The Experts below are selected from a list of 354 Experts worldwide ranked by ideXlab platform

Pornkamol Unrean - One of the best experts on this subject based on the ideXlab platform.

  • systematic optimization of fed batch simultaneous saccharification and fermentation at high solid loading based on enzymatic hydrolysis and dynamic metabolic modeling of saccharomyces cerevisiae
    Applied Microbiology and Biotechnology, 2016
    Co-Authors: Pornkamol Unrean, Sutamat Khajeeram, Kobkul Laoteng
    Abstract:

    An integrative simultaneous saccharification and fermentation (SSF) modeling is a useful guiding tool for rapid process optimization to meet the techno-economic requirement of industrial-scale Lignocellulosic Ethanol Production. In this work, we have developed the SSF model composing of a metabolic network of a Saccharomyces cerevisiae cell associated with fermentation kinetics and enzyme hydrolysis model to quantitatively capture dynamic responses of yeast cell growth and fermentation during SSF. By using model-based design of feeding profiles for substrate and yeast cell in the fed-batch SSF process, an efficient Ethanol Production with high titer of up to 65 g/L and high yield of 85 % of theoretical yield was accomplished. The Ethanol titer and productivity was increased by 47 and 41 %, correspondingly, in optimized fed-batch SSF as compared to batch process. The developed integrative SSF model is, therefore, considered as a promising approach for systematic design of economical and sustainable SSF bioprocessing of lignocellulose.

  • Optimization and techno-economic assessment of high-solid fed-batch saccharification and Ethanol fermentation by Scheffersomyces stipitis and Saccharomyces cerevisiae consortium
    Renewable Energy, 2016
    Co-Authors: Pornkamol Unrean, Sutamat Khajeeram
    Abstract:

    In the present work, technological and economical potentials of sugarcane bagasse-to-Ethanol process using Scheffersomyces stipitis/S. cerevisiae consortium were investigated. A fed-batch enzyme saccharification followed by fermentation (SHF) using optimized yeast consortium achieved a maximum Ethanol titer of 60 g/L with Ethanol yield exceeding 70% of theoretical. Techno-economic analysis was assessed using a fully integrated process flowsheeting model, showing the optimized fed-batch yeast co-culture as the most cost-effective configuration with the Ethanol yield of 250 kg-Ethanol/ton-bagasse. The minimal Ethanol selling price was 26.7 baht/L-Ethanol, closed to the current Ethanol selling price from cassava-based process. Process sensitivity analyses revealed the potentials for further cost reduction up to 44% by reducing enzyme dosage and increasing Ethanol titer. Hence, this study provides an economically viable prototype for high-titer Lignocellulosic Ethanol Production using S. stipitis/S. cerevisiae consortium which may offer better economic value than starch-based process.

  • Model-based optimization of Scheffersomyces stipitis and Saccharomyces cerevisiae co-culture for efficient Lignocellulosic Ethanol Production
    Bioresources and Bioprocessing, 2015
    Co-Authors: Pornkamol Unrean, Sutamat Khajeeram
    Abstract:

    The utilization of both C6 and C5 sugars is required for economical Lignocellulosic bio-based processes. A co-culture system containing multiple strains of the same or different organisms holds promise for conversion of the sugar mixture available in different Lignocellulosic feedstock into Ethanol. Herein a co-culture kinetic model has been developed which can describe the co-cultivation of S. stipitis and S. cerevisiae for Ethanol fermentation in mixed C6/C5 sugars. The predicted fermentation kinetics and Ethanol Production performance agreed well with experimental results, thus validating the model. The co-culture kinetic model has been implemented to design the optimal cell ratio for efficient conversion of rice straw or sugarcane bagasse feedstock into Ethanol. The results reveal that the optimal co-culture system could enhance Ethanol titer by up to 26 %, and Ethanol productivity by up to 29 % compared to a single-strain culture. The maximum Ethanol titer and productivity reached by the optimized co-culture was 46 and 0.49 g/l h, respectively. The co-culture model described here is a useful tool for rapid optimization of S. stipitis/S. cerevisiae co-culture for efficient and sustainable Lignocellulosic Ethanol Production to meet the economic requirements of the Lignocellulosic Ethanol industry. The developed modeling tool also provides a systematic strategy for designing the optimal cell ratio of co-culture, leading to efficient fermentation of the C6/C5 sugars available in any biomass feedstock.

  • metabolic pathway analysis of scheffersomyces pichia stipitis effect of oxygen availability on Ethanol synthesis and flux distributions
    Applied Microbiology and Biotechnology, 2012
    Co-Authors: Pornkamol Unrean, Nhung H A Nguyen
    Abstract:

    Elementary mode analysis (EMA) identifies all possible metabolic states of the cell metabolic network. Investigation of these states can provide a detailed insight into the underlying metabolism in the cell. In this study, the flux states of Scheffersomyces (Pichia) stipitis metabolism were examined. It was shown that increasing oxygen levels led to a decrease of Ethanol synthesis. This trend was confirmed by experimental evaluation of S. stipitis in glucose–xylose fermentation. The oxygen transfer rate for an optimal Ethanol Production was 1.8 mmol/l/h, which gave the Ethanol yield of 0.40 g/g and the Ethanol productivity of 0.25 g/l/h. For a better understanding of the cell’s regulatory mechanism in response to oxygenation levels, EMA was used to examine metabolic flux patterns under different oxygen levels. Up- and downregulation of enzymes in the network during the change of culturing condition from oxygen limitation to oxygen sufficiency were identified. The results indicated the flexibility of S. stipitis metabolism to cope with oxygen availability. In addition, relevant genetic targets towards improved Ethanol-producing strains under all oxygenation levels were identified. These targeted genes limited the metabolic functionality of the cell to function according to the most efficient Ethanol synthesis pathways. The presented approach is promising and can contribute to the development of culture optimization and strain engineers for improved Lignocellulosic Ethanol Production by S. stipitis.

Ola Wallberg - One of the best experts on this subject based on the ideXlab platform.

  • Integrating enzyme fermentation in Lignocellulosic Ethanol Production: life-cycle assessment and techno-economic analysis
    Biotechnology for Biofuels, 2017
    Co-Authors: Johanna Olofsson, Zsolt Barta, Pål Börjesson, Ola Wallberg
    Abstract:

    Cellulase enzymes have been reported to contribute with a significant share of the total costs and greenhouse gas emissions of Lignocellulosic Ethanol Production today. A potential future alternative to purchasing enzymes from an off-site manufacturer is to integrate enzyme and Ethanol Production, using microorganisms and part of the Lignocellulosic material as feedstock for enzymes. This study modelled two such integrated process designs for Ethanol from logging residues from spruce Production, and compared it to an off-site case based on existing data regarding purchased enzymes. Greenhouse gas emissions and primary energy balances were studied in a life-cycle assessment, and cost performance in a techno-economic analysis. The base case scenario suggests that greenhouse gas emissions per MJ of Ethanol could be significantly lower in the integrated cases than in the off-site case. However, the difference between the integrated and off-site cases is reduced with alternative assumptions regarding enzyme dosage and the environmental impact of the purchased enzymes. The comparison of primary energy balances did not show any significant difference between the cases. The minimum Ethanol selling price, to reach break-even costs, was from 0.568 to 0.622 EUR L−1 for the integrated cases, as compared to 0.581 EUR L−1 for the off-site case. An integrated process design could reduce greenhouse gas emissions from lignocellulose-based Ethanol Production, and the cost of an integrated process could be comparable to purchasing enzymes produced off-site. This study focused on the environmental and economic assessment of an integrated process, and in order to strengthen the comparison to the off-site case, more detailed and updated data regarding industrial off-site enzyme Production are especially important.

  • techno economic evaluation of integrated first and second generation Ethanol Production from grain and straw
    Biotechnology for Biofuels, 2016
    Co-Authors: Elisabeth Joelsson, Borbala Erdei, Mats Galbe, Ola Wallberg
    Abstract:

    Background Integration of first- and second-generation Ethanol Production can facilitate the introduction of second-generation Lignocellulosic Ethanol Production. Consolidation of the second-generation with the first-generation process can potentially reduce the downstream processing cost for the second-generation process as well as providing the first-generation process with energy. This study presents novel experimental results from integrated first- and second-generation Ethanol Production from grain and wheat straw in a process development unit. The results were used in techno-economic evaluations to investigate the feasibility of the plant, in which the main co-products were distiller’s dried grains with solubles and biogas.

  • techno economic evaluation of integrated first and second generation Ethanol Production from grain and straw
    Biotechnology for Biofuels, 2016
    Co-Authors: Elisabeth Joelsson, Borbala Erdei, Mats Galbe, Ola Wallberg
    Abstract:

    Integration of first- and second-generation Ethanol Production can facilitate the introduction of second-generation Lignocellulosic Ethanol Production. Consolidation of the second-generation with the first-generation process can potentially reduce the downstream processing cost for the second-generation process as well as providing the first-generation process with energy. This study presents novel experimental results from integrated first- and second-generation Ethanol Production from grain and wheat straw in a process development unit. The results were used in techno-economic evaluations to investigate the feasibility of the plant, in which the main co-products were distiller’s dried grains with solubles and biogas. An overall glucose to Ethanol yield, of 81 % of the theoretical, based on glucose available in the raw material, was achieved in the experiments. A positive net present value was found for all the base case scenarios and the minimal Ethanol selling price varied between 0.45 and 0.53 EUR/L Ethanol. The revenue increased with combined xylose and glucose fermentation and biogas upgrading to vehicle fuel quality. A decrease in the biogas yield from 80 to 60 % also largely affects the net present value. The energy efficiency for the energy content in products available for sale compared with the incoming energy content varied from 74 to 80 %. One of the two main configurations can be chosen when designing an integrated first- and second-generation Ethanol Production plant from grain and straw: that producing biogas or that producing distiller’s dried grains with solubles from the xylose sugars. The choice depends mainly on the local market and prices for distiller’s dried grains with solubles and biogas, since the prices for both co-products have fluctuated a great deal in recent years. In the current study, however, distiller’s dried grains with solubles were found to be a more promising co-product than biogas, if the biogas was not upgraded to vehicle fuel quality. It was also concluded that additional experimental data from biogas Production using first- and second-generation substrates are required to obtain improved economic evaluations.

Wolter Prins - One of the best experts on this subject based on the ideXlab platform.

  • Production and characterization of slow pyrolysis biochar from lignin-rich digested stillage from Lignocellulosic Ethanol Production
    Biomass and Bioenergy, 2019
    Co-Authors: Stef Ghysels, Frederik Ronsse, Dane Dickinson, Wolter Prins
    Abstract:

    Abstract Lignin-rich digested stillage as a novel feedstock for biochar Production was subjected to slow pyrolysis. The lignin residue stemmed from a Lignocellulosic Ethanol pilot run with poplar, from which the stillage was anaerobically digested prior to pyrolysis. Pyrolysis conditions were optimized to meet guidelines put forth by the International Biochar Initiative and the European Biochar Certificate (molar H/Corg ratio 0.7 and O/Corg ratio 0.4 ), as biochar could be carbon-negative upon soil amendment, while reallocating nutrients to the field. Bench-scale pyrolysis of the lignin residue and straw were conducted according to a 33 factorial design with center runs (ranges: 370–450 °C highest treatment temperature, 5–45 min holding time and 5–50 °C.min−1 heating rate). Parametric and nonparametric statistics revealed that the highest treatment temperature was by far the most influencing factor for both feedstocks which ‘pushed’ H/C and O/C ratios within the desired range. Lignin-based biochar can be obtained with 50.7% yield, a H/C ratio of 0.70 and an O/C ratio of 0.20, already at 384 °C. This is considerably better when compared to straw-based biochar with identical H/C and O/C ratios, which came with a lower yield (33.7%) and required a modestly higher temperature (410 °C). Results from this study emphasize the feasibility to integrate slow pyrolysis in a Lignocellulosic biorefinery.

  • Production and characterization of slow pyrolysis biochar from lignin rich digested stillage from Lignocellulosic Ethanol Production
    ISSN: 0961-9534, 2019
    Co-Authors: Stef Ghysels, Frederik Ronsse, Dane Dickinson, Wolter Prins
    Abstract:

    Lignin-rich digested stillage as a novel feedstock for biochar Production was subjected to slow pyrolysis. The lignin residue stemmed from a Lignocellulosic Ethanol pilot run with poplar, from which the stillage was anaerobically digested prior to pyrolysis. Pyrolysis conditions were optimized to meet guidelines put forth by the International Biochar Initiative and the European Biochar Certificate (molar H/C-org ratio and O/C-org ratio <0.4), as biochar could be carbon-negative upon soil amendment, while reallocating nutrients to the field. Bench-scale pyrolysis of the lignin residue and straw were conducted according to a 3(3) factorial design with center runs (ranges: 370-450 degrees C highest treatment temperature, 5-45 min holding time and 5-50 degrees C.min(-1) heating rate). Parametric and nonparametric statistics revealed that the highest treatment temperature was by far the most influencing factor for both feedstocks which 'pushed' H/C and O/C ratios within the desired range. Lignin-based biochar can be obtained with 50.7% yield, a H/C ratio of 0.70 and an O/C ratio of 0.20, already at 384 degrees C. This is considerably better when compared to straw-based biochar with identical H/C and O/C ratios, which came with a lower yield (33.7%) and required a modestly higher temperature (410 degrees C). Results from this study emphasize the feasibility to integrate slow pyrolysis in a Lignocellulosic biorefinery.

Raj Boopathy - One of the best experts on this subject based on the ideXlab platform.

  • evaluation of pretreatment methods for Lignocellulosic Ethanol Production from energy cane variety l 79 1002
    International Biodeterioration & Biodegradation, 2013
    Co-Authors: Sri Harjati V Suhardi, Bijeta Prasai, David Samaha, Raj Boopathy
    Abstract:

    Approximately half of the 80 billion tons of crop produced annually around the world remains as residue that could serve as a renewable resource to produce valuable products such as Ethanol and butanol. Ethanol produced from Lignocellulosic biomass is a promising renewable alternative to diminishing oil and gas liquid fuels. Sugarcane is an important industry in Louisiana. The recently released variety of “energy cane” has great potential to sustain a competitive sugarcane industry. It has been demonstrated that fuel-grade Ethanol can be produced from post harvest sugarcane residue in the past, but optimized Ethanol Production was not achieved. Optimization of the fermentation process requires efficient pretreatment to release cellulose and hemicellulose from Lignocellulosic complex of plant fiber. Determining optimal pretreatment techniques for fermentation is essential for the success of Lignocellulosic Ethanol Production process. The purpose of this study was to evaluate three pretreatment methods for the energy cane variety L 79-1002 for maximum Lignocellulosic Ethanol Production. The pretreatments include alkaline pretreatment, dilute acid hydrolysis, and solid-state fungal pretreatment process using brown rot and white rot fungi. Pretreated biomass was enzymatically saccharified and subjected to fermentation using a recombinant Escherichia coli FBR5. The results revealed that all pretreatment processes produced Ethanol. However, the best result was observed in dilute acid hydrolysis followed by alkaline pretreatment and solid-state fungal pretreatment.

  • combined biological and chemical pretreatment method for Lignocellulosic Ethanol Production from energy cane
    Renewable Bioresources, 2013
    Co-Authors: Sri Harjati V Suhardi, Bijeta Prasai, David Samaha, Raj Boopathy
    Abstract:

    Abstract The process of converting Lignocellulosic biomass to Ethanol involves pretreatment to disrupt the complex of lignin, cellulose, and hemicellulose, freeing cellulose and hemicellulose for enzymatic saccharification and

  • Ethanol Production from Lignocellulosic biomass of energy cane
    International Biodeterioration & Biodegradation, 2011
    Co-Authors: Sara Shields, Raj Boopathy
    Abstract:

    Ethanol produced from Lignocellulosic biomass is a renewable alternative to diminishing petroleum based liquid fuels. The release of many new sugarcane varieties by the United States Department of Agriculture to be used as energy crops is a promising feedstock alternative. Energy cane produces large amounts of biomass that can be easily transported, and Production does not compete with food supply and prices because energy cane can be grown on marginal land instead of land for food crops. The purpose of this study was to evaluate energy cane for Lignocellulosic Ethanol Production. Energy cane variety L 79-1002 was pretreated with weak sulfuric acid to remove lignin. In this study, 1.4 M sulfuric acid pretreated type II energy cane had a higher Ethanol yield after fermentation by Klebsiella oxytoca without enzymatic saccharification than 0.8 M and 1.6 M sulfuric acid pretreated type II energy cane. Pretreated biomass was inoculated with K. oxytoca for cellulose fermentation and Pichia stipitis for hemicellulose fermentation under simultaneous saccahrification and fermentation (SSF) and separate hydrolysis and fermentation (SHF) conditions. For enzymatic saccharification of cellulose, the cellulase and β-glucanase cocktail significantly increased Ethanol Production compared to the Ethanol Production of fermented acid pretreated energy cane without enzymatic saccharification. The results revealed that energy cane variety L 79-1002 produced maximum cellulosic Ethanol under SHF (6995 mg/L) and produced 3624 mg/L Ethanol from fermentation of hemicellulosic sugars.

Lucilia Domingues - One of the best experts on this subject based on the ideXlab platform.

  • xylose fermentation efficiency of industrial saccharomyces cerevisiae yeast with separate or combined xylose reductase xylitol dehydrogenase and xylose isomerase pathways
    Biotechnology for Biofuels, 2019
    Co-Authors: Joana T Cunha, Pedro O Soares, Aloia Romani, Johan M Thevelein, Lucilia Domingues
    Abstract:

    Background Xylose isomerase (XI) and xylose reductase/xylitol dehydrogenase (XR/XDH) pathways have been extensively used to confer xylose assimilation capacity to Saccharomyces cerevisiae and tackle one of the major bottlenecks in the attainment of economically viable Lignocellulosic Ethanol Production. Nevertheless, there is a lack of studies comparing the efficiency of those pathways both separately and combined. In this work, the XI and/or XR/XDH pathways were introduced into two robust industrial S. cerevisiae strains, evaluated in synthetic media and corn cob hemicellulosic hydrolysate and the results were correlated with the differential enzyme activities found in the xylose-pathway engineered strains.

  • xylose fermentation efficiency of industrial saccharomyces cerevisiae yeast with separate or combined xylose reductase xylitol dehydrogenase and xylose isomerase pathways
    Biotechnology for Biofuels, 2019
    Co-Authors: Joana T Cunha, Pedro O Soares, Aloia Romani, Johan M Thevelein, Lucilia Domingues
    Abstract:

    Xylose isomerase (XI) and xylose reductase/xylitol dehydrogenase (XR/XDH) pathways have been extensively used to confer xylose assimilation capacity to Saccharomyces cerevisiae and tackle one of the major bottlenecks in the attainment of economically viable Lignocellulosic Ethanol Production. Nevertheless, there is a lack of studies comparing the efficiency of those pathways both separately and combined. In this work, the XI and/or XR/XDH pathways were introduced into two robust industrial S. cerevisiae strains, evaluated in synthetic media and corn cob hemicellulosic hydrolysate and the results were correlated with the differential enzyme activities found in the xylose-pathway engineered strains. The sole expression of XI was found to increase the fermentative capacity of both strains in synthetic media at 30 °C and 40 °C: decreasing xylitol accumulation and improving xylose consumption and Ethanol Production. Similar results were observed in fermentations of detoxified hydrolysate. However, in the presence of Lignocellulosic-derived inhibitors, a positive synergistic effect resulted from the expression of both XI and XR/XDH, possibly caused by a cofactor equilibrium between the XDH and furan detoxifying enzymes, increasing the Ethanol yield by more than 38%. This study clearly shows an advantage of using the XI from Clostridium phytofermentans to attain high Ethanol productivities and yields from xylose. Furthermore, and for the first time, the simultaneous utilization of XR/XDH and XI pathways was compared to the single expression of XR/XDH or XI and was found to improve Ethanol Production from non-detoxified hemicellulosic hydrolysates. These results extend the knowledge regarding S. cerevisiae xylose assimilation metabolism and pave the way for the construction of more efficient strains for use in Lignocellulosic industrial processes.

  • Xylose fermentation efficiency of industrial Saccharomyces cerevisiae yeast with separate or combined xylose reductase/xylitol dehydrogenase and xylose isomerase pathways
    BMC, 2019
    Co-Authors: Joana T Cunha, Pedro O Soares, Aloia Romani, Johan M Thevelein, Lucilia Domingues
    Abstract:

    Abstract Background Xylose isomerase (XI) and xylose reductase/xylitol dehydrogenase (XR/XDH) pathways have been extensively used to confer xylose assimilation capacity to Saccharomyces cerevisiae and tackle one of the major bottlenecks in the attainment of economically viable Lignocellulosic Ethanol Production. Nevertheless, there is a lack of studies comparing the efficiency of those pathways both separately and combined. In this work, the XI and/or XR/XDH pathways were introduced into two robust industrial S. cerevisiae strains, evaluated in synthetic media and corn cob hemicellulosic hydrolysate and the results were correlated with the differential enzyme activities found in the xylose-pathway engineered strains. Results The sole expression of XI was found to increase the fermentative capacity of both strains in synthetic media at 30 °C and 40 °C: decreasing xylitol accumulation and improving xylose consumption and Ethanol Production. Similar results were observed in fermentations of detoxified hydrolysate. However, in the presence of Lignocellulosic-derived inhibitors, a positive synergistic effect resulted from the expression of both XI and XR/XDH, possibly caused by a cofactor equilibrium between the XDH and furan detoxifying enzymes, increasing the Ethanol yield by more than 38%. Conclusions This study clearly shows an advantage of using the XI from Clostridium phytofermentans to attain high Ethanol productivities and yields from xylose. Furthermore, and for the first time, the simultaneous utilization of XR/XDH and XI pathways was compared to the single expression of XR/XDH or XI and was found to improve Ethanol Production from non-detoxified hemicellulosic hydrolysates. These results extend the knowledge regarding S. cerevisiae xylose assimilation metabolism and pave the way for the construction of more efficient strains for use in Lignocellulosic industrial processes