Science.gov

Sample records for piret kiristaja uudo

  1. Analytical solution of Luedeking-Piret equation for a batch fermentation obeying Monod growth kinetics.

    PubMed

    Garnier, Alain; Gaillet, Bruno

    2015-12-01

    Not so many fermentation mathematical models allow analytical solutions of batch process dynamics. The most widely used is the combination of the logistic microbial growth kinetics with Luedeking-Piret bioproduct synthesis relation. However, the logistic equation is principally based on formalistic similarities and only fits a limited range of fermentation types. In this article, we have developed an analytical solution for the combination of Monod growth kinetics with Luedeking-Piret relation, which can be identified by linear regression and used to simulate batch fermentation evolution. Two classical examples are used to show the quality of fit and the simplicity of the method proposed. A solution for the combination of Haldane substrate-limited growth model combined with Luedeking-Piret relation is also provided. These models could prove useful for the analysis of fermentation data in industry as well as academia.

  2. Computing and interpreting specific production rates in a chemostat in steady state according to the Luedeking-Piret model.

    PubMed

    Thierie, Jacques

    2013-01-01

    The Luedeking-Piret model is an empirical relationship which is very widely used in cell cultures to evaluate specific production rates of some products (metabolites or others). It constitutes a very common method of calculation as much in fundamental as in applied research and especially for designing and optimizing industrial processes in very varied fields. However, this model appears to be frequently deficient and has to be greatly adapted, practically, one might say, for each individual case. Obviously, this is a very great drawback, requiring a great deal of time spent on it and one that greatly lessens the 'universality' of the model. This work reveals that it is possible to give the initial Luedeking-Piret model a much more general scope. The used method revealed metabolic switches that have never been suspected until now. Confirmation of the method would certainly give a precious general tool both to optimize production processes and to increase understanding of some physiological states of cells in chemostat.

  3. Addressing the problem of interruptability in the construction of large space structures

    NASA Technical Reports Server (NTRS)

    Davidson, Roger A.; Morgenthaler, George W.

    1989-01-01

    Large scale space missions of the near future will depend upon successful multi-launch coordination and construction in the space environment. One of the main challenges is how to accomplish a valid global analysis of a construction project with the intent of improving safety, reducing overall mission cost, and total construction time. These three items are dependent on the interruptability of the project, which is the ability of the project to recover from unplanned interruptions; such as failure of the launch vehicle; sudden, on-orbit, crew illness; or damage from a space debris impact on the partially completed space structure. A new method for addressing and analyzing this type of problem is being developed. The method is called Program Interruptability and Risk Evaluation Technique, or PIRET. PIRET has been developed in order to model and analyze potential interruptability concerns of the construction of the U.S. Space Station Freedom (SSF), although PIRET is applicable to any complex, multi-launch structural assembly. This paper is a progress report on the continuing research of the NASA Center for Space Construction at the University of Colorado, Boulder into this area of space construction interruptability. The paper will define the problem of interruptability, will diagram the PIRET approach to space construction, will share results from a preliminary PIRET analysis of SSF, and will show that PIRET is a useful tool for modelling space construction interruptability.

  4. Addressing the problem of interruptability in the construction of large space structures

    NASA Technical Reports Server (NTRS)

    Davidson, Roger A.; Morgenthaler, George W.

    1989-01-01

    Large scale space missions of the near future will depend upon successful multi-launch coordination and construction in the space environment. One of the main challenges is how to accomplish a valid global analysis of a construction project with the intent of improving safety, reducing overall mission cost, and total construction time. These three items are dependent on the interruptability of the project, which is the ability of the project to recover from unplanned interruptions; such as failure of the launch vehicle; sudden, on-orbit, crew illness; or damage from a space debris impact on the partially completed space structure. A new method for addressing and analyzing this type of problem is being developed. The method is called Program Interruptability and Risk Evaluation Technique, or PIRET. PIRET has been developed in order to model and analyze potential interruptability concerns of the construction of the U.S. Space Station Freedom (SSF), although PIRET is applicable to any complex, multi-launch structural assembly. This paper is a progress report on the continuing research of the NASA Center for Space Construction at the University of Colorado, Boulder into this area of space construction interruptability. The paper will define the problem of interruptability, will diagram the PIRET approach to space construction, will share results from a preliminary PIRET analysis of SSF, and will show that PIRET is a useful tool for modelling space construction interruptability.

  5. Kinetic model for microbial growth and desulphurisation with Enterobacter sp.

    PubMed

    Liu, Long; Guo, Zhiguo; Lu, Jianjiang; Xu, Xiaolin

    2015-02-01

    Biodesulphurisation was investigated by using Enterobacter sp. D4, which can selectively desulphurise and convert dibenzothiophene into 2-hydroxybiphenyl (2-HBP). The experimental values of growth, substrate consumption and product generation were obtained at 95 % confidence level of the fitted values using three models: Hinshelwood equation, Luedeking-Piret and Luedeking-Piret-like equations. The average error values between experimental values and fitted values were less than 10 %. These kinetic models describe all the experimental data with good statistical parameters. The production of 2-HBP in Enterobacter sp. was by "coupled growth".

  6. Installation Development Environmental Assessment at Joint Base Andrews-Naval Air Facility Washington Prince George’s County, Maryland

    DTIC Science & Technology

    2013-04-01

    Migratory birds, especially waterfowl, are common at JBA because of the ponds and wetlands and the proximity of JBA to the Chesapeake Bay . Reptiles found at...the proposed projects would occur in a Chesapeake and Atlantic Coastal Bays Critical Area. Tidal Wetlands None of the Tidal Wetlands Policies are...Service Chesapeake Bay Field Office 177 Admiral Cochrane Drive Annapolis, MD 21401 Ms. Fern Piret Director of Planning Prince George’s County

  7. Mathematical model of Chlorella minutissima UTEX2341 growth and lipid production under photoheterotrophic fermentation conditions

    PubMed Central

    Yang, JinShui; Rasa, Ehsan; Tantayotai, Prapakorn; Scow, Kate M.; Yuan, HongLi; Hristova, Krassimira R.

    2012-01-01

    To reduce the cost of algal biomass production, mathematical model was developed for the first time to describe microalgae growth, lipid production and glycerin consumption under photoheterotrophic conditions based on logistic, Luedeking–Piret and Luedeking–Piret-like equations. All experiments were conducted in a 2 L batch reactor without considering CO2 effect on algae’s growth and lipid production. Biomass and lipid production increased with glycerin as carbon source and were well described by the logistic and Luedeking–Piret equations respectively. Model predictions were in satisfactory agreement with measured data and the mode of lipid production was growth-associated. Sensitivity analysis was applied to examine the effects of certain important parameters on model performance. Results showed that S0, the initial concentration of glycerin, was the most significant factor for algae growth and lipid production. This model is applicable for prediction of other single cell algal species but model testing is recommended before scaling up the fermentation of process. PMID:21115343

  8. Plasmon-induced resonance energy transfer for solar energy conversion

    NASA Astrophysics Data System (ADS)

    Li, Jiangtian; Cushing, Scott K.; Meng, Fanke; Senty, Tess R.; Bristow, Alan D.; Wu, Nianqiang

    2015-09-01

    In Förster resonance energy transfer (FRET), energy non-radiatively transfers from a blue-shifted emitter to a red-shifted absorber by dipole-dipole coupling. This study shows that plasmonics enables the opposite transfer direction, transferring the plasmonic energy towards the short-wavelength direction to induce charge separation in a semiconductor. Plasmon-induced resonance energy transfer (PIRET) differs from FRET because of the lack of a Stoke's shift, non-local absorption effects and a strong dependence on the plasmon's dephasing rate and dipole moment. PIRET non-radiatively transfers energy through an insulating spacer layer, which prevents interfacial charge recombination losses and dephasing of the plasmon from hot-electron transfer. The distance dependence of dipole-dipole coupling is mapped out for a range of detuning across the plasmon resonance. PIRET can efficiently harvest visible and near-infrared sunlight with energy below the semiconductor band edge to help overcome the constraints of band-edge energetics for single semiconductors in photoelectrochemical cells, photocatalysts and photovoltaics.

  9. Stochastic growth logistic model with aftereffect for batch fermentation process

    SciTech Connect

    Rosli, Norhayati; Ayoubi, Tawfiqullah; Bahar, Arifah; Rahman, Haliza Abdul; Salleh, Madihah Md

    2014-06-19

    In this paper, the stochastic growth logistic model with aftereffect for the cell growth of C. acetobutylicum P262 and Luedeking-Piret equations for solvent production in batch fermentation system is introduced. The parameters values of the mathematical models are estimated via Levenberg-Marquardt optimization method of non-linear least squares. We apply Milstein scheme for solving the stochastic models numerically. The effciency of mathematical models is measured by comparing the simulated result and the experimental data of the microbial growth and solvent production in batch system. Low values of Root Mean-Square Error (RMSE) of stochastic models with aftereffect indicate good fits.

  10. Stochastic growth logistic model with aftereffect for batch fermentation process

    NASA Astrophysics Data System (ADS)

    Rosli, Norhayati; Ayoubi, Tawfiqullah; Bahar, Arifah; Rahman, Haliza Abdul; Salleh, Madihah Md

    2014-06-01

    In this paper, the stochastic growth logistic model with aftereffect for the cell growth of C. acetobutylicum P262 and Luedeking-Piret equations for solvent production in batch fermentation system is introduced. The parameters values of the mathematical models are estimated via Levenberg-Marquardt optimization method of non-linear least squares. We apply Milstein scheme for solving the stochastic models numerically. The effciency of mathematical models is measured by comparing the simulated result and the experimental data of the microbial growth and solvent production in batch system. Low values of Root Mean-Square Error (RMSE) of stochastic models with aftereffect indicate good fits.

  11. Minimizing Pollution in Cleaning and Degreasing Operations

    DTIC Science & Technology

    1993-11-01

    Chemical Engineering 230 Ross Hall L Auburn University AL 36849-5127 DTIC A US EPA/RREL .ELECTE B 26 W Martin Luther King Driv MAR 16 19940 Cincinnati...01-280-5500 Standard Form 298 (Rev 2-89) PiretCr~ed by ANSI Std M3-16 299-102 7. (continued) (2) US EPA/RREL 26 W Martin Luther King Drive Cincinnati...Laboratory (EPA/RREL), 26 W Martin Luther King Drive, Cincinnati OH 45268. This technical report summarizes work done between 14 February 1989 and 10

  12. [Effect of salicylic acid on cell growth and polysaccharide production in suspension cultures of protocorm-like bodies from Dendrobium huoshanense].

    PubMed

    Wang, Bo; Pan, Lihua; Luo, Jianping; Zha, Xueqiang

    2009-07-01

    Polysaccharides from Dendrobium huoshanense possess immunostimulating activity, antioxidant activity and anticataract activity. In order to produce the active polysaccharides from Dendrobium huoshanense through cell culture, we investigated the effects of salicylic acid on cell growth, accumulation of polysaccharides and utilization of carbon source in suspension cultures of protocorm-like bodies from Dendrobium huoshanense. Although salicylic acid slightly inhibited the cell growth, it was beneficial to the utilization of carbon source, thus leading to significant increase in the contents of polysaccharides. The highest polysaccharide production occurred on the medium supplied with 100 micromoI/L salicylic acid. After 18 days of culture the production of polysaccharides reached 3.129 g/L, which was 1.63 times that of the control. Further, we established the kinetic models describing cell growth, polysaccharide production and carbon source utilization based on Logistic equation, Luedeking-Piret equation and Luedeking-Piret-Like equation. The calculated values from the kinetic models showed a good fit to the experimental values, suggesting that salicylic acid could be an effective compound to enhance the production of active polysaccharides from protcorm-like bodies from Dendrobium huoshanense.

  13. Effects of aeration on growth and on production of bacteriocins and other metabolites in cultures of eight strains of lactic acid bacteria.

    PubMed

    Vázquez, J A; Mirón, J; González, M P; Murado, M A

    2005-11-01

    In general, it is accepted that the production of bacteriocins in lactic acid bacteria cultures implies moderately to highly restrictive conditions regarding the availability of oxygen. However, the situation appears to be more complex, probably owing to the facultative anaerobic character of these microorganisms. By studying the culture of eight strains of lactic acid bacteria carried out in vessels with different loads of medium within an interval that determines linearly the minimum availability of oxygen, the existence of three types of behavior was highlighted: production increases (1) with the availability of oxygen, (2) with the restriction of this availability, and (3) toward both extremes of these conditions, diminishing in intermediate situations. These behaviors affected not only the production of bacteriocins, but also their metabolic character (in the Luedeking and Piret sense), as well as the production of other characteristic metabolites, such as lactic acid, acetic acid, and ethanol.

  14. Modelling the Biphasic Growth and Product Formation by Enterococcus faecium CECT 410 in Realkalized Fed-Batch Fermentations in Whey

    PubMed Central

    Guerra, Nelson Pérez; Fajardo, Paula; Fuciños, Clara; Amado, Isabel Rodríguez; Alonso, Elisa; Torrado, Ana; Pastrana, Lorenzo

    2010-01-01

    The influence of initial pH on growth and nutrient (total sugars, nitrogen, and phosphorous) consumption by Enterococcus faecium CECT 410 was studied during batch cultures in whey. With these data, two realkalized fed-batch fermentations were developed using different feeding substrates. The shift from homolactic to mixed acid fermentation, the biphasic kinetics observed for cell growth and nitrogen consumption and the increase in the concentrations of biomass and products (lactic acid, acetic acid, ethanol, and butane-2,3-diol) were the most noteworthy observations of these cultures. Modelling the fed-batch growth of Ent. faecium with the Logistic and bi-Logistic models was not satisfactory. However, biomass production was best mathematically described with the use of a double Monod model, which was expressed in terms of biomass, product accumulation, and nitrogen utilization. Product formation was successfully modelled with a modified form of the Luedeking and Piret model developed in this study. PMID:20689729

  15. Mechanistic Understanding of the Plasmonic Enhancement for Solar Water Splitting.

    PubMed

    Zhang, Peng; Wang, Tuo; Gong, Jinlong

    2015-09-23

    H2 generation by solar water splitting is one of the most promising solutions to meet the increasing energy demands of the fast developing society. However, the efficiency of solar-water-splitting systems is still too low for practical applications, which requires further enhancement via different strategies such as doping, construction of heterojunctions, morphology control, and optimization of the crystal structure. Recently, integration of plasmonic metals to semiconductor photocatalysts has been proved to be an effective way to improve their photocatalytic activities. Thus, in-depth understanding of the enhancement mechanisms is of great importance for better utilization of the plasmonic effect. This review describes the relevant mechanisms from three aspects, including: i) light absorption and scattering; ii) hot-electron injection and iii) plasmon-induced resonance energy transfer (PIRET). Perspectives are also proposed to trigger further innovative thinking on plasmonic-enhanced solar water splitting. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  16. Simulation of citric acid production by rotating disk contactor.

    PubMed

    Sakurai, A; Imai, H; Takenaka, Y; Sakakibara, M

    1997-12-20

    A simple model was presented to describe the time courses of citric acid production by a rotating disc contactor (RDC) using Aspergillus niger. The model is expressed by Monod-type cell growth, Luedeking-Piret-type citric acid production rate equations, and the diffusion equation for oxygen in the biofilm. The model contains five parameters which were determined by the nonlinear least squares method by fitting the numerical solution to the experimental data. In solving the equations, the cell density of the biofilm was estimated from the value of cellular mass per unit of biofilm area using an empirical equation. The experimental time courses in citric acid production period were well simulated with this model. The relation between the specific biofilm surface area and the rate of citric acid production was also explained by the simulation using the average values of five parameters of twelve runs. (c) 1997 John Wiley & Sons, Inc. Biotechnol Bioeng 56: 689-696, 1997.

  17. Theoretical maximum efficiency of solar energy conversion in plasmonic metal-semiconductor heterojunctions.

    PubMed

    Cushing, Scott K; Bristow, Alan D; Wu, Nianqiang

    2015-11-28

    Plasmonics can enhance solar energy conversion in semiconductors by light trapping, hot electron transfer, and plasmon-induced resonance energy transfer (PIRET). The multifaceted response of the plasmon and multiple interaction pathways with the semiconductor makes optimization challenging, hindering design of efficient plasmonic architectures. Therefore, in this paper we use a density matrix model to capture the interplay between scattering, hot electrons, and dipole-dipole coupling through the plasmon's dephasing, including both the coherent and incoherent dynamics necessary for interactions on the plasmon's timescale. The model is extended to Shockley-Queisser limit calculations for both photovoltaics and solar-to-chemical conversion, revealing the optimal application of each enhancement mechanism based on plasmon energy, semiconductor energy, and plasmon dephasing. The results guide application of plasmonic solar-energy harvesting, showing which enhancement mechanism is most appropriate for a given semiconductor's weakness, and what nanostructures can achieve the maximum enhancement.

  18. Assessment of a process to degrade metal working fluids using Pseudomonas stutzeri CECT 930 and indigenous microbial consortia.

    PubMed

    Moscoso, F; Deive, F J; Villar, P; Pena, R; Herrero, L; Longo, M A; Sanromán, M A

    2012-01-01

    The development of a novel biological process to treat metal working fluids (MWFs)-containing effluents at bioreactor scale was pursued in this work. The bacteria Pseudomonas stutzeri CECT 930 was investigated for the first time as an alternative agent for MWF degradation. An adequate medium design and mixing and aeration system, as well as an appropriate microorganism proved to be crucial for reaching high levels of degradation by P. stutzeri and by an indigenous consortium (about 70% and 50% of reduction in total petroleum hydrocarbon content in less than 2 wk, respectively). Additionally, as there is no information in literature trying to kinetically characterize an MWF-polluted effluent degradation process, all the experimental data were fitted to logistic and Luedeking and Piret models, that allowed to elucidate the growth-associated character of the biodegradation process.

  19. Efficient PAHs biodegradation by a bacterial consortium at flask and bioreactor scale.

    PubMed

    Moscoso, F; Teijiz, I; Deive, F J; Sanromán, M A

    2012-09-01

    In this work, the biodegradation of three polycyclic aromatic hydrocarbons (PAHs) such as Phenanthrene (PHE), Pyrene (PYR) and Benzo[a]anthracene (BaA) has been investigated. A bacterial consortium consisting of two strains was used for the first time based on preliminary promising biodegradation data. They were tentatively identified as Staphylococcus warneri and Bacillus pumilus. Degradation values higher than 85% were obtained for each single PAH when operating at flask scale, whereas minimum levels of 90% of PAHs removal were obtained after just 3 days of cultivation at bioreactor scale. The operation in cometabolic conditions led to maximum levels about 75% and 100% at flask and bioreactor scale, respectively. All the experimental data were analyzed in the light of logistic and Luedeking and Piret type models, with the purpose to better characterize the biodegradation process by S. warneri and B. pumilus. Finally, the metabolic pathway followed to degrade each PAH was ascertained.

  20. Growth characteristics of freeze-tolerant baker's yeast Saccharomyces cerevisiae AFY in aerobic batch culture.

    PubMed

    Ji, Meng; Miao, Yelian; Chen, Jie Yu; You, Yebing; Liu, Feilong; Xu, Lin

    2016-01-01

    Saccharomyces cerevisiae AFY is a novel baker's yeast strain with strong freeze-tolerance, and can be used for frozen-dough processing. The present study armed to clarify the growth characteristics of the yeast AFY. Aerobic batch culture experiments of yeast AFY were carried out using media with various initial glucose concentrations, and the culture process was analyzed kinetically. The growth of the yeast AFY exhibited a diauxic pattern with the first growth stage consuming glucose and the second growth stage consuming ethanol. The cell yield decreased with increasing initial glucose concentration in the first growth stage, and also decreased with increasing initial ethanol concentration in the second growth stage. In the initial glucose concentration range of 5.0-40.0 g/L, the simultaneous equations of Monod equation, Luedeking-Piret equation and pseudo-Luedeking-Piret equation could be used to describe the concentrations of cell, ethanol and glucose in either of the two exponential growth phases. At the initial glucose concentrations of 5.0, 10.0 and 40.0 g/L, the first exponential growth phase had a maximal specific cell growth rate of 0.52, 0.98 and 0.99 h(-1), while the second exponential growth phase had a maximal specific cell growth rate of 0.11, 0.06 and 0.07 h(-1), respectively. It was indicated that the efficiency of the yeast production could be improved by reducing the ethanol production in the first growth stage.

  1. Kinetic studies on batch cultivation of Trichoderma reesei and application to enhance cellulase production by fed-batch fermentation.

    PubMed

    Ma, Lijuan; Li, Chen; Yang, Zhenhua; Jia, Wendi; Zhang, Dongyuan; Chen, Shulin

    2013-07-20

    Reducing the production cost of cellulase as the key enzyme for cellulose hydrolysis to fermentable sugars remains a major challenge for biofuel production. Because of the complexity of cellulase production, kinetic modeling and mass balance calculation can be used as effective tools for process design and optimization. In this study, kinetic models for cell growth, substrate consumption and cellulase production in batch fermentation were developed, and then applied in fed-batch fermentation to enhance cellulase production. Inhibition effect of substrate was considered and a modified Luedeking-Piret model was developed for cellulase production and substrate consumption according to the growth characteristics of Trichoderma reesei. The model predictions fit well with the experimental data. Simulation results showed that higher initial substrate concentration led to decrease of cellulase production rate. Mass balance and kinetic simulation results were applied to determine the feeding strategy. Cellulase production and its corresponding productivity increased by 82.13% after employing the proper feeding strategy in fed-batch fermentation. This method combining mathematics and chemometrics by kinetic modeling and mass balance can not only improve cellulase fermentation process, but also help to better understand the cellulase fermentation process. The model development can also provide insight to other similar fermentation processes.

  2. Optimization, kinetics and antioxidant activity of exopolysaccharide produced from rhizosphere isolate, Pseudomonas fluorescens CrN6.

    PubMed

    Sirajunnisa, Abdul Razack; Vijayagopal, Velayutham; Sivaprakash, Bhaskar; Viruthagiri, Thangavelu; Surendhiran, Duraiarasan

    2016-01-01

    Pseudomonas fluorescens, isolated from rhizosphere soil, was exploited for the production of exopolysaccharide (EPS). A medium was constituted to enhance the yield of EPS. This study involved an agro waste as carbon substrate, rice bran, a replacement of glucose. Plackett-Burman statistical design was applied to evaluate the selected sixteen components from which, rice bran, peptone, NaCl and MnCl2 were found to be effective and significant on the fermentation process. To study the concentration of each component, central composite design was carried out and response surface plots indicated that the following concentrations significantly enhanced the production - rice bran 5.02%, peptone 0.35%, NaCl 0.51%, MnCl2 0.074%. Kinetic modeling was also performed to simulate the process parameters. Logistic model for microbial growth and Luedeking-Piret equation for product formation and substrate utilization were found to fit the experiment. The present investigation resulted in a maximum yield of 4.62g of EPS/L at 48h. High DPPH scavenging ability was a positive indication to use EPS as an antioxidant. The extracted polysaccharide could thus be ecofriendly due to its biodegradability and nontoxicity, and subjected to various industrial and pharmaceutical applications.

  3. Biodegradation kinetics of thin-stillage treatment by Aspergillus awamori and characterization of recovered chitosan.

    PubMed

    Ray, S Ghosh; Ghangrekar, M M

    2016-02-01

    An attempt has been made to provide solution for distillery wastewater using fungal pretreatment followed by an anaerobic process to achieve higher organic matter removal, which is a challenge at present with currently adopted technologies. Submerged growth kinetics of distillery wastewater supernatant by Aspergillus awamori was also evaluated. The proposed kinetic models using a logistic equation for fungal growth and the Leudeking-Piret equation for product formation were validated experimentally, and substrate consumption equation was derived using estimated kinetic coefficients. Up to 59.6 % chemical oxygen demand (COD) and 70 % total organic carbon (TOC) removals were observed in 96 h of fungal incubation. Maximum specific growth rate of fungi, coefficient of biomass yield on substrate and growth-associated product formation coefficient were estimated to be 0.07 ± 0.01 h(-1), 0.614 kg biomass/kg utilized COD and 0.215 kg CO2/kg utilized TOC, respectively. The chitosan recovery of 0.072-0.078 kg/kg of dry mycelium was obtained using dilute sulphuric acid extraction, showing high purity and characteristic chitosan properties according to FTIR and XRD analyses. After anaerobic treatment of the fungal pretreated effluent with COD concentration of 7.920 ± 0.120 kg COD/m(3) (organic loading rate of 3.28 kg COD/m(3) day), overall COD reduction of 91.07 % was achieved from distillery wastewater.

  4. Decolourization of anaerobically digested and polyaluminium chloride treated distillery spentwash in a fungal stirred tank aerobic reactor.

    PubMed

    Singh, S S; Dikshit, A K

    2011-11-01

    Decolourization of anaerobically digested and polyaluminium chloride treated distillery spentwash was studied in a fungal stirred tank aerobic reactor without dilution of wastewater. Aspergillus niger isolate IITB-V8 was used as the fungal inoculum. The main objectives of the study were to optimize the stirrer speed for achieving maximum decolourization and to determine the kinetic parameters. A mathematical model was developed to describe the batch culture kinetics. Volumetric oxygen transfer coefficient (k (L) a) was obtained using dynamic method. The maximum specific growth rate and growth yield of fungus were determined using Logistic equation and using Luedeking-Piret equation. 150 rpm was found to be optimum stirrer speed for overall decolourization of 87%. At the optimum stirrer speed, volumetric oxygen transfer coefficient (k (L) a) was 0.4957 min(-1) and the maximum specific growth rate of fungus was 0.224 h(-1). The values of yield coefficient (Y ( x/s)) and maintenance coefficient (m (s)) were found to be 0.48 g cells (g substrate)(-1) and 0.015 g substrate (g cells)(-1) h(-1).

  5. A New Temperature Control Shifting Strategy for Enhanced Triterpene Production by Ganoderma lucidum G0119 Based on Submerged Liquid Fermentation.

    PubMed

    Feng, Jie; Feng, Na; Zhang, Jing-Song; Yang, Yan; Jia, Wei; Lin, Chi-Chung

    2016-10-01

    Temperature control is a very important factor on triterpene productivity in submerged liquid fermentation. Temperature effects from 23 to 32 °C on triterpene production by Ganoderma lucidum G0119 were investigated in 6-L stirred fermentor. Logistic and Luedeking-Piret equations were used to estimate the mycelial growth and triterpene production kinetics by regression analysis. On that basis, a temperature-shifting fermentation control strategy was established. From 0 to 61 h, culturing was performed at 32 °C to get high specific mycelial growth rate. Between 62 and 127 h, the temperature was decreased stepwise from 31 to 30 °C to maintain high triterpene productivity. After 128 h, temperature was maintained at 29 °C to minimize triterpene production inhibition and sustain high productivity. Elevated triterpene level (0.269 g L(-1)), yield (0.0101 g g(-1)), and productivity (0.00207 g (L h)(-1)) were achieved representing 27.32, 13.94, and 37.11 % higher than submerged liquid fermentation at constant temperature of 29 °C, respectively, feasible for the industrial scale.

  6. Biosynthesis of poly(3-hydroxybutyrate) (PHB) by Cupriavidus necator H16 from jatropha oil as carbon source.

    PubMed

    Batcha, Abeed Fatima Mohidin; Prasad, D M Reddy; Khan, Maksudur R; Abdullah, Hamidah

    2014-05-01

    Poly(3-hydroxybutyrate) (PHB) is a biodegradable polymer that can be synthesized through bacterial fermentation. In this study, Cupriavidus necator H16 is used to synthesize PHB by using Jatropha oil as its sole carbon source. Different variables mainly jatropha oil and urea concentrations, and agitation rate were investigated to determine the optimum condition for microbial fermentation in batch culture. Based on the results, the highest cell dry weight and PHB concentrations of 20.1 and 15.5 g/L, respectively, were obtained when 20 g/L of jatropha oil was used. Ethanol was used as external stress factor and the addition of 1.5 % ethanol at 38 h had a positive effect with a high PHB yield of 0.987 g PHB/g jatropha oil. The kinetic studies for cell growth rate and PHB production were conducted and the data were fitted with Logistic and Leudeking–Piret models. The rate constants were evaluated and the theoretical values were in accordance with the experimental data obtained

  7. [Construction and application of black-box model for glucoamylase production by Aspergillus niger].

    PubMed

    Li, Lianwei; Lu, Hongzhong; Xia, Jianye; Chu, Ju; Zhuang, Yingping; Zhang, Siliang

    2015-07-01

    Carbon-limited continuous culture was used to study the relationship between the growth of Aspergillus niger and the production of glucoamylase. The result showed that when the specific growth rate was lower than 0.068 h(-1), the production of glucoamylase was growth-associated, when the specific growth rate was higher than 0.068 h(-1), the production of glucoamylase was not growth-associated. Based on the result of continuous culture, the Monod dynamics model of glucose consumption of A. niger was constructed, Combining Herbert-Pirt equation of glucose and oxygen consumption with Luedeking-Piret equation of enzyme production, the black-box model of Aspergillus niger for enzyme production was established. The exponential fed-batch culture was designed to control the specific growth rate at 0.05 h(-1) by using this model and the highest yield for glucoamylase production by A. niger reached 0.127 g glucoamylase/g glucose. The black-box model constructed in this study successfully described the glucoamylase production by A. niger and the result of the model fitted the measured value well. The black-box model could guide the design and optimization of glucoamylase production by A. niger.

  8. Mathematical modelling and process optimization of a continuous 5-stage bioreactor cascade for production of poly[-(R)-3-hydroxybutyrate] by Cupriavidus necator.

    PubMed

    Horvat, Predrag; Vrana Špoljarić, Ivna; Lopar, Markan; Atlić, Aid; Koller, Martin; Braunegg, Gerhart

    2013-09-01

    A multistage system for poly(hydroxyalkanoate) (PHA) production consisting of five continuous stirred tank reactors in series (5-CSTR) with Cupriavidus necator DSM 545 as production strain was modelled using formal kinetic relations. Partially growth-associated production of PHA under nitrogen limited growth was chosen as modelling strategy, thus the Luedeking-Piret's model of partial growth-associated product synthesis was applied as working hypothesis. Specific growth rate relations adjusted for double substrate (C and N source) limited growth according to Megee et al. and Mankad-Bungay relation were tested. The first stage of the reactor cascade was modelled according to the principle of nutrient balanced continuous biomass production system, the second one as two substrate controlled process, while the three subsequent reactors were adjusted to produce PHB under continuous C source fed and nitrogen deficiency. Simulated results of production obtained by the applied mathematical models and computational optimization indicate that PHB productivity of the whole system could be significantly increased (from experimentally achieved 2.14 g L(-1) h(-1) to simulated 9.95 g L(-1) h(-1)) if certain experimental conditions would have been applied (overall dilution rate, C and N source feed concentration). Additionally, supplemental feeding strategy for switching from batch to continuous mode of cultivation was proposed to avoid substrate inhibition.

  9. Kinetic characterization and fed-batch fermentation for maximal simultaneous production of esterase and protease from Lysinibacillus fusiformis AU01.

    PubMed

    Divakar, K; Suryia Prabha, M; Nandhinidevi, G; Gautam, P

    2017-04-21

    The simultaneous production of intracellular esterase and extracellular protease from the strain Lysinibacillus fusiformis AU01 was studied in detail. The production was performed both under batch and fed-batch modes. The maximum yield of intracellular esterase and protease was obtained under full oxygen saturation at the beginning of the fermentation. The data were fitted to the Luedeking-Piret model and it was shown that the enzyme (both esterase and protease) production was growth associated. A decrease in intracellular esterase and increase in the extracellular esterase were observed during late stationary phase. The appearance of intracellular proteins in extracellular media and decrease in viable cell count and biomass during late stationary phase confirmed that the presence of extracellular esterase is due to cell lysis. Even though the fed-batch fermentation with different feeding strategies showed improved productivity, feeding yeast extract under DO-stat fermentation conditions showed highest intracellular esterase and protease production. Under DO-stat fed-batch cultivation, maximum intracellular esterase activity of 820 × 10(3) U/L and extracellular protease activity of 172 × 10(3) U/L were obtained at the 16th hr. Intracellular esterase and extracellular protease production were increased fivefold and fourfold, respectively, when compared to batch fermentation performed under shake flask conditions.

  10. [Piggery wastewater cultivating bioflocculant-producing flora B-737 and the fermentation characteristics].

    PubMed

    Pei, Rui-lin; Xin, Xin; Zhang, Xue-qiao; Zhou, Ying-qin; Yao, Li; Yang, Yi-jin

    2013-05-01

    Piggery wastewater was used as a cheap alternative medium for a bioflocculant-producing bacterial flora B-737. Effects of COD concent, addition of ammonium oxalate or phosphate on the cell growth and bioflocculant yield were investigated, and the fermentation kinetics was studied in the optimal culture media. The results showed that the piggery wastewater (COD was about 3000 mg x L(-1), TN was about 170 mg x L(-1)) had a suitable C/N ratio for the growth and fermentation of flora B-737, with addition of only 1.6 g x L(-1) K2HPO4 and 0.8 g x L(-1) KH2PO4, flora B-737 grew well and the bioflocculant yield reached 1.5 g x L(-1), in the meantime, the COD and TN of the wastewater was reduced by 61.9% and 53.6%, respectively. Not only was the medium cost reduced by over 90% , but it was a new way to recycle piggery wastewater. In addition, the dynamic models on cell growth and flocculants formation in the fermentation process of B-737 were established according to the equation of Logistic and Luedeking-Piret, respectively.

  11. Effect of EPS on biofilm structure and function as revealed by an individual-based model of biofilm growth.

    PubMed

    Kreft, J U; Wimpenny, J W

    2001-01-01

    We have simulated a nitrifying biofilm with one ammonia and one nitrite oxidising species in order to elucidate the effect of various extracellular polymeric substance (EPS) production scenarios on biofilm structure and function. The individual-based model (IbM) BacSim simulates diffusion of all substrates on a two-dimensional lattice. Each bacterium is individually simulated as a sphere of given size in a continuous, three-dimensional space. EPS production kinetics was described by a growth rate dependent and an independent term (Leudeking-Piret equation). The structure of the biofilm was dramatically influenced by EPS production or capsule formation. EPS production decreased growth of producers and stimulated growth of non-producers because of the energy cost involved. For the same reason, EPS accumulation can fall as its rate of production increases. The patchiness and roughness of the biofilm decreased and the porosity increased due to EPS production. EPS density was maximal in the middle of the vertical profile. Introduction of binding forces between like cells increased clustering.

  12. Scale-up and kinetic modeling for bioethanol production.

    PubMed

    Imamoglu, Esra; Sukan, Fazilet Vardar

    2013-09-01

    Bioethanol was produced from acidic hydrolysate of rice hulls using recombinant Escherichia coli KO11. Two different issues (scale-up and kinetic modeling) were evaluated simultaneously and concomitantly for bioethanol production. During the step-wise scale-up process from 100 mL shaken flask to 10 L stirred-tank bioreactor, the constant Reynolds number and the constant impeller tip speed were evaluated as scale-up methodologies under laboratory conditions. It was determined that the volumetric bioethanol productivity was 88% higher in 10 L bioreactor in comparison to the value of 0.21 g L(-1) h(-1) in shaken flask. The modified Monod and Luedeking-Piret models provided an accurate approach for the modeling of the experimental data. Ethanol concentration reached the maximum level of 29.03 g/L, which was 5% higher than the value of model prediction in 10 L bioreactor. The findings of this research could contribute to the industrial scale productions especially from lignocellulosic raw materials.

  13. Simultaneous production of amylases and proteases by Bacillus subtilis in brewery wastes.

    PubMed

    Sánchez Blanco, Alina; Palacios Durive, Osmar; Batista Pérez, Sulema; Díaz Montes, Zoraida; Pérez Guerra, Nelson

    2016-01-01

    The simultaneous production of amylase (AA) and protease (PA) activity by Bacillus subtilis UO-01 in brewery wastes was studied by combining the response surface methodology with the kinetic study of the process. The optimum conditions (T=36.0°C and pH=6.8) for high biomass production (0.92g/L) were similar to the conditions (T=36.8°C and pH=6.6) for high AA synthesis (9.26EU/mL). However, the maximum PA level (9.77EU/mL) was obtained at pH 7.1 and 37.8°C. Under these conditions, a considerably high reduction (between 69.9 and 77.8%) of the initial chemical oxygen demand of the waste was achieved. In verification experiments under the optimized conditions for production of each enzyme, the AA and PA obtained after 15h of incubation were, respectively, 9.35 and 9.87EU/mL. By using the Luedeking and Piret model, both enzymes were classified as growth-associated metabolites. Protease production delay seemed to be related to the consumption of non-protein and protein nitrogen. These results indicate that the brewery waste could be successfully used for a high scale production of amylases and proteases at a low cost. Copyright © 2016 Sociedade Brasileira de Microbiologia. Published by Elsevier Editora Ltda. All rights reserved.

  14. Biohydrogen Production and Kinetic Modeling Using Sediment Microorganisms of Pichavaram Mangroves, India

    PubMed Central

    Mullai, P.; Sridevi, K.

    2013-01-01

    Mangrove sediments host rich assemblages of microorganisms, predominantly mixed bacterial cultures, which can be efficiently used for biohydrogen production through anaerobic dark fermentation. The influence of process parameters such as effect of initial glucose concentration, initial medium pH, and trace metal (Fe2+) concentration was investigated in this study. A maximum hydrogen yield of 2.34, 2.3, and 2.6 mol H2 mol−1 glucose, respectively, was obtained under the following set of optimal conditions: initial substrate concentration—10,000 mg L−1, initial pH—6.0, and ferrous sulphate concentration—100 mg L−1, respectively. The addition of trace metal to the medium (100 mg L−1 FeSO4 ·7H2O) enhanced the biohydrogen yield from 2.3 mol H2 mol−1 glucose to 2.6 mol H2 mol−1 glucose. Furthermore, the experimental data was subjected to kinetic analysis and the kinetic constants were estimated with the help of well-known kinetic models available in the literature, namely, Monod model, logistic model and Luedeking-Piret model. The model fitting was found to be in good agreement with the experimental observations, for all the models, with regression coefficient values >0.92. PMID:24319679

  15. Outer membrane vesicles (OMV) production of Neisseria meningitidis serogroup B in batch process.

    PubMed

    Santos, Sílvia; Arauz, Luciana Juncioni de; Baruque-Ramos, Júlia; Lebrun, Ivo; Carneiro, Sylvia Mendes; Barreto, Sandra Alves; Schenkman, Rocilda Perazzini Furtado

    2012-09-14

    Serogroup B outer membrane vesicles (OMV) with iron regulated proteins (IRP) from Neisseria meningitidis constitute the antigen for the vaccine against the disease caused by this bacterium. Aiming to enhance final OMV concentration, seven batch experiments were carried out under four different conditions: (i) with original Catlin medium; (ii) with original Catlin medium and lactate and amino acids pulse at the 6th cultivation hour; (iii) with Catlin medium with double initial concentrations of lactate and amino acids and (iv) Catlin medium without glycerol and with double initial concentrations of lactate and amino acids. The cultivation experiments were carried out in a 7-L bioreactor under the following conditions: 36°C, 0.5atm, overlay air 1L/min, agitation: 250-850 rpm, and O(2) control at 10%, 20 h. After lactate and amino acids exhaustion, cell growth reached stationary phase and a significant release increase of OMV was observed. According to the Luedeking & Piret model, OMV liberation is non-growth associated. Glycerol was not consumed during cultivation. The maximum OMV concentration value attained was 162 mg/L with correspondent productivity of 8.1mg/(Lh) employing Catlin medium with double initial concentrations of lactate and amino acids. The obtained OMV satisfied constitution and protein pattern criteria and were suitable for vaccine production. Copyright © 2012 Elsevier Ltd. All rights reserved.

  16. Matrix notation for efficient development of first-principles models within PAT applications: integrated modeling of antibiotic production with Streptomyces coelicolor.

    PubMed

    Sin, Gürkan; Odman, Peter; Petersen, Nanna; Lantz, Anna Eliasson; Gernaey, Krist V

    2008-09-01

    A matrix notation coupled to macroscopic principles is introduced as a means to develop first- principles models in an efficient and structured way within PAT applications. The notation was evaluated for developing an integrated biological, chemical (pH modeling) and physical (gas-liquid exchange) model for describing antibiotic production with Streptomyces coelicolor in batch fermentations. The model provided statistically adequate fits to all the monitored macroscopic biological, chemical and physical data of the process, except the phosphate uptake dynamics. This phosphate discrepancy is hypothesized to result from the internal storage of phosphate as polyphosphate prior to the exponential growth phase. The antibiotic production was associated with the stationary phase and its kinetics was adequately described using a modified Luedeking-Piret equation. Further, the maintenance was best described by employing a combination of Pirt and Herbert models, a result that was supported by a model-based hypothesis testing. Overall the process knowledge currently incorporated in the model is believed to be useful both for process optimization purposes and for further testing of hypotheses aiming at improving the mechanistic understanding of antibiotic production with S. coelicolor. Last but not least, the matrix notation is believed to be a promising supporting tool for efficient development and communication of complex dynamic models within a PAT framework.

  17. Medium factor optimization and fermentation kinetics for phenazine-1-carboxylic acid production by Pseudomonas sp. M18G.

    PubMed

    He, Li; Xu, Yu-Quan; Zhang, Xue-Hong

    2008-06-01

    We investigated the production of biofungicide phenazine-1-carboxlic (PCA) by Pseudomonas sp. M18G, a gacA-deficient mutant of M18 for PCA high-production. Glucose was chosen as the optimal carbon source and soy peptone as the nitrogen source. A Plackett-Burman design revealed that glucose, soy peptone and NaCl were the most significant factors in PCA fermentation. Response surface methodology (RSM) and artificial neural network (ANN) models involving the significant factors were developed using common data. The prediction accuracy of ANN was slightly higher compared to RSM. The genetic algorithm (GA) was used to search the optimal input space of the trained ANN model and find the corresponding PCA yield. The optimum composition was found to be: glucose 34.3 g L(-1), soy peptone 43.2 g L(-1), NaCl 5.7 g L(-1), and the predictive maximum PCA yield reached 980.1 microg mL(-1). The optimized medium allowed PCA yield to be increased from 673.3 to 966.7 microg mL(-1) after verification experiment tests. Additionally, PCA fermentation kinetics was investigated. Kinetic models based on the modified Logistic and Luedeking-Piret equations were developed, providing a good description of temporal variations of biomass (X), product (P), and substrate (S) in PCA fermentation.

  18. Modeling of the pyruvate production with Escherichia coli in a fed-batch bioreactor.

    PubMed

    Zelić, B; Vasić-Racki, D; Wandrey, C; Takors, R

    2004-07-01

    A family of 10 competing, unstructured models has been developed to model cell growth, substrate consumption, and product formation of the pyruvate producing strain Escherichia coli YYC202 ldhA::Kan strain used in fed-batch processes. The strain is completely blocked in its ability to convert pyruvate into acetyl-CoA or acetate (using glucose as the carbon source) resulting in an acetate auxotrophy during growth in glucose minimal medium. Parameter estimation was carried out using data from fed-batch fermentation performed at constant glucose feed rates of q(VG)=10 mL h(-1). Acetate was fed according to the previously developed feeding strategy. While the model identification was realized by least-square fit, the model discrimination was based on the model selection criterion (MSC). The validation of model parameters was performed applying data from two different fed-batch experiments with glucose feed rate q(VG)=20 and 30 mL h(-1), respectively. Consequently, the most suitable model was identified that reflected the pyruvate and biomass curves adequately by considering a pyruvate inhibited growth (Jerusalimsky approach) and pyruvate inhibited product formation (described by modified Luedeking-Piret/Levenspiel term).

  19. Nitrite inhibition of denitrification by Pseudomonas fluorescens

    SciTech Connect

    Almeida, J.S.; Julio, S.M.; Reis, M.A.M. |

    1995-05-05

    Using a pure culture of Pseudomonas fluorescens as a model system nitrite inhibition of denitrification was studied. A mineral media with acetate and nitrate as sole electron donor and acceptor, respectively, was used. Results obtained in continuous stirred-tank reactors (CSTR) operated at pH values between 6.6 and 7.8 showed that growth inhibition depended only on the nitrite undissociated fraction concentration (nitrous acid). A mathematical model to describe this dependence is put forward. The maximum nitrous acid concentration compatible with cell growth and denitrification activity was found to be 66 {mu}g N/L. Denitrification activity was partially associated with growth, as described by the Luedeking-Piret equation. However, when the freshly inoculated reactor was operated discontinuously, nitrite accumulation caused growth uncoupling from denitrification activity. The authors suggest that these results can be interpreted considering that (a) nitrous acid acts as a proton uncoupler; and (b) cultures continuously exposed to nitrous acid prevent the uncoupling effect but not the growth inhibition. Examination of the growth dependence on nitrite concentration at pH 7.0 showed that adapted cultures (growth on CSTR) are less sensitive to nitrous acid inhibition than the ones cultivated in batch.

  20. Comparative study of growth responses and screening of inter-specific OTA production kinetics by A. carbonarius isolated from grapes

    PubMed Central

    Lappa, Iliada K.; Kizis, Dimosthenis; Natskoulis, Pantelis I.; Panagou, Efstathios Z.

    2015-01-01

    The aim of this work was to assess OchratoxinA (OTA) production of different Aspergillus carbonarius isolates, evaluate their growth profile through different growth measurements, and reveal any underlying correlation between them. Ten different isolates of A. carbonarius isolated from Greek vineyards located in different geographical regions were examined in vitro for their OTA production potential after an incubation period of up to 11 days. All fungal isolates grew on a synthetic grape juice medium (SGM) similar to grape composition at optimum conditions of temperature and water activity (25°C and 0.98 aw). Samples for OTA determination were removed at 3, 5, 7, 9, and 11 days of growth and analyzed by HPLC. Based on OTA measurements the isolates were characterized by diverse OTA production ranging from 50 to 2000 ppb at day 11. The different fungal growth responses (colony diameter, colony area, biomass, biomass dry weight, and colony density) have been measured and correlated with toxin production by means of principal components analysis (PCA), confirming satisfactory correlation and explained over 99% of data variability. Leudeking-Piret model was also used to study OTA production with time, revealing a mixed-growth associated trend and pointing a fail-safe model with slightly better prediction through colony area. This approach contributes to the assessment of correlation between mycotoxin production and different methods of fungal growth determination in relation to time. PMID:26074896

  1. Viability of phenanthrene biodegradation by an isolated bacterial consortium: optimization and scale-up.

    PubMed

    Moscoso, F; Ferreira, L; Deive, F J; Morán, P; Sanromán, M A

    2013-02-01

    In the present work, biodegradation of phenanthrene by a bacterial consortium (LB2), isolated from lab-polluted soils has been investigated. The 16S rRNA gene-based molecular analysis revealed that the bacterial consortium LB2 consisted of two strains showing a very high homology with Staphylococcus warneri and Bacillus pumilus. The optimization of phenanthrene degradation by the consortium LB2, using a central composite face-centered design was carried out taking into account three important parameters such as temperature, pH, and phenanthrene concentration. Near complete phenanthrene degradation was reached by consortium LB2 at the optimal conditions (pH of 7.5 and 37.5 °C) in less than 48 h. Moreover, the efficiency of phenanthrene biodegradation was assessed by using logistic and Luedeking and Piret-type models. Finally, the process was implemented at bench-scale bioreactor and the main degradation routes were identified based on GC-MS data.

  2. Aeration effect on Spirulina platensis growth and γ-Linolenic acid production.

    PubMed

    Ronda, Srinivasa Reddy; Bokka, Chandra Sekhar; Ketineni, Chandrika; Rijal, Binod; Allu, Prasada Rao

    2012-01-01

    The influence of aeration on algal growth and gamma-linolenic acid (GLA) production in a bubble column photobioreactor was investigated. Studies were performed in a 20-L reactor at different aeration rates (0.2- 2.5 vvm). Static, continuous, and periodic operation of air resulted in 41.9%, 88.4%, and 108% air saturation of dissolved oxygen, for which the corresponding values of GLA were 2.3, 6.5, and 7.5 mg·g(-1) dry cell weight, respectively. An increase in the aeration rate from 0.2 to 2.5 vvm enhanced both the specific growth rate and GLA content under periodic sparging in the bicarbonate medium. With a 6-fold increase in the aeration rate, the GLA content of the alga increased by 69.64% (5.6-9.5 mg· g(-1) dry cell weight). In addition, the total fatty acid (TFA) content in dry biomass increased from 2.22% to 4.41%, whereas the algae maintained a constant GLA to TFA ratio within the aeration rate tested. The dependence of GLA production on the aeration rate was explained by interrelating the GLA production rate with the specific growth rate using the Luedeking and Piret mixed growth model.

  3. Relationship between kinetics of growth and production of exo-electrons: Case study with Geobacter toluenoxydans.

    PubMed

    Szöllősi, Attila; Narr, László; Kovács, Attila G; Styevkó, Gabriella

    2015-09-01

    Kinetics of growth and product formation of G. toluenoxydans DSMZ 19350 strain were investigated using sodium-acetate as substrate and Fe(3+)-ions and fumarate as electron acceptor. Response surface method was adapted for evaluation of growth of bacteria. Results showed that maximum growth was detected in the case of 2.2 g/L substrate concentration. Application of higher substrate concentration (>2.5 g/L sodium acetate) significantly inhibits the bacterial growth. Luong's model was found to be the most suitable to determine kinetic parameters (μ(max) = 0.033 1/h, KS = 0.205 g/L) of growth of G.toluenoxydans strain, and the growth was completely inhibited at substrate concentration higher than 3.1 g/L. In the case of product formation the Haldane model was used and kinetic parameters are μ(Pmax) = 0.123 mg/h, K(PS)= 0.184 g/L. Correlation between microbial growth and product formation was observed using the Luedeking-Piret empirical method. Both factors (growth and number of cells) affected significantly iron(III)-reduction, thus the product formation. These results are important and open the possibility to design a continuous MFC setting operating with G. toluenoxydans as biocatalyst.

  4. Aeration effect on Spirulina platensis growth and γ-Linolenic acid production

    PubMed Central

    Ronda, Srinivasa Reddy; Bokka, Chandra Sekhar; Ketineni, Chandrika; Rijal, Binod; Allu, Prasada Rao

    2012-01-01

    The influence of aeration on algal growth and gamma-linolenic acid (GLA) production in a bubble column photobioreactor was investigated. Studies were performed in a 20-L reactor at different aeration rates (0.2– 2.5 vvm). Static, continuous, and periodic operation of air resulted in 41.9%, 88.4%, and 108% air saturation of dissolved oxygen, for which the corresponding values of GLA were 2.3, 6.5, and 7.5 mg·g-1 dry cell weight, respectively. An increase in the aeration rate from 0.2 to 2.5 vvm enhanced both the specific growth rate and GLA content under periodic sparging in the bicarbonate medium. With a 6-fold increase in the aeration rate, the GLA content of the alga increased by 69.64% (5.6–9.5 mg· g-1 dry cell weight). In addition, the total fatty acid (TFA) content in dry biomass increased from 2.22% to 4.41%, whereas the algae maintained a constant GLA to TFA ratio within the aeration rate tested. The dependence of GLA production on the aeration rate was explained by interrelating the GLA production rate with the specific growth rate using the Luedeking and Piret mixed growth model. PMID:24031799

  5. Kinetics of growth and caffeine demethylase production of Pseudomonas sp. in bioreactor.

    PubMed

    Gummadi, Sathyanarayana N; Santhosh, Devarai

    2010-09-01

    The effect of various initial caffeine concentrations on growth and caffeine demethylase production by Pseudomonas sp. was studied in bioreactor. At initial concentration of 6.5 g l(-1) caffeine, Pseudomonas sp. showed a maximum specific growth rate of 0.2 h(-1), maximum degradation rate of 1.1 g h(-1), and caffeine demethylase activity of 18,762 U g CDW(-1) (CDW: cell dry weight). Caffeine degradation rate was 25 times higher in bioreactor than in shake flask. For the first time, we show highest degradation of 75 g caffeine (initial concentration 20 g l(-1)) in 120 h, suggesting that the tested strain has potential for successful bioprocess for caffeine degradation. Growth kinetics showed substrate inhibition phenomenon. Various substrate inhibition models were fitted to the kinetic data, amongst which the double-exponential (R(2) = 0.94), Luong (R(2) = 0.92), and Yano and Koga 2 (R(2) = 0.94) models were found to be the best. The Luedeking-Piret model showed that caffeine demethylase production kinetics was growth related. This is the first report on production of high levels of caffeine demethylase in batch bioreactor with faster degradation rate and high tolerance to caffeine, hence clearly suggesting that Pseudomonas sp. used in this study is a potential biocatalyst for industrial decaffeination.

  6. Statistical optimization for enhanced yields of probiotic Bacillus coagulans and its phage resistant mutants followed by kinetic modelling of the process.

    PubMed

    Pandey, Kavita R; Joshi, Chetan; Vakil, Babu V

    2016-01-01

    Probiotics are microorganisms which when administered in adequate amounts confer health benefits to the host. A leading pharmaceutical company producing Bacillus coagulans as a probiotic was facing the problem of recurring phage attacks. Two mutants viz. B. co PIII and B. co MIII that were isolated as phage resistant mutants after UV irradiation and MMS treatment of phage sensitive B. coagulans parental culture were characterized at functional and molecular level and were noted to have undergone interesting genetic changes. The non-specific genetic alterations induced by mutagenesis can also lead to alterations in cell performance. Hence, in the current study the parental strain and the two mutants were selected for shake flask optimization. Plackett-Burman design was used to select the significant culture variables affecting biomass production. Evolutionary operation method was applied for further optimization. The study showed wide variations in the nutritional requirements of phage resistant mutants, post exposure to mutagens. An increment of 150, 134 and 152 % was observed in the biomass productions of B. coagulans (parental type) and mutants B.co PIII and B.co MIII respectively, compared to the yield from one-factor-at-a-time technique. Using Logistic and modified Leudeking-Piret equations, biomass accumulation and substrate utilization efficiency of the bioprocess were determined. The experimental data was in agreement with the results predicted by statistical analysis and modelling. The developed model may be useful for controlling the growth and substrate consumption kinetics in large scale fermentation using B. coagulans.

  7. Optimization of Baker's Yeast Production on Date Extract Using Response Surface Methodology (RSM).

    PubMed

    Kara Ali, Mounira; Outili, Nawel; Ait Kaki, Asma; Cherfia, Radia; Benhassine, Sara; Benaissa, Akila; Kacem Chaouche, Noreddine

    2017-08-07

    This work aims to study the production of the biomass of S. cerevisiae on an optimized medium using date extract as the only carbon source in order to obtain a good yield of the biomass. The biomass production was carried out according to the central composite experimental design (CCD) as a response surface methodology using Minitab 16 software. Indeed, under optimal biomass production conditions, temperature (32.9 °C), pH (5.35) and the total reducing sugar extracted from dates (70.93 g/L), S. cerevisiae produced 40 g/L of their biomass in an Erlenmeyer after only 16 h of fermentation. The kinetic performance of the S. cerevisiae strain was investigated with three unstructured models i.e., Monod, Verhulst, and Tessier. The conformity of the experimental data fitted showed a good consistency with Monod and Tessier models with R² = 0.945 and 0.979, respectively. An excellent adequacy was noted in the case of the Verhulst model (R² = 0.981). The values of kinetic parameters (Ks, Xm, μm, p and q) calculated by the Excel software, confirmed that Monod and Verhulst were suitable models, in contrast, the Tessier model was inappropriately fitted with the experimental data due to the illogical value of Ks (-9.434). The profiles prediction of the biomass production with the Verhulst model, and that of the substrate consumption using Leudeking Piret model over time, demonstrated a good agreement between the simulation models and the experimental data.

  8. Unravelling the suitability of biological induction for halophilic lipase production by Halomonas sp. LM1C cultures.

    PubMed

    Gutiérrez-Arnillas, Esther; Arellano, María; Deive, Francisco J; Rodríguez, Ana; Sanromán, María Ángeles

    2017-09-01

    In this study, the viability of using biological induction as an alternative to the conventional chemical induction in lipase production by a novel halophilic microorganism, Halomonas sp. LM1C, has been demonstrated. Thus, a 9-times increase of lipase activity (3000U/L) was recorded when Staphylococcus equorum sp. AMC7 was present in the medium, which is competitive with the results obtained when Triton X-100 was added as chemical inducer. The GC-MS data allowed concluding the true nature of the biological inducer effect, as the existence of high percentages of isomeric forms of pentadecanoic acid were detected. The suitability of the proposed strategy was validated by operating at bench scale bioreactor, and the influence of bioreactor configuration on the biomass and lipolytic activity levels was studied. All the data were fitted to logistic and Luedeking & Piret models to characterize the bioprocess kinetics, concluding the growth-associated character of the produced lipolytic enzymes. Copyright © 2017 Elsevier Ltd. All rights reserved.

  9. Kinetic modeling and scale up of lipoic acid (LA) production from Saccharomyces cerevisiae in a stirred tank bioreactor.

    PubMed

    Jayakar, Shilpa S; Singhal, Rekha S

    2013-08-01

    Scale up studies for production of lipoic acid (LA) from Saccharomyces cerevisiae have been reported in this paper for the first time. LA production in batch mode was carried out in a stirred tank bioreactor at varying agitation and aeration with maximum LA production of 512 mg/L obtained at 350 rpm and 25 % dissolved oxygen in batch culture conditions. Thus, LA production increased from 352 mg/L in shake flask to 512 mg/L in batch mode in a 5 L stirred tank bioreactor. Biomass production under these conditions was mathematically explained using logistic equation and data obtained for LA production and substrate utilization were successfully fitted using Luedeking-Piret and Mercier's models. The kinetic studies showed LA production to be growth associated. Further enhancement of LA production was carried out using fed-batch (variable volume) and semi-continuous modes of fermentation. Semi-continuous fermentation with three feeding cycles of sucrose effectively increased the production of LA from 512 to 725 mg/L.

  10. Plasmonic Enhancement Mechanisms in Solar Energy Harvesting

    NASA Astrophysics Data System (ADS)

    Cushing, Scott K.

    possible: i) increasing light absorption in the semiconductor by light trapping through scattering, ii) transferring hot carriers from metal to semiconductor after light absorption in the metal, and iii) non-radiative excitation of interband transitions in the semiconductor by plasmon-induced resonant energy transfer (PIRET). The effects of the metal on charge transport and carrier recombination were also revealed. Next, it has been shown that the strength and balance of the three enhancement mechanisms is rooted in the plasmon's dephasing time, or how long it takes the collective electron oscillations to stop being collective. The importance of coherent effects in plasmonic enhancement is also shown. Based on these findings, a thermodynamic balance framework has been used to predict the theoretical maximum efficiency of solar energy conversion in plasmonic metal-semiconductor heterojunctions. These calculations have revealed how plasmonics is best used to address the different light absorption problems in semiconductors, and that not taking into account the plasmon's dephasing is the origin of low plasmonic enhancement Finally, to prove these guidelines, each of the three enhancement mechanisms has been translated into optimal device geometries, showing the plasmon's potential for solar energy harvesting. This dissertation identifies the three possible plasmonic enhancement mechanisms for the first time, discovering a new enhancement mechanism (PIRET) in the process. It has also been shown for the first time that the various plasmon-semiconductor interactions could be rooted in the plasmon's dephasing. This has allowed for the first maximum efficiency estimates which have combined all three enhancement mechanisms to be performed, and revealed that changes in the plasmon's dephasing leads to the disparity in reported plasmonic enhancements. These findings are combined to create optimal device design guidelines, which are proven by fabrication of several devices with top

  11. Optimization of Baker’s Yeast Production on Date Extract Using Response Surface Methodology (RSM)

    PubMed Central

    Kara Ali, Mounira; Outili, Nawel; Ait Kaki, Asma; Cherfia, Radia; Benhassine, Sara; Benaissa, Akila; Kacem Chaouche, Noreddine

    2017-01-01

    This work aims to study the production of the biomass of S. cerevisiae on an optimized medium using date extract as the only carbon source in order to obtain a good yield of the biomass. The biomass production was carried out according to the central composite experimental design (CCD) as a response surface methodology using Minitab 16 software. Indeed, under optimal biomass production conditions, temperature (32.9 °C), pH (5.35) and the total reducing sugar extracted from dates (70.93 g/L), S. cerevisiae produced 40 g/L of their biomass in an Erlenmeyer after only 16 h of fermentation. The kinetic performance of the S. cerevisiae strain was investigated with three unstructured models i.e., Monod, Verhulst, and Tessier. The conformity of the experimental data fitted showed a good consistency with Monod and Tessier models with R2 = 0.945 and 0.979, respectively. An excellent adequacy was noted in the case of the Verhulst model (R2 = 0.981). The values of kinetic parameters (Ks, Xm, μm, p and q) calculated by the Excel software, confirmed that Monod and Verhulst were suitable models, in contrast, the Tessier model was inappropriately fitted with the experimental data due to the illogical value of Ks (−9.434). The profiles prediction of the biomass production with the Verhulst model, and that of the substrate consumption using Leudeking Piret model over time, demonstrated a good agreement between the simulation models and the experimental data. PMID:28783118

  12. Modelling the growth kinetics of Kocuria marina DAGII as a function of single and binary substrate during batch production of β-Cryptoxanthin.

    PubMed

    Mitra, Ruchira; Chaudhuri, Surabhi; Dutta, Debjani

    2017-01-01

    In the present investigation, growth kinetics of Kocuria marina DAGII during batch production of β-Cryptoxanthin (β-CRX) was studied by considering the effect of glucose and maltose as a single and binary substrate. The importance of mixed substrate over single substrate has been emphasised in the present study. Different mathematical models namely, the Logistic model for cell growth, the Logistic mass balance equation for substrate consumption and the Luedeking-Piret model for β-CRX production were successfully implemented. Model-based analyses for the single substrate experiments suggested that the concentrations of glucose and maltose higher than 7.5 and 10.0 g/L, respectively, inhibited the growth and β-CRX production by K. marina DAGII. The Han and Levenspiel model and the Luong product inhibition model accurately described the cell growth in glucose and maltose substrate systems with a R (2) value of 0.9989 and 0.9998, respectively. The effect of glucose and maltose as binary substrate was further investigated. The binary substrate kinetics was well described using the sum-kinetics with interaction parameters model. The results of production kinetics revealed that the presence of binary substrate in the cultivation medium increased the biomass and β-CRX yield significantly. This study is a first time detailed investigation on kinetic behaviours of K. marina DAGII during β-CRX production. The parameters obtained in the study might be helpful for developing strategies for commercial production of β-CRX by K. marina DAGII.

  13. A kinetic model for product formation of microbial and mammalian cells

    SciTech Connect

    Zeng, A.P.

    1995-05-20

    Growth of microbial and mammalian cells can be classified into substrate-limited and substrate-sufficient growth according to the relative availability of the substrate (carbon and energy source) and other nutrients. It has been observed for a number of microbial and mammalian cells that the consumption rate of substrate and energy (ATP) is generally higher under substrate-sufficient conditions than under substrate limitation. Accordingly, the product formation under substrate excess often exhibits different patterns from those under substrate limitation. In this study, the Luedeking-Piret kinetic model is extended to include a term describing the effect of residual substrate concentration. The applicability of the extended model is demonstrated with three microbial cultures for the production of primary metabolites and three hybridoma cell cultures for the production of ammonia and lactic acid over a wide range of substrate concentration. Anaerobic fermentation of glycerol by Klebsiella pneumoniae is a multiproduct fermentation process. At a neutral pH value, acetic acid, ethanol, and 1,3-propanediol are the main fermentation products. Formation of acetic acid and/or ethanol is necessary for the generation by K. pneumoniae. The aerobic growth of bacillus strain TS1 on methanol has been studied in methanol-limited and methanol-sufficient hemostat cultures. Under methanol-limited conditions there is no extracellular product formed. However, under methanol-sufficient conditions, particularly with nitrogen limitation, metabolites such as acetic acid and 2-oxoglutaric acid are excreted into the culture medium above a certain level of residual methanol concentration.

  14. Extractive fermentation for enhanced production of thailandepsin A from Burkholderia thailandensis E264 using polyaromatic adsorbent resin Diaion HP-20.

    PubMed

    Liu, Bing; Hui, Junyuan; Cheng, Yi-Qiang; Zhang, Xuehong

    2012-05-01

    Thailandepsin A is natural product of Burkholderia thailandensis E264 with potent histone deacetylase inhibitory activities and promising anticancer activities. The titer of thailandepsin A is very low (less than 10 mg/l) from limited empirical fermentation. To facilitate preclinical evaluations and potentially clinical development of thailandepsin A, systematic optimization and extractive fermentation of thailandepsin A from B. thailandensis E264 culture in flasks were investigated in this pilot study. The main fermentation parameters--28°C, pH 7.0, inoculum ratio 1% (v/v), incubation duration 60 h, medium volume 26%, shaking speed 170 rpm, and chloroform as extracting solvent--were determined by single factor experiments. Polyaromatic adsorbent resin Diaion HP-20, when added at a concentration of 4% (w/v), was most effective to reduce feedback inhibition of thailandepsin A and to significantly increase the titer of target product. Central composite design was used to further optimize the fermentation medium for B. thailandensis E264. The optimized medium contains glucose 17.89 g/l, tryptone 34.98 g/l, potassium phosphate 24.84 g/l, and sodium citrate 0.01 g/l, which resulted in a large increase of the titer of thailandepsin A to 236.7 mg/l. Finally kinetic models based on the modified logistic and Luedeking-Piret equations were developed, delivering a good description of temporal variations of biomass, product, and substrate in the fermentation process, which could be used as references for developing large-scale fermentation.

  15. Fed-batch pediocin production by Pediococcus acidilactici NRRL B-5627 on whey.

    PubMed

    Pérez Guerra, Nelson; Bernárdez, Paula Fajardo; Agrasar, Ana Torrado; López Macías, Cristina; Castro, Lorenzo Pastrana

    2005-08-01

    Cell growth and pediocin production by Pediococcus acidilactici NRRL B-5627 on whey were compared by using batch fermentation and re-alkalized fed-batch fermentation. The batch fermentations were performed on DWG [DW (diluted whey) supplemented with 1% (w/v) glucose], DWYE [DW supplemented with 2% (w/v) yeast extract] and DWGYE (DW supplemented with 1% glucose plus 2% yeast extract) media. The fed-batch culture on DWYE medium was fed with a mixture of concentrated whey (48 g of total sugars/l) supplemented with 2% yeast extract and 400 g/l concentrated glucose. The re-alkalized fed-batch culture was characterized by higher biomass (6.57 g/l) and pediocin [517.6 BU (bacteriocin activity units)/ml] concentrations compared with the batch processes on MRS (de Man, Rogosa and Sharpe) broth (1.76 g/l and 493.2 BU/ml), DW (0.17 g/l and 57.7 BU/ml), DWG (0.14 g/l and 53.6 BU/ml), DWYE (1.43 g/l and 187.6 BU/ml) and DWGYE (1.28 g/l and 167.3 BU/ml) media. A mixed acid fermentation was observed during the growth of P. acidilactici NRRL B-5627 in the fed-batch culture on DWYE medium, and other products (acetic acid and ethanol) in addition to lactic acid accumulated in the medium. Mathematical models were set up to describe fed-batch production of biomass and pediocin by P. acidilactici. The models developed offer a better fit and a more realistic description of the experimental biomass and pediocin production data when compared with the logistic and Luedeking and Piret model.

  16. D-Lactic acid biosynthesis from biomass-derived sugars via Lactobacillus delbrueckii fermentation.

    PubMed

    Zhang, Yixing; Vadlani, Praveen V

    2013-12-01

    Poly-lactic acid (PLA) derived from renewable resources is considered to be a good substitute for petroleum-based plastics. The number of poly L-lactic acid applications is increased by the introduction of a stereocomplex PLA, which consists of both poly-L and D-lactic acid and has a higher melting temperature. To date, several studies have explored the production of L-lactic acid, but information on biosynthesis of D-lactic acid is limited. Pulp and corn stover are abundant, renewable lignocellulosic materials that can be hydrolyzed to sugars and used in biosynthesis of D-lactic acid. In our study, saccharification of pulp and corn stover was done by cellulase CTec2 and sugars generated from hydrolysis were converted to D-lactic acid by a homofermentative strain, L. delbrueckii, through a sequential hydrolysis and fermentation process (SHF) and a simultaneous saccharification and fermentation process (SSF). 36.3 g L(-1) of D-lactic acid with 99.8 % optical purity was obtained in the batch fermentation of pulp and attained highest yield and productivity of 0.83 g g(-1) and 1.01 g L(-1) h(-1), respectively. Luedeking-Piret model described the mixed growth-associated production of D-lactic acid with a maximum specific growth rate 0.2 h(-1) and product formation rate 0.026 h(-1), obtained for this strain. The efficient synthesis of D-lactic acid having high optical purity and melting point will lead to unique stereocomplex PLA with innovative applications in polymer industry.

  17. Kinetics analysis of growth and lactic acid production in pH-controlled batch cultures of Lactobacillus casei KH-1 using yeast extract/corn steep liquor/glucose medium.

    PubMed

    Ha, Mi-Young; Kim, Si-Wouk; Lee, Yong-Woon; Kim, Myong-Jun; Kim, Seong-Jun

    2003-01-01

    This study was performed to determine the optimal conditions of yeast extract, corn steep liquor and glucose concentration for the growth and lactic acid production of Lactobacillus casei KH-1 and to assess the effect of these conditions using a response surface methodology. A Box-Behnken design was used as an experimental design for the allocation of treatment combination as 17 pH-controlled batch cultures. The growth and product parameters were estimated by Gombertz, Leudeking and Piret models from experimental data, and analyzed statistically with response surfaces. The effects of yeast extract, corn steep liquor and glucose were significant for the maximum specific growth rate, mu(max) and the maximum biomass concentration, X(ma). The interaction of corn steep liquor and glucose indicated that the positive or negative effect of glucose on mu(max) in corn steep liquor below or above 2.1% could be explained by the glucose-dependent availability of a nutrient on mu(max) Although the experiment was achieved in pH-controlled batch culture for L. casei KH-1, the growth- and non-growth-associated production rate parameters, a and b, were significant in the response surface model. The growth and lactic acid production of L. casei KH-1 were strongly affected by glucose and the importance of the media composition was demonstrated. The estimated optimal conditions of the growth and lactic acid production of L. casei KH-1 were 1.276% and 0.697% for yeast extract, 3.505% and 1.708% for corn steep liquor, and 2.390% and 2.215% for glucose, respectively.

  18. Degradation of quinolizidine alkaloids of lupin by Rhizopus oligosporus.

    PubMed

    Ortega-David, Eduar; Rodríguez-Stouvenel, Aida

    2013-06-01

    Rhizopus oligosporus has proven beneficial in the detoxification of lupin seeds. The fermentation process is mainly affected by the initial pH in the medium. In the range of growth of mold, there are maximum enzymatic activities in pH of 3.5 and 5.5. Metabolism change occurs at these pH levels; therefore, we studied the growth, pH changes, dry matter intake, and alkaloid degradation within 48 h of fermentation. Cultures of lupin agar (LA) with pH of 3.5 and 5.5 were made in Petri dishes with lupin flour. Results showed pH directly affects the degradation of alkaloids and fungal growth. Detoxification levels achieved were 16.58 and 63.23 % in treatments LA 3.5 and LA 5.5, respectively. Fungal growth was 0.919 mg/cm(2) in LA 3.5 and 1.081 mg/cm(2) in LA 5.5. Maximum degradation rate in LA 5.5 was given between 16 and 20 h, which coincided with maximum fungal growth. Despite having similar dry matter intake in both treatments, a pH of 3.5 did not show the same degree of detoxification. The analysis with exponential, yield of growth, yield of dry matter intake and luedeking and piret equations, confirm the relation between intake and growth with detoxification. Dry matter intake equation predicts with R (2) of 0.94 the detoxification in LA 5.5. A pH of 5.5 is directly related with detoxification and fungal development.

  19. [Kinetic models for the effect of temperature on batch glutathione fermentation by Candida utilis].

    PubMed

    Wei, Gong-Yuan; Li, Yin; Du, Guo-Cheng; Chen, Jian

    2003-05-01

    Glutathione (L-gamma-glutamyl-L-cysteinylglycine), one of the major non-protein thiol compounds, is widely distributed in living cells and plays an important role in maintaining the normal redox environment of cells as an antioxidant. In the production of glutathione by fermentation, temperature is one of the most important environmental factors that affect the yield and the productivity of glutathione. Here the effect of temperature, varied from 24 degrees C to 32 degrees C, on the batch fermentation of glutathione in a 7 L stirred fermenter by Candida utilis WSH 02-08 was investigated. It was found that cell growth was hastened along with the increase of temperature. The maximum dry cell weight was achieved approximately 16 g/L under various temperatures, as soon as the glucose was exhausted. The effect of temperature on glutathione production was different from that on cell growth: the lower the temperature, the higher the glutathione production, i.e. the maximum glutathione concentration at 32 degrees C (235 mg/L) was only 75% and 64% of that at 30 degrees C and 26 degrees C, respectively. The maximum average specific growth rate (0.13 h(-1)) was achieved at 30 degrees C while the maximum glutathione concentration (366 mg x L(-1)) and the maximum intracellular glutathione content (2.3%) were obtained at 26 degrees C. Therefore, the optimum temperatures for cell growth and glutathione production are quite different in the batch fermentation. A modified Logistic equation was successfully applied to estimate the kinetics of cell growth. The maximum specific growth rate and the substrate inhibition constant, calculated from this equation, were both increased along with the temperature. In addition, the glutathione fermentation by C. utilis WSH 02-08 under various temperatures was proven to be a partial growth-associated process by estimating the process with the Luedeking-Piret equation. Based on the estimated parameon the estimated parameters, the effect of

  20. The uselessness of the Fast Gauss Transform for summing Gaussian radial basis function series

    NASA Astrophysics Data System (ADS)

    Boyd, John P.

    2010-02-01

    The Fast Gauss Transform is an algorithm for summing a series of Gaussians which is sometimes much faster than direct summation. Gaussian series in d dimensions are of the form ∑j=1N λjexp(-[α/h]2 ‖x-xj‖2) where the xj are the centers, h is the average separation between centers and α is the relative inverse width parameter. We show that the speed-up of the Fast Gauss Transform is bounded by a factor Ω(α). When α≪1, Ω can be large. However, when applied to Gaussian radial basis function interpolation, it is difficult to apply the Gaussian basis in this parameter range because the interpolation matrix is exponentially ill-conditioned: the condition number κ˜(1/2)exp{π2}/{4α2} for a uniform, one-dimensional grid, and larger still in two dimensions or when the grid is irregular. Furthermore, the Gaussian RBF interpolant is ill-conditioned for most series in the sense that the interpolant is the small difference of terms with exponentially large coefficients. Fornberg and Piret developed a "QR-basis" that ameliorates this difficulty for approximations on the surface of a sphere, but because the recombined basis functions are perturbed spherical harmonics, not Gaussians, the Fast Gauss Transform is no longer applicable. The solution of the interpolation matrix system by a preconditioned iteration is less sensitive to condition numbers than direct methods because iterations are self-correcting and also because the preconditioning reduces the spread of the eigenvalues. However, each iteration requires a matrix-vector multiply which is fast only if this operation can be performed by some species of Fast Summation. When α˜O(1), alas, we show that Ω is not large and the Fast Gauss Transform is not accelerative. Gaussian RBFs are unusual among RBF species through the absence of long-range interactions due to the exponential decay of the Gaussians with distance from their centers; many other RBF species do have long-range interactions, and it is well

  1. Using simple models to describe the kinetics of growth, glucose consumption, and monoclonal antibody formation in naive and infliximab producer CHO cells.

    PubMed

    López-Meza, Julián; Araíz-Hernández, Diana; Carrillo-Cocom, Leydi Maribel; López-Pacheco, Felipe; Rocha-Pizaña, María Del Refugio; Alvarez, Mario Moisés

    2016-08-01

    Despite their practical and commercial relevance, there are few reports on the kinetics of growth and production of Chinese hamster ovary (CHO) cells-the most frequently used host for the industrial production of therapeutic proteins. We characterize the kinetics of cell growth, substrate consumption, and product formation in naive and monoclonal antibody (mAb) producing recombinant CHO cells. Culture experiments were performed in 125 mL shake flasks on commercial culture medium (CD Opti CHO™ Invitrogen, Carlsbad, CA, USA) diluted to different glucose concentrations (1.2-4.8 g/L). The time evolution of cell, glucose, lactic acid concentration and monoclonal antibody concentrations was monitored on a daily basis for mAb-producing cultures and their naive counterparts. The time series were differentiated to calculate the corresponding kinetic rates (rx = d[X]/dt; rs = d[S]/dt; rp = d[mAb]/dt). Results showed that these cell lines could be modeled by Monod-like kinetics if a threshold substrate concentration value of [S]t = 0.58 g/L (for recombinant cells) and [S]t = 0.96 g/L (for naïve cells), below which growth is not observed, was considered. A set of values for μmax, and Ks was determined for naive and recombinant cell cultures cultured at 33 and 37 °C. The yield coefficient (Yx/s) was observed to be a function of substrate concentration, with values in the range of 0.27-1.08 × 10(7) cell/mL and 0.72-2.79 × 10(6) cells/mL for naive and recombinant cultures, respectively. The kinetics of mAb production can be described by a Luedeking-Piret model (d[mAb]/dt = αd[X]/dt + β[X]) with values of α = 7.65 × 10(-7) µg/cell and β = 7.68 × 10(-8) µg/cell/h for cultures conducted in batch-agitated flasks and batch and instrumented bioreactors operated in batch and fed-batch mode.

  2. PREFACE: Nanosafe2010: International Conference on Safe Production and Use of Nanomaterials

    NASA Astrophysics Data System (ADS)

    Sentein, Carole; Schuster, Frédéric; Tardif, François

    2011-07-01

    ESevertsov Inst. of Ecology and Evolution, RU KÜCK AUniv. Bremen, DE KUO Y-MChung Hwa University, TW KVITEK LPalacky Univ., CZ LABILLE JCEREGE, FR LAMMINEN EDekati, FI LARUE CCEA, FR LE BIHAN OINERIS, FR LE DUR DEcomesure, FR LECERF PCILAS, FR LEGRAND MCordouan, FR LELONG CUJF CEA, FR LIMOUSIN SINERIS, FR LINDELOEV JGEA Process Engineering, DK LIU P PChina Jiliang University, CN LIU WCEREGE, FR MACHEREY A-CCNRS, FR MAGGA YCEA, FR MAHLENDORF FUniversity Duisburg-Essen, DE MANIER NINERIS, FR MANZO LUniv. Pavia, IT MARCHETTO ACEA, FR MARCONE GUNICAMP, BR MARI DEPFL, CH MARIE-DESVERGNE CCEA, FR MARIE-LOUISE APSA Peugeot-Citroen, FR MARMUSE LNano-H S.A.S., FR MARRA JPhilips Research Aerasense, NL MASION ACEREGE, FR MATEI EPolitehnica University Bucharest, RO MATSUI YKyoto Univ., JP MATZKE MUniv. Gothenburg, SE MAYNE-L'HERMITE MCEA, FR MELINTE G ABabes-Bolyai University, RO MERINO CGrupo Antolin Ingenieria, ES MICHAUD-SORET ICEA, FR MICHELETTI CJRC, IT MONTIGEL EBasler Versicherungen, CH MONTOYA ERAMEM, ES MOSSUZ VCEA, FR MOTELLIER SCEA, FR MOTZKUS CLNE, FR MUIR BNaneum, GB NAKAMURA KJAPAN NUS CO., JP NEUBAUER NKarlsruhe Institute of Technologie, DE NEUMEISTER LBG ETEM, DE NGUYEN TNIST, US NIORT NINTERTEK, FR NOIRTIN AINTERTEK, FR NOWACK BEmpa, CH NYEMBE DUniv. Johannesburg, ZA Ó CLAONADH NDublin Institute of Technology, IE OBERDÖRSTER GUniv. Rochester, US OGURA IAIST, JP OSTIGUY CIRSST, CA OTSUKA KJFE Techno-Research Corp., JP OUF F-XIRSN, FR OUSACI SALMA, FR PAGET VCEA, FR PAILLEUX MEcole des Mines de Saint Etienne, FR PANDARD PINERIS, FR PANZER OEuropean Research Services, DE PARISELLI FCNRS, FR PERLET JNANO Magazine, GB PETERS RRIKILT, NL PETIT A-NCEA, FR PETKOVIC JNational Institute of Biology, SI PIMENOFF JBeneq, FI PINAULT MCEA, FR PIRET J-PUniv. Namur, BE PONTONE RTekna Plasma Systems, FR POURCHEZ JEcole des Mines de Saint Etienne, FR PRAETORIUS AETH Zurich, CH PRAT OCEA, FR PREVENSLIK TQED Radiations, CN PREVOST CIRSN, FR PROY HUART DFrance Nature Environnement, FR PUI