give important clues for future biocatalyst design. The modular construction of the model may also facilitate its use for other bioconversions with other biocatalysts.


Asunto(s)
Enzimas Inmovilizadas/metabolismo , Modelos Teóricos , Algoritmos , Difusión , Enzimas Inmovilizadas/análisis , Enzimas Inmovilizadas/química , Concentración de Iones de Hidrógeno , Estructura Molecular , Tamaño de la Partícula , Penicilina Amidasa/análisis , Penicilina Amidasa/química , Penicilina Amidasa/metabolismo , Temperatura
12.
Biotechnol Bioeng ; 89(6): 660-9, 2005 Mar 20.
Artículo en Inglés | MEDLINE | ID: mdl-15674826

RESUMEN

The quantitative intraparticle enzyme distribution of Assemblase, an industrially employed polydisperse immobilized penicillin-G acylase, was measured. Because of strong autofluorescence of the carrier, the generally applied technique of confocal scanning microscopy could not be used; light microscopy was our method of choice. To do so, Assemblase particles of various sizes were sectioned, labeled with antibodies specifically against the enzyme, and analyzed light microscopically. Image analysis software was developed and used to determine the intraparticle enzyme distribution, which was found to be heterogeneous, with most enzyme located in the outer regions of the particles. Larger particles showed steeper gradients than smaller ones. A mathematical representation of the intraparticle profiles, based on in-stationary enzyme diffusion into the particles, was validated successfully for a broad range of particle sizes using data for volume-averaged particle size and enzyme loading. The enzyme gradients determined in this work will be used as input for a physical model that quantitatively describes the complex behavior of Assemblase. Such a physical model will lead to identification of the current bottlenecks in Assemblase and can serve as a starting point for the design of improved biocatalysts that also may be based on intelligent use of enzyme gradients.


Asunto(s)
Enzimas Inmovilizadas/metabolismo , Penicilina Amidasa/análisis , Catálisis , Difusión , Matemática , Microscopía de Polarización , Tamaño de la Partícula , Reproducibilidad de los Resultados
13.
Appl Environ Microbiol ; 52(5): 1139-46, 1986 Nov.
Artículo en Inglés | MEDLINE | ID: mdl-16347213

RESUMEN

Anaerobic mixed-culture aggregates, which converted glucose to acetic, propionic, butyric, and valeric acids, were formed under controlled conditions of substrate feed (carbon limitation) and hydraulic regimen. The continuous-flow system used (anaerobic gas-lift reactor) was designed to retain bacterial aggregates in a well-mixed reactor. Carrier availability (i.e., liquid-suspended sand grains) proved necessary for bacterial aggregate formation from individual cells during reactor start-up. Electron microscopic examination revealed that incipient colonization of sand grains by bacteria from the bulk liquid occurred in surface irregularities, conceivably reflecting local quiescence. Subsequent confluent biofilm formation on sand grains proved to be unstable, however. Substrate depletion in the bulk liquid is assumed to weaken deeper parts of the biofilm due to cellular lysis, after which production of gas bubbles and liquid shearing forces cause sloughing. The resulting fragments, although sand free, were nevertheless large enough to be retained in the reactor and gradually grew larger through bacterial growth and by clumping together with other fragments. In the final steady state, high cell densities were maintained in the form of aggregates, while sand had virtually disappeared due to sampling losses and wash-out. Numerical cell densities within aggregates ranged from 10/ml at the periphery to very low values in the center. The cells were enmeshed in a polymer matrix containing polysaccharides; nevertheless, carbon sufficiency was not a prerequisite to sustain high hold-up ratios.

14.
Biotechnol Bioeng ; 30(2): 233-8, 1987 Aug 05.
Artículo en Inglés | MEDLINE | ID: mdl-18581304

RESUMEN

A start-up routine for a novel type of anaerobic gas-lift reactor using sand as support particles for Bacterial adhesion and involving a dilution rate shift-up is shown to result in rapid formation of mixed-culture aggregates from freely suspended cells. Formation of aggregates changed the general metabolism from acetate-butyrate production to acetate-propionate production. This change is attributed to a selection by washout, favoring propionate-producing bacteria with superior adhesive properties. Sand is shown to be essential in establishing, but not in sustaining, elevated holdup ratios. The importance of maintenance processes and cellular lysis in deeper parts of aggregates are manifest from a reduced effluent biomass concentration and a pronounced production of valeric acid.

15.
Biotechnol Bioeng ; 31(7): 718-24, 1988 May.
Artículo en Inglés | MEDLINE | ID: mdl-18584670

RESUMEN

The starting point for the present investigations was the finding that increasing influent concentrations from 10 to 380 mmol/L glucose decreased the attainable growth rate of an acidogenic population in continuous culture from 0.52 to 0.05 h(-1) To account for this phenomenon, a new kinetic model is developed that combines substrate and product inhibition. Both effects are connected through the product yield, giving rise to a complex dependency of the growth rate on the substrate concentration. As a main feature, the maximum attainable growth rate decreases almost hyperbolically above some optimal substrate concentration in the influent. Furthermore, under certain conditions the kinetic model predicts the existence of three steady states: a high-conversion and a low-conversion state that are both stable and a metastable intermediate state. The latter states from the multiple-steady-state region are to be avoided, and eventual transitions to these states may have important consequences for the stability and the operation of such reaction systems. Substrate as well as product inhibition is reported for Propionibacterium freundenreichii and recently could be demonstrated for the above-mentioned acidogenic population. The proposed model allows optimization of anaerobic wastewater treatment processes and is applicable also to other fermentations.

16.
Enzyme Microb Technol ; 28(6): 510-514, 2001 Apr 05.
Artículo en Inglés | MEDLINE | ID: mdl-11267645

RESUMEN

Effective diffusion coefficients (D(e)) of antibiotic A40926 and its deacylated derivative were determined in Ca-alginate (2% wt/wt) and kappa-carrageenan (2.6% wt/wt) gel beads with or without immobilized Actinoplanes teichomyceticus cells and/or soybean meal (SBM). The method used was based on transient concentration changes in a well-stirred antibiotic solution in which gel beads, initially free of solute, were suspended. Unsteady-state diffusion in a sphere was applied and D(e) determined from the best fit of experimental data. A40926 showed markedly different diffusion characteristics than its deacylated derivative. Diffusivity of deacyl-A40926 in alginate or carrageenan gel beads was six to seven times that of A40926. Large differences in partition coefficients (Kp) were also found. In case of beads without additions, A40926, in contrast to deacyl-A40926, strongly partitioned to the liquid phase. Introduction of SBM and/or mycelium in the gel beads decreased the effective diffusivity of deacyl-A40926, but increased its partitioning to the solid phase. Our findings indicate that a relatively moderate structural change of a lipoglycopeptide molecule could lead to a major change in its diffusion/partition characteristics.

17.
Cytotechnology ; 21(3): 263-77, 1996 Jan.
Artículo en Inglés | MEDLINE | ID: mdl-22358758

RESUMEN

Hybridomas were cultured under steady-state conditions in a series of two continuous stirred-tank reactors (CSTRs), using a serum-free medium. The substrate not completely converted in the first CSTR, was transported with the cells to the second one and very low growth rates, high death rates, and lysis of viable cells were observed in this second CSTR. These conditions are hardly accessible in a single vessel, because such experiments would be extremely time-consuming and unstable due to a low viability. In contrast to what is often observed in literature, kinetic parameters could thus be derived without the neccessity for extrapolation to lower growth rates. Good agreement with literature averages for other hybridomas was found. Furthermore, showing that the reactor series is a valuable research tool for kinetic studies under extreme conditions, the possibility to observe cell death under stable and defined steady-state conditions offers interesting opportunities to investigate apoptosis and necrosis. Additionally, a model was developed that describes hybridoma growth and monoclonal antibody production in the bioreactor cascade on the basis of glutamine metabolism. Good agreement between the model and the experiments was found.

18.
Biotechnol Bioeng ; 69(5): 548-58, 2000 Sep 05.
Artículo en Inglés | MEDLINE | ID: mdl-10898864

RESUMEN

To develop a bioreactor for solid-to-solid conversions, the conversion of solid Ca-maleate to solid Ca-D-malate by permeabilized Pseudomonas pseudoalcaligenes was studied. In a bioreactor seeded with product (Ca-D-malate) crystals, growth of Ca-D-malate crystals is the last step in the solid-to-solid conversion and is described here. Crystal growth is described as a transport process followed by surface processes. In contrast to the linear rate law obeyed by the transport process, the surface processes of a crystal-growth process can also obey a parabolic or exponential rate law. Growth of Ca-D-malate crystals from a supersaturated aqueous solution was found to be surface-controlled and obeyed an exponential rate law. Based on this rate law, a kinetic model was developed which describes the decrease in supersaturation due to Ca-D-malate crystal growth as a function of the constituent ions, Ca(2+) and D-malate(2-). The kinetic parameters depended on temperature, but, as expected (surface-controlled), they were hardly affected by the stirring speed.


Asunto(s)
Reactores Biológicos , Biotecnología/métodos , Malatos/química , Modelos Químicos , Calcio/química , Cristalización , Cinética , Solubilidad , Propiedades de Superficie
19.
Biotechnol Bioeng ; 69(6): 597-606, 2000 Sep 20.
Artículo en Inglés | MEDLINE | ID: mdl-10918134

RESUMEN

A quantitative model for the conversion of a solid-substrate salt to a solid-product salt in a batch bioreactor seeded with product crystals is presented. The overall process consists of six serial steps (with dissolution and crystallization each in themselves complex multistep processes): solid-salt dissolution, salt dissociation into an ionic substrate and a counter-ion, bioconversion accompanied by biocatalyst inactivation, complexation of the ionic product with the counter-ion, and salt crystal growth. In the model, the consecutive steps are integrated, including biocatalyst inactivation and assuming that salt dissociation and complexation of ions are at equilibrium. Model parameters were determined previously in separate independent experiments. To validate the model, either dissolved or solid Ca-maleate was converted to solid Ca-D-malate by permeabilized Pseudomonas pseudoalcaligenes in a batch bioreactor seeded with Ca-D-malate crystals. The model very well predicted the concentrations of all components in the liquid phase (Ca-maleate, Ca(2+), maleate(2-), D-malate(2-), and Ca-D-malate) and the amounts of the solid phases (Ca-maleate. H(2)O and Ca-D-malate. 3H(2)O), especially when high initial amounts of Ca-maleate. H(2)O and Ca-D-malate. 3H(2)O were present.


Asunto(s)
Reactores Biológicos , Biotecnología/métodos , Calcio/química , Calcio/metabolismo , Catálisis , Simulación por Computador , Cristalización , Cinética , Maleatos/química , Maleatos/metabolismo , Permeabilidad , Inhibidores de Proteasas/química , Inhibidores de Proteasas/metabolismo , Pseudomonas/metabolismo , Sales (Química)/química , Sales (Química)/metabolismo , Compuestos de Tosilo/química , Compuestos de Tosilo/metabolismo
20.
Bioprocess Biosyst Eng ; 26(1): 11-7, 2003 Nov.
Artículo en Inglés | MEDLINE | ID: mdl-13680334

RESUMEN

Pseudomonas putida MC2 produces 3-methylcatechol from toluene in aqueous medium. A second phase of 1-octanol may improve total product accumulation. To optimise the design of such a biphasic process, a process model was developed, both for one- and two-phase applications. The insights obtained by the model predictions showed the importance of different process parameters (like growth substrate concentration and partition coefficient) on growth of biomass, accumulation of 3-methylcatechol and processing time. For future applications, the process model can be used to ensure enough extraction capacity from aqueous to octanol phase. It is a useful tool to define the optimum process conditions, depending on the desired optimisation parameter: product concentration or processing time.


Asunto(s)
1-Octanol/metabolismo , Reactores Biológicos/microbiología , Catecoles/metabolismo , Técnicas de Cultivo de Célula/métodos , Modelos Biológicos , Pseudomonas putida/crecimiento & desarrollo , Pseudomonas putida/metabolismo , Tolueno/metabolismo , Catecoles/aislamiento & purificación , División Celular/fisiología , Simulación por Computador , Pseudomonas putida/citología , Control de Calidad , Reproducibilidad de los Resultados , Sensibilidad y Especificidad
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