Kinetics Of Ethanol Production Research Articles

Variation in glucose metabolism under acidified sodium nitrite mediated nitrosative stress in Saccharomyces cerevisiae.

The work aimed to understand the important changes during glucose metabolism in Saccharomyces cerevisiae under acidified sodium nitrite (ac.NaNO2 ) mediated nitrosative stress. Confocal microscopy and fluorescence-activated cell sorting analysis were performed to investigate the generation of reactive nitrogen and oxygen species, and redox homeostasis under nitrosative stress was also characterized. Quantitative PCR analysis revealed that the expression of ADH genes was upregulated under such condition, whereas the ACO2 gene was downregulated. Some of the enzymes of the tricarboxylic acid cycle were partially inhibited, whereas malate metabolism and alcoholic fermentation were increased under nitrosative stress. Kinetics of ethanol production was also characterized. A network analysis was conducted to validate our findings. In the presence of ac.NaNO2 , in vitro protein tyrosine nitration formation was checked by western blotting using pure alcohol dehydrogenase and aconitase. Alcoholic fermentation rate was increased under stress condition and this altered metabolism might be conjoined with the defence machinery to overcome the nitrosative stress. This is the first work of this kind where the role of metabolism under nitrosative stress has been characterized in S. cerevisiae and it will provide a base to develop an alternative method of industrial ethanol production.

Performance of xylose-fermenting yeasts in oat and soybean hulls hydrolysate and improvement of ethanol production using immobilized cell systems.

We investigated the fermentation of a mixture of oat and soybean hulls (1:1) subjected to acid (AH) or enzymatic (EH) hydrolyses, with both showing high osmotic pressures (> 1200Osmkg-1) for the production of ethanol. Yeasts of genera Spathaspora, Scheffersomyces, Sugiymaella, and Candida, most of them biodiverse Brazilian isolates and previously untested in bioprocesses, were cultivated in these hydrolysates. Spathaspora passalidarum UFMG-CM-469 showed the best ethanol production kinetics in suspended cells cultures in acid hydrolysate, under microaerobic and anaerobic conditions. This strain was immobilized in LentiKats® (polyvinyl alcohol) and cultured in AH and EH. Supplementation of hydrolysates with crude yeast extract and peptone was also performed. The highest ethanol production was obtained using hydrolysates supplemented with crude yeast extract (AH-CYE and EH-CYE) showing yields of 0.40 and 0.44gg-1, and productivities of 0.39 and 0.29g(Lh)-1, respectively. The reuse of the immobilized cells was tested in sequential fermentations of AH-CYE, EH-CYE, and a mixture of acid and enzymatic hydrolysates (AEH-CYE) operated under batch fluidized bed, with ethanol yields ranging from 0.31 to 0.40gg-1 and productivities from 0.14 to 0.23g(Lh)-1. These results warrant further research using Spathaspora yeasts for second-generation ethanol production.

Development of a green liquor dregs pretreatment for enhanced glucose recovery from corn cobs and kinetic assessment on various bioethanol fermentation types

This study optimized a novel pretreatment of corn cob wastes (CCW) using green liquor dregs (GLD), a waste product from the chemical kraft pulping industry. Subsequently, the microbial growth and ethanol production kinetics of different bioprocess types were comparatively evaluated using the logistic and modified Gompertz models respectively. The optimized GLD pretreatment conditions released a maximum glucose yield of 0.42 g/g. Separate hydrolysis and fermentation (SHF), simultaneous saccharification and fermentation (SSF) and SSF with pre hydrolysis (PSSF) processes were assessed and gave comparable kinetic data. The SHF and PSSF processes displayed slightly higher microbial and bioethanol kinetic coefficients compared to the SSF system. Implications from this study provide major insights for reducing energy, time and costs incurred with lignocellulosic substrate pretreatment, bioethanol process design and scale up. Additionally, the study demonstrates a possible route for beneficiation of waste material such as GLD.

Mathematical Modeling of Ethanol Production through Batch Fermentation of Glucose with Kluveromyces Marxianus

Mathematical models are a means of representing essential aspects of reality (process, phenomenon, object, element, system, etc.) with the help of mathematical constructs. Mathematical models typically offer convenience and cost advantages over other means of obtaining the required information on reality. In the last decades, continuing progress has been observed in applications of mathematical modeling in biological growth. This research developed a mathematical model that illustrated the kinetics of ethanol production, incorporating both fermentation time and temperature from the batch fermentation of glucose with Kluveromyces Maxianus. Glucose biomass was found to decrease linearly with temperature rise and the modified Gompertz model was used to describe the ethanol production. The arhenious plot was used to illustrate the temperature dependence rate of the reaction. Matlab 9.0 and Microsoft Excel 2007 were the statistical software used for the iteration and the estimation of thebiological parameters. The derived mathematical model could be adapted to illustrate the kinetics of ethanol production to the stationary phase during the fermentation of glucose as influenced by temperature and fermentation time using Kluveromyces Maxianus.

Evaluation of fermentation kinetics of acid-treated corn cob hydrolysate for xylose fermentation in the presence of acetic acid by Pichia stipitis.

The efficient utilization of lignocellulosic biomass for ethanol production depends on the fermentability of the biomass hydrolysate obtained after pretreatment. In this work we evaluated the kinetics of ethanol production from xylose using Pichia stipitis in acid-treated corn cob hydrolysate. Acetic acid is one of the main inhibitors in corn cob hydrolysate that negatively impacts kinetics of xylose fermentation by P. stipitis. Unstructured kinetic model has been formulated that describes cell mass growth and ethanol production as a function of xylose, oxygen, ethanol, and acetic acid concentration. Kinetic parameters were estimated under different operating conditions affecting xylose fermentation. This is the first report on kinetics of xylose fermentation by P. stipitis which includes inhibition of acetic acid on growth and product formation. In the presence of acetic acid in the hydrolysate, the model accurately predicted reduction in maximum specific growth rate (from 0.23 to 0.15h-1) and increase in ethanol yield per unit biomass (from 3 to 6.2gg-1), which was also observed during experimental trials. Presence of acetic acid in the fermentation led to significant reduction in the cell growth rate, reduction in xylose consumption and ethanol production rate. The developed model accurately described physiological state of P. stipitis during corn cob hydrolysate fermentation. Proposed model can be used to predict the influence of xylose, ethanol, oxygen, and acetic acid concentration on cell growth and ethanol productivity in industrial fermentation.

Sustaining ethanol production from lime pretreated water hyacinth biomass using mono and co-cultures of isolated fungal strains with Pichia stipitis

Background: The high rate of propagation and easy availability of water hyacinth has made it a renewable carbon source for biofuel production. The present study was undertaken to screen the feasibility of using water hyacinth's hemicelluloses as a substrate for alcohol production by microbial fermentation using mono and co-cultures of Trichoderma reesei and Fusarium oxysporum with Pichia stipitis. Results: In separate hydrolysis and fermentation (SHF), the alkali pretreated water hyacinth biomass was saccharified by crude fungal enzymes of T. reesei, F. oxysporum and then fermented by P. stipitis. In simultaneous saccharification and fermentation (SSF), the saccharification and fermentation was carried out simultaneously at optimized conditions using mono and co-cultures of selected fungal strains. Finally, the ethanol production kinetics were analyzed by appropriate methods. The higher crystalline index (66.7%) and the Fourier transform infrared (FTIR) spectra showed that the lime pretreatment possibly increased the availability of cellulose and hemicelluloses for enzymatic conversion. In SSF, the co-culture fermentation using T. reesei and P. stipitis was found to be promising with a higher yield of ethanol (0.411 g g �1 ) at 60 h. The additional yield comparable with the monocultures was due to the xylanolytic activity of P. stipitis which ferments pentose sugars into ethanol. In SHF, the pretreatment followed by crude enzymatic hydrolysis and fermentation resulted in a significantly lesser yield of ethanol (0.344 g g �1 )a t 96 h. Conclusions: It is evident from the study that the higher ethanol production was attained in a shorter period in the co-culture system containing T. reesei and the xylose fermenting yeast P. stipitis. SSF of pretreated water hyacinth biomass (WHB) with P. stipitis instead of traditional yeast is found to be an effective biofuel production process.

INDISIM-Saccha, an individual-based model to tackle Saccharomyces cerevisiae fermentations

This contribution develops and implements INDISIM-Saccha, a spatially explicit IBM model to analyze the dynamics of Saccharomyces cerevisiae anaerobic cultures evolving in a liquid medium with glucose as a main carbon source and organic and inorganic nitrogen sources. The model has been parameterized, calibrated and its adequacy assessed using available experimental data. The growth of the yeast population and the glucose depletion were simulated, and changes in the ethanol production kinetics resulting from differences in the size distribution of the cells making up the inocula were examined in silico. Uncertainty on the initial estimated values of the model parameters was reduced by means of an iterative process involving a computational full factorial experiment, and the parameter values reproducing simultaneously glucose depletion and growth curves of batch cultures in two initial glucose concentrations were selected. The model adequacy was assessed with multiple both individual and population patterns not previously used in the calibration process carried out. Three virtual experiments were conducted from inocula with different cell size distributions. The maximum yeast cell number, the specific growth rate and the time to achieve the maximum ethanol produced were studied. Although the ethanol obtained was similar in the three studied situations, the time required to achieve it was significantly different, fermentations started by inocula made up of greater cells showed increased productivity. Due to the importance of S. cerevisiae in both fundamental research and industrial production contexts, having a calibrated computational model capable of studying the structures of this yeast population and the profiles of the fermentations carried out by it represents a noteworthy advancement in the field of microbial ecology.

Kinetics of Bioethanol Production from Glycerol by Enterobacter Aerogenes

Kinetics of ethanol production from glycerol as sole carbon source using Enterobacter aerogenes were evaluated in batch fermentation with initial glycerol range from 10 to 120 g L-1 under 240 hr incubation at 30°C and pH 7. E. aerogenes was able to grow and produce the maximum ethanol concentration of 136.7 mM at the initial glycerol concentration of 20 g L-1. At this glycerol concentration, glycerol was completely utilized after 40 hr fermentation and ethanol yield was 0.7 mol mol-1. Microbial growth appeared to decrease when the initial glycerol concentrations were increased. In the initial glycerol concentration range of 10-45 g L-1, glycerol utilization was approximately 90% after 40 hr fermentation. Minimal amount volatile fatty acids and 1, 3-propanediol were detected.

Kinetic Modeling of Ethanol Production by Scheffersomyces stipitis from Xylose

This work focuses on the kinetics of ethanol production by Scheffersomyces stipitis on xylose with the development of a mathematical model considering the effect of substrate and product concentrations on growth rate. Experiments were carried out in batch and continuous modes, with substrate concentration varying from 7.2 to 145 g L(-1). Inhibitory effects on cell growth, substrate uptake, and ethanol production rates were found to be considerable. Kinetic parameters were obtained through linear and non-linear regression methods. Experiments in continuous mode were performed at different dilution rates to evaluate the inhibitory effect of ethanol. A mixed mathematical model which combined Andrews and Levenspiel's models, combining substrate and product inhibition, was used. A quasi-Newton routine was applied to obtain a more accurate fitting of kinetic parameters. The parameters such as cell to product factor (YP/X) and limiting cell yield (YX) were shown to be dependent on substrate concentration. The kinetic model fitted satisfactorily the experimental data.

The Kinetics of Ethanol Production from Cane Molasses by Saccharomyces cerevisiae in a Batch Bioreactor

The present study was aimed at achieving a better understanding about fermentation condition by Saccharomyces cerevisiae with cane molasses for bioethanol production. The biosynthesis of ethanol was conducted via S. cerevisiae from cane molasses at pH 4.5 and 30°C. The fermentation was carried out in triplicate with various feed concentrations of molasses for S. cerevisiae in a batch bioreactor. S. cerevisiae produced ethanol at 9.3 ± 1.8 g/l with a biomass yield of 0.57 g/g after 36 h. The kinetic of growth dependence on molasses was represented by Andrew equation to predict the inhibition constant in the cultures media.

Ethanol Production from Whey by Kluyveromyces marxianus in Batch Fermentation System: Kinetics Parameters Estimation

Whey is the liquid remaining after milk has been curdled and strained. It is a by-product of the manufacture of cheese or casein and has several commercial uses. In environmental point of view, whey is kind of waste which has high pollution level due to it’s contain high organic compound with BOD and COD value 50 and 80 g/L respectively. On the other side, whey also contain an amount of lactose (4.5%-5%); lactose can be used as carbon source and raw material for producing ethanol via fermentation using yeast strain Kluyveromyces marxianus. The objective of this research is to investigate the ethanol production kinetics from crude whey through fermentation using Kluyveromyces marxianus and to predict the model kinetics parameter. The yeast was able to metabolize most of the lactose within 16 h to give 8.64 g/L ethanol, 4.43 g/L biomass, and remain the 3.122 g/L residual lactose. From the results presented it also can be concluded that common kinetic model for microbial growth, substrate consumption, and product formation is a good alternative to describe an experimental batch fermentation of Kluyveromyces marxianus grown on a medium composed of whey. The model was found to be capable of reflecting all batch culture phases to a certain degree of accuracy, giving the parameter value: μmax, Ks, YX/S, α, β : 0.32, 10.52, 0.095, 1.52, and 0.11 respectively.© 2013 by Authors, Published by BCREC Group. This is an open access article under the CC BY-SA License (https://creativecommons.org/licenses/by-sa/4.0)

Ethanol Production from Whey by Kluyveromyces marxianus in Batch Fermentation System: Kinetics Parameters Estimation

Whey is the liquid remaining after milk has been curdled and strained. It is a by-product of the manufacture of cheese or casein and has several commercial uses. In environmental point of view, whey is kind of waste which has high pollution level due to it’s contain high organic compound with BOD and COD value 50 and 80 g/L respectively. On the other side, whey also contain an amount of lactose (4.5%-5%); lactose can be used as carbon source and raw material for producing ethanol via fermentation using yeast strain Kluyveromyces marxianus . The objective of this research is to investigate the ethanol production kinetics from crude whey through fermentation using Kluyveromyces marxianus and to predict the model kinetics parameter. The yeast was able to metabolize most of the lactose within 16 h to give 8.64 g/L ethanol, 4.43 g/L biomass, and remain the 3.122 g/L residual lactose. From the results presented it also can be concluded that common kinetic model for microbial growth, substrate consumption, and product formation is a good alternative to describe an experimental batch fermentation of Kluyveromyces marxianus grown on a medium composed of whey. The model was found to be capable of reflecting all batch culture phases to a certain degree of accuracy, giving the parameter value: μmax, Ks, YX/S, α, β : 0.32, 10.52, 0.095, 1.52, and 0.11 respectively. © 2013 BCREC UNDIP. All rights reserved ( Selected Paper from International Conference on Chemical and Material Engineering (ICCME) 2012 ) Received: 27th September 2012; Revised: 29th November 2012; Accepted: 7th December 2012 [ How to Cite : D. Ariyanti, H. Hadiyanto, (2013). Ethanol Production from Whey by Kluyveromyces marxianus in Batch Fermentation System: Kinetics Parameters Estimation. Bulletin of Chemical Reaction Engineering & Catalysis , 7 (3): 179-184. (doi:10.9767/bcrec.7.3.4044.179-184)] [ Permalink/DOI : http://dx.doi.org/10.9767/bcrec.7.3.4044.179-184 ] View in |

Kinetics of ethanol production from sugarcane bagasse enzymatic hydrolysate concentrated with molasses under cell recycle

In this work, a kinetic model for ethanol fermentation from sugarcane bagasse enzymatic hydrolysate concentrated with molasses was developed. A model previously developed for fermentation of pure molasses was modified by the inclusion of a new term for acetic acid inhibition on microorganism growth rate and the kinetic parameters were estimated as functions of temperature.The influence of the hydrolysate on the kinetic parameters is analyzed by comparing with the parameters from fermentation of pure molasses. The impact of cells recycling in the kinetic parameters is also evaluated, as well as on the ethanol yield and productivity. The model developed described accurately most of the fermentations performed in several successive batches for temperatures from 30 to 38°C.

Evaluation of the alcoholic fermentation kinetics of enzymatic hydrolysates from sugarcane bagasse (Saccharum officinarumL.)

Background The efficient production of bioethanol by Saccharomyces cerevisiae using lignocellulosic biomass as raw material depends on the fermentability of the hydrolysates. In this work the evaluation of the kinetics of ethanol production by S. cerevisiae using enzymatic hydrolysates was performed and compared with the kinetics of diluted sugarcane molasses fermentation. Results A term for inhibition by acetic acid was added to a previous model, the kinetic parameters were re-estimated and the model has been shown to describe accurately new experiments with distinct hydrolysates proportions as fermentative media. Among all the kinetic parameters, a great reduction in μmax (from 0.437 to 0.37 h−1, at 34°C), and increment in Ypx (from 9.89 to 16.63 kg kg−1, at 34°C) were noted, which strongly affected the kinetics of fermentation. Conclusions The kinetic parameters obtained for hydrolysates differed very significantly from those obtained using molasses, which shows that models developed to describe the kinetics of first generation ethanol production need to be reformulated and adapted to describe the kinetics of second generation ethanol fermentation. The productivities achieved were between 1 and 3 kg m-3 h−1, which are considered acceptable for alcoholic fermentations in batch mode, showing the good fermentability of hydrolysates even without detoxification. © 2012 Society of Chemical Industry

Laboratory metabolic evolution improves acetate tolerance and growth on acetate of ethanologenic Escherichia coli under non-aerated conditions in glucose-mineral medium

In this work, Escherichia coli MG1655 was engineered to produce ethanol and evolved in a laboratory process to obtain an acetate tolerant strain called MS04 (E. coli MG1655: ΔpflB, ΔadhE, ΔfrdA, ΔxylFGH, ΔldhA, PpflB::pdc ( Zm ) -adhB ( Zm ), evolved). The growth and ethanol production kinetics of strain MS04 were determined in mineral medium, mainly under non-aerated conditions, supplemented with glucose in the presence of different concentrations of sodium acetate at pH7.0 and at different values of acid pH and a constant concentration of sodium acetate (2g/l). Results revealed an increase in the specific growth rate, cell mass formation, and ethanol volumetric productivity at moderate concentrations of sodium acetate (2-10g/l), in addition to a high tolerance to acetate because it was able to grow and produce a high yield of ethanol in the presence of up to 40g/l of sodium acetate. Genomic analysis of the ΔpflB evolved strain identified that a chromosomal deletion of 27.3kb generates the improved growth and acetate tolerance in MG1655 ΔpflB derivative strains. This deletion comprises genes related to the respiration of nitrate, repair of alkylated DNA and synthesis of the ompC gene coding for porin C, cytochromes C, thiamine, and colonic acid. Strain MS04 is advantageous for the production of ethanol from hemicellulosic hydrolysates that contain acetate.

Two‐stage Hydrolysis of Invasive Algal Feedstock for Ethanol FermentationF

The overall goal of this work was to develop a saccharification method for the production of third generation biofuel (i.e. bioethanol) using feedstock of the invasive marine macroalga Gracilaria salicornia. Under optimum conditions (120 °C and 2% sulfuric acid for 30 min), dilute acid hydrolysis of the homogenized invasive plants yielded a low concentration of glucose (4.1 mM or 4.3 g glucose/kg fresh algal biomass). However, two-stage hydrolysis of the homogenates (combination of dilute acid hydrolysis with enzymatic hydrolysis) produced 13.8 g of glucose from one kilogram of fresh algal feedstock. Batch fermentation analysis produced 79.1 g EtOH from one kilogram of dried invasive algal feedstock using the ethanologenic strain Escherichia coli KO11. Furthermore, ethanol production kinetics indicated that the invasive algal feedstock contained different types of sugar, including C(5) -sugar. This study represents the first report on third generation biofuel production from invasive macroalgae, suggesting that there is great potential for the production of renewable energy using marine invasive biomass.

Kinetics of ethanol production by Zymomonas mobilis using low-grade wheat flour in batch fermentation

Kinetics of ethanol production by Zymomonas mobilis using low-grade wheat flour in batch fermentation

Influence of the reactor shape on the kinetics of ethanol production in laboratory-scale batch fermentation tests carried out in unstirred vessels

The influence of the shape of laboratory-scale unstirred reactors on the kinetics of ethanol production in batch ethanol fermentation was studied. Two reactors were used: a 1-L glass measuring cylinder and a 2-L Erlenmeyer flask. The volume of inoculated medium in each reactor was 1,000 mL. The above influence was affected by the ratio between the initial yeast cells concentration (X0: ~ 7 g/L, ~ 14 g/L, and ~ 21 g/L, dry matter) and the initial glucose concentration (S0: ~ 100 g/L, ~ 150 g/L and ~ 200 g/L). When X0/S0 increased from 0.038 to 0.219 the influence of the reactor shape decreased, and was not observed when X0/S0 = 0.22 to 0.24. The reactor shape practically did not affect the ethanol yield, the final yeast cells concentration and both the viability and the morphology of the cells in tests carried out at the same value of X0/S0.

Fermentation kinetics of ethanol production from glucose and xylose by recombinant Saccharomyces 1400(pLNH33).

Fermentation kinetics of ethanol production from glucose, xylose, and their mixtures using a recombinant Saccharomyces 1400(pLNH33) are reported. Single-substrate kinetics indicate that the specific growth rate of the yeast and the specific ethanol productivity on glucose as the substrate was greater than on xylose as a substrate. Ethanol yields from glucose and xylose fermentation were typically 95 and 80% of the theoretical yield, respectively. The effect of ethanol inhibition is more pronounced for xylose fermentation than for glucose fermentation. Studies on glucose-xylose mixtures indicate that the recombinant yeast co-ferments glucose and xylose. Fermentation of a 52.8 g/L glucose and 56.3 g/L xylose mixture gave an ethanol concentration of 47.9 g/L after 36 h. Based on a theoretical yield of 0.51 g ethanol/g sugars, the ethanol yield from this experiment (for data up to 24 h) was calculated to be 0.46 g ethanol/g sugar or 90% of the theoretical yield. The specific growth rate of the yeast on glucose-xylose mixtures was found to lie between the specific growth rate on glucose and the specific growth rate on xylose. Kinetic studies were used to develop a fermentation model incorporating the effects of substrate inhibition, product inhibition, and inoculum size. Good agreements were obtained between model predictions and experimental data from batch fermentation of glucose, xylose, and their mixtures.

Batch fermentation kinetics of ethanol production by Zymomonas mobilis on cellulose hydrolysate

Growth and ethanol production by three strains (MSN77, thermotolerant, SBE15, osmotolerant and wild type ZM4) of the bacterium Zymomonas mobilis were tested in a rich medium containing the hexose fraction from a cellulose hydrolysate (Aspen wood). The variations of yield and kinetic parameters with fermentation time revealed an inhibition of growth by the ethanol produced. This inhibition may result from the increase in medium osmolality due to ethanol formation from glucose.