Processing of Lignocellulosics Feedstocks for Biofuels and Co-products Via Consolidated Bioprocessing with the Thermophilic Bacterium, Clostridium Thermocellum Strain DSMZ 1237 PDF Download
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Author: Valery Agbor
Publisher:
ISBN:
Category :
Languages : en
Pages : 0
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Book Description
Processing of lignocellulosic biomass for transportation fuels and other biocommodities in integrated biorefineries has been proposed as the future for emerging sustainable economies. Currently bioprocessing strategies are all multi-step processes involving extensive physicochemical pretreatments and costly amounts of exogenous enzyme addition. Consolidated bioprocessing (CBP), or direct microbial conversion, is a strategy that combines all the stages of production into one step, thus avoiding the use of expensive pretreatments and exogenous enzymes that reduce the economic viability of the products produced. With a growing trend towards increased consolidation, most of the reported work on CBP has been conducted with soluble sugars or commercial reagent grade cellulose. For CBP to become practical fermentative guidelines with native feedstocks and purified cellulose need to be delineated through specific substrate characterization as it relates to possible industrial fermentation. By carefully reviewing the fundamentals of biomass pretreatments for CBP, a comparative assessment of the fermentability of non-food agricultural residue and processed biomass was conducted with Clostridium thermocellum DSMZ 1237. Cell growth, and both gaseous and liquid fermentation end-product profiles of C. thermocellum as a CBP processing candidate was characterised. Batch fermentation experiments to investigate the effect of cellulose content, pretreatment, and substrate concentration, revealed that higher yields were correlated with higher cellulose content. Pretreatment of native substrates that increased access of the bacterial cells and enzymes to cellulose chains in the biomass substrate were key parameters that determined the overall bioconversion of a given feedstock to end-products. The contribution of amorphous cellulose (CAC) in different biomass substrates subjected to the same pretreatment conditions was identified as a novel factor that contributed to differences in bioconversion and end-product synthesis patterns. Although the overall yield of end products was low following bioaugmentation with exogenous glycosyl hydrolases from free-enzyme systems and cellulosome extracts. Treatment of biomass substrates with glycosyl hydrolase enzymes was observed to increase the rate of bioconversion of native feedstocks in biphasic manner during fermentation with C. thermocellum. A "quotient of accessibility" was identified as a feedstock agnostic guideline for biomass digestibility.
Author: Valery Agbor
Publisher:
ISBN:
Category :
Languages : en
Pages : 0
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Book Description
Processing of lignocellulosic biomass for transportation fuels and other biocommodities in integrated biorefineries has been proposed as the future for emerging sustainable economies. Currently bioprocessing strategies are all multi-step processes involving extensive physicochemical pretreatments and costly amounts of exogenous enzyme addition. Consolidated bioprocessing (CBP), or direct microbial conversion, is a strategy that combines all the stages of production into one step, thus avoiding the use of expensive pretreatments and exogenous enzymes that reduce the economic viability of the products produced. With a growing trend towards increased consolidation, most of the reported work on CBP has been conducted with soluble sugars or commercial reagent grade cellulose. For CBP to become practical fermentative guidelines with native feedstocks and purified cellulose need to be delineated through specific substrate characterization as it relates to possible industrial fermentation. By carefully reviewing the fundamentals of biomass pretreatments for CBP, a comparative assessment of the fermentability of non-food agricultural residue and processed biomass was conducted with Clostridium thermocellum DSMZ 1237. Cell growth, and both gaseous and liquid fermentation end-product profiles of C. thermocellum as a CBP processing candidate was characterised. Batch fermentation experiments to investigate the effect of cellulose content, pretreatment, and substrate concentration, revealed that higher yields were correlated with higher cellulose content. Pretreatment of native substrates that increased access of the bacterial cells and enzymes to cellulose chains in the biomass substrate were key parameters that determined the overall bioconversion of a given feedstock to end-products. The contribution of amorphous cellulose (CAC) in different biomass substrates subjected to the same pretreatment conditions was identified as a novel factor that contributed to differences in bioconversion and end-product synthesis patterns. Although the overall yield of end products was low following bioaugmentation with exogenous glycosyl hydrolases from free-enzyme systems and cellulosome extracts. Treatment of biomass substrates with glycosyl hydrolase enzymes was observed to increase the rate of bioconversion of native feedstocks in biphasic manner during fermentation with C. thermocellum. A "quotient of accessibility" was identified as a feedstock agnostic guideline for biomass digestibility.
Author: Rajesh K. Sani
Publisher: Springer
ISBN: 3319744593
Category : Science
Languages : en
Pages : 313
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Book Description
This book presents a review and in-depth analyses of improved biotechnological processes emphasizing critical aspects and challenges of lignocellulosic biomass conversion into biofuels and value-added products especially using extremophiles and recombinant microorganisms. The book specifically comprises extremophilic production of liquid and gaseous biofuels (bioethanol, biobutanol, biodiesel, biohydrogen, and biogas) as well as value added products (e.g. single cell protein, hydrocarbons, lipids, exopolysaccharides, and polyhydroxyalkanoates). The book also provides the knowledge on how to develop safe, more efficient, sustainable, and economical integrated processes for enhanced conversion of lignocellulosic feedstocks to liquid and gaseous biofuels. Finally the book describes how to perform the techno-economical and life-cycle assessments of new integrated processes involving extremophiles. These modeling exercises are critical in addressing any deficiencies associated with the demonstration of an integrated biofuels and value-added products production process at pilot scale as well as demonstration on the commercialization scale.
Author: Avinash P. Ingle
Publisher: John Wiley & Sons
ISBN: 1119568838
Category : Science
Languages : en
Pages : 407
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Book Description
A text to the advances and development of novel technologies in the production of high-value products from economically viable raw materials Lignocellulosic Biorefining Technologiesis an essential guide to the most recent advances and developments of novel technologies in the production of various high-value products from economically viable raw materials. Written by a team of experts on the topic, the book covers important topics specifically on production of economical and sustainable products such as various biofuels, organic acids, enzymes, biopigments, biosurfactants, etc. The book highlights the important aspects of lignocellulosic biorefining including structure, function, and chemical composition of the plant cell wall and reviews the details about the various components present in the lignocellulosic biomass and their characterizations. The authors explore the various approaches available for processing lignocellulosic biomass into second generation sugars and focus on the possibilities of utilization of lignocellulosic feedstocks for the production of biofuels and biochemicals. Each chapter includes a range of clear, informative tables and figures, and contains relevant references of published articles. This important text: Provides cutting-edge information on the recent developments in lignocellulose biorefinery Reviews production of various economically important and sustainable products, such as biofuels, organic acids, biopigments, and biosurfactants Highlights several broad-ranging areas of recent advances in the utilization of a variety of lignocellulosic feedstocks Provides a valuable, authoritative reference for anyone interested in the topic Written for post-graduate students and researchers in disciplines such as biotechnology, bioengineering, forestry, agriculture, and chemical industry, Lignocellulosic Biorefining Technologies is an authoritative and updated guide to the knowledge about various biorefining technologies.
Author: Jean-Luc Wertz
Publisher: CRC Press
ISBN: 1466573074
Category : Science
Languages : en
Pages : 540
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Book Description
Written with a diverse audience in mind, this book describes the current status, development, and future prospects for the critical technology of second-generation biorefineries, specifically with a focus on lignocellulosic materials as feedstock. It provides an overview of the issues behind this technological transition, and it provides, in depth,
Author: Ninad Dushyant Kothari
Publisher:
ISBN: 9780438429550
Category : Biomass energy
Languages : en
Pages : 246
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Book Description
There is an urgent need to replace petroleum-based transportation fuels with renewable and sustainable fuels to reduce the deteriorating impact of greenhouse gas emissions on climate change. Biofuels would not only provide a sustainable energy source but also help countries reduce their dependence on imported petroleum. Ethanol made from corn starch and cane sugar is presently the largest biotechnology-based product and commands a large share of the alternative fuels market. However, it is important to move towards making ethanol from lignocellulosic biomass that, unlike corn starch and cane sugar, does not have an important alternative use as food. However, biological conversion of this plentiful material suffers from high enzyme costs that stymie competitiveness. Clostridium thermocellum is a multifunctional ethanol producer capable of enzyme production, enzymatic saccharification, and fermentation that is fundamental to the consolidated bioprocessing (CBP) approach of ethanol production from lignocellulosic biomass. CBP eliminates the supplementation of expensive enzymes that are required in the traditional approach of ethanol production. However, the recalcitrance of lignocellulosic biomass is still a hindrance to effective ethanol production. C. thermocellum is unable to achieve complete biomass digestion and sugar release without pretreatment of lignocellulosic biomass. This work focuses on extensive process development for effective integration of CBP with four different thermochemical pretreatments of switchgrass. First, cellulose loading for C. thermocellum flask fermentations was optimized to understand the impacts of substrate structural features on digestion by C. thermocellum under non-inhibitory conditions. Next, the impact of various cellulose properties including, but not limited to, crystallinity, surface area, pore size, and degree of polymerization, was studied on C. thermocellum digestion of model cellulosic substrates compared to fungal enzymatic hydrolysis. With an extensive understanding of C. thermocellum fermentations on model substrates the interdependency of switchgrass structural features with thermochemical and biological digestion was studied. Process configurations to achieve complete cellulose solubilization and total sugar release from switchgrass were finally defined. The comprehensive nature of integration of four different thermochemical and two different biological approaches in this work is unparalleled and could provide a platform to systematically develop cost effective ethanol production from lignocellulosic biomass in the future.
Author: Vincenza Faraco
Publisher: Springer Science & Business Media
ISBN: 3642378617
Category : Science
Languages : en
Pages : 207
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Book Description
Bioethanol has been recognized as a potential alternative to petroleum-derived transportation fuels. Even if cellulosic biomass is less expensive than corn and sugarcane, the higher costs for its conversion make the near-term price of cellulosic ethanol higher than that of corn ethanol and even more than that of sugarcane ethanol. Conventional process for bioethanol production from lignocellulose includes a chemical/physical pre-treatment of lignocellulose for lignin removal, mostly based on auto hydrolysis and acid hydrolysis, followed by saccharification of the free accessible cellulose portions of the biomass. The highest yields of fermentable sugars from cellulose portion are achieved by means of enzymatic hydrolysis, currently carried out using a mix of cellulases from the fungus Trichoderma reesei. Reduction of (hemi)cellulases production costs is strongly required to increase competitiveness of second generation bioethanol production. The final step is the fermentation of sugars obtained from saccharification, typically performed by the yeast Saccharomyces cerevisiae. The current process is optimized for 6-carbon sugars fermentation, since most of yeasts cannot ferment 5-carbon sugars. Thus, research is aimed at exploring new engineered yeasts abilities to co-ferment 5- and 6-carbon sugars. Among the main routes to advance cellulosic ethanol, consolidate bio-processing, namely direct conversion of biomass into ethanol by a genetically modified microbes, holds tremendous potential to reduce ethanol production costs. Finally, the use of all the components of lignocellulose to produce a large spectra of biobased products is another challenge for further improving competitiveness of second generation bioethanol production, developing a biorefinery.
Author: Keikhosro Karimi
Publisher: Springer
ISBN: 3319140337
Category : Technology & Engineering
Languages : en
Pages : 334
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Book Description
This volume provides the technical information required for the production of biofuels and chemicals from lignocellulosic biomass. It starts with a brief overview of the importance, applications, and production processes of different lignocellulosic products. Further chapters review the perspectives of waste-based biofuels and biochemicals; the pretreatment of lignocellulosic biomass for biofuel production; cellulolytic enzyme systems for the hydrolysis of lignocelluloses; and basic and applied aspects of the production of bioethanol, biogas, biohydrogen, and biobutanol from lignocelluloses. This book is recommended for researchers and engineers and particularly students taking biofuel courses at graduate level.
Author: L.R. Lynd
Publisher: Springer
ISBN:
Category : Science
Languages : en
Pages : 176
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Book Description
Author: Trevor Zuroff
Publisher:
ISBN:
Category :
Languages : en
Pages :
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Book Description
Lignocellulose represents an abundant, renewable resource for the production of liquid transportation fuels to fulfill the energy demand of a growing, developing global population. However, the recalcitrant nature of the biomaterial has perplexed scientists for decades; lignocellulosic fuels still cost two to five times more to produce than their petroleum-derived counterparts. A novel class of bioprocess designs are necessary to overcome the costs associated with conversion of this obstinate feedstock. An intensified processing scheme, termed consolidated bioprocessing, was touted as an economically feasible bioprocessing strategy where consolidation of processing steps was thought to enhance both process and economic efficiencies. Yet no single organism has been discovered or engineered that is capable of efficient consolidated bioprocessing. On the other hand, nature executes what may be the ultimate consolidated bioprocess through conversion of plant material to carbon dioxide and methane as part of the global carbon cycle. The concerted action of numerous naturally-occurring microorganisms overcomes many of the issues encountered in industrial, single-organism lignocellulose bioprocessing. In this dissertation, based on a nature-inspired design, a two-member microbial consortium was developed for the conversion of cellulose to fuel. Cooperation is induced between the cellulolytic, anaerobic bacterium Clostridium phytofermentans and Saccharomyces cerevisiae via oxygen diffusion, controlling consortium populations and promoting fuel production. S. cerevisiae consumes oxygen to protect C. phytofermentans which in return degrades cellulose providing soluble carbon for the yeast. This symbiotic design improves ethanol and/or hydrocarbon production from purified cellulose over two-fold. Detailed analyses of C. phytofermentans biofilm formation and fermentation characteristics revealed that glucose and ethanol are robust inhibitors of C. phytofermentans surface attachment and growth, respectively. Ethanol tolerance was improved via strain evolution and metabolic engineering was applied to overcome an adaptive reduction in ethanol yield. Finally, a comprehensive mathematical framework was developed to model the consortium and provide insight into the intricate cooperation toward improving system productivity. In summary, inspired by naturally occurring microbial ecosystems, this dissertation describes the application of scientific and engineering principles to improve the viability of microbial consortia for industrial-scale conversion of lignocellulosic biomass to fuel.
Author: Alan Froese
Publisher:
ISBN:
Category :
Languages : en
Pages : 0
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Book Description
Alternative low-carbon transportation fuels, such as biofuels, are needed to replace or supplement fossil fuels in order to lower global greenhouse gas emissions and combat climate change. Lignocellulosic biofuels have relatively low carbon emissions and are created using the non-food parts of crops and other plants, such as the leaves and stems, which are comprised mostly of a tough material called lignocellulose, composed of cellulose, hemicellulose, and lignin. One of the best lignocellulose degraders found in nature that is also capable of fermenting the released sugars to ethanol is Clostridium thermocellum, although improvements in both lignocellulose hydrolysis extent and ethanol yields are needed for commercial viability. C. thermocellum, considered a cellulose-degrading specialist, was co-cultured with two different hemicellulose-specialists, C. stercorarium and Thermoanaerobacter thermohydrosulfuricus. The hypothesis was that the co-cultures might degrade more lignocellulose owing to the additional hydrolytic enzymes supplied by the partners and their ability to uptake the inhibitory hemicellulose sugars. All co-culture combinations were found to solubilize more wheat straw, among other lignocellulose materials, and produce more end-products, including ethanol, than C. thermocellum alone. These co-cultures were stable over multiple serial passages, on either wheat straw or pure cellulose, although some evidence of carbon competition was observed. The tri-culture was successfully used to screen the digestibility of various lignocellulose materials, revealing substantial difference between cattail harvested in different seasons. Cross-feeding of vital growth factors was observed between the various co-culture members in a defined medium. The metabolism of C. thermocellum is atypical compared to many organisms, including the absence of a pyruvate kinase, and its substitution with both a malate shunt and a putative pyruvate phosphate dikinase (PPDK), which may act to increase net ATP yields from glycolysis. The PPDK was cloned into E. coli, expressed, purified, and characterized, confirming its function as a PPDK for glycolysis and revealing strong activation by ammonium. The kinetic characterization of the PPDK will help inform future studies that measure and model levels of important intracellular metabolites, such as pyrophosphate and ammonium, to better understand the metabolism of C. thermocellum and allow further metabolic engineering to increase ethanol yields.
