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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. Studies on cultivation kinetics for elastase production by Bacillus sp. EL31410.

    PubMed

    Chen, Qi-He; He, Guo-Qing; Schwarz, Paul

    2004-06-01

    It was the first time to study elastase batch cultivation kinetics. This paper discusses the growth kinetics, elastase production, and substrate consumption kinetics model of Bacillus sp. EL31410 in batch cultivation. A simple model was proposed using a logistic equation for growth, the Luedeking-Piret equation for elastase production, and the Luedeking-Piret-like equation for glucose consumption. The model appeared to provide a reasonable description for each parameter during the growth phase. This study could provide some support for studying elastase fermentation kinetics, especially for studying its singular growth phenomenon. However, the model for elastase production is not good for explaining the real process and is still up to research. PMID:15161197

  3. Evaluation of medium components by Plackett-Burman statistical design for lipase production by Candida rugosa and kinetic modeling.

    PubMed

    Rajendran, Aravindan; Palanisamy, Anbumathi; Thangavelu, Viruthagiri

    2008-03-01

    Lipase production by Candida rugosa was carried out in submerged fermentation. Plackett-Burman statistical experimental design was applied to evaluate the fermentation medium components. The effect of twelve medium components was studied in sixteen experimental trials. Glucose, olive oil, peptone and FeCl3.6H2O were found to have more significance on lipase production by Candida rugosa. Maximum lipase activity of 3.8 u mL(-1) was obtained at 50 h of fermentation period. The fermentation was carried out at optimized temperature of 30 degrees C, initial pH of 6.8 and shaking speed of 120 r/min. Unstructured kinetic models were used to simulate the experimental data. Logistic model, Luedeking-Piret model and modified Luedeking-Piret model were found suitable to efficiently predict the cell mass, lipase production and glucose consumption respectively with high determination coefficient(R2). From the estimated values of the Luedeking-Piret kinetic model parameters, alpha and beta, it was found that the lipase production by Candida rugosa is growth associated.

  4. 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

  5. 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.

  6. Methanol bioconversion by Butyribacterium methylotrophicum--batch fermentation yield and kinetics

    SciTech Connect

    Datta, R.; Ogeltree, J.

    1983-04-01

    Butyribacterium methylotrophicum is an anaerobic bacterium that can convert methanol to butyrate. This ability to produce longer-chain carbon compounds from C/sub 1/ substrates could be of commercial significance. The fermentation rates and product formation depend on the methanol/bicarbonate ratios during fermentation. The kinetics of batch fermentation fit the Luedeking-Piret model with growth and maintenance associated product formation. Butyrate yield of 0.256 mol/mol methanol (ca. 85% of theoretical yield) has been obtained in batch fermentation.

  7. 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.

  8. Pullulan from peat hydrolyzate fermentation kinetics.

    PubMed

    Boa, J M; Leduy, A

    1987-09-01

    The Luedeking-Piret equation was used to fit the kinetic data of pullulan fermentations from peat hydrolyzate substrate. In batch mode, the kinetic parameters m, n, alpha, and beta varied as a function of fermentation conditions: aeration rate, agitation speed, and temperature. In constant-feed fed-batch mode, the parameters Varied according to the feed rates. In peat hydrolyzate medium, the polysaccharide synthesis was strongly growth associated in batch and continuous fermentations but entirely growth associated in fedbatch fermentations. The fed-batch mode of fermentation with an appropriate feed rate is more advantageous with respect to batch and continuous fermentations. Therefore, if the fermentation is started batchwise and then followed by fed-batch mode at a constant feed rate, the overall polysaccharide productivity (g pullulan/L h) is significantly higher than those obtained with batch or continuous fermentations using the same total medium volume.

  9. Homo-fermentative production of D-lactic acid by Lactobacillus sp. employing casein whey permeate as a raw feed-stock.

    PubMed

    Prasad, Saurav; Srikanth, Katla; Limaye, Anil M; Sivaprakasam, Senthilkumar

    2014-06-01

    Casein whey permeate (CWP), a lactose-enriched dairy waste effluent, is a viable feed stock for the production of value-added products. Two lactic acid bacteria were cultivated in a synthetic casein whey permeate medium with or without pH control. Lactobacillus lactis ATCC 4797 produced D-lactic acid (DLA) at 12.5 g l(-1) in a bioreactor. The values of Leudking-Piret model parameters suggested that lactate was a growth-associated product. Batch fermentation was also performed employing CWP (35 g lactose l(-1)) with casein hydrolysate as a nitrogen supplement in a bioreactor. After 40 h, L. lactis produced 24.3 g lactic acid l(-1) with an optical purity >98 %. Thus CWP may be regarded as a potential feed-stock for DLA production. PMID:24563313

  10. 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.

  11. 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.

  12. 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. PMID:27186467

  13. 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).

  14. 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.

  15. 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. PMID:23702163

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

    PubMed

    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

  17. Effects of dissolved oxygen and agitation on production of serratiopeptidase by Serratia marcescens NRRL B-23112 in stirred tank bioreactor and its kinetic modeling.

    PubMed

    Pansuriya, Ruchir; Singhal, Rekha

    2011-04-01

    The effects of the agitation and aeration rates on the production of serratiopeptidase (SRP) in a 5-L fermentor (working volume 2-l) were systematically investigated using Serratia marcescens NRRL B-23112. The dissolved oxygen concentration, pH, biomass, SRP yield, and maltose utilization were all continuously measured during the course of the fermentation runs. The efficiencies of the aeration and agitation were evaluated based on the volumetric mass transfer coefficient (K(L)a). The maximum SRP production of 11,580 EU/ml with a specific SRP productivity of 78.8 EU/g/h was obtained with an agitation of 400 rpm and aeration of 0.075 vvm, which was 58% higher than the shake-flask level. The KLa for the fermentation system supporting the maximum production (400 rpm, 0.075 vvm) was 11.3 h(-1). Under these fermentor optimized conditions, kinetic modeling was performed to understand the detailed course of the fermentation process. The resulting logistic and Luedeking-Piret models provided an effective description of the SRP fermentation, where the correlation coefficients for cell growth, SRP formation, and substrate consumption were 0.99, 0.94, and 0.84, respectively, revealing a good agreement between the model-predicted and experimental results. The kinetic analysis of the batch fermentation process for the production of SRP demonstrated the SRP production to be mixed growth associated.

  18. 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. PMID:27266628

  19. 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.

  20. 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.

  1. 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.

  2. Fed-batch Fermentation of Lactic Acid Bacteria to Improve Biomass Production: A Theoretical Approach

    NASA Astrophysics Data System (ADS)

    Beng Lee, Boon; Tham, Heng Jin; Chan, Eng Seng

    Recently, fed-batch fermentation has been introduced in an increasing number of fermentation processes. Previous researches showed that fed-batch fermentation can increase the biomass yield of many strains. Improvement of the biomass yield is interested because biomass from lactic acid bacteria (LAB) fermentation is widely used in food and pharmaceutical industry. The aim of this research is to study the ability and feasibility of fed-batch fermentation to improve biomass production of LAB. Appropriate model has been selected from literature. Monod equation described the substrate limitation of LAB and the product inhibition of LAB follows a non-competitive model. Furthermore, the lactic acid production follows Luedeking and Piret model. Then the models are applied to simulate the fermentation of batch and fed-batch cultures by using MATLAB. From the results of simulation, fed-batch fermentation showed that substrate limitation and substrate inhibition can be avoided. Besides that, the variable volume fed-batch fermentation also showed that product inhibition can be eliminated by diluting the product concentration with added fresh feed. However, it was found that fed-batch fermentation is not economically feasible because large amount of substrate is required to reduce the product inhibition effect. Therefore, fed-batch fermentation plays more importance role if the fermentation strain has high Ks value or low Kp value.

  3. 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.

  4. 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. PMID:26551573

  5. Process optimization and kinetic modelling of cyclic (1→3, 1→6)-β-glucans production from Bradyrhizobium japonicum MTCC120.

    PubMed

    Nair, Anju V; Gummadi, Sathyanarayana N; Doble, Mukesh

    2016-05-20

    Cyclic (1→3, 1→6)-β-glucans are water soluble, biocompatible polymers with potential applications in food and pharmaceutical industries but have not yet been exploited due to their poor yield. In the present study statistical experimental design methodology was employed to improve their production. Initial screening indicated arabinose and peptone as best carbon and nitrogen source respectively, for glucan production. Arabinose and osmolyte concentrations as well as pH significantly contributed to the glucan production. Central composite design indicated a significant interaction between osmolyte concentration and pH on glucan production. The maximum amount of cyclic glucan produced was 6.7g/L in a 2.5L reactor in batch conditions. The logistic equation for cell growth and Luedeking-Piret equation for glucan production could satisfactorily simulate the batch kinetics data. Cyclic β-glucans could efficiently encapsulate a hydrophobic molecule, curcumin and increase its solubility in water, thus indicating that these glucans have potential as drug delivery systems.

  6. Modeling kinetics of aflatoxin production by Aspergillus flavus in maize-based medium and maize grain.

    PubMed

    Garcia, Daiana; Ramos, Antonio J; Sanchis, Vicente; Marín, Sonia

    2013-03-15

    Predictive mycology has dealt mainly with germination, growth and inactivation of fungi while the issue of mycotoxin production remains relatively unexplored. Very few studies provide biomass dry weight/colony size data along with mycotoxin data for the same sample times, thus the ratio mycotoxin accumulation per fungal biomass dry weight/colony size has rarely been reported. For this reason, the objective of the present study was to model the kinetics of mycotoxin production under the assumption of existing both no-growth-associated and growth-associated production. Aspergillus flavus was chosen as a model mycotoxigenic microorganism, and it was grown in maize agar medium and maize grain at 0.90 and 0.99 aw at 25°C. A significant positive correlation (p<0.05) was observed among the biomass responses (colony radius and biomass dry weight) in agar medium and colony radius in maize at both aw levels assayed. The Luedeking-Piret model was used to model AFB1 production and reasonable percentages of variability were explained. Moreover, AFB1 production was in general slightly better predicted through colony area. As conclusion, aflatoxin production may follow a mixed-growth associated trend, confirming that toxin formation does not present a clear delay in relation to growth under certain conditions. PMID:23422844

  7. 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

  8. Biohydrogen production and kinetic modeling using sediment microorganisms of Pichavaram mangroves, India.

    PubMed

    Mullai, P; Rene, Eldon R; 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 (Fe(2+)) 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.

  9. 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. PMID:20495941

  10. 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.

  11. 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

  12. Modeling for gellan gum production by Sphingomonas paucimobilis ATCC 31461 in a simplified medium.

    PubMed

    Wang, Xia; Xu, Ping; Yuan, Yong; Liu, Changlong; Zhang, Dezhong; Yang, Zhengting; Yang, Chunyu; Ma, Cuiqing

    2006-05-01

    Gellan gum production was carried out by Sphingomonas paucimobilis ATCC 31461 in a simplified medium with a short incubation time, and a kinetic model for understanding, controlling, and optimizing the fermentation process was proposed. The results revealed that glucose was the best carbon source and that the optimal concentration was 30 g liter(-1). As for the fermenting parameters, considerably large amounts of gellan gum were yielded by an 8-h-old culture and a 4% inoculum at 200 rpm on a rotary shaker. Under the optimized conditions, the maximum level of gellan gum (14.75 g liter(-1)) and the highest conversion efficiency (49.17%) were obtained in a 30-liter fermentor in batch fermentation. Logistic and Luedeking-Piret models were confirmed to provide a good description of gellan gum fermentation, which gave some support for the study of gellan gum fermentation kinetics. Additionally, this study is the first demonstration that gellan gum production is largely growth associated by analysis of kinetics in its batch fermentation process. Based on model prediction, higher gellan gum production (17.71 g liter(-1)) and higher conversion efficiency (57.12%) were obtained in fed-batch fermentation at the same total glucose concentration (30 g liter(-1)).

  13. 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

  14. 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

  15. Optimization of medium composition for lipase production by Candida rugosa NCIM 3462 using response surface methodology.

    PubMed

    Rajendran, Aravindan; Thangavelu, Viruthagiri

    2007-05-01

    A sequential optimization approach using statistical design of experiments was employed to enhance the lipase production by Candida rugosa in submerged batch fermentation. Twelve medium components were evaluated initially using the Plackett-Burman 2-level factorial design. The significant variables affecting lipase production were found to be glucose, olive oil, peptone, (NH4)2SO4, and FeCl3.6H2O. Various vegetable oils were tested in the second step, and among them, groundnut oil was found to be the best inducer for lipase production by C. rugosa. The third step was to identify the optimal values of the significant medium components with groundnut oil as the inducer using response surface methodology. The regression equation obtained from the experimental data designed using a central composite design was solved, and analyzing the response surface contour plots, the optimal concentrations of the significant variables were determined. A maximum lipase activity of 5.95 U.mL-1, which is 1.64 times the maximum activity obtained in the Plackett-Burman experimental trials, was observed. The optimum combination of medium constituents contained 19.604 g.L-1 glucose, 13.065 mL.L-1 groundnut oil, 7.473 g.L-1 peptone, 0.962 g.L-1 (NH4)2SO4, 0.0019 g.L-1 FeCl3.6H2O, and other insignificant components at the fixed level. A predictive model of the combined effects of the independent variables using response surface methodology and an artificial neural network was proposed. The unstructured kinetic models, logistic model, and Luedeking-Piret model were used to describe cell mass and lipase production. The parameters of the models were evaluated and the lipase production by C. rugosa was found to be growth associated.

  16. 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. PMID:23435939

  17. 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.

  18. 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.

  19. Kinetic modeling, production and characterization of an acidic lipase produced by Enterococcus durans NCIM5427 from fish waste.

    PubMed

    Ramakrishnan, Vrinda; Goveas, Louella Concepta; Halami, Prakash M; Narayan, Bhaskar

    2015-03-01

    Enterococcus durans NCIM5427 (ED-27), capable of producing an intracellular acid stable lipase, was isolated from fish processing waste. Its growth and subsequent lipase production was optimized by Box Behneken design (optimized conditions: 5 % v/v fish waste oil (FWO), 0.10 mg/ml fish waste protein hydrolysates (FWPH) at 48 h of fermentation time). Under optimized conditions, ED-27 showed a 3.0 fold increase (207.6 U/ml to 612.53 U/ml) in lipase production, as compared to un-optimized conditions. Cell growth and lipase production was modeled using Logistic and Luedeking-Piret model, respectively; and lipase production by ED-27 was found to be growth-associated. Lipase produced by ED-27 showed stability at low pH ranges from 2 to 5 with its optimal activity at 30 °C , pH 4.6; showed metal ion dependent activity wherein its catalytic activity was activated by barium, sodium, lithium and potassium (10 mM); reduced by calcium and magnesium (10 mM). However, iron and mercury (5 mM) completely inactivated the enzyme. In addition, modifying agents like SDS, DTT, β-ME (1%v/v) increased activity of lipase of ED-27; while, PMSF, DEPC and ascorbic acid resulted in a marked decrease. ED-27 had maximum cell growth of 9.90309 log CFU/ml under optimized conditions as compared to 13 log CFU/ml in MRS. The lipase produced has potential application in poultry and slaughterhouse waste management. PMID:25745201

  20. An empirical model on extractive lactic acid bioconversion.

    PubMed

    Srivastava, A; Yunus, R; Roychoudhury, P K

    1999-01-01

    The commercial production of lactic acid through fermentation process has always been in competition with its chemical synthesis process (Kirk Othmer, 1995). Lactic acid produced through the fermentation process has to cope with the problems of purification to meet the required quality standards. An attempt to improve the fermentative production is possible by proper design of an industrial process involving low capital cost for the plant. Also, the low energy costs both in its fermentation and purification, are required. In the commercial interest, the investment cost should be minimised, which is possible only when the cell density in fermenter is high. It means that the inhibitory effect of the product on process kinetics must be minimised. Based on these requirements, the extractive bioconversion technique is one of the approaches to achieve the commercially viable lactic acid production. Extractive lactic acid bioconversion using ion-exchange resin process has already been described in our earlier publications (Srivastava e al., 1992: Roychoudhury et al., 1995) It is always an advantage to develop a process model, thus opening an area of biotechnological improvements to the process. In the present paper, an empirical mathematical model has been described to explain this extractive bioconversion using ion-exchange resin process. It was based on generalised Monod's growth model and Leudeking and Piret equation. The system was defined with the assumption that the microbial growth can be represented as a single reaction; only a very little part of the substrate is utilised for the maintenance of the cells. The effect of end product inhibition on growth and product formation kinetics has also been considered in this model. A non-linear regression technique was used for evaluation of bioconversion kinetic parameters. The fourth order Runge Kutta method was used for solving the differential equations. The results of this process simulation are also discussed in the

  1. 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