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Sample records for multiple lignocellulosic pretreatment

  1. Method for pretreating lignocellulosic biomass

    SciTech Connect

    Kuzhiyil, Najeeb M.; Brown, Robert C.; Dalluge, Dustin Lee

    2015-08-18

    The present invention relates to a method for pretreating lignocellulosic biomass containing alkali and/or alkaline earth metal (AAEM). The method comprises providing a lignocellulosic biomass containing AAEM; determining the amount of the AAEM present in the lignocellulosic biomass; identifying, based on said determining, the amount of a mineral acid sufficient to completely convert the AAEM in the lignocellulosic biomass to thermally-stable, catalytically-inert salts; and treating the lignocellulosic biomass with the identified amount of the mineral acid, wherein the treated lignocellulosic biomass contains thermally-stable, catalytically inert AAEM salts.

  2. Fungal pretreatment of lignocellulosic biomass.

    PubMed

    Wan, Caixia; Li, Yebo

    2012-01-01

    Pretreatment is a crucial step in the conversion of lignocellulosic biomass to fermentable sugars and biofuels. Compared to thermal/chemical pretreatment, fungal pretreatment reduces the recalcitrance of lignocellulosic biomass by lignin-degrading microorganisms and thus potentially provides an environmentally-friendly and energy-efficient pretreatment technology for biofuel production. This paper provides an overview of the current state of fungal pretreatment by white rot fungi for biofuel production. The specific topics discussed are: 1) enzymes involved in biodegradation during the fungal pretreatment; 2) operating parameters governing performance of the fungal pretreatment; 3) the effect of fungal pretreatment on enzymatic hydrolysis and ethanol production; 4) efforts for improving enzymatic hydrolysis and ethanol production through combinations of fungal pretreatment and physical/chemical pretreatment; 5) the treatment of lignocellulosic biomass with lignin-degrading enzymes isolated from fungal pretreatment, with a comparison to fungal pretreatment; 6) modeling, reactor design, and scale-up of solid state fungal pretreatment; and 7) the limitations and future perspective of this technology.

  3. The Zymomonas mobilis regulator hfq contributes to tolerance against multiple lignocellulosic pretreatment inhibitors.

    PubMed

    Yang, Shihui; Pelletier, Dale A; Lu, Tse-Yuan S; Brown, Steven D

    2010-05-07

    Zymomonas mobilis produces near theoretical yields of ethanol and recombinant strains are candidate industrial microorganisms. To date, few studies have examined its responses to various stresses at the gene level. Hfq is a conserved bacterial member of the Sm-like family of RNA-binding proteins, coordinating a broad array of responses including multiple stress responses. In a previous study, we observed Z. mobilis ZM4 gene ZMO0347 showed higher expression under anaerobic, stationary phase compared to that of aerobic, stationary conditions. We generated a Z. mobilis hfq insertion mutant AcRIM0347 in an acetate tolerant strain (AcR) background and investigated its role in model lignocellulosic pretreatment inhibitors including acetate, vanillin, furfural and hydroxymethylfurfural (HMF). Saccharomyces cerevisiae Lsm protein (Hfq homologue) mutants and Lsm protein overexpression strains were also assayed for their inhibitor phenotypes. Our results indicated that all the pretreatment inhibitors tested in this study had a detrimental effect on both Z. mobilis and S. cerevisiae, and vanillin had the most inhibitory effect followed by furfural and then HMF for both Z. mobilis and S. cerevisiae. AcRIM0347 was more sensitive than the parental strain to the inhibitors and had an increased lag phase duration and/or slower growth depending upon the conditions. The hfq mutation in AcRIM0347 was complemented partially by trans-acting hfq gene expression. We also assayed growth phenotypes for S. cerevisiae Lsm protein mutant and overexpression phenotypes. Lsm1, 6, and 7 mutants showed reduced tolerance to acetate and other pretreatment inhibitors. S. cerevisiae Lsm protein overexpression strains showed increased acetate and HMF resistance as compared to the wild-type, while the overexpression strains showed greater inhibition under vanillin stress conditions. We have shown the utility of the pKNOCK suicide plasmid for mutant construction in Z. mobilis, and constructed a Gateway

  4. Lignocellulosic Biomass Pretreatment Using AFEX

    NASA Astrophysics Data System (ADS)

    Balan, Venkatesh; Bals, Bryan; Chundawat, Shishir P. S.; Marshall, Derek; Dale, Bruce E.

    Although cellulose is the most abundant organic molecule, its susceptibility to hydrolysis is restricted due to the rigid lignin and hemicellulose protection surrounding the cellulose micro fibrils. Therefore, an effective pretreatment is necessary to liberate the cellulose from the lignin-hemicellulose seal and also reduce cellulosic crystallinity. Some of the available pretreatment techniques include acid hydrolysis, steam explosion, ammonia fiber expansion (AFEX), alkaline wet oxidation, and hot water pretreatment. Besides reducing lignocellulosic recalcitrance, an ideal pretreatment must also minimize formation of degradation products that inhibit subsequent hydrolysis and fermentation. AFEX is an important pretreatment technology that utilizes both physical (high temperature and pressure) and chemical (ammonia) processes to achieve effective pretreatment. Besides increasing the surface accessibility for hydrolysis, AFEX promotes cellulose decrystallization and partial hemicellulose depolymerization and reduces the lignin recalcitrance in the treated biomass. Theoretical glucose yield upon optimal enzymatic hydrolysis on AFEX-treated corn stover is approximately 98%. Furthermore, AFEX offers several unique advantages over other pretreatments, which include near complete recovery of the pretreatment chemical (ammonia), nutrient addition for microbial growth through the remaining ammonia on pretreated biomass, and not requiring a washing step during the process which facilitates high solid loading hydrolysis. This chapter provides a detailed practical procedure to perform AFEX, design the reactor, determine the mass balances, and conduct the process safely.

  5. Lignocellulosic biomass pretreatment using AFEX.

    PubMed

    Balan, Venkatesh; Bals, Bryan; Chundawat, Shishir P S; Marshall, Derek; Dale, Bruce E

    2009-01-01

    Although cellulose is the most abundant organic molecule, its susceptibility to hydrolysis is restricted due to the rigid lignin and hemicellulose protection surrounding the cellulose micro fibrils. Therefore, an effective pretreatment is necessary to liberate the cellulose from the lignin-hemicellulose seal and also reduce cellulosic crystallinity. Some of the available pretreatment techniques include acid hydrolysis, steam explosion, ammonia fiber expansion (AFEX), alkaline wet oxidation, and hot water pretreatment. Besides reducing lignocellulosic recalcitrance, an ideal pretreatment must also minimize formation of degradation products that inhibit subsequent hydrolysis and fermentation. AFEX is an important pretreatment technology that utilizes both physical (high temperature and pressure) and chemical (ammonia) processes to achieve effective pretreatment. Besides increasing the surface accessibility for hydrolysis, AFEX promotes cellulose decrystallization and partial hemicellulose depolymerization and reduces the lignin recalcitrance in the treated biomass. Theoretical glucose yield upon optimal enzymatic hydrolysis on AFEX-treated corn stover is approximately 98%. Furthermore, AFEX offers several unique advantages over other pretreatments, which include near complete recovery of the pretreatment chemical (ammonia), nutrient addition for microbial growth through the remaining ammonia on pretreated biomass, and not requiring a washing step during the process which facilitates high solid loading hydrolysis. This chapter provides a detailed practical procedure to perform AFEX, design the reactor, determine the mass balances, and conduct the process safely.

  6. Lime pretreatment of lignocellulosic biomass

    NASA Astrophysics Data System (ADS)

    Chang, Shushien

    Lignocellulose is a valuable alternative energy source. The susceptibility of lignocellulosic biomass to enzymatic hydrolysis is constrained due to its structural features, so pretreatment is essential to enhance enzymatic digestibility. Of the chemicals used as pretreatment agents, it has been reported that alkalis improve biomass digestibility significantly. In comparison with other alkalis such as NaOH and ammonia, lime (calcium hydroxide) has many advantages; it is very inexpensive, is safe, and can be recovered by carbonating wash water. The effects of lime pretreatment were explored on switchgrass and poplar wood, representing herbaceous and woody biomass, respectively. The effects of pretreatment conditions (time, temperature, lime loading, water loading, particle size, and oxygen pressure) have been systematically studies. Lime alone enhances the digestibility of switchgrass significantly; under the recommended conditions, the 3-d total sugar (glucose + xylose) yields of lime-treated switchgrass were 7 times that of untreated sample. When treating poplar wood, lime must be combined with oxygen to achieve high digestibility; oxidative lime pretreatment increased the 3-d total sugar yield of poplar wood to 12 times that of untreated sample. In a fundamental study, to determine why lime pretreatment is effective, the effects of three structural features on enzymatic digestibility were studied: lignin content, acetyl content, and crystallinity index (CrI). Poplar wood was treated with peracetic acid, potassium hydroxide, and ball milling to produce model lignocelluloses with a broad spectrum of lignin contents, acetyl contents, and CrI, respectively. Enzymatic hydrolysis was performed on the model lignocelluloses to determine the digestibility. Correlations between lignin/carbohydrate ratio, acetyl/carbohydrate ratio, CrI and digestibility were developed. The 95% prediction intervals show that the correlations predict the 1-h and 3-d total sugar conversions of

  7. The Zymomonas mobilis regulator hfq contributes to tolerance against multiple lignocellulosic pretreatment inhibitors

    SciTech Connect

    Yang, Shihui; Pelletier, Dale A; Lu, Tse-Yuan; Brown, Steven D

    2010-01-01

    Zymomonas mobilis produces near theoretical yields of ethanol and recombinant strains are candidate industrial microorganisms. To date, few studies have examined its responses to various stresses at the gene level. Hfq is a conserved bacterial member of the Sm-like family of RNA-binding proteins, coordinating a broad array of responses including multiple stress responses. In a previous study, we observed Z. mobilis ZM4 gene ZMO0347 showed higher expression under anaerobic, stationary phase compared to that of aerobic, stationary conditions. We have shown the utility of the pKNOCK suicide plasmid for mutant construction in Z. mobilis, and constructed a Gateway compatible expression plasmid for use in Z. mobilis for the first time. We have also used genetics to show Z. mobilis Hfq and S. cerevisiae Lsm proteins play important roles in resisting multiple, important industrially relevant inhibitors. The conserved nature of this global regulator offers the potential to apply insights from these fundamental studies for further industrial strain development.

  8. Pretreatment of lignocellulosic biomass using Fenton chemistry

    USDA-ARS?s Scientific Manuscript database

    Pretreatment is a necessary step in “biomass to biofuel conversion” due to the recalcitrant nature of lignocellulosic biomass. White-rot fungi utilize peroxidases and hydrogen peroxide (in vivo Fenton chemistry) to degrade lignin. In an attempt to mimic this process, solution phase Fenton chemistry ...

  9. Cellulose pretreatments of lignocellulosic substrates

    NASA Technical Reports Server (NTRS)

    Weil, J.; Westgate, P.; Kohlmann, K.; Ladisch, M. R.; Mitchell, C. A. (Principal Investigator)

    1994-01-01

    Cellulose in inedible plant materials, forestry residues, and municipal wastes must be pretreated to disrupt its physical structure, thereby making its hydrolysis to glucose practical. Developments since 1991 are summarized.

  10. Cellulose pretreatments of lignocellulosic substrates

    NASA Technical Reports Server (NTRS)

    Weil, J.; Westgate, P.; Kohlmann, K.; Ladisch, M. R.; Mitchell, C. A. (Principal Investigator)

    1994-01-01

    Cellulose in inedible plant materials, forestry residues, and municipal wastes must be pretreated to disrupt its physical structure, thereby making its hydrolysis to glucose practical. Developments since 1991 are summarized.

  11. Extrusion Pretreatment of Lignocellulosic Biomass: A Review

    PubMed Central

    Zheng, Jun; Rehmann, Lars

    2014-01-01

    Bioconversion of lignocellulosic biomass to bioethanol has shown environmental, economic and energetic advantages in comparison to bioethanol produced from sugar or starch. However, the pretreatment process for increasing the enzymatic accessibility and improving the digestibility of cellulose is hindered by many physical-chemical, structural and compositional factors, which make these materials difficult to be used as feedstocks for ethanol production. A wide range of pretreatment methods has been developed to alter or remove structural and compositional impediments to (enzymatic) hydrolysis over the last few decades; however, only a few of them can be used at commercial scale due to economic feasibility. This paper will give an overview of extrusion pretreatment for bioethanol production with a special focus on twin-screw extruders. An economic assessment of this pretreatment is also discussed to determine its feasibility for future industrial cellulosic ethanol plant designs. PMID:25334065

  12. Pretreatments to enhance the digestibility of lignocellulosic biomass.

    PubMed

    Hendriks, A T W M; Zeeman, G

    2009-01-01

    Lignocellulosic biomass represents a rather unused source for biogas and ethanol production. Many factors, like lignin content, crystallinity of cellulose, and particle size, limit the digestibility of the hemicellulose and cellulose present in the lignocellulosic biomass. Pretreatments have as a goal to improve the digestibility of the lignocellulosic biomass. Each pretreatment has its own effect(s) on the cellulose, hemicellulose and lignin; the three main components of lignocellulosic biomass. This paper reviews the different effect(s) of several pretreatments on the three main parts of the lignocellulosic biomass to improve its digestibility. Steam pretreatment, lime pretreatment, liquid hot water pretreatments and ammonia based pretreatments are concluded to be pretreatments with high potentials. The main effects are dissolving hemicellulose and alteration of lignin structure, providing an improved accessibility of the cellulose for hydrolytic enzymes.

  13. 'Cradle-to-grave' assessment of existing lignocellulose pretreatment technologies.

    PubMed

    da Costa Sousa, Leonardo; Chundawat, Shishir P S; Balan, Venkatesh; Dale, Bruce E

    2009-06-01

    Pretreatment is considered to be a central unit process in a biorefinery to convert lignocellulosic biomass into fuels and chemicals, affecting all other operations in the process. A variety of technologies to pretreat lignocellulosic biomass are available today, which encompass a wide range of physical, chemical, and biological based processes. Among these, chemical based pretreatments are considered to be the most promising for future biorefineries. However, several key criteria regarding technical, economical, and environmental considerations should be critically analyzed when adapting these technologies for the nascent biorefinery industry. This review will discuss the most important pretreatment methods available today and will highlight key criteria for the development of a future ideal pretreatment.

  14. Evaluation of four ionic liquids for pretreatment of lignocellulosic biomass

    PubMed Central

    2014-01-01

    Background Lignocellulosic biomass is highly recalcitrant and various pretreatment techniques are needed to facilitate its effective enzymatic hydrolysis to produce sugars for further conversion to bio-based chemicals. Ionic liquids (ILs) are of interest in pretreatment because of their potential to dissolve lignocellulosic materials including crystalline cellulose. Results Four imidazolium-based ionic liquids (ILs) ([C=C2C1im][MeCO2], [C4C1im][MeCO2], [C4C1im][Cl], and [C4C1im][HSO4]) well known for their capability to dissolve lignocellulosic species were synthesized and then used for pretreatment of substrates prior to enzymatic hydrolysis. In order to achieve a broad evaluation, seven cellulosic, hemicellulosic and lignocellulosic substrates, crystalline as well as amorphous, were selected. The lignocellulosic substrates included hybrid aspen and Norway spruce. The monosaccharides in the enzymatic hydrolysate were determined using high-performance anion-exchange chromatography. The best results, as judged by the saccharification efficiency, were achieved with [C4C1im][Cl] for cellulosic substrates and with the acetate-based ILs for hybrid aspen and Norway spruce. After pretreatment with acetate-based ILs, the conversion to glucose of glucan in recalcitrant softwood lignocellulose reached similar levels as obtained with pure crystalline and amorphous cellulosic substrates. IL pretreatment of lignocellulose resulted in sugar yields comparable with that obtained with acidic pretreatment. Heterogeneous dissolution with [C4C1im][HSO4] gave promising results with aspen, the less recalcitrant of the two types of lignocellulose included in the investigation. Conclusions The ability of ILs to dissolve lignocellulosic biomass under gentle conditions and with little or no by-product formation contributes to making them highly interesting alternatives for pretreatment in processes where high product yields are of critical importance. PMID:24779378

  15. Green methods of lignocellulose pretreatment for biorefinery development.

    PubMed

    Capolupo, Laura; Faraco, Vincenza

    2016-11-01

    Lignocellulosic biomass is the most abundant, low-cost, bio-renewable resource that holds enormous importance as alternative source for production of biofuels and other biochemicals that can be utilized as building blocks for production of new materials. Enzymatic hydrolysis is an essential step involved in the bioconversion of lignocellulose to produce fermentable monosaccharides. However, to allow the enzymatic hydrolysis, a pretreatment step is needed in order to remove the lignin barrier and break down the crystalline structure of cellulose. The present manuscript is dedicated to reviewing the most commonly applied "green" pretreatment processes used in bioconversion of lignocellulosic biomasses within the "biorefinery" concept. In this frame, the effects of different pretreatment methods on lignocellulosic biomass are described along with an in-depth discussion on the benefits and drawbacks of each method, including generation of potentially inhibitory compounds for enzymatic hydrolysis, effect on cellulose digestibility, and generation of compounds toxic for the environment, and energy and economic demand.

  16. Processes for pretreating lignocellulosic biomass: A review

    SciTech Connect

    McMillan, J D

    1992-11-01

    This paper reviews existing and proposed pretreatment processes for biomass. The focus is on the mechanisms by which the various pretreatments act and the influence of biomass structure and composition on the efficacy of particular pretreatment techniques. This analysis is used to identify pretreatment technologies and issues that warrant further research.

  17. Processes for pretreating lignocellulosic biomass: A review

    SciTech Connect

    McMillan, J.D.

    1992-11-01

    This paper reviews existing and proposed pretreatment processes for biomass. The focus is on the mechanisms by which the various pretreatments act and the influence of biomass structure and composition on the efficacy of particular pretreatment techniques. This analysis is used to identify pretreatment technologies and issues that warrant further research.

  18. Lignocellulosic Biomass Pretreatment: A Key to Its Successful Bioconversion to Fuel Ethanol

    USDA-ARS?s Scientific Manuscript database

    Native lignocellulosic biomass is very resistant to degradation by enzymes. Prior pretreatment is essential for efficient conversion of lignocellulosic feedstock to ethanol. In this presentation, various pretreatment options such as dilute acid, alkali, alkaline peroxide, wet oxidation, steam expl...

  19. Harnessing the potential of ligninolytic enzymes for lignocellulosic biomass pretreatment.

    PubMed

    Masran, Ruqayyah; Zanirun, Zuraidah; Bahrin, Ezyana Kamal; Ibrahim, Mohamad Faizal; Lai Yee, Phang; Abd-Aziz, Suraini

    2016-06-01

    Abundant lignocellulosic biomass from various industries provides a great potential feedstock for the production of value-added products such as biofuel, animal feed, and paper pulping. However, low yield of sugar obtained from lignocellulosic hydrolysate is usually due to the presence of lignin that acts as a protective barrier for cellulose and thus restricts the accessibility of the enzyme to work on the cellulosic component. This review focuses on the significance of biological pretreatment specifically using ligninolytic enzymes as an alternative method apart from the conventional physical and chemical pretreatment. Different modes of biological pretreatment are discussed in this paper which is based on (i) fungal pretreatment where fungi mycelia colonise and directly attack the substrate by releasing ligninolytic enzymes and (ii) enzymatic pretreatment using ligninolytic enzymes to counter the drawbacks of fungal pretreatment. This review also discusses the important factors of biological pretreatment using ligninolytic enzymes such as nature of the lignocellulosic biomass, pH, temperature, presence of mediator, oxygen, and surfactant during the biodelignification process.

  20. Methods for producing extracted and digested products from pretreated lignocellulosic biomass

    DOEpatents

    Chundawat, Shishir; Sousa, Leonardo Da Costa; Cheh, Albert M.; Balan; , Venkatesh; Dale, Bruce

    2017-05-16

    Methods for producing extracted and digested products from pretreated lignocellulosic biomass are provided. The methods include converting native cellulose I.sub..beta. to cellulose III.sub.I by pretreating the lignocellulosic biomass with liquid ammonia under certain conditions, and performing extracting or digesting steps on the pretreated/converted lignocellulosic biomass.

  1. The role of pretreatment in improving the enzymatic hydrolysis of lignocellulosic materials.

    PubMed

    Sun, Shaoni; Sun, Shaolong; Cao, Xuefei; Sun, Runcang

    2016-01-01

    Lignocellulosic materials are among the most promising alternative energy resources that can be utilized to produce cellulosic ethanol. However, the physical and chemical structure of lignocellulosic materials forms strong native recalcitrance and results in relatively low yield of ethanol from raw lignocellulosic materials. An appropriate pretreatment method is required to overcome this recalcitrance. For decades various pretreatment processes have been developed to improve the digestibility of lignocellulosic biomass. Each pretreatment process has a different specificity on altering the physical and chemical structure of lignocellulosic materials. In this paper, the chemical structure of lignocellulosic biomass and factors likely affect the digestibility of lignocellulosic materials are discussed, and then an overview about the most important pretreatment processes available are provided. In particular, the combined pretreatment strategies are reviewed for improving the enzymatic hydrolysis of lignocellulose and realizing the comprehensive utilization of lignocellulosic materials. Copyright © 2015 Elsevier Ltd. All rights reserved.

  2. Understanding Ionic Liquid Pretreatment of Lignocellulosic Biomasses

    USDA-ARS?s Scientific Manuscript database

    Pretreatment of biomass is essential for breaking apart highly ordered and crystalline plant cell walls and loosening the lignin and hemicellulose conjugation to cellulose microfibrills, thereby facilitating enzyme accessibility and adsorption and reducing costs of downstream saccharification proces...

  3. Ferric chloride assisted plasma pretreatment of lignocellulose.

    PubMed

    Ravindran, Rajeev; Sarangapani, Chaitanya; Jaiswal, Swarna; Cullen, P J; Jaiswal, Amit K

    2017-06-26

    In this study, a novel pretreatment for spent coffee waste (SCW) has been proposed which combines two techniques viz. atmospheric air plasma and FeCl3 to create a superior pretreatment that involves Fenton chemistry. The pretreatment was optimised employing Taguchi Design of Experiments, and five parameters were taken into consideration viz. biomass loading, FeCl3 concentration, H2SO4 concentration, plasma discharge voltage and treatment time. The composition analysis of the pretreated SCW revealed substantial amounts of lignin removal, with a maximum for process conditions of 70kV for 2min in an acidic environment containing 1% H2SO4. FTIR, XRD and DSC were performed to characterise the samples. The pretreated SCW after enzymatic hydrolysis yielded 0.496g of reducing sugar/g of SCW. The hydrolysate was subjected to fermentation by S. cerevisiae and led to the production of 18.642g/l of ethanol with a fermentation efficiency of 74%, which was a two fold increase in yield compared to the control. Copyright © 2017 Elsevier Ltd. All rights reserved.

  4. Conversion of lignocellulosics pretreated with liquid hot water to ethanol

    SciTech Connect

    Walsum, G.P. van; Laser, M.S.; Lynd, L.R.

    1996-12-31

    Lignocellulosic materials pretreated using liquid hot water (LHW) (220{degrees}C, 5 MPa, 120 s) were fermented to ethanol by batch simultaneous saccharification and fermentation (SSF) using Saccharomyces cerevisiae in the presence of Trichoderma reesei cellulose. SSF of sugarcane bagasse (as received), aspen chips (smallest dimension 3 mm), and mixed hardwood flour (-60 +70 mesh) resulted in 90% conversion to ethanol in 2-5 d at enzyme loadings of 15-30 FPU/g. In most cases, 90% of the final conversion was achieved within 75 h of inoculation. Comminution of the pretreated substrates did not affect the conversion to ethanol. The hydrolysate produced from the LHW pretreatment showed slight inhibition of batch growth of S. cerevisiae. Solids pretreated at a concentration of 100 g/L were as reactive as those pretreated at a lower concentration, provided that the temperature was maintained at 220{degrees}C. 51 refs., 3 figs., 4 tabs.

  5. Facile pretreatment of lignocellulosic biomass using deep eutectic solvents.

    PubMed

    Zhang, Cheng-Wu; Xia, Shu-Qian; Ma, Pei-Sheng

    2016-11-01

    In this work, three kinds of deep eutectic solvents (DESs) were facilely prepared and used in the pretreatment of corncob, including monocarboxylic acid/choline chloride, dicarboxylic acid/choline chloride and polyalcohol/choline chloride. The enhanced delignification and subsequent enzymatic hydrolysis efficiency were found to be related to the acid amount, acid strength and the nature of hydrogen bond acceptors. The XRD, SEM and FT-IR results consistently indicated that the structures of corncob were disrupted by the removal of lignin and hemicellulose in the pretreatment process. In addition, the optimal pretreatment temperature and time were 90°C and 24h, respectively. This study explored the roles of various DESs combinations, pretreatment temperature and time to better utilize the DESs in the pretreatment of lignocellulosic biomass. Copyright © 2016 Elsevier Ltd. All rights reserved.

  6. Physiochemical characterization of lignocellulosic biomass dissolution by flowthrough pretreatment

    DOE PAGES

    Yan, Lishi; Pu, Yunqiao; Bowden, Mark; ...

    2015-11-24

    In this study, comprehensive understanding of biomass solubilization chemistry in aqueous pretreatment such as water-only and dilute acid flowthrough pretreatment is of fundamental importance to achieve the goal of valorizing biomass to fermentable sugars and lignin for biofuels production. In this study, poplar wood was flowthrough pretreated by water-only or 0.05% (w/w) sulfuric acid at different temperatures (220–270 °C), flow rate (25 mL/min), and reaction times (8–90 min), resulting in significant disruption of the lignocellulosic biomass. Ion chromatography (IC), Fourier transform infrared (FTIR) spectroscopy, X-ray diffraction (XRD) analysis, and solid state cross-polarization/magic angle spinning (CP/MAS) 13C nuclear magnetic resonance (NMR)more » spectroscopy were applied to characterize the pretreated biomass whole slurries in order to reveal depolymerization as well as solubilization mechanism and identify unique dissolution structural features during these pretreatments. Results showed temperature-dependent cellulose decrystallization in flowthrough pretreatment. Crystalline cellulose was completely disrupted, and mostly converted to amorphous cellulose and oligomers by water-only operation at 270 °C for 10 min and by 0.05 wt % H2SO4 flowthrough pretreatment at 220 °C for 12 min. Flowthrough pretreatment with 0.05% (w/w) H2SO4 led to a greater disruption of structures in pretreated poplar at a lower temperature compared to water-only pretreatment.« less

  7. Reactors for High Solid Loading Pretreatment of Lignocellulosic Biomass.

    PubMed

    Zhang, Jian; Hou, Weiliang; Bao, Jie

    2016-01-01

    The review summarized the types, the geometry, and the design principle of pretreatment reactors at high solid loading of lignocellulose material. Among the reactors used, the explosion reactors and the helical stirring reactors are to be considered as the practical form for high solids loading pretreatment operation; the comminution reactors and the extruder reactors are difficult to be used as an independent unit, but possible to be used in the combined form with other types of reactors. The principles of the pretreatment reactor design at high solid loading were discussed and several basic principles for the design were proposed. This review provided useful information for choosing the reactor types and designing the geometry of pretreatment operation at the high solids loading.

  8. Pretreatment and enzymatic hydrolysis of lignocellulosic biomass

    NASA Astrophysics Data System (ADS)

    Corredor, Deisy Y.

    The performance of soybean hulls and forage sorghum as feedstocks for ethanol production was studied. The main goal of this research was to increase fermentable sugars' yield through high-efficiency pretreatment technology. Soybean hulls are a potential feedstock for production of bio-ethanol due to their high carbohydrate content (≈50%) of nearly 37% cellulose. Soybean hulls could be the ideal feedstock for fuel ethanol production, because they are abundant and require no special harvesting and additional transportation costs as they are already in the plant. Dilute acid and modified steam-explosion were used as pretreatment technologies to increase fermentable sugars yields. Effects of reaction time, temperature, acid concentration and type of acid on hydrolysis of hemicellulose in soybean hulls and total sugar yields were studied. Optimum pretreatment parameters and enzymatic hydrolysis conditions for converting soybean hulls into fermentable sugars were identified. The combination of acid (H2SO4, 2% w/v) and steam (140°C, 30 min) efficiently solubilized the hemicellulose, giving a pentose yield of 96%. Sorghum is a tropical grass grown primarily in semiarid and dry parts of the world, especially in areas too dry for corn. The production of sorghum results in about 30 million tons of byproducts mainly composed of cellulose, hemicellulose, and lignin. Forage sorghum such as brown midrib (BMR) sorghum for ethanol production has generated much interest since this trait is characterized genetically by lower lignin concentrations in the plant compared with conventional types. Three varieties of forage sorghum and one variety of regular sorghum were characterized and evaluated as feedstock for fermentable sugar production. Fourier transform infrared spectroscopy (FTIR), scanning electron microscope (SEM) and X-Ray diffraction were used to determine changes in structure and chemical composition of forage sorghum before and after pretreatment and enzymatic hydrolysis

  9. Pretreatment methods of lignocellulosic biomass for anaerobic digestion.

    PubMed

    Amin, Farrukh Raza; Khalid, Habiba; Zhang, Han; Rahman, Sajid U; Zhang, Ruihong; Liu, Guangqing; Chen, Chang

    2017-12-01

    Agricultural residues, such as lignocellulosic materials (LM), are the most attractive renewable bioenergy sources and are abundantly found in nature. Anaerobic digestion has been extensively studied for the effective utilization of LM for biogas production. Experimental investigation of physiochemical changes that occur during pretreatment is needed for developing mechanistic and effective models that can be employed for the rational design of pretreatment processes. Various-cutting edge pretreatment technologies (physical, chemical and biological) are being tested on the pilot scale. These different pretreatment methods are widely described in this paper, among them, microaerobic pretreatment (MP) has gained attention as a potential pretreatment method for the degradation of LM, which just requires a limited amount of oxygen (or air) supplied directly during the pretreatment step. MP involves microbial communities under mild conditions (temperature and pressure), uses fewer enzymes and less energy for methane production, and is probably the most promising and environmentally friendly technique in the long run. Moreover, it is technically and economically feasible to use microorganisms instead of expensive chemicals, biological enzymes or mechanical equipment. The information provided in this paper, will endow readers with the background knowledge necessary for finding a promising solution to methane production.

  10. Chemical and physicochemical pretreatment of lignocellulosic biomass: a review.

    PubMed

    Brodeur, Gary; Yau, Elizabeth; Badal, Kimberly; Collier, John; Ramachandran, K B; Ramakrishnan, Subramanian

    2011-01-01

    Overcoming the recalcitrance (resistance of plant cell walls to deconstruction) of lignocellulosic biomass is a key step in the production of fuels and chemicals. The recalcitrance is due to the highly crystalline structure of cellulose which is embedded in a matrix of polymers-lignin and hemicellulose. The main goal of pretreatment is to overcome this recalcitrance, to separate the cellulose from the matrix polymers, and to make it more accessible for enzymatic hydrolysis. Reports have shown that pretreatment can improve sugar yields to higher than 90% theoretical yield for biomass such as wood, grasses, and corn. This paper reviews different leading pretreatment technologies along with their latest developments and highlights their advantages and disadvantages with respect to subsequent hydrolysis and fermentation. The effects of different technologies on the components of biomass (cellulose, hemicellulose, and lignin) are also reviewed with a focus on how the treatment greatly enhances enzymatic cellulose digestibility.

  11. Chemical and Physicochemical Pretreatment of Lignocellulosic Biomass: A Review

    PubMed Central

    Brodeur, Gary; Yau, Elizabeth; Badal, Kimberly; Collier, John; Ramachandran, K. B.; Ramakrishnan, Subramanian

    2011-01-01

    Overcoming the recalcitrance (resistance of plant cell walls to deconstruction) of lignocellulosic biomass is a key step in the production of fuels and chemicals. The recalcitrance is due to the highly crystalline structure of cellulose which is embedded in a matrix of polymers-lignin and hemicellulose. The main goal of pretreatment is to overcome this recalcitrance, to separate the cellulose from the matrix polymers, and to make it more accessible for enzymatic hydrolysis. Reports have shown that pretreatment can improve sugar yields to higher than 90% theoretical yield for biomass such as wood, grasses, and corn. This paper reviews different leading pretreatment technologies along with their latest developments and highlights their advantages and disadvantages with respect to subsequent hydrolysis and fermentation. The effects of different technologies on the components of biomass (cellulose, hemicellulose, and lignin) are also reviewed with a focus on how the treatment greatly enhances enzymatic cellulose digestibility. PMID:21687609

  12. Physiochemical characterization of lignocellulosic biomass dissolution by flowthrough pretreatment

    SciTech Connect

    Yan, Lishi; Pu, Yunqiao; Bowden, Mark; Ragauskas, Arthur J.; Yang, Bin

    2015-11-24

    In this study, comprehensive understanding of biomass solubilization chemistry in aqueous pretreatment such as water-only and dilute acid flowthrough pretreatment is of fundamental importance to achieve the goal of valorizing biomass to fermentable sugars and lignin for biofuels production. In this study, poplar wood was flowthrough pretreated by water-only or 0.05% (w/w) sulfuric acid at different temperatures (220–270 °C), flow rate (25 mL/min), and reaction times (8–90 min), resulting in significant disruption of the lignocellulosic biomass. Ion chromatography (IC), Fourier transform infrared (FTIR) spectroscopy, X-ray diffraction (XRD) analysis, and solid state cross-polarization/magic angle spinning (CP/MAS) 13C nuclear magnetic resonance (NMR) spectroscopy were applied to characterize the pretreated biomass whole slurries in order to reveal depolymerization as well as solubilization mechanism and identify unique dissolution structural features during these pretreatments. Results showed temperature-dependent cellulose decrystallization in flowthrough pretreatment. Crystalline cellulose was completely disrupted, and mostly converted to amorphous cellulose and oligomers by water-only operation at 270 °C for 10 min and by 0.05 wt % H2SO4 flowthrough pretreatment at 220 °C for 12 min. Flowthrough pretreatment with 0.05% (w/w) H2SO4 led to a greater disruption of structures in pretreated poplar at a lower temperature compared to water-only pretreatment.

  13. Structural modifications of lignocellulosics by pretreatments to enhance enzymatic hydrolysis

    SciTech Connect

    Gharpuray, M.M.; Lee, Y.F.; Fan, L.T.

    1983-01-01

    In this work an evaluation was made of a wide variety of single and multiple pretreatment methods for enhancing the rate of enzymatic hydrolysis of wheat straw. A multiple pretreatment consisted of a physical pretreatment followed by a chemical pretreatment. The structural features of wheat straw, including the specific surface area, crystallinity index, and lignin content, were measured to understand the mechanism of the enhancement in the hyrolysis rate upon pretreatment. It has been found that, in general, multiple pretreatments were not promising, since the hydrolysis rates rarely exceeded those achieved by single pretreatments. Ball-milling pretreatment was found to be effective in increasing the specific surface area and decreasing the crystallinity index. Treatment with ethylene glycol was highly effective in increasing the specific surface area, in addition to a high degree of delignification. Peracetic acid pretreatment was highly effective in delignifying substrate. Among multiple pretreatments, those involving peracetic acid treatment generally had lower crystallinity indices and lignin content values. The relationship between the hydrolysis rate and the set of structural features indicated that an increase in surface area and a decrease in the crystallinity and lignin content enhance the hydrolysis; the specific surface area is the most influential of the structural features, followed by the lignin content. (Refs. 23).

  14. Sulfite pretreatment to overcome recalcitrance of lignocellulose (SPORL) for robust enzymatic saccharification of hardwoods

    Treesearch

    G. S. Wang; X. J. Pan; Junyong Zhu; Roland Gleisner; D. Rockwood

    2009-01-01

    This study demonstrates sulfite pretreatment to overcome recalcitrance of lignocellulose (SPORL) for robust bioconversion of hardwoods. With only about 4% sodium bisulfite charge on aspen and 30-min pretreatment at temperature 180[...

  15. Recalcitrant carbohydrates after enzymatic hydrolysis of pretreated lignocellulosic biomass

    SciTech Connect

    Alcantara, Maria Angeles Bermudez; Azadi, Parastoo; Garcia, Bruno Diez; Reyes-Sosa, Francisco Manuel

    2016-10-06

    To reduce the cost of the enzymes for the hydrolysis of lignocellulosic biomass, two main strategies have been followed: one, the reduction of enzyme dosing by the use of more efficient and stable enzymatic cocktails; another, to include accessory enzymes in the cocktails to increase yields by reducing the recalcitrant carbohydrate fraction remaining at the end of the process. To guide this second strategy, we have explored the chemical bond composition of different fractions of recalcitrant carbohydrates after enzymatic hydrolysis. As a result, two lignocellulosic feedstocks of relevance for the biofuels industry have been analyzed, corn stover and sugarcane straw. On comparing the composition of chemical bonds of the starting pretreated material with samples after standard and forced hydrolysis (with enzyme overdosing), we obtained similar sugar and chemical bond composition. In conclusion, this suggests that the current enzymatic cocktails bear the set of enzymes needed to hydrolyze these feedstocks. From our point of view, the results show the need for a parallel fine-tuning of the enzymatic cocktails with the pretreatment process to maximize sugar release yield.

  16. Recalcitrant carbohydrates after enzymatic hydrolysis of pretreated lignocellulosic biomass

    DOE PAGES

    Alcantara, Maria Angeles Bermudez; Dobruchowska, Justyna; Azadi, Parastoo; ...

    2016-10-06

    To reduce the cost of the enzymes for the hydrolysis of lignocellulosic biomass, two main strategies have been followed: one, the reduction of enzyme dosing by the use of more efficient and stable enzymatic cocktails; another, to include accessory enzymes in the cocktails to increase yields by reducing the recalcitrant carbohydrate fraction remaining at the end of the process. To guide this second strategy, we have explored the chemical bond composition of different fractions of recalcitrant carbohydrates after enzymatic hydrolysis. As a result, two lignocellulosic feedstocks of relevance for the biofuels industry have been analyzed, corn stover and sugarcane straw.more » On comparing the composition of chemical bonds of the starting pretreated material with samples after standard and forced hydrolysis (with enzyme overdosing), we obtained similar sugar and chemical bond composition. In conclusion, this suggests that the current enzymatic cocktails bear the set of enzymes needed to hydrolyze these feedstocks. From our point of view, the results show the need for a parallel fine-tuning of the enzymatic cocktails with the pretreatment process to maximize sugar release yield.« less

  17. Recalcitrant carbohydrates after enzymatic hydrolysis of pretreated lignocellulosic biomass.

    PubMed

    Alcántara, María Ángeles Bermúdez; Dobruchowska, Justyna; Azadi, Parastoo; García, Bruno Díez; Molina-Heredia, Fernando P; Reyes-Sosa, Francisco Manuel

    2016-01-01

    To reduce the cost of the enzymes for the hydrolysis of lignocellulosic biomass, two main strategies have been followed: one, the reduction of enzyme dosing by the use of more efficient and stable enzymatic cocktails; another, to include accessory enzymes in the cocktails to increase yields by reducing the recalcitrant carbohydrate fraction remaining at the end of the process. To guide this second strategy, we have explored the chemical bond composition of different fractions of recalcitrant carbohydrates after enzymatic hydrolysis. Two lignocellulosic feedstocks of relevance for the biofuels industry have been analyzed, corn stover and sugarcane straw. On comparing the composition of chemical bonds of the starting pretreated material with samples after standard and forced hydrolysis (with enzyme overdosing), we obtained similar sugar and chemical bond composition. This suggests that the current enzymatic cocktails bear the set of enzymes needed to hydrolyze these feedstocks. From our point of view, the results show the need for a parallel fine-tuning of the enzymatic cocktails with the pretreatment process to maximize sugar release yield.

  18. Structural modification of lignocellulosics by pretreatments to enhance enzymatic hydrolysis.

    PubMed

    Gharpuray, M M; Lee, Y H; Fan, L T

    1983-01-01

    In this work an evaluation was made of a wide variety of single and multiple pretreatment methods for enhancing the rate of enzymatic hydrolysis of wheat straw. A multiple pretreatment consisted of a physical pretreatment followed by a chemical pretreatment. The structural features of wheat straw, including the specific surface area, crystallinity index, and lignin content, were measured to understand the mechanism of the enhancement in the hydrolysis rate upon pretrement. It has been found that, in general, multiple pretreatments were not promising, since the hydrolysis rates rarely exceeded those achieved by single pretreatments. Ballmilling pretreatment was found to be effective in increasing the specific surface area and decreasing the crystallinity index. Treatment with ethylene glycol was highly effective in increasing the specific surface area, in addition to a high degree of delignification. Peracetic acid pretreatment was highly effective in delignifying substrate. Among multiple pretreatments, those involving peracetic acid treatment generally had lower crystallinity indices and lignin content values. The relationship between the hydrolysis rate and the set of structural features indicated that an increase in surface area and a decrease in the crystallinity and lignin content enhance the hydrolysis; the specific surface area is the most influential of the structural features, followed by the lignin content.

  19. Pretreatment of lignocellulosic materials for efficient bioethanol production.

    PubMed

    Galbe, Mats; Zacchi, Guido

    2007-01-01

    Second-generation bioethanol produced from various lignocellulosic materials, such as wood, agricultural or forest residues, has the potential to be a valuable substitute for, or a complement to, gasoline. One of the crucial steps in the ethanol production is the hydrolysis of the hemicellulose and cellulose to monomer sugars. The most promising method for hydrolysis of cellulose to glucose is by use of enzymes, i.e. cellulases. However, in order to make the raw material accessible to the enzymes some kind of pretreatment is necessary. During the last few years a large number of pretreatment methods have been developed, comprising methods working at low pH, i.e. acid based, medium pH (without addition of catalysts), and high pH, i.e. with a base as catalyst. Many methods have been shown to result in high sugar yields, above 90% of theoretical for agricultural residues, especially for corn stover. For more recalcitrant materials, e.g. softwood, acid hydrolysis and steam pretreatment with acid catalyst seem to be the methods that can be used to obtain high sugar and ethanol yields. However, for more accurate comparison of different pretreatment methods it is necessary to improve the assessment methods under real process conditions. The whole process must be considered when a performance evaluation is to be made, as the various pretreatment methods give different types of materials. (Hemicellulose sugars can be obtained either in the liquid as monomer or oligomer sugars, or in the solid material to various extents; lignin can be either in the liquid or remain in the solid part; the composition and amount/concentration of possible inhibitory compounds also vary.) This will affect how the enzymatic hydrolysis should be performed (e.g. with or without hemicellulases), how the lignin is recovered and also the use of the lignin co-product.

  20. Chemical pretreatment of lignocellulosic agroindustrial waste for methane production.

    PubMed

    Pellera, Frantseska-Maria; Gidarakos, Evangelos

    2017-04-26

    This study investigates the effect of different chemical pretreatments on the solubilization and the degradability of different solid agroindustrial waste, namely winery waste, cotton gin waste, olive pomace and juice industry waste. Eight different reagents were investigated, i.e. sodium hydroxide (NaOH), sodium bicarbonate (NaHCO3), sodium chloride (NaCl), citric acid (H3Cit), acetic acid (AcOH), hydrogen peroxide (H2O2), acetone (Me2CO) and ethanol (EtOH), under three condition sets resulting in treatments of varying intensity, depending on process duration, reagent dosage and temperature. Results indicated that chemical pretreatment under more severe conditions is more effective on the solubilization of lignocellulosic substrates, such as those of the present study and among the investigated reagents, H3Cit, H2O2 and EtOH appeared to be the most effective to this regard. At the same time, although chemical pretreatment in general did not improve the methane potential of the substrates, moderate to high severity conditions were found to generally be the most satisfactory in terms of methane production from pretreated materials. In fact, moderate severity treatments using EtOH for winery waste, H3Cit for olive pomace and H2O2 for juice industry waste and a high severity treatment with EtOH for cotton gin waste, resulted in maximum specific methane yield values. Ultimately, the impact of pretreatment parameters on the different substrates seems to be dependent on their characteristics, in combination with the specific mode of action of each reagent. The overall energy balance of such a system could probably be improved by using lower operating powers and higher solid to liquid ratios. Copyright © 2017 Elsevier Ltd. All rights reserved.

  1. Autohydrolysis Pretreatment of Lignocellulosic Biomass for Bioethanol Production

    NASA Astrophysics Data System (ADS)

    Han, Qiang

    Autohydrolysis, a simple and environmental friendly process, has long been studied but often abandoned as a financially viable pretreatment for bioethanol production due to the low yields of fermentable sugars at economic enzyme dosages. The introduction of mechanical refining can generate substantial improvements for autohydrolysis process, making it an attractive pretreatment technology for bioethanol commercialization. In this study, several lignocellulosic biomass including wheat straw, switchgrass, corn stover, waste wheat straw have been subjected to autohydrolysis pretreatment followed by mechanical refining to evaluate the total sugar recovery at affordable enzyme dosages. Encouraging results have been found that using autohydrolysis plus refining strategy, the total sugar recovery of most feedstock can be as high as 76% at 4 FPU/g enzymes dosages. The mechanical refining contributed to the improvement of enzymatic sugar yield by as much as 30%. Three non-woody biomass (sugarcane bagasse, wheat straw, and switchgrass) and three woody biomass (maple, sweet gum, and nitens) have been subjected to autohydrolysis pretreatment to acquire a fundamental understanding of biomass characteristics that affect the autohydrolysis and the following enzymatic hydrolysis. It is of interest to note that the nonwoody biomass went through substantial delignification during autohydrolysis compared to woody biomass due to a significant amount of p-coumaric acid and ferulic acid. It has been found that hardwood which has a higher S/V ratio in the lignin structure tends to have a higher total sugar recovery from autohydrolysis pretreatment. The economics of bioethanol production from autohydrolysis of different feedstocks have been investigated. Regardless of different feedstocks, in the conventional design, producing bioethanol and co-producing steam and power, the minimum ethanol revenues (MER) required to generate a 12% internal rate of return (IRR) are high enough to

  2. Enzymatic pretreatment of lignocellulosic wastes to improve biogas production.

    PubMed

    Ziemiński, K; Romanowska, I; Kowalska, M

    2012-06-01

    The effect of enzymatic pretreatment of sugar beet pulp and spent hops prior to methane fermentation was determined in this study. These industrial residues were subjected to enzymatic digestion before anaerobic fermentation because of high fiber content (of 85.1% dry matter (DM) and 57.7% DM in sugar beet pulp and spent hops, respectively). Their 24h hydrolysis with a mix of enzymatic preparations Celustar XL and Agropect pomace (3:1, v/v), with endoglucanase, xylanase and pectinase activities, was most effective. Reducing sugars concentrations in hydrolysates of sugar beet pulp and spent hops were by 88.9% and 59.4% higher compared to undigested materials. The highest yield of biogas was obtained from the enzymatic hydrolysate of sugar beet pulp (183.39 mL/d from 1g COD at fermenter loading with organic matter of 5.43 g COD/L × d). Fermentation of sugar beet pulp gave 19% less biogas. Methane fermentation of spent hops hydrolysate yielded 121.47 mL/d biogas from 1g COD (at 6.02 g COD/L × d, 13% more than from spent hops). These results provide evidence that suitable enzymatic pretreatment of lignocellulosic wastes improve biogas yield from anaerobic fermentation.

  3. Factors affecting seawater-based pretreatment of lignocellulosic date palm residues.

    PubMed

    Fang, Chuanji; Thomsen, Mette Hedegaard; Frankær, Christian Grundahl; Bastidas-Oyanedel, Juan-Rodrigo; Brudecki, Grzegorz P; Schmidt, Jens Ejbye

    2017-09-01

    Seawater-based pretreatment of lignocellulosic biomass is an innovative process at research stage. With respect to process optimization, factors affecting seawater-based pretreatment of lignocellulosic date palm residues were studied for the first time in this paper. Pretreatment temperature (180°C-210°C), salinity of seawater (0ppt-50ppt), and catalysts (H2SO4, Na2CO3, and NaOH) were investigated. The results showed that pretreatment temperature exerted the largest influence on seawater-based pretreatment in terms of the enzymatic digestibility and fermentability of pretreated solids, and the inhibition of pretreatment liquids to Saccharomyces cerevisiae. Salinity showed the least impact to seawater-based pretreatment, which widens the application spectrum of saline water sources such as brines discharged in desalination plant. Sulfuric acid was the most effective catalyst for seawater-based pretreatment compared with Na2CO3 and NaOH. Copyright © 2017 Elsevier Ltd. All rights reserved.

  4. Ethylenediamine pretreatment changes cellulose allomorph and lignin structure of lignocellulose at ambient pressure.

    PubMed

    Qin, Lei; Li, Wen-Chao; Zhu, Jia-Qing; Liang, Jing-Nan; Li, Bing-Zhi; Yuan, Ying-Jin

    2015-01-01

    Pretreatment of lignocellulosic biomass is essential to increase the cellulase accessibility for bioconversion of lignocelluloses by breaking down the biomass recalcitrance. In this work, a novel pretreatment method using ethylenediamine (EDA) was presented as a simple process to achieve high enzymatic digestibility of corn stover (CS) by heating the biomass-EDA mixture with high solid-to-liquid ratio at ambient pressure. The effect of EDA pretreatment on lignocellulose was further studied. High enzymatic digestibility of CS was achieved at broad pretreatment temperature range (40-180 °C) during EDA pretreatment. Herein, X-ray diffractogram analysis indicated that cellulose I changed to cellulose III and amorphous cellulose after EDA pretreatment, and cellulose III content increased along with the decrease of drying temperature and the increase of EDA loading. Lignin degradation was also affected by drying temperature and EDA loading. Images from scanning electron microscope and transmission electron microscope indicated that lignin coalesced and deposited on the biomass surface during EDA pretreatment, which led to the delamination of cell wall. HSQC NMR analysis showed that ester bonds of p-coumarate and ferulate units in lignin were partially ammonolyzed and ether bonds linking the phenolic monomers were broken during pretreatment. In addition, EDA-pretreated CS exhibited good fermentability for simultaneous saccharification and co-fermentation process. EDA pretreatment improves the enzymatic digestibility of lignocellulosic biomass significantly, and the improvement was caused by the transformation of cellulose allomorph, lignin degradation and relocalization in EDA pretreatment.

  5. Elucidating the Role of Ferrous Ion Cocatalyst in Enhancing Dilute Acid Pretreatment of Lignocellulosic Biomass

    SciTech Connect

    Wei, H.; Donohoe, B. S.; Vinzant, T. B.; Ciesielski, P. N.; Wang, W.; Gedvilas, L. M.; Zeng, Y.; Johnson, D. K.; Ding, S. Y.; Himmel, M. E.; Tucker, M. P.

    2011-01-01

    Recently developed iron cocatalyst enhancement of dilute acid pretreatment of biomass is a promising approach for enhancing sugar release from recalcitrant lignocellulosic biomass. However, very little is known about the underlying mechanisms of this enhancement. In the current study, our aim was to identify several essential factors that contribute to ferrous ion-enhanced efficiency during dilute acid pretreatment of biomass and to initiate the investigation of the mechanisms that result in this enhancement. During dilute acid and ferrous ion cocatalyst pretreatments, we observed concomitant increases in solubilized sugars in the hydrolysate and reducing sugars in the (insoluble) biomass residues. We also observed enhancements in sugar release during subsequent enzymatic saccharification of iron cocatalyst-pretreated biomass. Fourier transform Raman spectroscopy showed that major peaks representing the C-O-C and C-H bonds in cellulose are significantly attenuated by iron cocatalyst pretreatment. Imaging using Prussian blue staining indicated that Fe{sup 2+} ions associate with both cellulose/xylan and lignin in untreated as well as dilute acid/Fe{sup 2+} ion-pretreated corn stover samples. Analyses by scanning electron microscopy and transmission electron microscopy revealed structural details of biomass after dilute acid/Fe{sup 2+} ion pretreatment, in which delamination and fibrillation of the cell wall were observed. By using this multimodal approach, we have revealed that (1) acid-ferrous ion-assisted pretreatment increases solubilization and enzymatic digestion of both cellulose and xylan to monomers and (2) this pretreatment likely targets multiple chemistries in plant cell wall polymer networks, including those represented by the C-O-C and C-H bonds in cellulose.

  6. Deconstruction of ionic liquid pretreated lignocellulosic biomass using mono-component cellulases and hemicellulases and commercial mixtures

    USDA-ARS?s Scientific Manuscript database

    Lignocellulosic biomass is comprised of cellulose and hemicellulose, sources of polysaccharides, and lignin, a macromolecule with extensive aromaticity. Lignocellulose requires pretreatment before biochemical conversion to its monomeric sugars which can provide a renewable carbon based feedstock for...

  7. Pretreatment of Lignocellulosic Biomass with Ionic Liquids and Ionic Liquid-Based Solvent Systems.

    PubMed

    Hou, Qidong; Ju, Meiting; Li, Weizun; Liu, Le; Chen, Yu; Yang, Qian

    2017-03-20

    Pretreatment is very important for the efficient production of value-added products from lignocellulosic biomass. However, traditional pretreatment methods have several disadvantages, including low efficiency and high pollution. This article gives an overview on the applications of ionic liquids (ILs) and IL-based solvent systems in the pretreatment of lignocellulosic biomass. It is divided into three parts: the first deals with the dissolution of biomass in ILs and IL-based solvent systems; the second focuses on the fractionation of biomass using ILs and IL-based solvent systems as solvents; the third emphasizes the enzymatic saccharification of biomass after pretreatment with ILs and IL-based solvent systems.

  8. Recent Advances in the Application of Inorganic Salt Pretreatment for Transforming Lignocellulosic Biomass into Reducing Sugars.

    PubMed

    Loow, Yu-Loong; Wu, Ta Yeong; Tan, Khang Aik; Lim, Yung Shen; Siow, Lee Fong; Jahim, Jamaliah Md; Mohammad, Abdul Wahab; Teoh, Wen Hui

    2015-09-30

    Currently, the transformation of lignocellulosic biomass into value-added products such as reducing sugars is garnering attention worldwide. However, efficient hydrolysis is usually hindered by the recalcitrant structure of the biomass. Many pretreatment technologies have been developed to overcome the recalcitrance of lignocellulose such that the components can be reutilized more effectively to enhance sugar recovery. Among all of the utilized pretreatment methods, inorganic salt pretreatment represents a more novel method and offers comparable sugar recovery with the potential for reducing costs. The use of inorganic salt also shows improved performance when it is integrated with other pretreatment technologies. Hence, this paper is aimed to provide a detailed overview of the current situation for lignocellulosic biomass and its physicochemical characteristics. Furthermore, this review discusses some recent studies using inorganic salt for pretreating biomass and the mechanisms involved during the process. Finally, some prospects and challenges using inorganic salt are highlighted.

  9. Organic solvent pretreatment of lignocellulosic biomass for biofuels and biochemicals: A review.

    PubMed

    Zhang, Ke; Pei, Zhijian; Wang, Donghai

    2016-01-01

    Lignocellulosic biomass represents the largest potential volume and lowest cost for biofuel and biochemical production. Pretreatment is an essential component of biomass conversion process, affecting a majority of downstream processes, including enzymatic hydrolysis, fermentation, and final product separation. Organic solvent pretreatment is recognized as an emerging way ahead because of its inherent advantages, such as the ability to fractionate lignocellulosic biomass into cellulose, lignin, and hemicellulose components with high purity, as well as easy solvent recovery and solvent reuse. Objectives of this review were to update and extend previous works on pretreatment of lignocellulosic biomass for biofuels and biochemicals using organic solvents, especially on ethanol, methanol, ethylene glycol, glycerol, acetic acid, and formic acid. Perspectives and recommendations were given to fully describe implementation of proper organic solvent pretreatment for future research.

  10. Augmented digestion of lignocellulose by steam explosion, acid and alkaline pretreatment methods: a review.

    PubMed

    Singh, Joginder; Suhag, Meenakshi; Dhaka, Anil

    2015-03-06

    Lignocellulosic materials can be explored as one of the sustainable substrates for bioethanol production through microbial intervention as they are abundant, cheap and renewable. But at the same time, their recalcitrant structure makes the conversion process more cumbersome owing to their chemical composition which adversely affects the efficiency of bioethanol production. Therefore, the technical approaches to overcome recalcitrance of biomass feedstock has been developed to remove the barriers with the help of pretreatment methods which make cellulose more accessible to the hydrolytic enzymes, secreted by the microorganisms, for its conversion to glucose. Pretreatment of lignocellulosic biomass in cost effective manner is a major challenge to bioethanol technology research and development. Hence, in this review, we have discussed various aspects of three commonly used pretreatment methods, viz., steam explosion, acid and alkaline, applied on various lignocellulosic biomasses to augment their digestibility alongwith the challenges associated with their processing.

  11. Pretreatment of Lignocellulosic Wastes to Improve Ethanol and Biogas Production: A Review

    PubMed Central

    Taherzadeh, Mohammad J.; Karimi, Keikhosro

    2008-01-01

    Lignocelluloses are often a major or sometimes the sole components of different waste streams from various industries, forestry, agriculture and municipalities. Hydrolysis of these materials is the first step for either digestion to biogas (methane) or fermentation to ethanol. However, enzymatic hydrolysis of lignocelluloses with no pretreatment is usually not so effective because of high stability of the materials to enzymatic or bacterial attacks. The present work is dedicated to reviewing the methods that have been studied for pretreatment of lignocellulosic wastes for conversion to ethanol or biogas. Effective parameters in pretreatment of lignocelluloses, such as crystallinity, accessible surface area, and protection by lignin and hemicellulose are described first. Then, several pretreatment methods are discussed and their effects on improvement in ethanol and/or biogas production are described. They include milling, irradiation, microwave, steam explosion, ammonia fiber explosion (AFEX), supercritical CO2 and its explosion, alkaline hydrolysis, liquid hot-water pretreatment, organosolv processes, wet oxidation, ozonolysis, dilute-and concentrated-acid hydrolyses, and biological pretreatments. PMID:19325822

  12. Influence of lignin addition on the enzymatic digestibility of pretreated lignocellulosic biomasses.

    PubMed

    Wang, Wangxia; Zhu, Yangsu; Du, Jing; Yang, Yiqin; Jin, Yongcan

    2015-04-01

    The presence of lignin in lignocellulosic biomass is correlated with its enzymatic digestibility. Their correlation and mechanism have been investigated widely but have not been elucidated clearly. In this study, hydrophilic sulfonated lignin and hydrophobic kraft lignin were introduced into the enzymatic hydrolysis process to investigate their effects on the enzymatic digestibility of different pretreated lignocellulose. The influence of lignin addition on the enzymatic digestibility varied with both introduced lignin type and the pretreatment methods of substrates. Slight enhancement of enzymatic hydrolysis was observed for all substrates by adding kraft lignin. The addition of sulfonated lignin could effectively improve the enzymatic digestibility of green liquor and acidic bisulfite pretreated materials, but had little effect on sulfite-formaldehyde pretreated samples. The enzymatic digestibility of green liquor pretreated masson pine increased from 42% without lignin addition to 75% with 0.3g/g-substrate sulfonated lignin addition.

  13. Supercritical fluids as a green technology for the pretreatment of lignocellulosic biomass.

    PubMed

    Daza Serna, L V; Orrego Alzate, C E; Cardona Alzate, C A

    2016-01-01

    One of the main drawbacks for using lignocellulosic biomass is related to its recalcitrance. The pretreatment of lignocellulosic biomass plays an important role for delignification and crystallinity reduction purposes. In this work rice husk (RH) was submitted to supercritical pretreatment at 80°C and 270 bar with the aim to determine the effect on lignin content, crystallinity as well as enzymatic digestibility. The yields obtained were compared with dilute sulfuric acid pretreatment as base case. Additionally a techno-economic and environmental comparison of the both pretreatment technologies was performed. The results show a lignin content reduction up to 90.6% for the sample with 75% moisture content using a water-ethanol mixture. The results for crystallinity and enzymatic digestibility demonstrated that no reductions were reached. Supercritical pretreatment presents the best economical and environmental performance considering the solvents and carbon dioxide recycling.

  14. Dry pretreatment of lignocellulose with extremely low steam and water usage for bioethanol production.

    PubMed

    Zhang, Jian; Wang, Xiusheng; Chu, Deqiang; He, Yanqing; Bao, Jie

    2011-03-01

    Two rarely noticed but important parameters of the dilute sulfuric acid pretreatment of lignocellulose biomass, the feedstock filling ratio to the pretreatment reactor and the solids/liquid presoaking ratio, were extensively studied. The effects of the two parameters on the steam consumption, waste water generation, and pretreatment efficiency were investigated. At the full filling ratio and high solids/liquid presoaking ratio, this "dry" pretreatment method provided at least the following advantages: (1) the steam consumption was significantly reduced; (2) no aqueous acid containing waste water was generated; (3) high solids content of the pretreated materials were obtained and the consequent saccharification and fermentation was carried out at high solids loading easily. This method was applied to various lignocellulose feedstocks successfully and provided a practical means to produce ethanol economically feasible. Copyright © 2011 Elsevier Ltd. All rights reserved.

  15. Lignocellulose pretreatment in a fungus-cultivating termite

    Treesearch

    Hongjie Li; Daniel J. Yelle; Chang Li; Mengyi Yang; Jing Ke; Ruijuan Zhang; Yu Liu; Na Zhu; Shiyou Liang; Xiaochang Mo; John Ralph; Cameron R. Currie; Jianchu Mo

    2017-01-01

    Depolymerizing lignin, the complex phenolic polymer fortifying plant cell walls, is an essential but challenging starting point for the lignocellulosics industries. The variety of ether– and carbon–carbon interunit linkages produced via radical coupling during lignification limit chemical and biological depolymerization efficiency. In an ancient fungus-cultivating...

  16. Mimicking the Fenton reaction-induced wood decay by fungi for pretreatment of lignocellulose.

    PubMed

    Jung, Young Hoon; Kim, Hyun Kyung; Park, Hyun Min; Park, Yong-Cheol; Park, Kyungmoon; Seo, Jin-Ho; Kim, Kyoung Heon

    2015-03-01

    In this study, the Fenton reaction, which is naturally used by fungi for wood decay, was employed to pretreat rice straw and increase the enzymatic digestibility for the saccharification of lignocellulosic biomass. Using an optimized Fenton's reagent (FeCl3 and H2O2) for pretreatment, an enzymatic digestibility that was 93.2% of the theoretical glucose yield was obtained. This is the first report of the application of the Fenton reaction to lignocellulose pretreatment at a moderate temperature (i.e., 25°C) and with a relatively high loading of biomass (i.e., 10% (w/v)). Substantial improvement in the process economics of cellulosic fuel and chemical production can be achieved by replacing the conventional pretreatment with this Fenton-mimicking process. Copyright © 2014 Elsevier Ltd. All rights reserved.

  17. High-pressure homogenization pretreatment of four different lignocellulosic biomass for enhancing enzymatic digestibility.

    PubMed

    Jin, Shuguang; Zhang, Guangming; Zhang, Panyue; Fan, Shiyang; Li, Fan

    2015-04-01

    Grass clipping, corn straw, catalpa sawdust and pine sawdust were pretreated with high-pressure homogenization (HPH) to enhance the enzymatic digestibility. With a working pressure of 10 MPa, all the four lignocellulosic biomass were significantly changed, such as decrease in particle size, structure destruction, and crystallinity change. Results showed that lignocellulosic biomass pretreated with HPH yielded more reducing sugar, which was suitable for subsequent biofuel production. After 48-h enzymatic hydrolysis, the maximum reducing sugar yield of 229.42 mg/g was achieved for grass clipping. For corn straw, the enzymatic hydrolysis efficiency increased by 68.37% at most. However, reducing sugar yield of catalpa sawdust and pine sawdust was relatively lower. Low lignin content and crystallinity might make grass clipping the most suitable material for HPH pretreatment, thus leading to high hydrolysis efficiency. HPH pretreatment could increase biofuel output in a mild condition without adding any chemicals. Copyright © 2015 Elsevier Ltd. All rights reserved.

  18. Dilute acid pretreatment of lignocellulose for whole slurry ethanol fermentation.

    PubMed

    Jung, Young Hoon; Kim, In Jung; Kim, Hyun Kyung; Kim, Kyoung Heon

    2013-03-01

    Dilute sulfuric acid pretreatment of oil palm empty fruit bunches (EFB) followed by the whole slurry fermentation of the pretreated EFB slurry was investigated. The optimized pretreatment conditions were at 1% (w/v) sulfuric acid with 3 min ramping to 190 °C in a microwave digester. Pretreated and washed EFB exhibited enzymatic digestibility of 88.5% of theoretical glucose yield after 48 h of hydrolysis. When the whole slurry of pretreated and neutralized EFB was used in simultaneous saccharification and fermentation (SSF) using cellulase and Saccharomyces cerevisiae, sulfuric acid-pretreated EFB resulted in 52.5% of theoretical ethanol yield based on total glucan in the untreated initial EFB after 72 h of SSF. When pretreated EFB slurry was treated with activated carbon before subjecting to SSF, the SSF furnished 87.5% ethanol yield based on the initial glucan content in untreated EFB (after 48 h of SSF). Copyright © 2012 Elsevier Ltd. All rights reserved.

  19. Biological pretreatment of lignocellulosic substrates for enhanced delignification and enzymatic digestibility.

    PubMed

    Saritha, M; Arora, Anju; Lata

    2012-06-01

    Sheer enormity of lignocellulosics makes them potential feedstock for biofuel production but, their conversion into fermentable sugars is a major hurdle. They have to be pretreated physically, chemically, or biologically to be used by fermenting organisms for production of ethanol. Each lignocellulosic substrate is a complex mix of cellulose, hemicellulose and lignin, bound in a matrix. While cellulose and hemicellulose yield fermentable sugars, lignin is the most recalcitrant polymer, consisting of phenyl-propanoid units. Many microorganisms in nature are able to attack and degrade lignin, thus making access to cellulose easy. Such organisms are abundantly found in forest leaf litter/composts and especially include the wood rotting fungi, actinomycetes and bacteria. These microorganisms possess enzyme systems to attack, depolymerize and degrade the polymers in lignocellulosic substrates. Current pretreatment research is targeted towards developing processes which are mild, economical and environment friendly facilitating subsequent saccharification of cellulose and its fermentation to ethanol. Besides being the critical step, pretreatment is also cost intensive. Biological treatments with white rot fungi and Streptomyces have been studied for delignification of pulp, increasing digestibility of lignocellulosics for animal feed and for bioremediation of paper mill effluents. Such lignocellulolytic organisms can prove extremely useful in production of bioethanol when used for removal of lignin from lignocellulosic substrate and also for cellulase production. Our studies on treatment of hardwood and softwood residues with Streptomyces griseus isolated from leaf litter showed that it enhanced the mild alkaline solubilisation of lignins and also produced high levels of the cellulase complex when growing on wood substrates. Lignin loss (Klason lignin) observed was 10.5 and 23.5% in case of soft wood and hard wood, respectively. Thus, biological pretreatment process for

  20. Saccharomyces cerevisiae engineered to convert pretreated lignocellulosic sugars anaerobically to ethanol

    USDA-ARS?s Scientific Manuscript database

    Advanced high-throughput screening has resulted in the discovery of several yeast strains that can utilize hexose as well as pentose sugars fully anaerobically. This is the first report of strains that are capable of utilizing pentose and hexose sugars from pretreated lignocellulosic feedstocks ful...

  1. Multi-scale visualization and characterization of lignocellulosic plant cell wall deconstruction during thermochemical pretreatment

    Treesearch

    Shishir P. S. Chundawat; Bryon S. Donohoe; Leonardo da Costa Sousa; Thomas Elder; Umesh P. Agarwal; Fachuang Lu; John Ralph; Michael E. Himmel; Venkatesh Balan; Bruce E. Dale

    2011-01-01

    Deconstruction of lignocellulosic plant cell walls to fermentable sugars by thermochemical and/or biological means is impeded by several poorly understood ultrastructural and chemical barriers. A promising thermochemical pretreatment called ammonia fiber expansion (AFEX) overcomes the native recalcitrance of cell walls through subtle morphological and physicochemical...

  2. Thermochemical pretreatment of lignocellulose to enhance methane fermentation: II. Evaluation and application of pretreatment model.

    PubMed

    Baugh, K D; Levy, J A; McCarty, P L

    1988-01-01

    A model was developed and evaluated as a tool for predicting the formation of soluble products from staged thermochemical treatment of lignocellulosic materials under acidic conditions typical of autohydrolysis. The model was used to predict the general trend of hemi-cellulose and cellulose hydrolysis between pH 2 and 4 and temperatures of 170-230 degrees C, and results were compared with experimental data. When the model was evaluated for this range of temperatures and pH values, results indicated: (1) a relatively low temperature (175 degrees C) during the first stage allows hydrolysis of the hemi-cellulose polysaccharides without significant mono-saccharide decomposition, (2) subsequent stages at higher temperatures (equal or greater than 200 degrees C) are needed for significant cellulose hydrolysis, but glucose decomposition will also occur, and, (3) a pH in the range of 2-2.5 will enhance polysaccharide hydrolysis while limiting monosaccharide decomposition. The model's predictions, indicating that the formation of biodegradable products could be optimized using Pretreatments at pH 2-2.5 for the pH range evaluated, were confirmed in experiments with white fir as a representative lig nocellulose.

  3. Effect of moisture on pretreatment efficiency for anaerobic digestion of lignocellulosic substrates.

    PubMed

    Peces, M; Astals, S; Mata-Alvarez, J

    2015-12-01

    The present study evaluates the effect of moisture in low-temperature and ultrasound pretreatment on lignocellulosic substrates anaerobic biodegradability, where brewer's spent grain was used as model substrate. Besides moisture content, low-temperature pretreatment was also evaluated in terms of temperature (60-80°C) and exposure time (12-72 h). Likewise, ultrasonication was also evaluated in terms of specific energy (1000-50,000 kJ kg TS(-1)). In addition, the effect of substrate particle size reduction by milling pretreatment was also considered. The results clearly demonstrated that substrate moisture (total solid concentration) is a significant parameter for pretreatment performance, although it has been rarely considered in pretreatment optimisation. Specifically, moisture optimisation increased the methane yield of brewer's spent grain by 6% for low-temperature pretreatment (60°C), and by 14% for ultrasound pretreatment (1000 kJ kg TS(-1)) towards the control (without pretreatment). In both pretreatments, the experimental optimum total solid concentration was 100 gTS kg(-1). Thus, lowering substrate moisture, a strategy suggested attaining energetic pretreatment feasibility, needs to be analysed as another pretreatment variable since it might have limited correlation. Finally, a preliminary energetic balance of the pretreatments under study showed that the extra methane production could not cover the energetic pretreatment expenses.

  4. Supercritical CO2 and ionic liquids for the pretreatment of lignocellulosic biomass in bioethanol production.

    PubMed

    Gu, Tingyue; Held, Michael A; Faik, Ahmed

    2013-01-01

    Owing to high petroleum prices, there has been a major push in recent years to use lignocellulosic biomass as biorefinery feedstocks. Unfortunately, by nature's design, lignocellulosic biomass is notoriously recalcitrant. Cellulose is the most abundant renewable carbon source on the planet and comprises glucan polysaccharides which self-assemble into paracrystalline microfibrils. The extent of cellulose crystallinity largely contributes to biomass recalcitrance. Additionally, cellulose microfibrils are embedded into both hemicellulose and lignin polymeric networks, making cellulose accessibility an additional obstacle. Pretreatment is necessary before enzymatic hydrolysis in order to liberate high yields of glucose and other fermentable sugars from biomass polysaccharides. This work discusses two pretreatment methods, supercritical CO2 and ionic liquids (ILs). Both methods utilize green solvents that do not emit toxic vapours. Mechanisms for destroying or weakening biomass recalcitrance have been explored. Various pretreatment operating parameters such as temperature, pressure, time, dry biomass/solvent ratio, water content, etc. have been investigated for the pretreatment of various biomass types such as corn stover, switchgrass, sugarcane bagasse, soft and hard wood. The two pretreatment methods have their pros and cons. For example, supercritical CO2 explosion pretreatment uses inexpensive CO2, but requires a high pressure. By comparison, while IL pretreatment does not require an elevated pressure, ILs are still too expensive for large-scale uses. Further research and development are needed to make the two green pretreatment methods practical.

  5. A comprehensive review on pre-treatment strategy for lignocellulosic food industry waste: Challenges and opportunities.

    PubMed

    Ravindran, Rajeev; Jaiswal, Amit Kumar

    2016-01-01

    Lignocellulose is a generic term used to describe plant biomass. It is the most abundant renewable carbon resource in the world and is mainly composed of lignin, cellulose and hemicelluloses. Most of the food and food processing industry waste are lignocellulosic in nature with a global estimate of up to 1.3 billion tons/year. Lignocellulose, on hydrolysis, releases reducing sugars which is used for the production of bioethanol, biogas, organic acids, enzymes and biosorbents. However, structural conformation, high lignin content and crystalline cellulose hinder its use for value addition. Pre-treatment strategies facilitate the exposure of more cellulose and hemicelluloses for enzymatic hydrolysis. The present article confers about the structure of lignocellulose and how it influences enzymatic degradation emphasising the need for pre-treatments along with a comprehensive analysis and categorisation of the same. Finally, this article concludes with a detailed discussion on microbial/enzymatic inhibitors that arise post pre-treatment and strategies to eliminate them. Copyright © 2015 Elsevier Ltd. All rights reserved.

  6. Improved pretreatment of lignocellulosic biomass using enzymatically-generated peracetic acid.

    PubMed

    Yin, DeLu Tyler; Jing, Qing; AlDajani, Waleed Wafa; Duncan, Shona; Tschirner, Ulrike; Schilling, Jonathan; Kazlauskas, Romas J

    2011-04-01

    Release of sugars from lignocellulosic biomass is inefficient because lignin, an aromatic polymer, blocks access of enzymes to the sugar polymers. Pretreatments remove lignin and disrupt its structure, thereby enhancing sugar release. In previous work, enzymatically generated peracetic acid was used to pretreat aspen wood. This pretreatment removed 45% of the lignin and the subsequent saccharification released 97% of the sugars remaining after pretreatment. In this paper, the amount of enzyme needed is reduced tenfold using first, an improved enzyme variant that makes twice as much peracetic acid and second, a two-phase reaction to generate the peracetic acid, which allows enzyme reuse. In addition, the eight pretreatment cycles are reduced to only one by increasing the volume of peracetic acid solution and increasing the temperature to 60 °C and the reaction time to 6h. For the pretreatment step, the weight ratio of peracetic acid to wood determines the amount of lignin removed.

  7. Comparison of different pretreatment methods for separation hemicellulose from straw during the lignocellulosic bioethanol production

    NASA Astrophysics Data System (ADS)

    Eisenhuber, Katharina; Krennhuber, Klaus; Steinmüller, Viktoria; Kahr, Heike; Jäger, Alexander

    2013-04-01

    The combustion of fossil fuels is responsible for 73% of carbon dioxide emissions into the atmosphere and consequently contributes to global warming. This fact has enormously increased the interest in the development of methods to reduce greenhouse gases. Therefore, the focus is on the production of biofuels from lignocellulosic agricultural residues. The feedstocks used for 2nd generation bioethanol production are lignocellulosic raw materials like different straw types or energy crops like miscanthus sinensis or arundo donax. Lignocellulose consists of hemicellulose (xylose and arabinose), which is bonded to cellulose (glucose) and lignin. Prior to an enzymatic hydrolysis of the polysaccharides and fermentation of the resulting sugars, the lignocelluloses must be pretreated to make the sugar polymers accessible to enzymes. A variety of pretreatment methods are described in the literature: thermophysical, acid-based and alkaline methods.In this study, we examined and compared the most important pretreatment methods: Steam explosion versus acid and alkaline pretreatment. Specific attention was paid to the mass balance, the recovery of C 5 sugars and consumption of chemicals needed for pretreatment. In lab scale experiments, wheat straw was either directly pretreated by steam explosion or by two different protocols. The straw was either soaked in sulfuric acid or in sodium hydroxide solution at different concentrations. For both methods, wheat straw was pretreated at 100°C for 30 minutes. Afterwards, the remaining straw was separated by vacuum filtration from the liquid fraction.The pretreated straw was neutralized, dried and enzymatically hydrolyzed. Finally, the sugar concentrations (glucose, xylose and arabinose) from filtrate and from hydrolysate were determined by HPLC. The recovery of xylose from hemicellulose was about 50% using the sulfuric acid pretreatment and less than 2% using the sodium hydroxide pretreatment. Increasing concentrations of sulfuric acid

  8. Production of ligninolytic enzymes by white rot fungi on lignocellulosic wastes using novel pretreatments.

    PubMed

    Pandey, A K; Vishwakarma, S K; Srivastava, A K; Pandey, V K; Agrawal, S; Singh, M P

    2014-12-24

    Production of extracellular ligninolytic enzymes (laccase and polyphenol oxidase) secreted by three species of white rot fungi (Pleurotus florida, P. flabellatus and P. sajor—caju) under in vivo condition was studied on two lignocellulosic substrates i.e., paddy straw and wheat straw. These lignocellulosic substrates were treated with neem (Azadirachta indica) oil and ashoka (Saraca indica) leaves extract. Between the two lignocellulosic substrates, paddy straw pretreated with neem oil supported maximum activity of laccase and polyphenol oxidase (PPO). The activities of both the enzymes were low on the 5th day of cultivation which increased on the 10th day and reached at peak on the 15th day. Thereafter, there was continuous decrease in the enzymatic activity. Among the three species, P. flabellatus (P3) showed maximum ligninolytic enzymatic activity followed by P. florida (P2)and P. sajor—caju (P1).

  9. Solar assisted alkali pretreatment of garden biomass: Effects on lignocellulose degradation, enzymatic hydrolysis, crystallinity and ultra-structural changes in lignocellulose

    SciTech Connect

    Gabhane, Jagdish; William, S.P.M. Prince; Vaidya, Atul N.; Das, Sera; Wate, Satish R.

    2015-06-15

    Highlights: • SAAP is an efficient and economic means of pretreatment. • SAAP was found to be efficient in lignin and hemicellulose removal. • SAAP enhanced the enzymatic hydrolysis. • FTIR, XRD and SEM provided vivid understanding about the mode of action of SAAP. • Mass balance closer of 98% for pretreated GB confirmed the reliability of SAAP. - Abstract: A comprehensive study was carried out to assess the effectiveness of solar assisted alkali pretreatment (SAAP) on garden biomass (GB). The pretreatment efficiency was assessed based on lignocellulose degradation, conversion of cellulose into reducing sugars, changes in the ultra-structure and functional groups of lignocellulose and impact on the crystallinity of cellulose, etc. SAAP was found to be efficient for the removal of lignin and hemicellulose that facilitated enzymatic hydrolysis of cellulose. FTIR and XRD studies provided details on the effectiveness of SAAP on lignocellulosic moiety and crystallinity of cellulose. Scanning electron microscopic analysis showed ultra-structural disturbances in the microfibrils of GB as a result of pretreatment. The mass balance closer of 97.87% after pretreatment confirmed the reliability of SAAP pretreatment. Based on the results, it is concluded that SAAP is not only an efficient means of pretreatment but also economical as it involved no energy expenditure for heat generation during pretreatment.

  10. Overcoming Biomass Recalcitrance by Combining Genetically Modified Switchgrass and Cellulose Solvent-Based Lignocellulose Pretreatment

    PubMed Central

    Zhao, Bingyu; Zhang, Y.-H. Percival

    2013-01-01

    Decreasing lignin content of plant biomass by genetic engineering is believed to mitigate biomass recalcitrance and improve saccharification efficiency of plant biomass. In this study, we compared two different pretreatment methods (i.e., dilute acid and cellulose solvent) on transgenic plant biomass samples having different lignin contents and investigated biomass saccharification efficiency. Without pretreatment, no correlation was observed between lignin contents of plant biomass and saccharification efficiency. After dilute acid pretreatment, a strong negative correlation between lignin content of plant samples and overall glucose release was observed, wherein the highest overall enzymatic glucan digestibility was 70% for the low-lignin sample. After cellulose solvent- and organic solvent-based lignocellulose fractionation pretreatment, there was no strong correlation between lignin contents and high saccharification efficiencies obtained (i.e., 80–90%). These results suggest that the importance of decreasing lignin content in plant biomass to saccharification was largely dependent on pretreatment choice and conditions. PMID:24086283

  11. Surface properties correlate to the digestibility of hydrothermally pretreated lignocellulosic Poaceae biomass feedstocks.

    PubMed

    Djajadi, Demi T; Hansen, Aleksander R; Jensen, Anders; Thygesen, Lisbeth G; Pinelo, Manuel; Meyer, Anne S; Jørgensen, Henning

    2017-01-01

    Understanding factors that govern lignocellulosic biomass recalcitrance is a prerequisite for designing efficient 2nd generation biorefining processes. However, the reasons and mechanisms responsible for quantitative differences in enzymatic digestibility of various biomass feedstocks in response to hydrothermal pretreatment at different severities are still not sufficiently understood. Potentially important lignocellulosic feedstocks for biorefining, corn stover (Zea mays subsp. mays L.), stalks of Miscanthus × giganteus, and wheat straw (Triticum aestivum L.) were systematically hydrothermally pretreated; each at three different severities of 3.65, 3.83, and 3.97, respectively, and the enzymatic digestibility was assessed. Pretreated samples of Miscanthus × giganteus stalks were the least digestible among the biomass feedstocks producing ~24 to 66.6% lower glucose yields than the other feedstocks depending on pretreatment severity and enzyme dosage. Bulk biomass composition analyses, 2D nuclear magnetic resonance, and comprehensive microarray polymer profiling were not able to explain the observed differences in recalcitrance among the pretreated feedstocks. However, methods characterizing physical and chemical features of the biomass surfaces, specifically contact angle measurements (wettability) and attenuated total reflectance-Fourier transform infrared (ATR-FTIR) spectroscopy (surface biopolymer composition) produced data correlating pretreatment severity and enzymatic digestibility, and they also revealed differences that correlated to enzymatic glucose yield responses among the three different biomass types. The study revealed that to a large extent, factors related to physico-chemical surface properties, namely surface wettability as assessed by contact angle measurements and surface content of hemicellulose, lignin, and wax as assessed by ATR-FTIR rather than bulk biomass chemical composition correlated to the recalcitrance of the tested biomass

  12. Transcriptome analysis of Zymomonas mobilis ZM4 reveals mechanisms of tolerance and detoxification of phenolic aldehyde inhibitors from lignocellulose pretreatment

    USDA-ARS?s Scientific Manuscript database

    Background: Phenolic aldehydes generated from lignocellulose pretreatment exhibited severe toxic inhibitions on microbial growth and fermentation. Numerous tolerance studies against furfural, 5-hydroxymethyl-2-furaldehyde (HMF), acetate, and ethanol were reported, but studies on inhibition of phenol...

  13. Lignocellulose Recalcitrance Screening by Integrated High Throughput Hydrothermal Pretreatment and Enzymatic Saccharification

    SciTech Connect

    Selig, M. J.; Tucker, M. P.; Sykes, R. W.; Reichel, K. L.; Brunecky, R.; Himmel, M. E.; Davis, M. F.; Decker, S. R.

    2010-04-01

    We report a novel 96-well multiplate reactor system for comparative analysis of lignocellulose recalcitrance via integrated hydrothermal pretreatment and enzymatic saccharification. The system utilizes stackable nickel/gold-plated 96-well aluminum reactor plates, a clamping device fit to a standard Parr reactor, and robotics for efficient liquids and solids handling. A capacity of 20 plates allows up to 1,920 separate hydrothermal reactions per run. Direct and rapid analysis of key end-products, glucose and xylose, is facilitated by the use of glucose oxidase/peroxidase and xylose dehydrogenase-linked assays. To demonstrate efficacy, a set of 755 poplar core samples from the US Department of Energy's BioEnergy Science Center was tested. Total sugar release ranged from 0.17 to 0.64 g/g of biomass and correlated strongly with the ratio of syringyl to guaiacyl lignins in the samples. Variance among sample replicates was sufficiently minimal to permit clear assignment of differences in recalcitrance throughout this large sample set.

  14. Comparison of different pretreatment methods for lignocellulosic materials. Part II: Influence of pretreatment on the properties of rye straw lignin.

    PubMed

    Wörmeyer, Kai; Ingram, Thomas; Saake, Bodo; Brunner, Gerd; Smirnova, Irina

    2011-03-01

    Several processes have been suggested to convert various types of lignocellulosic biomass into lignin products and saccharides. This paper evaluates the suitability of an organosolv process, a process using soda, a hydrothermal process and a process developed in this work, called the "Aquasolve process" for inclusion into a lignocellulosic biorefinery concept. Part II of this paper investigates the influence of the different pretreatment processes on the properties of rye straw lignin and evaluates their ability to produce high recoveries of high quality lignin. Specifications for high quality lignin products are defined and the isolated lignin fractions are analysed by Klason lignin, carbohydrate and ash content, elemental analysis, thermo-gravimetric analysis, (31)P NMR, and size exclusion chromatography. The organosolv process shows the largest lignin recovery, followed by the soda and Aquasolve processes. Lignin products from the soda process, the Aquasolve process and with reservation the organosolv process show interesting properties for polymer applications.

  15. Biodelignification of lignocellulose substrates: An intrinsic and sustainable pretreatment strategy for clean energy production.

    PubMed

    Chandel, Anuj K; Gonçalves, Bruna C M; Strap, Janice L; da Silva, Silvio S

    2015-01-01

    Lignocellulosic biomass (LB) is a promising sugar feedstock for biofuels and other high-value chemical commodities. The recalcitrance of LB, however, impedes carbohydrate accessibility and its conversion into commercially significant products. Two important factors for the overall economization of biofuel production is LB pretreatment to liberate fermentable sugars followed by conversion into ethanol. Sustainable biofuel production must overcome issues such as minimizing water and energy usage, reducing chemical usage and process intensification. Amongst available pretreatment methods, microorganism-mediated pretreatments are the safest, green, and sustainable. Native biodelignifying agents such as Phanerochaete chrysosporium, Pycnoporous cinnabarinus, Ceriporiopsis subvermispora and Cyathus stercoreus can remove lignin, making the remaining substrates amenable for saccharification. The development of a robust, integrated bioprocessing (IBP) approach for economic ethanol production would incorporate all essential steps including pretreatment, cellulase production, enzyme hydrolysis and fermentation of the released sugars into ethanol. IBP represents an inexpensive, environmentally friendly, low energy and low capital approach for second-generation ethanol production. This paper reviews the advancements in microbial-assisted pretreatment for the delignification of lignocellulosic substrates, system metabolic engineering for biorefineries and highlights the possibilities of process integration for sustainable and economic ethanol production.

  16. Understanding changes in cellulose crystalline structure of lignocellulosic biomass during ionic liquid pretreatment by XRD.

    PubMed

    Zhang, Jiafu; Wang, Yixun; Zhang, Liye; Zhang, Ruihong; Liu, Guangqing; Cheng, Gang

    2014-01-01

    X-ray diffraction (XRD) was used to understand the interactions of cellulose in lignocellulosic biomass with ionic liquids (ILs). The experiment was designed in such a way that the process of swelling and solubilization of crystalline cellulose in plant cell walls was followed by XRD. Three different feedstocks, switchgrass, corn stover and rice husk, were pretreated using 1-butyl-3-methylimidazolium acetate ([C4mim][OAc]) at temperatures of 50-130°C for 6h. At a 5 wt.% biomass loading, increasing pretreatment temperature led to a drop in biomass crystallinity index (CrI), which was due to swelling of crystalline cellulose. After most of the crystalline cellulose was swollen with IL molecules, a low-order structure was found in the pretreated samples. Upon further increasing temperature, cellulose II structure started to form in the pretreated biomass samples as a result of solubilization of cellulose in [C4mim][OAc] and subsequent regeneration.

  17. Solar assisted alkali pretreatment of garden biomass: Effects on lignocellulose degradation, enzymatic hydrolysis, crystallinity and ultra-structural changes in lignocellulose.

    PubMed

    Gabhane, Jagdish; William, S P M Prince; Vaidya, Atul N; Das, Sera; Wate, Satish R

    2015-06-01

    A comprehensive study was carried out to assess the effectiveness of solar assisted alkali pretreatment (SAAP) on garden biomass (GB). The pretreatment efficiency was assessed based on lignocellulose degradation, conversion of cellulose into reducing sugars, changes in the ultra-structure and functional groups of lignocellulose and impact on the crystallinity of cellulose, etc. SAAP was found to be efficient for the removal of lignin and hemicellulose that facilitated enzymatic hydrolysis of cellulose. FTIR and XRD studies provided details on the effectiveness of SAAP on lignocellulosic moiety and crystallinity of cellulose. Scanning electron microscopic analysis showed ultra-structural disturbances in the microfibrils of GB as a result of pretreatment. The mass balance closer of 97.87% after pretreatment confirmed the reliability of SAAP pretreatment. Based on the results, it is concluded that SAAP is not only an efficient means of pretreatment but also economical as it involved no energy expenditure for heat generation during pretreatment. Copyright © 2015 Elsevier Ltd. All rights reserved.

  18. Pretreatment of lignocellulosic biomass with renewable cholinium ionic liquids: Biomass fractionation, enzymatic digestion and ionic liquid reuse.

    PubMed

    An, Yan-Xia; Zong, Min-Hua; Wu, Hong; Li, Ning

    2015-09-01

    Pretreatment of lignocelluloses is a key step in the biorefinery for production of biofuels and valuable platform chemicals. In this work, various lignocelluloses were pretreated using cholinium ionic liquids (ILs) that are wholly composed of biomaterials, and fractionated into carbohydrate-rich materials (CRMs) and lignin-rich materials (LRMs). Cholinium ILs were found to be effective pretreatment solvents for grass lignocelluloses as well as eucalyptus, resulting in significant improvements in the glucose yields (58-75%) in subsequent enzymatic hydrolysis, while they were inefficient to make pine susceptible to biodegradation. Approximately 46% of lignin in native rice straw was fractionated as LRM after pretreatment using cholinium argininate ([Ch][Arg]). [Ch][Arg] showed excellent recyclability, and the total recovery was as high as 75% after reused for 8 cycles. Besides, rice straw pretreated by the recycled IL remained highly digestible, and good glucose yields (63-75%) were achieved after its enzymatic hydrolysis. Copyright © 2015 Elsevier Ltd. All rights reserved.

  19. Enhanced Solid-State Biogas Production from Lignocellulosic Biomass by Organosolv Pretreatment

    PubMed Central

    Mirmohamadsadeghi, Safoora; Zamani, Akram; Horváth, Ilona Sárvári

    2014-01-01

    Organosolv pretreatment was used to improve solid-state anaerobic digestion (SSAD) for methane production from three different lignocellulosic substrates (hardwood elm, softwood pine, and agricultural waste rice straw). Pretreatments were conducted at 150 and 180°C for 30 and 60 min using 75% ethanol solution as an organic solvent with addition of sulfuric acid as a catalyst. The statistical analyses showed that pretreatment temperature was the significant factor affecting methane production. Optimum temperature was 180°C for elmwood while it was 150°C for both pinewood and rice straw. Maximum methane production was 152.7, 93.7, and 71.4 liter per kg carbohydrates (CH), which showed up to 32, 73, and 84% enhancement for rice straw, elmwood, and pinewood, respectively, compared to those from the untreated substrates. An inverse relationship between the total methane yield and the lignin content of the substrates was observed. Kinetic analysis of the methane production showed that the process followed a first-order model for all untreated and pretreated lignocelluloses. PMID:25243134

  20. Bioconversion of un-pretreated lignocellulosic materials by a microbial consortium XDC-2.

    PubMed

    Hui, Wang; Jiajia, Li; Yucai, Lü; Peng, Guo; Xiaofen, Wang; Kazuhiro, Mochidzuki; Zongjun, Cui

    2013-05-01

    The present study investigated the degradation of un-pretreated wheat straw, corn stalk, and rice straw by a lignocellulose-degrading microbial consortium XDC-2. Following six days of cultivation, exocellular xylanase activities were 414.9, 491.9, and 335 U/mL, respectively. After 12 days, the rice straw had lost 39.71% of its weight, hemicellulose and cellulose losses of 78.27% and 14.08%, respectively. The total amount of volatile products reached a maximum on day six for rice straw degradation. The four major types of volatile products were acetic acid, propionic acid, butanoic acid, and glycerin, all of which would be suitable substrates for conversion to methanol by anaerobic digestion. According to PCR-DGGE analysis, XDC-2 remained stable during the degradation process of untreated lignocellulosic biomass. These results demonstrate the potential for further development and application of XDC-2; it is capable of degrading un-pretreated lignocellulosic materials, and has a low cost of operation. Copyright © 2013 Elsevier Ltd. All rights reserved.

  1. Assessing Cellulase Performance on Pretreated Lignocellulosic Biomass Using Saccharification and Fermentation-Based Protocols

    NASA Astrophysics Data System (ADS)

    Dowe, Nancy

    Cellulase enzyme is a key cost component in the production of fuels and chemicals from lignocellulosic biomass. Cellulolytic ability of the enzyme preparation is often measured by activity assays using model substrates such as filter paper. Using lignocellulosic biomass as the substrate to assess enzyme performance has the potential of being more process relevant. We describe two procedures that use washed pretreated cellulosic material to measure the efficacy of cellulase enzymes. First, a saccharification assay that measures glucose yield as a function of the amount of cellulase used in the process. And second, the simultaneous saccharification and fermentation (SSF) assay measures cellulase performance by the amount of ethanol produced from enzymatic hydrolysis of the cellulosic material. You can use both assays to screen cellulases under a variety of substrate types, loadings, and process conditions.

  2. Techno-economic analysis of different pretreatment processes for lignocellulosic-based bioethanol production.

    PubMed

    da Silva, André Rodrigues Gurgel; Torres Ortega, Carlo Edgar; Rong, Ben-Guang

    2016-10-01

    In this work, a method based on process synthesis, simulation and evaluation has been used to setup and study the industrial scale lignocellulosic bioethanol productions processes. Scenarios for pretreatment processes of diluted acid, liquid hot water and ammonia fiber explosion were studied. Pretreatment reactor temperature, catalyst loading and water content as well as solids loading in the hydrolysis reactor were evaluated regarding its effects on the process energy consumption and bioethanol concentration. The best scenarios for maximizing ethanol concentration and minimizing total annual costs (TAC) were selected and their minimum ethanol selling price was calculated. Ethanol concentration in the range of 2-8% (wt.) was investigated after the pretreatment. The best scenarios maximizing the ethanol concentration and minimizing TAC obtained a reduction of 19.6% and 30.2% respectively in the final ethanol selling price with respect to the initial base case.

  3. Sulfite pretreatment to overcome recalcitrance of lignocellulose (SPORL) for robust enzymatic saccharification of hardwoods.

    PubMed

    Wang, G S; Pan, X J; Zhu, J Y; Gleisner, R; Rockwood, D

    2009-01-01

    This study demonstrates sulfite pretreatment to overcome recalcitrance of lignocellulose (SPORL) for robust bioconversion of hardwoods. With only about 4% sodium bisulfite charge on aspen and 30-min pretreatment at temperature 180 degrees C, SPORL can achieve near-complete cellulose conversion to glucose in a wide range of pretreatment liquor of pH 2.0-4.5 in only about 10 h enzymatic hydrolysis. The enzyme loading was about 20 FPU cellulase plus 30 CBU beta-glucosidase per gram of cellulose. The production of fermentation inhibitor furfural was less than 20 mg/g of aspen wood at pH 4.5. With pH 4.5, SPORL avoided reactor corrosion problem and eliminated the need for substrate neutralization prior to enzymatic hydrolysis. Similar results were obtained from maple and eucalyptus.

  4. Multifaceted metabolomics approaches for characterization of lignocellulosic biomass degradation products formed during ammonia fiber expansion pretreatment

    NASA Astrophysics Data System (ADS)

    Vismeh, Ramin

    Lignocellulosic biomass represents a rather unused resource for production of biofuels, and it offers an alternative to food sources including corn starch. However, structural and compositional impediments limit the digestibility of sugar polymers in biomass cell walls. Thermochemical pretreatments improve accessibility of cellulose and hemicellulose to hydrolytic enzymes. However, most pretreatment methods generate compounds that either inhibit enzymatic hydrolysis or exhibit toxicity to fermentive microorganisms. Characterization and quantification of these products are essential for understanding chemistry of the pretreatment and optimizing the process efficiency to achieve higher ethanol yields. Identification of oligosaccharides released during pretreatment is also critical for choosing hydrolases necessary for cost-effective hydrolysis of cellulose and hemicellulose to fermentable monomeric sugars. Two chapters in this dissertation describe new mass spectrometry-based strategies for characterization and quantification of products that are formed during ammonia fiber expansion (AFEX) pretreatment of corn stover. Comparison of Liquid Chromatography Mass Spectrometry (LC/MS) profiles of AFEX-treated corn stover (AFEXTCS) and untreated corn stover (UTCS) extract shows that ammonolysis of lignin carbohydrate ester linkages generates a suite of nitrogenous compounds that are present only in the AFEXTCS extract and represent a loss of ammonia during processing. Several of these products including acetamide, feruloyl, coumaroyl and diferuloyl amides were characterized and quantified in the AFEXTCS extracts. The total amount of characterized and uncharacterized phenolic amides measured 17.4 mg/g AFEXTCS. Maillard reaction products including pyrazines and imidazoles were also identified and measured in the AFEXTCS extract totaling almost 1 mg/g AFEXTCS. The total of quantified nitrogenous products that are formed during AFEX was 43.4 mg/g AFEXTCS which was equivalent

  5. Alkaline/peracetic acid as a pretreatment of lignocellulosic biomass for ethanol fuel production

    NASA Astrophysics Data System (ADS)

    Teixeira, Lincoln Cambraia

    Peracetic acid is a lignin oxidation pretreatment with low energy input by which biomass can be treated in a silo type system for improving enzymatic digestibility of lignocellulosic materials for ethanol production. Experimentally, ground hybrid poplar wood and sugar cane bagasse are placed in plastic bags and a peracetic acid solution is added to the biomass in different concentrations based on oven-dry biomass. The ratio of solution to biomass is 6:1; after initial mixing of the resulting paste, a seven-day storage period at about 20°C is used in this study. As a complementary method, a series of pre-pretreatments using stoichiometric amounts of sodium hydroxide and ammonium hydroxide based on 4-methyl-glucuronic acid and acetyl content in the biomass is been performed before addition of peracetic acid. The alkaline solutions are added to the biomass in a ratio of 14:1 solution to biomass; the slurry is mixed for 24 hours at ambient temperature. The above procedures give high xylan content substrates. Consequently, xylanase/beta-glucosidase combinations are more effective than cellulase preparations in hydrolyzing these materials. The pretreatment effectiveness is evaluated using standard enzymatic hydrolysis and simultaneous saccharification and cofermentation (SSCF) procedures. Hybrid poplar wood pretreated with 15 and 21% peracetic acid based on oven-dry weight of wood gives glucan conversion yields of 76.5 and 98.3%, respectively. Sugar cane bagasse pretreated with the same loadings gives corresponding yields of 85.9 and 93.1%. Raw wood and raw bagasse give corresponding yields of 6.8 and 28.8%, respectively. The combined 6% NaOH/15% peracetic acid pretreatments increase the glucan conversion yields from 76.5 to 100.0% for hybrid poplar wood and from 85.9 to 97.6% for sugar cane bagasse. Respective ethanol yields of 92.8 and 91.9% are obtained from 6% NaOH/15% peracetic acid pretreated materials using recombinant Zymomonas mobilis CP4/pZB5. Peracetic acid

  6. Physical and chemical pretreatment of lignocellulosics in pineapple (Ananus comosus) peels dried for investment

    NASA Astrophysics Data System (ADS)

    Sukkaew, Adulsman; Boonsong, Panthip; Thongpradistha, Sriubol; Intan, Maimoon

    2017-08-01

    Pineapple (Ananus comosus) Peels, once known as waste from agricultural, can be a problem when we eliminate in agriculture and industry. The current technology can help preliminarily to solve this problem. The sustainable solution to this problem is lignocellulosics pretreatments for converted saccharide as a carbon source for ethanol production. The objective of this study is the investigation of pineapple peels pretreatment to produce fermentable sugar by drying and digesting 5% sulfuric acid (H2SO4). And study of cost economic passed selection for investment. The result found that the best investment of drying was 100 °C at 11 hours for the sulphuric acid which could be easily crushed into a fine powder. Moreover, digestion of pineapple peels gave the best total sugar 252.2 g/l by 5% H2SO4 incubated for 60 minutes at room temperature. The pineapple peels were digested by 5%H2SO4 concentration by incubating for 60 minutes at room temperature, finding to be the best condition and the lowest investment. Finally, the optimisation of investment and management for lignocellulosic pretreatment will improve efficiency of strategy for economic and energy development.

  7. Supercritical carbon dioxide pretreatment of corn stover and switchgrass for lignocellulosic ethanol production.

    PubMed

    Narayanaswamy, Naveen; Faik, Ahmed; Goetz, Douglas J; Gu, Tingyue

    2011-07-01

    Supercritical CO(2) (SC-CO(2)), a green solvent suitable for a mobile lignocellulosic biomass processor, was used to pretreat corn stover and switchgrass at various temperatures and pressures. The CO(2) pressure was released as quickly as possible by opening a quick release valve during the pretreatment. The biomass was hydrolyzed after pretreatment using cellulase combined with β-glucosidase. The hydrolysate was analyzed for the amount of glucose released. Glucose yields from corn stover samples pretreated with SC-CO(2) were higher than the untreated sample's 12% glucose yield (12 g/100g dry biomass) and the highest glucose yield of 30% was achieved with SC-CO(2) pretreatment at 3500 psi and 150°C for 60 min. The pretreatment method showed very limited improvement (14% vs. 12%) in glucose yield for switchgrass. X-ray diffraction results indicated no change in crystallinity of the SC-CO(2) treated corn stover when compared to the untreated, while SEM images showed an increase in surface area.

  8. High-solids biphasic CO2-H2O pretreatment of lignocellulosic biomass.

    PubMed

    Luterbacher, Jeremy S; Tester, Jefferson W; Walker, Larry P

    2010-10-15

    A high pressure (200 bar) CO(2)-H(2)O process was developed for pretreating lignocellulosic biomass at high-solid contents, while minimizing chemical inputs. Hardwood was pretreated at 20 and 40 (wt.%) solids. Switchgrass, corn stover, big bluestem, and mixed perennial grasses (a co-culture of big bluestem and switchgrass) were pretreated at 40 (wt.%) solids. Operating temperatures ranged from 150 to 250 degrees C, and residence times from 20 s to 60 min. At these conditions a biphasic mixture of an H(2)O-rich liquid (hydrothermal) phase and a CO(2)-rich supercritical phase coexist. Following pretreatment, samples were then enzymatically hydrolyzed. Total yields, defined as the fraction of the theoretical maximum, were determined for glucose, hemicellulose sugars, and two degradation products: furfural and 5-hydroxymethylfurfural. Response surfaces of yield as a function of temperature and residence time were compared for different moisture contents and biomass species. Pretreatment at 170 degrees C for 60 min gave glucose yields of 77%, 73%, and 68% for 20 and 40 (wt.%) solids mixed hardwood and mixed perennial grasses, respectively. Pretreatment at 160 degrees C for 60 min gave glucan to glucose yields of 81% for switchgrass and 85% for corn stover.

  9. Selection of the best chemical pretreatment for lignocellulosic substrate Prosopis juliflora.

    PubMed

    Naseeruddin, Shaik; Srilekha Yadav, K; Sateesh, L; Manikyam, Ananth; Desai, Suseelendra; Venkateswar Rao, L

    2013-05-01

    Pretreatment is a pre-requisite step in bioethanol production from lignocellulosic biomass required to remove lignin and increase the porosity of the substrate for saccharification. In the present study, chemical pretreatment of Prosopis juliflora was performed using alkali (NaOH, KOH, and NH3), reducing agents (Na2S2O4, Na2SO3) and NaClO2 in different concentration ranges at room temperature (30±2 °C) to remove maximum lignin with minimum sugar loss. Further, biphasic acid hydrolysis of the various pretreated substrates was performed at mild temperatures. Considering the amount of holocellulose hydrolyzed and inhibitors released during hydrolysis, best chemical pretreatment was selected. Among all the chemicals investigated, pretreatment with sodium dithionite at concentration of 2% (w/v) removed maximum lignin (80.46±1.35%) with a minimum sugar loss (2.56±0.021%). Subsequent biphasic acid hydrolysis of the sodium dithionite pretreated substrate hydrolyzed 40.09±1.22% of holocellulose and released minimum amount of phenolics (1.04±0.022 g/L) and furans (0.41±0.012 g/L) in the hydrolysate.

  10. Using FTIR spectroscopy to model alkaline pretreatment and enzymatic saccharification of six lignocellulosic biomasses.

    PubMed

    Sills, Deborah L; Gossett, James M

    2012-04-01

    Fourier transform infrared, attenuated total reflectance (FTIR-ATR) spectroscopy, combined with partial least squares (PLS) regression, accurately predicted solubilization of plant cell wall constituents and NaOH consumption through pretreatment, and overall sugar productions from combined pretreatment and enzymatic hydrolysis. PLS regression models were constructed by correlating FTIR spectra of six raw biomasses (two switchgrass cultivars, big bluestem grass, a low-impact, high-diversity mixture of prairie biomasses, mixed hardwood, and corn stover), plus alkali loading in pretreatment, to nine dependent variables: glucose, xylose, lignin, and total solids solubilized in pretreatment; NaOH consumed in pretreatment; and overall glucose and xylose conversions and yields from combined pretreatment and enzymatic hydrolysis. PLS models predicted the dependent variables with the following values of coefficient of determination for cross-validation (Q²): 0.86 for glucose, 0.90 for xylose, 0.79 for lignin, and 0.85 for total solids solubilized in pretreatment; 0.83 for alkali consumption; 0.93 for glucose conversion, 0.94 for xylose conversion, and 0.88 for glucose and xylose yields. The sugar yield models are noteworthy for their ability to predict overall saccharification through combined pretreatment and enzymatic hydrolysis per mass dry untreated solids without a priori knowledge of the composition of solids. All wavenumbers with significant variable-important-for-projection (VIP) scores have been attributed to chemical features of lignocellulose, demonstrating the models were based on real chemical information. These models suggest that PLS regression can be applied to FTIR-ATR spectra of raw biomasses to rapidly predict effects of pretreatment on solids and on subsequent enzymatic hydrolysis. Copyright © 2011 Wiley Periodicals, Inc.

  11. Enzyme pretreatment of grass lignocellulose for potential high-value co-products and an improved fermentable substrate.

    PubMed

    Anderson, William F; Peterson, Joy; Akin, Danny E; Morrison, W Herbert

    2005-01-01

    Crops such as switchgrass (Panicum virgatum L.), bermudagrass(Cynodon dactylon L.), or napiergrass (Pennisetum purpureum Schumach.)have the capacity to produce large quantities of lignocellulose for biofuel(1). To facilitate use of lignocellulosic material for ethanol, it will be necessaryto determine cost-efficient pretreatments to enhance the conversion tofermentable sugars. The lignified residual products from ethanol productioncould also provide a value-added co-product for industrial feedstocks(e.g., nutritional antioxidants, ultraviolet absorbers, resins).

  12. High selective delignification using oxidative ionic liquid pretreatment at mild conditions for efficient enzymatic hydrolysis of lignocellulose.

    PubMed

    Pang, Zhiqiang; Lyu, Wenkang; Dong, Cuihua; Li, Hongxing; Yang, Guihua

    2016-08-01

    Herein, the oxidative ionic liquid (IL) pretreatment for overcoming recalcitrance of lignocellulose with selective delignification was investigated, and the subsequent enzymatic hydrolysis was evaluated. IL pretreatment incorporating oxygen delignification could enhance lignin extraction with high selectivity at low carbohydrate loss. The dual-action of oxidative decomposition and dissolution by 1-butyl-3-methlimidazolium chloride (BmimCl) on biomass were synergistically acted, accounting for efficient recalcitrance removal. In addition, the mild oxidative IL treatment only slightly converted crystalline cellulose into amorphous structure, and the extensive extraction of the amorphous lignin and carbohydrate resulted to the expose of cellulose with high susceptibility. Correspondingly, the enzymatic hydrolysis of the pretreated lignocellulose was greatly enhanced. The oxidative IL treatment at mild conditions, collaborating BmimCl treatment with oxygen delignification is a promising and effective system for overcoming the robust structure of lignocellulose.

  13. Effect of structural changes of lignocelluloses material upon pre-treatment using green solvents

    NASA Astrophysics Data System (ADS)

    Gunny, Ahmad Anas Nagoor; Arbain, Dachyar; Jamal, Parveen

    2017-04-01

    The Malaysia Biomass strategy 2020 stated that the key step of biofuel production from biomass lies on the pretreatment process. Conventional `pre-treatment' methods are `non-green" and costly. The recent green and cost-effective biomass pretreatment is using new generation of Ionic Liquids also known as Deep Eutectic Solvents (DESs). DESs are made of renewable components are cheaper, greener and the process synthesis are easier. Thus, the present paper concerns with the preparation of various combination of DES and to study the effect of DESs pretreatment process on microcrystalline cellulose (MCC), a model substrate. The crystalline structural changes were studied using using X-ray Diffraction Methods, Fourier Transformed Infrared Spectroscopy (FTIR) and surface area and pore size analysis. Results showed reduction of crystalline structure of MCC treated with the DESs and increment of surface area and pore size of MCC after pre-treatment process. These results indicated the DES has successfully converted the lignocelluloses material in the form suitable for hydrolysis and conversion to simple sugar.

  14. Modeling Sucrose Hydrolysis in Dilute Sulfuric Acid Solutions at Pretreatment Conditions for Lignocellulosic Biomass

    SciTech Connect

    Bower, S.; Wickramasinghe, R.; Nagle, N. J.; Schell, D. J.

    2008-01-01

    Agricultural and herbaceous feedstocks may contain appreciable levels of sucrose. The goal of this study was to evaluate the survivability of sucrose and its hydrolysis products, fructose and glucose, during dilute sulfuric acid processing at conditions typically used to pretreat lignocellulose biomass. Solutions containing 25 g/l sucrose with 0.1-2.0% (w/w) sulfuric acid concentrations were treated at temperatures of 160-200 C for 3-12 min. Sucrose was observed to completely hydrolyze at all treatment conditions. However, appreciable concentrations of fructose and glucose were detected and glucose was found to be significantly more stable than fructose. Different mathematical approaches were used to fit the kinetic parameters for acid-catalyzed thermal degradation of these sugars. Since both sugars may survive dilute acid pretreatment, they could provide an additional carbon source for production of ethanol and other bio-based products.

  15. The effects of cathodic micro-voltage combined with hydrothermal pretreatment on methane fermentation of lignocellulose substrate

    NASA Astrophysics Data System (ADS)

    Liu, Dianxin; Ning, Ping; Qu, Guangfei; Huang, Xi; Liu, Yuhuan; Zhang, Jian

    2017-05-01

    The methane fermentation study assisted with cathodic micro-voltage was carried out to investigate the electric field effects on the fermentation of hydrothermally pretreated lignocellulose substrate. It was illustrated that a 0.25V cathode voltage and hydrothermal pretreatment could improve the biogas production, biogas quality and lignocellulose degradation ratio significantly. The cumulative biogas productions in the fermentation of hydrothermally pretreated cow dungs at 50°C, 150°C and 200°C with a 0.25V cathode voltage were observed in a total of 6640mL, 9218mL and 9456mL respectively over a detention time of 33 days. In comparison with the fermentation pretreated at 200°C without any voltage, nearly doubled of cumulative biogas production was obtained in the process of cathode-assisted fermentation. It was also observed that the daily methane content greater than or equal to 70% in the biogas generated with cathode voltage were clearly greater than that without voltages. Furthermore, the fermentation applied with a 0.25V cathode voltage had resulted into significant increases of 12.64% and 9.44% in lignin and cellulose degradation ratio relative to voltage free fermentation. And in the process of fermentation applied with cathode voltage, the final lignocellulose degradation ratio increased with the hydrothermal pretreatment temperature. Thus, the hydrothermal pretreatment and assisting fermentation with low cathode voltage can effectively promote the lignocellulose degradation. All results revealed that cathodic micro-voltage combined with hydrothermal pretreatment can remarkably improve the fermentation of lignocellulosic materials, indicating that a more effective fermentation technology can be developed by applying with cathodic micro-voltage.

  16. Powerful peracetic acid-ionic liquid pretreatment process for the efficient chemical hydrolysis of lignocellulosic biomass.

    PubMed

    Uju; Goto, Masahiro; Kamiya, Noriho

    2016-08-01

    The aim of this work was to design a new method for the efficient saccharification of lignocellulosic biomass (LB) using a combination of peracetic acid (PAA) pretreatment with ionic liquid (IL)-HCl hydrolysis. The pretreatment of LBs with PAA disrupted the lignin fractions, enhanced the dissolution of LB and led to a significant increase in the initial rate of the IL-HCl hydrolysis. The pretreatment of Bagasse with PAA prior to its 1-buthyl-3-methylimidazolium chloride ([Bmim][Cl])-HCl hydrolysis, led to an improvement in the cellulose conversion from 20% to 70% in 1.5h. Interestingly, the 1-buthyl-3-methylpyridium chloride ([Bmpy][Cl])-HCl hydrolysis of Bagasse gave a cellulose conversion greater than 80%, with or without the PAA pretreatment. For LB derived from seaweed waste, the cellulose conversion reached 98% in 1h. The strong hydrolysis power of [Bmpy][Cl] was attributed to its ability to transform cellulose I to II, and lowering the degree of polymerization of cellulose.

  17. By-products resulting from lignocellulose pretreatment and their inhibitory effect on fermentations for (bio)chemicals and fuels.

    PubMed

    van der Pol, Edwin C; Bakker, Robert R; Baets, Peter; Eggink, Gerrit

    2014-12-01

    Lignocellulose might become an important feedstock for the future development of the biobased economy. Although up to 75 % of the lignocellulose dry weight consists of sugar, it is present in a polymerized state and cannot be used directly in most fermentation processes for the production of chemicals and fuels. Several methods have been developed to depolymerize the sugars present in lignocellulose, making the sugars available for fermentation. In this review, we describe five different pretreatment methods and their effect on the sugar and non-sugar fraction of lignocellulose. For several pretreatment methods and different types of lignocellulosic biomass, an overview is given of by-products formed. Most unwanted by-products present after pretreatment are dehydrated sugar monomers (furans), degraded lignin polymers (phenols) and small organic acids. Qualitative and quantitative effects of these by-products on fermentation processes have been studied. We conclude this review by giving an overview of techniques and methods to decrease inhibitory effects of unwanted by-products.

  18. A critical review on analysis in pretreatment of lignocelluloses: Degree of polymerization, adsorption/desorption, and accessibility.

    PubMed

    Karimi, Keikhosro; Taherzadeh, Mohammad J

    2016-03-01

    The pretreatment of lignocelluloses results in changes in the different properties of these materials. In a recent review (Karimi and Taherzadeh, 2016), the details of compositional, imaging, and crystallinity analyses of lignocelluloses were reviewed and critically discussed. Changes in the cellulose degree of polymerization, accessibility, and enzyme adsorption/desorption by pretreatments are also among the effective parameters. This paper deals with the measurement techniques, modifications, and relation to bioconversions, as well as the challenges of these three properties. These analyses are very helpful to investigate the pretreatment processes; however, the pretreatments are very complicated and challenging processes. It is not easily possible to study the effects of only one of these parameters and even to find which one is the dominant one. Moreover, it is not possible to accurately predict the changes in the bioconversion yield using these methods.

  19. Evaluation of mountain beetle-infested lodgepole pine for cellulosic ethanol production by sulfite pretreatment to overcome recalcitrance of lignocellulose

    Treesearch

    X. Luo; R. Gleisner; S. Tian; J. Negron; W. Zhu; E. Horn; X. J. Pan; J. Y. Zhu

    2010-01-01

    The potentials of deteriorated mountain pine beetle (Dendroctonus ponderosae)-killed lodgepole pine (Pinus contorta) trees for cellulosic ethanol production were evaluated using the sulfite pretreatment to overcome recalcitrance of lignocellulose (SPORL) process. The trees were harvested from two sites in the United States Arapaho-Roosevelt National Forest, Colorado....

  20. Facile pretreatment of lignocellulosic biomass at high loadings in room temperature ionic liquids.

    PubMed

    Wu, Hong; Mora-Pale, Mauricio; Miao, Jianjun; Doherty, Thomas V; Linhardt, Robert J; Dordick, Jonathan S

    2011-12-01

    Ionic liquids (ILs) have emerged as attractive solvents for lignocellulosic biomass pretreatment in the production of biofuels and chemical feedstocks. However, the high cost of ILs is a key deterrent to their practical application. Here, we show that acetate based ILs are effective in dramatically reducing the recalcitrance of corn stover toward enzymatic polysaccharide hydrolysis even at loadings of biomass as high as 50% by weight. Under these conditions, the IL serves more as a pretreatment additive rather than a true solvent. Pretreatment of corn stover with 1-ethyl-3-methylimidizolium acetate ([Emim] [OAc]) at 125 ± 5°C for 1 h resulted in a dramatic reduction of cellulose crystallinity (up to 52%) and extraction of lignin (up to 44%). Enzymatic hydrolysis of the IL-treated biomass was performed with a common commercial cellulase/xylanase from Trichoderma reesei and a commercial β-glucosidase, and resulted in fermentable sugar yields of ∼80% for glucose and ∼50% for xylose at corn stover loadings up to 33% (w/w) and 55% and 34% for glucose and xylose, respectively, at 50% (w/w) biomass loading. Similar results were observed for the IL-facilitated pretreatment of switchgrass, poplar, and the highly recalcitrant hardwood, maple. At 4.8% (w/w) corn stover, [Emim][OAc] can be readily reused up to 10 times without removal of extracted components, such as lignin, with no effect on subsequent fermentable sugar yields. A significant reduction in the amount of IL combined with facile recycling has the potential to enable ILs to be used in large-scale biomass pretreatment. Copyright © 2011 Wiley Periodicals, Inc.

  1. Fast Microwave-assisted Pretreatment for Bioconversion of Sawdust Lignocellulose to Glucose

    NASA Astrophysics Data System (ADS)

    Nyoman Sudiana, I.; Mitsudo, Seitaro; Endang Susilowati, Prima; Ketut Sutiari, Desak; Widana Arsana, Made; Zamrun Firihu, Muhammad; Ode Ngkoimani, La; Aba, La; Sahaluddin Hasan, Erzam; Cahyono, Edi; Sabchevski, Svilen; Aripin, Haji; Gde Suastika, Komang

    2017-05-01

    A preliminary study of application microwave energy for bioconversion of cellulosic sawdust to glucose was performed. The effects of the microwave were compared to those of the conventional method for each solvent. It was expected that a broader mechanism responsible for the microwave effects on the chemical processes, especially the pretreatment on the hydrolysis of cellulose can be explained. Reagents used were an acid (HCl), an alkali (NaOH), and distilled water (H2O). The experimental results showed that the microwave-assisted pretreatment on the lignocellulosic sawdust faster than by using conventional heating (hotplate). Moreover by using microwave a higher glucose content compared to the conventional method was found. With microwave during hydrolisis, high temperatures and high reagent concentrations were not required. Pretreatment with a microwave at 800 Watt and solvent NaOH 22,50 mg/mL at a temperature of 120°c appeared to be most efficient found in this experiment. These results indicate that microwave effective for bioconversion of cellulosic sawdust to glucose. The microstructure evaluation by using SEM and XRD should be performed to understand more detail the effect especially on their cellulosic structural evolution.

  2. Effect of enzymatic pretreatment of various lignocellulosic substrates on production of phenolic compounds and biomethane potential.

    PubMed

    Schroyen, Michel; Vervaeren, Han; Vandepitte, Hanne; Van Hulle, Stijn W H; Raes, Katleen

    2015-09-01

    Pretreatment of lignocellulosic biomass is necessary to enhance the hydrolysis, which is the rate-limiting step in biogas production. Laccase and versatile peroxidase are enzymes known to degrade lignin. Therefore, the impact of enzymatic pretreatment was studied on a variety of biomass. A significant higher release in total phenolic compounds (TPC) was observed, never reaching the inhibiting values for anaerobic digestion. The initial concentration of TPC was higher in the substrates containing more lignin, miscanthus and willow. The anaerobic digestion of these two substrates resulted in a significant lower biomethane production (68.8-141.7 Nl/kg VS). Other substrates, corn stover, flax, wheat straw and hemp reached higher biomethane potential values (BMP), between 241 and 288 Nl/kg VS. Ensilaged maize reached 449 Nl/kg VS, due to the ensilation process, which can be seen as a biological and acid pretreatment. A significant relation (R(2) = 0.89) was found between lignin content and BMP. Copyright © 2015 Elsevier Ltd. All rights reserved.

  3. Utilization of hydrolysate from lignocellulosic biomass pretreatment to generate electricity by enzymatic fuel cell system.

    PubMed

    Kim, Sung Bong; Kim, Dong Sup; Yang, Ji Hyun; Lee, Junyoung; Kim, Seung Wook

    2016-04-01

    The waste hydrolysate after dilute acid pretreatment (DAP) of lignocellulosic biomass was utilized to generate electricity using an enzymatic fuel cell (EFC) system. During DAP, the components of biomass containing hemicellulose and other compounds are hydrolyzed, and glucose is solubilized into the dilute acid solution, called as the hydrolysate liquid. Glucose oxidase (GOD) and laccase (Lac) were assembled on the electrode of the anode and cathode, respectively. Cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) were measured, and the maximum power density was found to be 1.254×10(3) μW/cm(2). The results indicate that the hydrolysate from DAP is a reliable electrolyte containing the fuel of EFC. Moreover, the impurities in the hydrolysate such as phenols and furans slightly affected the charge transfer on the surface of the electrode, but did not affect the power generation of the EFC system in principal.

  4. Pretreating lignocellulosic biomass by the concentrated phosphoric acid plus hydrogen peroxide (PHP) for enzymatic hydrolysis: evaluating the pretreatment flexibility on feedstocks and particle sizes.

    PubMed

    Wang, Qing; Wang, Zhanghong; Shen, Fei; Hu, Jinguang; Sun, Fubao; Lin, Lili; Yang, Gang; Zhang, Yanzong; Deng, Shihuai

    2014-08-01

    In order to seek a high-efficient pretreatment path for converting lignocellulosic feedstocks to fermentable sugars by enzymatic hydrolysis, the concentrated H₃PO₄ plus H₂O₂ (PHP) was attempted to pretreat different lignocellulosic biomass for evaluating the pretreatment flexibility on feedstocks. Meanwhile, the responses of pretreatment to particle sizes were also evaluated. When the PHP-pretreatment was employed (final H₂O₂ and H₃PO₄ concentration of 1.77% and 80.0%), 71-96% lignin and more than 95% hemicellulose in various feedstocks (agricultural residues, hardwood, softwood, bamboo, and their mixture, and garden wastes mixture) can be removed. Consequently, more than 90% glucose conversion was uniformly achieved indicating PHP greatly improved the pretreatment flexibility to different feedstocks. Moreover, when wheat straw and oak chips were PHP-pretreated with different sizes, the average glucose conversion reached 94.9% and 100% with lower coefficient of variation (7.9% and 0.0%), which implied PHP-pretreatment can significantly weaken the negative effects of feedstock sizes on subsequent conversion.

  5. Optimization of hydrothermal pretreatment of lignocellulosic biomass in the bioethanol production process.

    PubMed

    Nitsos, Christos K; Matis, Konstantinos A; Triantafyllidis, Kostas S

    2013-01-01

    The natural resistance to enzymatic deconstruction exhibited by lignocellulosic materials has designated pretreatment as a key step in the biological conversion of biomass to ethanol. Hydrothermal pretreatment in pure water represents a challenging approach because it is a method with low operational costs and does not involve the use of organic solvents, difficult to handle chemicals, and "external" liquid or solid catalysts. In the present work, a systematic study has been performed to optimize the hydrothermal treatment of lignocellulosic biomass (beech wood) with the aim of maximizing the enzymatic digestibility of cellulose in the treated solids and obtaining a liquid side product that could also be utilized for the production of ethanol or valuable chemicals. Hydrothermal treatment experiments were conducted in a batch-mode, high-pressure reactor under autogeneous pressure at varying temperature (130-220 °C) and time (15-180 min) regimes, and at a liquid-to-solid ratio (LSR) of 15. The intensification of the process was expressed by the severity factor, log R(o). The major changes induced in the solid biomass were the dissolution/removal of hemicellulose to the process liquid and the partial removal and relocation of lignin on the external surface of biomass particles in the form of recondensed droplets. The above structural changes led to a 2.5-fold increase in surface area and total pore volume of the pretreated biomass solids. The enzymatic hydrolysis of cellulose to glucose increased from less than 7 wt% for the parent biomass to as high as 70 wt% for the treated solids. Maximum xylan recovery (60 wt%) in the hydrothermal process liquid was observed at about 80 wt% hemicellulose removal; this was accomplished by moderate treatment severities (log R(o)=3.8-4.1). At higher severities (log R(o)=4.7), xylose degradation products, mainly furfural and formic acid, were the predominant chemicals formed. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGa

  6. Utilization of Ionic Liquids in Lignocellulose Biorefineries as Agents for Separation, Derivatization, Fractionation, or Pretreatment.

    PubMed

    Peleteiro, Susana; Rivas, Sandra; Alonso, José L; Santos, Valentín; Parajó, Juan C

    2015-09-23

    Ionic liquids (ILs) can play multiple roles in lignocellulose biorefineries, including utilization as agents for the separation of selected compounds or as reaction media for processing lignocellulosic materials (LCM). Imidazolium-based ILs have been proposed for separating target components from LCM biorefinery streams, for example, the dehydration of ethanol-water mixtures or the extractive separation of biofuels (ethanol, butanol) or lactic acid from the respective fermentation broths. As in other industries, ILs are potentially suitable for removing volatile organic compounds or carbon dioxide from gaseous biorefinery effluents. On the other hand, cellulose dissolution in ILs allows homogeneous derivatization reactions to be carried out, opening new ways for product design or for improving the quality of the products. Imidazolium-based ILs are also suitable for processing native LCM, allowing the integral benefit of the feedstocks via separation of polysaccharides and lignin. Even strongly lignified materials can yield cellulose-enriched substrates highly susceptible to enzymatic hydrolysis upon ILs processing. Recent developments in enzymatic hydrolysis include the identification of ILs causing limited enzyme inhibition and the utilization of enzymes with improved performance in the presence of ILs.

  7. Aromatic inhibitors derived from ammonia-pretreated lignocellulose hinder bacterial ethanologenesis by activating regulatory circuits controlling inhibitor efflux and detoxification

    PubMed Central

    Keating, David H.; Zhang, Yaoping; Ong, Irene M.; McIlwain, Sean; Morales, Eduardo H.; Grass, Jeffrey A.; Tremaine, Mary; Bothfeld, William; Higbee, Alan; Ulbrich, Arne; Balloon, Allison J.; Westphall, Michael S.; Aldrich, Josh; Lipton, Mary S.; Kim, Joonhoon; Moskvin, Oleg V.; Bukhman, Yury V.; Coon, Joshua J.; Kiley, Patricia J.; Bates, Donna M.; Landick, Robert

    2014-01-01

    Efficient microbial conversion of lignocellulosic hydrolysates to biofuels is a key barrier to the economically viable deployment of lignocellulosic biofuels. A chief contributor to this barrier is the impact on microbial processes and energy metabolism of lignocellulose-derived inhibitors, including phenolic carboxylates, phenolic amides (for ammonia-pretreated biomass), phenolic aldehydes, and furfurals. To understand the bacterial pathways induced by inhibitors present in ammonia-pretreated biomass hydrolysates, which are less well studied than acid-pretreated biomass hydrolysates, we developed and exploited synthetic mimics of ammonia-pretreated corn stover hydrolysate (ACSH). To determine regulatory responses to the inhibitors normally present in ACSH, we measured transcript and protein levels in an Escherichia coli ethanologen using RNA-seq and quantitative proteomics during fermentation to ethanol of synthetic hydrolysates containing or lacking the inhibitors. Our study identified four major regulators mediating these responses, the MarA/SoxS/Rob network, AaeR, FrmR, and YqhC. Induction of these regulons was correlated with a reduced rate of ethanol production, buildup of pyruvate, depletion of ATP and NAD(P)H, and an inhibition of xylose conversion. The aromatic aldehyde inhibitor 5-hydroxymethylfurfural appeared to be reduced to its alcohol form by the ethanologen during fermentation, whereas phenolic acid and amide inhibitors were not metabolized. Together, our findings establish that the major regulatory responses to lignocellulose-derived inhibitors are mediated by transcriptional rather than translational regulators, suggest that energy consumed for inhibitor efflux and detoxification may limit biofuel production, and identify a network of regulators for future synthetic biology efforts. PMID:25177315

  8. Aromatic inhibitors derived from ammonia-pretreated lignocellulose hinder bacterial ethanologenesis by activating regulatory circuits controlling inhibitor efflux and detoxification

    SciTech Connect

    Keating, David H.; Zhang, Yaoping; Ong, Irene M.; McIlwain, Sean; Morales, Eduardo H.; Grass, Jeffrey A.; Tremaine, Mary; Bothfeld, William; Higbee, Alan; Ulbrich, Arne; Balloon, Allison J.; Westphall, Michael S.; Aldrich, Josh; Lipton, Mary S.; Kim, Joonhoon; Moskvin, Oleg V.; Bukhman, Yury V.; Coon, Joshua J.; Kiley, Patricia J.; Bates, Donna M.; Landick, Robert

    2014-08-13

    Efficient microbial conversion of lignocellulosic hydrolysates to biofuels is a key barrier to the economically viable deployment of lignocellulosic biofuels. A chief contributor to this barrier is the impact on microbial processes and energy metabolism of lignocellulose-derived inhibitors, including phenolic carboxylates, phenolic amides (for ammonia-pretreated biomass), phenolic aldehydes, and furfurals. To understand the bacterial pathways induced by inhibitors present in ammonia-pretreated biomass hydrolysates, which are less well studied than acid-pretreated biomass hydrolysates, we developed and exploited synthetic mimics of ammonia-pretreated corn stover hydrolysate (ACSH). To determine regulatory responses to the inhibitors normally present in ACSH, we measured transcript and protein levels in an Escherichia coli ethanologen using RNA-seq and quantitative proteomics during fermentation to ethanol of synthetic hydrolysates containing or lacking the inhibitors. Our study identified four major regulators mediating these responses, the MarA/SoxS/Rob network, AaeR, FrmR, and YqhC. Induction of these regulons was correlated with a reduced rate of ethanol production, buildup of pyruvate, depletion of ATP and NAD(P)H, and an inhibition of xylose conversion. The aromatic aldehyde inhibitor 5-hydroxymethylfurfural appeared to be reduced to its alcohol form by the ethanologen during fermentation, whereas phenolic acid and amide inhibitors were not metabolized. Together, our findings establish that the major regulatory responses to lignocellulose-derived inhibitors are mediated by transcriptional rather than translational regulators, suggest that energy consumed for inhibitor efflux and detoxification may limit biofuel production, and identify a network of regulators for future synthetic biology efforts.

  9. Cellulose accessibility limits the effectiveness of minimum cellulase loading on the efficient hydrolysis of pretreated lignocellulosic substrates

    PubMed Central

    2011-01-01

    A range of lignocellulosic feedstocks (including agricultural, softwood and hardwood substrates) were pretreated with either sulfur dioxide-catalyzed steam or an ethanol organosolv procedure to try to establish a reliable assessment of the factors governing the minimum protein loading that could be used to achieve efficient hydrolysis. A statistical design approach was first used to define what might constitute the minimum protein loading (cellulases and β-glucosidase) that could be used to achieve efficient saccharification (defined as at least 70% glucan conversion) of the pretreated substrates after 72 hours of hydrolysis. The likely substrate factors that limit cellulose availability/accessibility were assessed, and then compared with the optimized minimum amounts of protein used to obtain effective hydrolysis. The optimized minimum protein loadings to achieve efficient hydrolysis of seven pretreated substrates ranged between 18 and 63 mg protein per gram of glucan. Within the similarly pretreated group of lignocellulosic feedstocks, the agricultural residues (corn stover and corn fiber) required significantly lower protein loadings to achieve efficient hydrolysis than did the pretreated woody biomass (poplar, douglas fir and lodgepole pine). Regardless of the substantial differences in the source, structure and chemical composition of the feedstocks, and the difference in the pretreatment technology used, the protein loading required to achieve efficient hydrolysis of lignocellulosic substrates was strongly dependent on the accessibility of the cellulosic component of each of the substrates. We found that cellulose-rich substrates with highly accessible cellulose, as assessed by the Simons' stain method, required a lower protein loading per gram of glucan to obtain efficient hydrolysis compared with substrates containing less accessible cellulose. These results suggest that the rate-limiting step during hydrolysis is not the catalytic cleavage of the

  10. Torque measurements reveal large process differences between materials during high solid enzymatic hydrolysis of pretreated lignocellulose

    PubMed Central

    2012-01-01

    Background A common trend in the research on 2nd generation bioethanol is the focus on intensifying the process and increasing the concentration of water insoluble solids (WIS) throughout the process. However, increasing the WIS content is not without problems. For example, the viscosity of pretreated lignocellulosic materials is known to increase drastically with increasing WIS content. Further, at elevated viscosities, problems arise related to poor mixing of the material, such as poor distribution of the enzymes and/or difficulties with temperature and pH control, which results in possible yield reduction. Achieving good mixing is unfortunately not without cost, since the power requirements needed to operate the impeller at high viscosities can be substantial. This highly important scale-up problem can easily be overlooked. Results In this work, we monitor the impeller torque (and hence power input) in a stirred tank reactor throughout high solid enzymatic hydrolysis (< 20% WIS) of steam-pretreated Arundo donax and spruce. Two different process modes were evaluated, where either the impeller speed or the impeller power input was kept constant. Results from hydrolysis experiments at a fixed impeller speed of 10 rpm show that a very rapid decrease in impeller torque is experienced during hydrolysis of pretreated arundo (i.e. it loses its fiber network strength), whereas the fiber strength is retained for a longer time within the spruce material. This translates into a relatively low, rather WIS independent, energy input for arundo whereas the stirring power demand for spruce is substantially larger and quite WIS dependent. By operating the impeller at a constant power input (instead of a constant impeller speed) it is shown that power input greatly affects the glucose yield of pretreated spruce whereas the hydrolysis of arundo seems unaffected. Conclusions The results clearly highlight the large differences between the arundo and spruce materials, both in terms of

  11. Pretreated Lignocellulosic Waste Mediated Biosynthesis of Silver Nanoparticles Under Room Temperature

    NASA Astrophysics Data System (ADS)

    Manjamadha, V. P.; Muthukumar, Karuppan

    2016-10-01

    The current work elucidates the utilization of biowaste as a valuable reducing agent for the synthesis of silver nanoparticles. In this study, the wastewater generated during the alkaline pretreatment of lignocellulosic wastes (APLW) was used as a bioreductant to reduce silver nitrate under room temperature. Synthesis of stable silver nanoparticles (AgNPs) was achieved rapidly on addition of APLW into the silver nitrate solution (1mM). The morphological characterization of AgNPs was performed using field emission scanning electron microscopy (FESEM). The micrograph clearly depicted the presence of spherical AgNPs. The presence of elemental silver along with biomoilties was determined using energy dispersive X-ray spectroscopy (EDAX) analysis. The X-ray diffraction (XRD) study proved the crystalline form of stable AgNPs. The AgNPs exhibited excellent antibacterial performance against Gram negative organism. The immediate bioreduction of silver ions using APLW was well illustrated in the present study. Thus, APLW serve as an alternative source for reducing agents instead of utilizing valuable medicinal plants for nanoparticles synthesis.

  12. Survey of renewable chemicals produced from lignocellulosic biomass during ionic liquid pretreatment

    PubMed Central

    2013-01-01

    Background Lignin is often overlooked in the valorization of lignocellulosic biomass, but lignin-based materials and chemicals represent potential value-added products for biorefineries that could significantly improve the economics of a biorefinery. Fluctuating crude oil prices and changing fuel specifications are some of the driving factors to develop new technologies that could be used to convert polymeric lignin into low molecular weight lignin and or monomeric aromatic feedstocks to assist in the displacement of the current products associated with the conversion of a whole barrel of oil. We present an approach to produce these chemicals based on the selective breakdown of lignin during ionic liquid pretreatment. Results The lignin breakdown products generated are found to be dependent on the starting biomass, and significant levels were generated on dissolution at 160°C for 6 hrs. Guaiacol was produced on dissolution of biomass and technical lignins. Vanillin was produced on dissolution of kraft lignin and eucalytpus. Syringol and allyl guaiacol were the major products observed on dissolution of switchgrass and pine, respectively, whereas syringol and allyl syringol were obtained by dissolution of eucalyptus. Furthermore, it was observed that different lignin-derived products could be generated by tuning the process conditions. Conclusions We have developed an ionic liquid based process that depolymerizes lignin and converts the low molecular weight lignin fractions into a variety of renewable chemicals from biomass. The generated chemicals (phenols, guaiacols, syringols, eugenol, catechols), their oxidized products (vanillin, vanillic acid, syringaldehyde) and their easily derivatized hydrocarbons (benzene, toluene, xylene, styrene, biphenyls and cyclohexane) already have relatively high market value as commodity and specialty chemicals, green building materials, nylons, and resins. PMID:23356589

  13. High-efficiency ethanol production from lignocellulosic residues pretreated with alkaline H/sub 2/O/sub 2/

    SciTech Connect

    Gould, J.M.; Freer, S.N.

    1984-06-01

    Pretreatment should be economic and should not utilize toxic reagents. In this study locally obtained residues were used - wheat straw, cornstalks, corn husks and kenaf -as substrates. The high efficiency of glucose production from alkaline H/sub 2/O/sub 2/ pretreated lignocellulosic residues made these materials excellent substrates for ethanol production by Saccharomyces cerevisiae in combined saccharification/fermentation experiments. Results showed that overall efficiency of ethanol formation was 90% for pretreated corn cobs, stalks and husks compared to 50% for untreated materials. Yields from kenaf and oak were also enhanced although below the theoretical maximum. The lignin containing supernatant does not appear to be inhibitory to Saccharomyces cerevisiae growth or ethanol production. The improvement in conversion efficiency is apparently the result of the removal of about one half of the lignin along with an apparent reduction in the degree of crystallinity within the cellulose structure itself. 16 references.

  14. Combined Dilute Acid and Solvent Based Pretreatment of Agricultural Wastes for Efficient Lignocellulosic Fractionation and Biofuels Production

    SciTech Connect

    Brodeur, G.; Ramakrishnan, S.; Wilson, C.; Telotte, J.; Collier, J.; Stickel, J.

    2013-01-01

    A true biorefinery for processing lignocellulosic biomass should achieve maximum utilization of all major constituents (cellulose, hemicellulose, & lignin) within the feedstock. In this work a combined pretreatment process of dilute acid (DA) and N-methyl morpholine N-oxide (NMMO) is described that allows for both fractionation and subsequent complete hydrolysis of the feedstocks (corn stover and sugarcane bagasse). During this multi-step processing, the dilute acid pretreatment solubilizes the majority (>90%) of the hemicellulosic fraction, while the NMMO treatment yields a cellulosic fraction that is completely digestible within 48 hours at low enzyme loadings. With both the cellulosic and hemicellulosic fractions being converted into separate, dissolved sugar fractions, the remaining portion is nearly pure lignin. When used independently, DA and NMMO pretreatments are only able to achieve ~80% and ~45% cellulosic conversion, respectively. Mass balance calculations along with experimental results are used to illustrate the feasibility of separation and recycling of NMMO.

  15. Multiple levels of synergistic collaboration in termite lignocellulose digestion.

    PubMed

    Scharf, Michael E; Karl, Zachary J; Sethi, Amit; Boucias, Drion G

    2011-01-01

    In addition to evolving eusocial lifestyles, two equally fascinating aspects of termite biology are their mutualistic relationships with gut symbionts and their use of lignocellulose as a primary nutrition source. Termites are also considered excellent model systems for studying the production of bioethanol and renewable bioenergy from 2nd generation (non-food) feedstocks. While the idea that gut symbionts are the sole contributors to termite lignocellulose digestion has remained popular and compelling, in recent years host contributions to the digestion process have become increasingly apparent. However, the degree to which host and symbiont, and host enzymes, collaborate in lignocellulose digestion remain poorly understood. Also, how digestive enzymes specifically collaborate (i.e., in additive or synergistic ways) is largely unknown. In the present study we undertook translational-genomic studies to gain unprecedented insights into digestion by the lower termite Reticulitermes flavipes and its symbiotic gut flora. We used a combination of native gut tissue preparations and recombinant enzymes derived from the host gut transcriptome to identify synergistic collaborations between host and symbiont, and also among enzymes produced exclusively by the host termite. Our findings provide important new evidence of synergistic collaboration among enzymes in the release of fermentable monosaccharides from wood lignocellulose. These monosaccharides (glucose and pentoses) are highly relevant to 2(nd)-generation bioethanol production. We also show that, although significant digestion capabilities occur in host termite tissues, catalytic tradeoffs exist that apparently favor mutualism with symbiotic lignocellulose-digesting microbes. These findings contribute important new insights towards the development of termite-derived biofuel processing biotechnologies and shed new light on selective forces that likely favored symbiosis and, subsequently, group living in primitive

  16. Assessment of hydrothermal pretreatment of various lignocellulosic biomass with CO2 catalyst for enhanced methane and hydrogen production.

    PubMed

    Eskicioglu, Cigdem; Monlau, Florian; Barakat, Abdellatif; Ferrer, Ivet; Kaparaju, Prasad; Trably, Eric; Carrère, Hélène

    2017-09-01

    Hydrothermal pretreatment of five lignocellulosic substrates (i.e. wheat straw, rice straw, biomass sorghum, corn stover and Douglas fir bark) were conducted in the presence of CO2 as a catalyst. To maximize disintegration and conversion into bioenergy (methane and hydrogen), pretreatment temperatures and subsequent pressures varied with a range of 26-175 °C, and 25-102 bars, respectively. Among lignin, cellulose and hemicelluloses, hydrothermal pretreatment caused the highest reduction (23-42%) in hemicelluloses while delignification was limited to only 0-12%. These reductions in structural integrity resulted in 20-30% faster hydrolysis rates during anaerobic digestion for the pretreated substrates of straws, sorghum, and corn stover while Douglas fir bark yielded 172% faster hydrolysis/digestion due to its highly refractory nature in the control. Furans and phenolic compounds formed in the pretreated hydrolyzates were below the inhibitory levels for methane and hydrogen production which had a range of 98-340 ml CH4/g volatile solids (VS) and 5-26 ml H2/g VS, respectively. Results indicated that hydrothermal pretreatment is able to accelerate the rate of biodegradation without generating high levels of inhibitory compounds while showing no discernible effect on ultimate biodegradation. Copyright © 2017 Elsevier Ltd. All rights reserved.

  17. Two-temperature stage biphasic CO2-H2O pretreatment of lignocellulosic biomass at high solid loadings.

    PubMed

    Luterbacher, Jeremy S; Tester, Jefferson W; Walker, Larry P

    2012-06-01

    Most biomass pretreatment processes for monosaccharide production are run at low-solid concentration (<10 wt%) and use significant amounts of chemical catalysts. Biphasic CO(2) -H(2) O mixtures could provide a more sustainable pretreatment medium while using high-solid contents. Using a stirred reactor for high solids (40 wt%, biomass water mixture) biphasic CO(2)-H(2) O pretreatment of lignocellulosic biomass allowed us to explore the effects of particle size and mixing on mixed hardwood and switchgrass pretreatment. Subsequently, a two-temperature stage pretreatment was introduced. After optimization, a short high-temperature stage at 210°C (16 min for hardwood and 1 min for switchgrass) was followed by a long low-temperature stage at 160°C for 60 min. Glucan to glucose conversion yields of 83% for hardwood and 80% for switchgrass were obtained. Total molar sugar yields of 65% and 55% were obtained for wood and switchgrass, respectively, which consisted of a 10% points improvement over those obtained during our previous study despite a 10-fold increase in particle size. These yields are similar to those obtained with other major pretreatment technologies for wood and within 10% of major technologies for switchgrass despite the absence of chemical catalysts, the use of large particles (0.95 cm) and high solid contents (40 wt%).

  18. Enzyme Characterization of Cellulase and Hemicellulases Component Enzymes and Saccharification of Ionic Liquid Pretreated Lignocellulosic Biomass

    USDA-ARS?s Scientific Manuscript database

    Lignocellulosic biomass is comprised of cellulose and hemicellulose, sources of polysaccharides, and lignin, a macromolecule with extensive aromaticity. Terrestrial biomass can provide a renewable carbon based feedstock for fuel and chemical production. However, recalcitrance of biomass to deconstru...

  19. Biodetoxification of toxins generated from lignocellulose pretreatment using a newly isolated fungus, Amorphotheca resinae ZN1, and the consequent ethanol fermentation

    PubMed Central

    2010-01-01

    Background Degradation of the toxic compounds generated in the harsh pretreatment of lignocellulose is an inevitable step in reducing the toxin level for conducting practical enzymatic hydrolysis and ethanol fermentation processes. Various detoxification methods have been tried and many negative outcomes were found using these methods, such as the massive freshwater usage and wastewater generation, loss of the fine lignocellulose particles and fermentative sugars and incomplete removal of inhibitors. An alternate method, biodetoxification, which degrades the toxins as part of their normal metabolism, was considered a promising option for the removal of toxins without causing the above problems. Results A kerosene fungus strain, Amorphotheca resinae ZN1, was isolated from the microbial community growing on the pretreated corn stover material. The degradation of the toxins as well as the lignocelluloses-derived sugars was characterized in different ways, and the results show that A. resinae ZN1 utilized each of these toxins and sugars as the sole carbon sources efficiently and grew quickly on the toxins. It was found that the solid-state culture of A. resinae ZN1 on various pretreated lignocellulose feedstocks such as corn stover, wheat straw, rice straw, cotton stalk and rape straw degraded all kinds of toxins quickly and efficiently. The consequent simultaneous saccharification and ethanol fermentation was performed at the 30% (wt/wt) solid loading of the detoxified lignocellulosic feedstocks without a sterilization step, and the ethanol titer in the fermentation broth reached above 40 g/L using food crop residues as feedstocks. Conclusions The advantages of the present biodetoxification by A. resinae ZN1 over the known detoxification methods include zero energy input, zero wastewater generation, complete toxin degradation, processing on solid pretreated material, no need for sterilization and a wide lignocellulose feedstock spectrum. These advantages make it

  20. Effect of dilute acid pretreatment severity on the bioconversion efficiency of Phalaris aquatica L. lignocellulosic biomass into fermentable sugars.

    PubMed

    Pappas, Ioannis A; Koukoura, Zoi; Tananaki, Chrisoula; Goulas, Christos

    2014-08-01

    The effect of dilute acid pretreatment severity on the bioconversion efficiency of Phalaris aquatica lignocellulosic biomass into fermentable sugar monomers was studied. The pretreatment conditions were expressed in a combined severity factor (CSF), ranged from 0.13 to 1.16. The concentration of xylose and total monomeric sugars released from hemicellulose increased with pretreatment as the CSF increased. Dilute acid pretreatment resulted in about 1.7-fold increase in glucose release relative to the untreated biomass, while CSF was positively correlated with glucose recovery. A maximum glucose yield of 85.05% was observed at high severity values (i.e. CSF 1.16) after 72 h. The total amount of sugars released (i.e. xylose and glucose) was increased with pretreatment severity and a maximum conversion efficiency of 76.1% of structural carbohydrates was obtained at a CSF=1. Our data indicated that Phalaris aquatica L. is an alternative bioethanol feedstock and that hemicellulose removal promotes glucose yield.

  1. Biorefining of Lignocellulosic Feedstock by a Modified Ammonia Fiber Expansion Pretreatment and Enzymatic Hydrolysis for Production of Fermentable Sugars.

    PubMed

    Kamm, Birgit; Leiß, Sebastian; Schönicke, Petra; Bierbaum, Matthias

    2017-01-10

    Wheat straw was pretreated and afterwards enzymatically hydrolyzed using a modified ammonia fiber expansion (AFEX) process under different reaction conditions to produce fermentable sugars. Instead of liquid ammonia, aqueous ammonia (25 % w/v) was used to test its influence on the sugar concentration and yield of the sugars. It is shown that a protein extraction after the pretreatment can distinctly improve the result obtained for the enzymatic hydrolysis. This modified AFEX process using aqueous ammonia represents a simpler and less expensive variant of the AFEX process usually described in literature. Thus, the described process can be used for the primary refining of lignocellulosic feedstocks in the sense of a roadmap for biorefinery. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  2. Comparative biochemical analysis after steam pretreatment of lignocellulosic agricultural waste biomass from Williams Cavendish banana plant (Triploid Musa AAA group).

    PubMed

    Kamdem, Irénée; Jacquet, Nicolas; Tiappi, Florian Mathias; Hiligsmann, Serge; Vanderghem, Caroline; Richel, Aurore; Jacques, Philippe; Thonart, Philippe

    2015-11-01

    The accessibility of fermentable substrates to enzymes is a limiting factor for the efficient bioconversion of agricultural wastes in the context of sustainable development. This paper presents the results of a biochemical analysis performed on six combined morphological parts of Williams Cavendish Lignocellulosic Biomass (WCLB) after steam cracking (SC) and steam explosion (SE) pretreatments. Solid (S) and liquid (L) fractions (Fs) obtained from SC pretreatment performed at 180°C (SLFSC180) and 210°C (SLFSC210) generated, after diluted acid hydrolysis, the highest proportions of neutral sugar (NS) contents, specifically 52.82 ± 3.51 and 49.78 ± 1.39%w/w WCLB dry matter (DM), respectively. The highest proportions of glucose were found in SFSC210 (53.56 ± 1.33%w/w DM) and SFSC180 (44.47 ± 0.00%w/w DM), while the lowest was found in unpretreated WCLB (22.70 ± 0.71%w/w DM). Total NS content assessed in each LF immediately after SC and SE pretreatments was less than 2%w/w of the LF DM, thus revealing minor acid autohydrolysis consequently leading to minor NS production during the steam pretreatment. WCLB subjected to SC at 210 °C (SC210) generated up to 2.7-fold bioaccessible glucan and xylan. SC and SE pretreatments showed potential for the deconstruction of WCLB (delignification, depolymerization, decrystallization and deacetylation), enhancing its enzymatic hydrolysis. The concentrations of enzymatic inhibitors, such as 2-furfuraldehyde and 5-(hydroxymethyl)furfural from LFSC210, were the highest (41 and 21 µg ml(-1), respectively). This study shows that steam pretreatments in general and SC210 in particular are required for efficient bioconversion of WCLB. Yet, biotransformation through biochemical processes (e.g., anaerobic digestion) must be performed to assess the efficiency of these pretreatments. © The Author(s) 2015.

  3. Peracetic acid-ionic liquid pretreatment to enhance enzymatic saccharification of lignocellulosic biomass.

    PubMed

    Uju; Abe, Kojiro; Uemura, Nobuyuki; Oshima, Toyoji; Goto, Masahiro; Kamiya, Noriho

    2013-06-01

    To enhance enzymatic saccharification of pine biomass, the pretreatment reagents peracetic acid (PAA) and ionic liquid (IL) were validated in single reagent pretreatments or combination pretreatments with different sequences. In a 1h saccharification, 5-25% cellulose conversion was obtained from the single pretreatment of PAA or IL. In contrast, a marked enhancement in conversion rates was achieved by PAA-IL combination pretreatments (45-70%). The PAA followed by IL (PAA+IL) pretreatment sequence was the most effective for preparing an enzymatic digestible regenerated biomass with 250-fold higher glucose formation rates than untreated biomass and 2- to 12-fold higher than single pretreatments with PAA or IL alone. Structural analysis confirmed that this pretreatment resulted in biomass with highly porous structural fibers associated with the reduction of lignin content and acetyl groups. Using the PAA+IL sequence, biomass loading in the pretreatment step can be increased from 5% to 15% without significant decrease in cellulose conversion.

  4. Biobutanol production from apple pomace: the importance of pretreatment methods on the fermentability of lignocellulosic agro-food wastes.

    PubMed

    Hijosa-Valsero, María; Paniagua-García, Ana I; Díez-Antolínez, Rebeca

    2017-09-20

    Apple pomace was studied as a possible raw material for biobutanol production. Five different soft physicochemical pretreatments (autohydrolysis, acids, alkalis, organic solvents and surfactants) were compared in a high-pressure reactor, whose working parameters (temperature, time and reagent concentration) were optimised to maximise the amount of simple sugars released and to minimise inhibitor generation. The pretreated biomass was subsequently subjected to a conventional enzymatic treatment to complete the hydrolysis. A thermal analysis (DSC) of the solid biomass indicated that lignin was mainly degraded during the enzymatic treatment. The hydrolysate obtained with the surfactant polyethylene glycol 6000 (PEG 6000) (1.96% w/w) contained less inhibitors than any other pretreatment, yet providing 42 g/L sugars at relatively mild conditions (100 °C, 5 min), and was readily fermented by Clostridium beijerinckii CECT 508 in 96 h (3.55 g/L acetone, 9.11 g/L butanol, 0.26 g/L ethanol; 0.276 gB/gS yield; 91% sugar consumption). Therefore, it is possible to optimise pretreatment conditions of lignocellulosic apple pomace to reduce inhibitor concentrations in the final hydrolysate and perform successful ABE fermentations without the need of a detoxification stage.

  5. A Comparative Study of Dilute acid and Ionic Liquid Pretreatment of Biomass and Model Lignocellulosics

    USDA-ARS?s Scientific Manuscript database

    Lignocellulosic biomass has the great potential to serve as the low cost and abundant feedstock for bioconversion into fermentable sugars, which can be further utilized for biofuel production. However, high lignin content, crystalline cellulose structure and the presence of ester linkages between l...

  6. Bioconversion of woody biomass to biofuel and lignin co-product using sulfite pretreatment to overcome the recalcitrance of lignocelluloses (SPORL)

    Treesearch

    Junyong Zhu; Chao Zhang; Roland Gleisner; Carl Houtman; Xuejun Pan

    2016-01-01

    Sulfite pretreatment to overcome the recalcitrance of lignocelluloses (SPORL) promises to provide efficient bioconversion of woody biomass into bioethanol and lignin co-products. Results from several laboratory and pilot-scale studies are presented to demonstrate SPORL performance, with comparisons to competing technologies. Excellent ethanol yields of up to...

  7. Production of cellulolytic enzymes by Pleurotus species on lignocellulosic wastes using novel pretreatments.

    PubMed

    Singh, M P; Pandey, A K; Vishwakarma, S K; Srivastava, A K; Pandey, V K; Singh, V K

    2014-12-24

    In the present investigation three species of Pleurotus i.e. P. sajor—caju (P1), P. florida (P2) and P. flabellatus (P3) along with two lignocellulosic substrates namely paddy straw and wheat straw were selected for evaluation of production of extracellular cellulolytic enzymes. During the cultivation of three species of Pleurotus under in vivo condition, the two lignocellulosic substrates were treated with plants extracts (aqueous extracts of ashoka leaves (A) and neem oil (B)), hot water (H) and chemicals (C).Among all treatments, neem oil treated substrates supported better enzyme production followed by aqueous extract of ashoka leaves, hot water and chemical treatment. Between the two substrates paddy straw supported better enzyme production than wheat straw. P. flabellatus showed maximum activity of exoglucanase, endoglucanase and β—glucosidase followed by P. florida and P. sajor—caju.

  8. Pretreatment of lignocellulosic biomass by cattle rumen fluid for methane production: Bacterial flora and enzyme activity analysis.

    PubMed

    Baba, Yasunori; Matsuki, Yu; Mori, Yumi; Suyama, Yoshihisa; Tada, Chika; Fukuda, Yasuhiro; Saito, Masanori; Nakai, Yutaka

    2017-01-29

    We attempted to develop a pretreatment method for methane fermentation of lignocellulosic biomass using cattle rumen fluid, treated as slaughterhouse waste. When rapeseed (Brassica napus L.) was added to the methane fermentation after being solubilized with rumen fluid, 1.5 times more methane was produced compared with untreated rapeseed. Analysis of the bacterial flora during rumen fluid treatment using the MiSeq next-generation sequencer showed that the predominant phylum shifted from Bacteroidetes, composed of amylolytic Prevotella spp., to Firmicutes, composed of cellulolytic and xylanolytic Ruminococcus spp., in only 6 h. In total, 7 cellulolytic, 25 cello-oligosaccharolytic, and 11 xylanolytic bacteria were detected after investigating the most abundant sequences of detected taxa. The relative abundance of two Ruminococcus species (Ruminococcus albus and R. flavefaciens), known as cellulolytic, cello-oligosaccharolytic, and xylanolytic bacteria, increased with increasing cellulose and hemicellulose degradation rates, and, finally, comprised 48% of all operational taxonomic units. The chronological observation of enzyme activities showed that cellulolytic and xylanolytic activities increased 6 h later, and that oligosaccharolytic activity increased 24 h later. This study detected six bacteria that participate in the degradation of aromatics derived from lignin, which have rarely been reported in rumen fluid. The constitution of the detected bacteria suggests that the aromatics were converted into acetate via benzoate. The list of microbes that cover all lignocellulose-degrading candidates will provide fundamental knowledge for future studies focusing on rumen microbes.

  9. Binding characteristics of Trichoderma reesei cellulases on untreated, ammonia fiber expansion (AFEX), and dilute-acid pretreated lignocellulosic biomass.

    PubMed

    Gao, Dahai; Chundawat, Shishir P S; Uppugundla, Nirmal; Balan, Venkatesh; Dale, Bruce E

    2011-08-01

    Studying the binding properties of cellulases to lignocellulosic substrates is critical to achieving a fundamental understanding of plant cell wall saccharification. Lignin auto-fluorescence and degradation products formed during pretreatment impede accurate quantification of individual glycosyl hydrolases (GH) binding to pretreated cell walls. A high-throughput fast protein liquid chromatography (HT-FPLC)-based method has been developed to quantify cellobiohydrolase I (CBH I or Cel7A), cellobiohydrolase II (CBH II or Cel6A), and endoglucanase I (EG I or Cel7B) present in hydrolyzates of untreated, ammonia fiber expansion (AFEX), and dilute-acid pretreated corn stover (CS). This method can accurately quantify individual enzymes present in complex binary and ternary protein mixtures without interference from plant cell wall-derived components. The binding isotherms for CBH I, CBH II, and EG I were obtained after incubation for 2 h at 4 °C. Both AFEX and dilute acid pretreatment resulted in increased cellulase binding compared with untreated CS. Cooperative binding of CBH I and/or CBH II in the presence of EG I was observed only for AFEX treated CS. Competitive binding between enzymes was found for certain other enzyme-substrate combinations over the protein loading range tested (i.e., 25-450 mg/g glucan). Langmuir single-site adsorption model was fitted to the binding isotherm data to estimate total available binding sites E(bm) (mg/g glucan) and association constant K(a) (L/mg). Our results clearly demonstrate that the characteristics of cellulase binding depend not only on the enzyme GH family but also on the type of pretreatment method employed. Copyright © 2011 Wiley Periodicals, Inc.

  10. Pretreatment of garden biomass using Fenton's reagent: influence of Fe(2+) and H2O2 concentrations on lignocellulose degradation.

    PubMed

    Bhange, Vivek P; William, Spm Prince; Sharma, Abhinav; Gabhane, Jagdish; Vaidya, Atul N; Wate, Satish R

    2015-01-01

    Garden biomass (GB) is defined as low density and heterogeneous waste fraction of garden rubbish like grass clippings, pruning, flowers, branches, weeds; roots. GB is generally different from other types of biomass. GB is mostly generated through maintenance of green areas. GB can be processed for bio energy production as it contains considerably good amount of cellulose and hemicellulose. However, pretreatment is necessary to delignify and facilitate disruption of cellulosic moiety. The aim of the present investigation was to pretreat GB using Fenton's reagent and to study the influence of Fe(2+) and H2O2 concentrations on degradation of lignin and cellulose. The data were statistically analyzed using ANOVA and numerical point prediction tool of MINITAB RELEASE 14 to optimize different process variables such as temperature, concentration of Fe(2+) and H2O2. The results of the present investigation showed that Fenton's reagent was effective on GB, however, concentration of Fe(2+) and H2O2 play crucial role in determining the efficiency of pretreatment. An increase in H2O2 concentration in Fenton's reagent significantly increased the rate of cellulose and lignin degradation in contrast to increasing concentration of Fe(2+) ion which led to a decrease in lignocellulosic degradation.

  11. An overview of key pretreatment processes employed for bioconversion of lignocellulosic biomass into biofuels and value added products.

    PubMed

    Chaturvedi, Venkatesh; Verma, Pradeep

    2013-10-01

    The hunt for alternative sources of energy generation that are inexpensive, ecofriendly, renewable and can replace fossil fuels is on, owing to the increasing demands of energy. One approach in this direction is the conversion of plant residues into biofuels wherein lignocellulose, which forms the structural framework of plants consisting of cellulose, hemicellulose and lignin, is first broken down and hydrolyzed into simple fermentable sugars, which upon fermentation form biofuels such as ethanol. A major bottleneck is to disarray lignin which is present as a protective covering and makes cellulose and hemicellulose recalcitrant to enzymatic hydrolysis. A number of biomass deconstruction or pretreatment processes (physical, chemical and biological) have been used to break the structural framework of plants and depolymerize lignin. This review surveys and discusses some major pretreatment processes pertaining to the pretreatment of plant biomass, which are used for the production of biofuels and other value added products. The emphasis is given on processes that provide maximum amount of sugars, which are subsequently used for the production of biofuels.

  12. Improved enzymatic hydrolysis of lignocellulosic biomass through pretreatment with plasma electrolysis.

    PubMed

    Gao, Jing; Chen, Li; Zhang, Jian; Yan, Zongcheng

    2014-11-01

    A comprehensive research on plasma electrolysis as pretreatment method for water hyacinth (WH) was performed based on lignin content, crystalline structure, surface property, and enzymatic hydrolysis. A large number of active particles, such as HO and H2O2, generated by plasma electrolysis could decompose the lignin of the biomass samples and reduce the crystalline index. An efficient pretreatment process made use of WH pretreated at a load of 48 wt% (0.15-0.18 mm) in FeCl3 solution for 30 min at 450 V. After the pretreatment, the sugar yield of WH was increased by 126.5% as compared with unpretreated samples. Copyright © 2014 Elsevier Ltd. All rights reserved.

  13. Two-stage dilute-acid and organic-solvent lignocellulosic pretreatment for enhanced bioprocessing

    DOE PAGES

    Brodeur, G.; Telotte, J.; Stickel, J. J.; ...

    2016-08-26

    A two stage pretreatment approach for biomass is developed in the current work in which dilute acid (DA) pretreatment is followed by a solvent based pretreatment (N-methyl morpholine N oxide -- NMMO). When the combined pretreatment (DAWNT) is applied to sugarcane bagasse and corn stover, the rates of hydrolysis and overall yields (>90%) are seen to dramatically improve and under certain conditions 48 h can be taken off the time of hydrolysis with the additional NMMO step to reach similar conversions. DAWNT shows a 2-fold increase in characteristic rates and also fractionates different components of biomass -- DA treatment removesmore » the hemicellulose while the remaining cellulose is broken down by enzymatic hydrolysis after NMMO treatment to simple sugars. The remaining residual solid is high purity lignin. Lastly, future work will focus on developing a full scale economic analysis of DAWNT for use in biomass fractionation.« less

  14. Two-stage dilute-acid and organic-solvent lignocellulosic pretreatment for enhanced bioprocessing

    SciTech Connect

    Brodeur, G.; Telotte, J.; Stickel, J. J.; Ramakrishnan, S.

    2016-08-26

    A two stage pretreatment approach for biomass is developed in the current work in which dilute acid (DA) pretreatment is followed by a solvent based pretreatment (N-methyl morpholine N oxide -- NMMO). When the combined pretreatment (DAWNT) is applied to sugarcane bagasse and corn stover, the rates of hydrolysis and overall yields (>90%) are seen to dramatically improve and under certain conditions 48 h can be taken off the time of hydrolysis with the additional NMMO step to reach similar conversions. DAWNT shows a 2-fold increase in characteristic rates and also fractionates different components of biomass -- DA treatment removes the hemicellulose while the remaining cellulose is broken down by enzymatic hydrolysis after NMMO treatment to simple sugars. The remaining residual solid is high purity lignin. Lastly, future work will focus on developing a full scale economic analysis of DAWNT for use in biomass fractionation.

  15. Liquid hot water pretreatment of lignocellulosic biomass for bioethanol production accompanying with high valuable products.

    PubMed

    Zhuang, Xinshu; Wang, Wen; Yu, Qiang; Qi, Wei; Wang, Qiong; Tan, Xuesong; Zhou, Guixiong; Yuan, Zhenhong

    2016-01-01

    Pretreatment is an essential prerequisite to overcome recalcitrance of biomass and enhance the ethanol conversion efficiency of polysaccharides. Compared with other pretreatment methods, liquid hot water (LHW) pretreatment not only reduces the downstream pressure by making cellulose more accessible to the enzymes but minimizes the formation of degradation products that inhibit the growth of fermentative microorganisms. Herein, this review summarized the improved LHW process for different biomass feedstocks, the decomposition behavior of biomass in the LHW process, the enzymatic hydrolysis of LHW-treated substrates, and production of high value-added products and ethanol. Moreover, a combined process producing ethanol and high value-added products was proposed basing on the works of Guangzhou Institute of Energy Conversion to make LHW pretreatment acceptable in the biorefinery of cellulosic ethanol.

  16. Two-stage dilute-acid and organic-solvent lignocellulosic pretreatment for enhanced bioprocessing

    SciTech Connect

    Brodeur, G.; Telotte, J.; Stickel, J. J.; Ramakrishnan, S.

    2016-08-26

    A two stage pretreatment approach for biomass is developed in the current work in which dilute acid (DA) pretreatment is followed by a solvent based pretreatment (N-methyl morpholine N oxide -- NMMO). When the combined pretreatment (DAWNT) is applied to sugarcane bagasse and corn stover, the rates of hydrolysis and overall yields (>90%) are seen to dramatically improve and under certain conditions 48 h can be taken off the time of hydrolysis with the additional NMMO step to reach similar conversions. DAWNT shows a 2-fold increase in characteristic rates and also fractionates different components of biomass -- DA treatment removes the hemicellulose while the remaining cellulose is broken down by enzymatic hydrolysis after NMMO treatment to simple sugars. The remaining residual solid is high purity lignin. Lastly, future work will focus on developing a full scale economic analysis of DAWNT for use in biomass fractionation.

  17. Two-stage dilute-acid and organic-solvent lignocellulosic pretreatment for enhanced bioprocessing.

    PubMed

    Brodeur, G; Telotte, J; Stickel, J J; Ramakrishnan, S

    2016-11-01

    A two stage pretreatment approach for biomass is developed in the current work in which dilute acid (DA) pretreatment is followed by a solvent based pretreatment (N-methyl morpholine N oxide - NMMO). When the combined pretreatment (DAWNT) is applied to sugarcane bagasse and corn stover, the rates of hydrolysis and overall yields (>90%) are seen to dramatically improve and under certain conditions 48h can be taken off the time of hydrolysis with the additional NMMO step to reach similar conversions. DAWNT shows a 2-fold increase in characteristic rates and also fractionates different components of biomass - DA treatment removes the hemicellulose while the remaining cellulose is broken down by enzymatic hydrolysis after NMMO treatment to simple sugars. The remaining residual solid is high purity lignin. Future work will focus on developing a full scale economic analysis of DAWNT for use in biomass fractionation.

  18. Mechanism of the positive effect of poly(ethylene glycol) addition in enzymatic hydrolysis of steam pretreated lignocelluloses.

    PubMed

    Sipos, Bálint; Szilágyi, Mátyás; Sebestyén, Zoltán; Perazzini, Raffaella; Dienes, Dóra; Jakab, Emma; Crestini, Claudia; Réczey, Kati

    2011-11-01

    The efficiency of enzymatic hydrolysis of lignocellulses can be increased by addition of surfactants and polymers, such as poly(ethylene glycol) (PEG). The effect of PEG addition on the cellulase adsorption was tested on various steam pretreated lignocellulose substrates (spruce, willow, hemp, corn stover, wheat straw, sweet sorghum bagasse). A positive effect of PEG addition was observed, as protein adsorption has decreased and free enzyme activities (FP, β-glucosidase) have increased due to the additive. However, the degree of enhancement differed among the substrates, being highest on steam pretreated spruce. Results of lignin analysis (pyrolysis-GC/MS, (31)P NMR) suggest that the effect of PEG addition is in connection with the amount of unsubstituted phenolic hydroxyl groups of lignin in the substrate. Adsorption experiments using two commercial enzyme preparations, Celluclast 1.5L (Trichoderma reesei cellulase) and Novozym 188 (Aspergillus niger β-glucosidase) suggested that enzyme origins affected on the adsorptivity of β-glucosidases. Copyright © 2011 Académie des sciences. Published by Elsevier SAS. All rights reserved.

  19. The impacts of pretreatment on the fermentability of pretreated lignocellulosic biomass: a comparative evaluation between ammonia fiber expansion and dilute acid pretreatment

    PubMed Central

    2009-01-01

    Background Pretreatment chemistry is of central importance due to its impacts on cellulosic biomass processing and biofuels conversion. Ammonia fiber expansion (AFEX) and dilute acid are two promising pretreatments using alkaline and acidic pH that have distinctive differences in pretreatment chemistries. Results Comparative evaluation on these two pretreatments reveal that (i) AFEX-pretreated corn stover is significantly more fermentable with respect to cell growth and sugar consumption, (ii) both pretreatments can achieve more than 80% of total sugar yield in the enzymatic hydrolysis of washed pretreated solids, and (iii) while AFEX completely preserves plant carbohydrates, dilute acid pretreatment at 5% solids loading degrades 13% of xylose to byproducts. Conclusion The selection of pretreatment will determine the biomass-processing configuration, requirements for hydrolysate conditioning (if any) and fermentation strategy. Through dilute acid pretreatment, the need for hemicellulase in biomass processing is negligible. AFEX-centered cellulosic technology can alleviate fermentation costs through reducing inoculum size and practically eliminating nutrient costs during bioconversion. However, AFEX requires supplemental xylanases as well as cellulase activity. As for long-term sustainability, AFEX has greater potential to diversify products from a cellulosic biorefinery due to lower levels of inhibitor generation and lignin loss. PMID:19961578

  20. The impacts of pretreatment on the fermentability of pretreated lignocellulosic biomass: a comparative evaluation between ammonia fiber expansion and dilute acid pretreatment.

    PubMed

    Lau, Ming W; Gunawan, Christa; Dale, Bruce E

    2009-12-04

    Pretreatment chemistry is of central importance due to its impacts on cellulosic biomass processing and biofuels conversion. Ammonia fiber expansion (AFEX) and dilute acid are two promising pretreatments using alkaline and acidic pH that have distinctive differences in pretreatment chemistries. Comparative evaluation on these two pretreatments reveal that (i) AFEX-pretreated corn stover is significantly more fermentable with respect to cell growth and sugar consumption, (ii) both pretreatments can achieve more than 80% of total sugar yield in the enzymatic hydrolysis of washed pretreated solids, and (iii) while AFEX completely preserves plant carbohydrates, dilute acid pretreatment at 5% solids loading degrades 13% of xylose to byproducts. The selection of pretreatment will determine the biomass-processing configuration, requirements for hydrolysate conditioning (if any) and fermentation strategy. Through dilute acid pretreatment, the need for hemicellulase in biomass processing is negligible. AFEX-centered cellulosic technology can alleviate fermentation costs through reducing inoculum size and practically eliminating nutrient costs during bioconversion. However, AFEX requires supplemental xylanases as well as cellulase activity. As for long-term sustainability, AFEX has greater potential to diversify products from a cellulosic biorefinery due to lower levels of inhibitor generation and lignin loss.

  1. Characterization of oxalic acid pretreatment on lignocellulosic biomass using oxalic acid recovered by electrodialysis.

    PubMed

    Lee, Hong-Joo; Seo, Young-Jun; Lee, Jae-Won

    2013-04-01

    The properties of pretreated biomass and hydrolysate obtained by oxalic acid pretreatment using oxalic acid recovered through electrodialysis (ED) were investigated. Most of the oxalic acid was recovered and some of the fermentation inhibitors were removed by ED. For the original hydrolysate, the ethanol production was very low and fermentable sugars were not completely consumed by Pichia stipitis during fermentation. Ethanol yield was less than 0.12 g/g in all stage. For the ED-treated hydrolysate, ethanol production was increased by up to two times in all stages compared to the original hydrolysate. The highest ethanol production was 19.38 g/l after 72 h which correspond to the ethanol yield of 0.33 g/g. Enzymatic conversion of the cellulose to glucose for all the pretreated biomass was in the range of 76.03 and 77.63%. The hydrolysis rate on each pretreated biomass was not significantly changed when oxalic acid recovered by ED was used for pretreatment. Copyright © 2013 Elsevier Ltd. All rights reserved.

  2. Ionic liquid pretreatment to increase succinic acid production from lignocellulosic biomass.

    PubMed

    Wang, Caixia; Yan, Daojiang; Li, Qiang; Sun, Wei; Xing, Jianmin

    2014-11-01

    In this study, pinewood and corn stover pretreated with the ionic liquid (IL) 1-allyl-3-methylimidazolium chloride (AmimCl) were used as a feedstock for succinic acid production. Results reveal that 5% (v/v) AmimCl inhibited bacterial growth, whereas 0.01% (v/v) AmimCl inhibited succinic acid production. AmimCl was effective in extracting cellulose from pinewood and in degrading pinewood into a uniform pulp, as revealed by scanning electron microscopy (SEM). The rate of enzymatic hydrolysis of pinewood extract reached 72.16%. The combinations of AmimCl pretreatment with steam explosion or with hot compressed water were effective in treating corn stover, whereas AmimCl treatment alone did not result in a significant improvement. Pinewood extract produced 20.7g/L succinic acid with an average yield of 0.37g per gram of biomass. Workflow calculations indicated pine wood pretreated with IL has a theoretical yield of succinic acid of 57.1%. IL pretreatment led to increase in succinic acid yields. Copyright © 2014 Elsevier Ltd. All rights reserved.

  3. Improvement of radio frequency (RF) heating-assisted alkaline pretreatment on four categories of lignocellulosic biomass.

    PubMed

    Wang, Xiaofei; Taylor, Steven; Wang, Yifen

    2016-10-01

    Pretreatment plays an important role in making the cellulose accessible for enzyme hydrolysis and subsequent conversion because it destroys more or less resistance and recalcitrance of biomass. Radio frequency (RF)-assisted dielectric heating was utilized in the alkaline pretreatment on agricultural residues (corn stover), herbaceous crops (switchgrass), hardwood (sweetgum) and softwood (loblolly pine). Pretreatment was performed at 90 °C with either RF or traditional water bath (WB) heating for 1 h after overnight soaking in NaOH solution (0.2 g NaOH/g Biomass). Pretreated materials were characterized by chemical compositional analysis, enzyme hydrolysis, scanning electron microscopy (SEM) and Fourier transform infrared spectroscopy (FTIR). The glucan yields of RF-heated four categories of hydrolysates were 89.6, 72.6, 21.7, and 9.9 %. Interestingly, RF heating raised glucan yield on switchgrass and sweetgum but not on corn stover or loblolly pine. The SEM images and FTIR spectra agreed with results of composition analysis and hydrolysis. GC-MS detected some compounds only from RF-heated switchgrass. These compounds were found by other researchers only in high-temperature (150-600 °C) and high-pressure pyrolysis processes.

  4. Impact of pre-treatments on properties of lignocelluloses and their accessibility for a subsequent carboxymethylation.

    PubMed

    Heise, Katja; Rossberg, Christine; Strätz, Juliane; Bäurich, Christian; Brendler, Erica; Keller, Harald; Fischer, Steffen

    2017-04-01

    In this issue, different chemical (alkaline and sulfite pulping, ozonolysis) and mechanical (vibratory ball milling) pre-treatments were utilized for activating wheat straw and beech sawdust prior to carboxymethylation. Detailed analysis by a range of methods, including Klason-lignin, cellulose and hemicellulose quantification, Powder-X-ray diffraction (PXRD) and attenuated total reflection (ATR) IR spectroscopy, enabled the investigation of material alterations. Subsequently, carboxymethylation was carried out with both untreated and activated materials, allowing the evaluation of activation steps by determining degrees of substitution with carboxymethyl groups (DSCM). Moreover, carboxymethylation conditions were optimized, realizing high DSCM of up to 1.05. Results further revealed that ball milling enhanced the subsequent conversion; whereas chemical pre-treatments did not effectively increase material accessibilities. Further studies on chemically untreated materials emphasized that a highly reactive surface was already generated in the course of the carboxymethylation, inter alia through the concomitant dissolution of matrix components.

  5. Chemical Preconversion: Application of Low-Severity Pretreatment Chemistries for Commoditization of Lignocellulosic Feedstock

    SciTech Connect

    David N. Thompson; Timothy Campbell; Bryan Bals; Troy Runge; Farzaneh Teymouri

    2013-05-01

    Securing biofuels project financing is challenging, in part because of risks in feedstock supply. Commoditization of the feedstock and decoupling its supply from the biorefinery will promote greater economies of scale, reduce feedstock supply risk and reduce the need for overdesign of biorefinery pretreatment technologies. We present benefits and detractions of applying low-severity chemical treatments or ‘chemical preconversion treatments’ to enable this approach through feedstock modification and densification early in the supply chain. General structural modifications to biomass that support cost-effective densification and transportation are presented, followed by available chemistries to achieve these modifications with minimal yield loss and the potential for harvesting value in local economies. A brief review of existing biomass pretreatment technologies for cellulolytic hydrolysis at biorefineries is presented, followed by a discussion toward economically applying the underlying chemistries at reduced severity in light of capital and operational limitations of small-scale feedstock depots.

  6. Fungal pretreatment of lignocellulose by Phanerochaete chrysosporium to produce ethanol from rice straw.

    PubMed

    Bak, Jin Seop; Ko, Ja Kyong; Choi, In-Geol; Park, Yong-Cheol; Seo, Jin-Ho; Kim, Kyoung Heon

    2009-10-15

    Phanerochaete chrysosporium is a wood-rot fungus that is capable of degrading lignin via its lignolytic system. In this study, an environmentally friendly fungal pretreatment process that produces less inhibitory substances than conventional methods was developed using P. chrysosporium and then evaluated by various analytical methods. To maximize the production of manganese peroxidase, which is the primary lignin-degrading enzyme, culture medium was optimized using response surface methodologies including the Plackett-Burman design and the Box-Behnken design. Fermentation of 100 g of rice straw feedstock containing 35.7 g of glucan (mainly in the form of cellulose) by cultivation with P. chrysosporium for 15 days in the media optimized by response surface methodology was resulted in a yield of 29.0 g of glucan that had an enzymatic digestibility of 64.9% of the theoretical maximum glucose yield. In addition, scanning electronic microscopy, confocal laser scanning microscopy, and X-ray diffractometry revealed significant microstructural changes, fungal growth, and a reduction of the crystallinity index in the pretreated rice straw, respectively. When the fungal-pretreated rice straw was used as a substrate for ethanol production in simultaneous saccharification and fermentation (SSF) for 24 h, the ethanol concentration, production yield and the productivity were 9.49 g/L, 58.2% of the theoretical maximum, and 0.40 g/L/h, respectively. Based on these experimental data, if 100 g of rice straw are subjected to fungal pretreatment and SSF, 9.9 g of ethanol can be produced after 96 h, which is 62.7% of the theoretical maximum ethanol yield.

  7. Simultaneous saccharification and fermentation of lignocellulosic residues pretreated with phosphoric acid-acetone for bioethanol production.

    PubMed

    Li, Hui; Kim, Nag-Jong; Jiang, Min; Kang, Jong Won; Chang, Ho Nam

    2009-07-01

    Bermudagrass, reed and rapeseed were pretreated with phosphoric acid-acetone and used for ethanol production by means of simultaneous saccharification and fermentation (SSF) with a batch and fed-batch mode. When the batch SSF experiments were conducted in a 3% low effective cellulose, about 16 g/L of ethanol were obtained after 96 h of fermentation. When batch SSF experiments were conducted with a higher cellulose content (10% effective cellulose for reed and bermudagrass and 5% for rapeseed), higher ethanol concentrations and yields (of more than 93%) were obtained. The fed-batch SSF strategy was adopted to increase the ethanol concentration further. When a higher water-insoluble solid (up to 36%) was applied, the ethanol concentration reached 56 g/L of an inhibitory concentration of the yeast strain used in this study at 38 degrees C. The results show that the pretreated materials can be used as good feedstocks for bioethanol production, and that the phosphoric acid-acetone pretreatment can effectively yield a higher ethanol concentration.

  8. Engineering and Two-Stage Evolution of a Lignocellulosic Hydrolysate-Tolerant Saccharomyces cerevisiae Strain for Anaerobic Fermentation of Xylose from AFEX Pretreated Corn Stover

    PubMed Central

    Parreiras, Lucas S.; Breuer, Rebecca J.; Avanasi Narasimhan, Ragothaman; Higbee, Alan J.; La Reau, Alex; Tremaine, Mary; Qin, Li; Willis, Laura B.; Bice, Benjamin D.; Bonfert, Brandi L.; Pinhancos, Rebeca C.; Balloon, Allison J.; Uppugundla, Nirmal; Liu, Tongjun; Li, Chenlin; Tanjore, Deepti; Ong, Irene M.; Li, Haibo; Pohlmann, Edward L.; Serate, Jose; Withers, Sydnor T.; Simmons, Blake A.; Hodge, David B.; Westphall, Michael S.; Coon, Joshua J.; Dale, Bruce E.; Balan, Venkatesh; Keating, David H.; Zhang, Yaoping; Landick, Robert; Gasch, Audrey P.; Sato, Trey K.

    2014-01-01

    The inability of the yeast Saccharomyces cerevisiae to ferment xylose effectively under anaerobic conditions is a major barrier to economical production of lignocellulosic biofuels. Although genetic approaches have enabled engineering of S. cerevisiae to convert xylose efficiently into ethanol in defined lab medium, few strains are able to ferment xylose from lignocellulosic hydrolysates in the absence of oxygen. This limited xylose conversion is believed to result from small molecules generated during biomass pretreatment and hydrolysis, which induce cellular stress and impair metabolism. Here, we describe the development of a xylose-fermenting S. cerevisiae strain with tolerance to a range of pretreated and hydrolyzed lignocellulose, including Ammonia Fiber Expansion (AFEX)-pretreated corn stover hydrolysate (ACSH). We genetically engineered a hydrolysate-resistant yeast strain with bacterial xylose isomerase and then applied two separate stages of aerobic and anaerobic directed evolution. The emergent S. cerevisiae strain rapidly converted xylose from lab medium and ACSH to ethanol under strict anaerobic conditions. Metabolomic, genetic and biochemical analyses suggested that a missense mutation in GRE3, which was acquired during the anaerobic evolution, contributed toward improved xylose conversion by reducing intracellular production of xylitol, an inhibitor of xylose isomerase. These results validate our combinatorial approach, which utilized phenotypic strain selection, rational engineering and directed evolution for the generation of a robust S. cerevisiae strain with the ability to ferment xylose anaerobically from ACSH. PMID:25222864

  9. Engineering and two-stage evolution of a lignocellulosic hydrolysate-tolerant Saccharomyces cerevisiae strain for anaerobic fermentation of xylose from AFEX pretreated corn stover.

    PubMed

    Parreiras, Lucas S; Breuer, Rebecca J; Avanasi Narasimhan, Ragothaman; Higbee, Alan J; La Reau, Alex; Tremaine, Mary; Qin, Li; Willis, Laura B; Bice, Benjamin D; Bonfert, Brandi L; Pinhancos, Rebeca C; Balloon, Allison J; Uppugundla, Nirmal; Liu, Tongjun; Li, Chenlin; Tanjore, Deepti; Ong, Irene M; Li, Haibo; Pohlmann, Edward L; Serate, Jose; Withers, Sydnor T; Simmons, Blake A; Hodge, David B; Westphall, Michael S; Coon, Joshua J; Dale, Bruce E; Balan, Venkatesh; Keating, David H; Zhang, Yaoping; Landick, Robert; Gasch, Audrey P; Sato, Trey K

    2014-01-01

    The inability of the yeast Saccharomyces cerevisiae to ferment xylose effectively under anaerobic conditions is a major barrier to economical production of lignocellulosic biofuels. Although genetic approaches have enabled engineering of S. cerevisiae to convert xylose efficiently into ethanol in defined lab medium, few strains are able to ferment xylose from lignocellulosic hydrolysates in the absence of oxygen. This limited xylose conversion is believed to result from small molecules generated during biomass pretreatment and hydrolysis, which induce cellular stress and impair metabolism. Here, we describe the development of a xylose-fermenting S. cerevisiae strain with tolerance to a range of pretreated and hydrolyzed lignocellulose, including Ammonia Fiber Expansion (AFEX)-pretreated corn stover hydrolysate (ACSH). We genetically engineered a hydrolysate-resistant yeast strain with bacterial xylose isomerase and then applied two separate stages of aerobic and anaerobic directed evolution. The emergent S. cerevisiae strain rapidly converted xylose from lab medium and ACSH to ethanol under strict anaerobic conditions. Metabolomic, genetic and biochemical analyses suggested that a missense mutation in GRE3, which was acquired during the anaerobic evolution, contributed toward improved xylose conversion by reducing intracellular production of xylitol, an inhibitor of xylose isomerase. These results validate our combinatorial approach, which utilized phenotypic strain selection, rational engineering and directed evolution for the generation of a robust S. cerevisiae strain with the ability to ferment xylose anaerobically from ACSH.

  10. Fed-Batch Enzymatic Saccharification of High Solids Pretreated Lignocellulose for Obtaining High Titers and High Yields of Glucose.

    PubMed

    Jung, Young Hoon; Park, Hyun Min; Kim, Dong Hyun; Yang, Jungwoo; Kim, Kyoung Heon

    2017-01-11

    To reduce the distillation costs of cellulosic ethanol, it is necessary to produce high sugar titers in the enzymatic saccharification step. To obtain high sugar titers, high biomass loadings of lignocellulose are necessary. In this study, to overcome the low saccharification yields and the low operability of high biomass loadings, a fed-batch saccharification process was developed using an enzyme reactor that was designed and built in-house. After optimizing the cellulase and biomass feeding profiles and the agitation speed, 132.6 g/L glucose and 76.0% theoretical maximum glucose were obtained from the 60 h saccharification of maleic acid-pretreated rice straw at a 30% (w/v) solids loading with 15 filter paper units (FPU) of Cellic CTec2/g glucan. This study demonstrated that through the proper optimization of fed-batch saccharification, both high sugar titers and high saccharification yields are possible, even with using the high solids loading (i.e., ≥30%) with the moderate enzyme loading (i.e., <15 FPU/g glucan). These results could be contributed to improving economic feasibility of the high solids saccharification process in cellulosic fuel and chemical production.

  11. A feasibility study on the multistage process for the oxalic acid pretreatment of a lignocellulosic biomass using electrodialysis.

    PubMed

    Lee, Hong-Joo; Ahn, Sung Ju; Seo, Young-Jun; Lee, Jae-Won

    2013-02-01

    The present study investigated the feasibility of the recovery and reuse oxalic acid in a multistage process for the pretreatment of a lignocellulosic biomass. Electrodialysis (ED), an electrochemical process using ion exchange membranes, was used to recover and reuse oxalic acid in the multistage process. The ED optimal condition for recover oxalic acid was potential of 10V and pH 2.2 in synthetic solutions. The recovery efficiency of oxalic acid from hydrolysates reached 100% at potential of 10V. The power consumption to treat 1mol of oxalic acid was estimated to be 41.0wh. At the same time, ethanol production increased up to 19g/L in the ED-treated hydrolysate, corresponding to ethanol productivity of 0.27g/L/h. It was clearly shown that bioethanol fermentation efficiency increased using the ED process, due to a small loss of fermentable sugar and a significantly high removal of inhibitory chemicals. Copyright © 2012 Elsevier Ltd. All rights reserved.

  12. Caldicellulosiruptor saccharolyticus transcriptomes reveal consequences of chemical pretreatment and genetic modification of lignocellulose.

    PubMed

    Blumer-Schuette, Sara E; Zurawski, Jeffrey V; Conway, Jonathan M; Khatibi, Piyum; Lewis, Derrick L; Li, Quanzi; Chiang, Vincent L; Kelly, Robert M

    2017-03-20

    Recalcitrance of plant biomass is a major barrier for commercially feasible cellulosic biofuel production. Chemical and enzymatic assays have been developed to measure recalcitrance and carbohydrate composition; however, none of these assays can directly report which polysaccharides a candidate microbe will sense during growth on these substrates. Here, we propose using the transcriptomic response of the plant biomass-deconstructing microbe, Caldicellulosiruptor saccharolyticus, as a direct measure of how suitable a sample of plant biomass may be for fermentation based on the bioavailability of polysaccharides. Key genes were identified using the global gene response of the microbe to model plant polysaccharides and various types of unpretreated, chemically pretreated and genetically modified plant biomass. While the majority of C. saccharolyticus genes responding were similar between plant biomasses; subtle differences were discernable, most importantly between chemically pretreated or genetically modified biomass that both exhibit similar levels of solubilization by the microbe. Furthermore, the results here present a new paradigm for assessing plant-microbe interactions that can be deployed as a biological assay to report on the complexity and recalcitrance of plant biomass.

  13. Role of Pretreatment and Conditioning Processes on Toxicity of Lignocellulosic Biomass Hydrolysates

    SciTech Connect

    Pienkos, P. T.; Zhang, M.

    2009-01-01

    The Department of Energy's Office of the Biomass Program has set goals of making ethanol cost competitive by 2012 and replacing 30% of 2004 transportation supply with biofuels by 2030. Both goals require improvements in conversions of cellulosic biomass to sugars as well as improvements in fermentation rates and yields. Current best pretreatment processes are reasonably efficient at making the cellulose/hemicellulose/lignin matrix amenable to enzymatic hydrolysis and fermentation, but they release a number of toxic compounds into the hydrolysate which inhibit the growth and ethanol productivity of fermentation organisms. Conditioning methods designed to reduce the toxicity of hydrolysates are effective, but add to process costs and tend to reduce sugar yields, thus adding significantly to the final cost of production. Reducing the cost of cellulosic ethanol production will likely require enhanced understanding of the source and mode of action of hydrolysate toxic compounds, the means by which some organisms resist the actions of these compounds, and the methodology and mechanisms for conditioning hydrolysate to reduce toxicity. This review will provide an update on the state of knowledge in these areas and can provide insights useful for the crafting of hypotheses for improvements in pretreatment, conditioning, and fermentation organisms.

  14. Influence of pretreatment with Fenton's reagent on biogas production and methane yield from lignocellulosic biomass.

    PubMed

    Michalska, Karina; Miazek, Krystian; Krzystek, Liliana; Ledakowicz, Stanisław

    2012-09-01

    Biomass from Miscanthus giganteus, Sida hermaphrodita and Sorghum Moensch was treated with Fenton's reagent for 2 hours under optimal conditions (pH=3, mass ratio of [Fe(2+)]:[H(2)O(2)] equals 1:25 for Miscanthus and Sorghum and 1:15 for Sida). The degrees of delignification were 30.3%, 62.3% and 48.1% for the three plant species, respectively. The volatile fatty acids concentration after chemical pretreatment was high enough for production of biogas with a high methane content. Combined chemical oxidation and enzymatic hydrolysis with cellulase and cellobiase led to glucose contents of above 4 g/L. Among the tested plants, the highest biogas production (25.2 Ndm(3)/kg TS fed) with a 75% methane content was obtained with Sorghum Moensch. The results of the three-step process of biomass degradation show the necessity of applying a chemical pretreatment such as oxidation with Fenton's reagent. Moreover, the coagulation of residual Fe(3+) ions is not required for high biogas production.

  15. Impact of lignins isolated from pretreated lignocelluloses on enzymatic cellulose saccharification.

    PubMed

    Barsberg, Søren; Selig, Michael Joseph; Felby, Claus

    2013-02-01

    Lignins were enzymatically isolated from corn stover and wheat straw samples and subjected to hydrothermal or wet oxidation pretreatments for enzyme adsorption experimentations. Lignin contents of the isolates ranged from 26 to 71 % (w/w); cellulose ranged from 3 to 22 % (w/w); xylan from 0.7 to 6 % (w/w) and ash was from 5.8 to 30 % (w/w). ATR-IR analyses indicated significant and similar levels of calcium in all lignin isolates. Commercial cellulase adsorption studies showed that the presence of these lignins had no significant impact on the total amount of adsorbed enzyme in cellulose and cellulose-lignin systems. Consequently, the presence of the lignins had minimal effect, if any, on enzymatic cellulose conversion. Furthermore, this result, coupled with significant calcium levels in the isolated lignins, supports previous work suggesting lignin-calcium complexes reduce enzyme-lignin interactions.

  16. Comparative study of corn stover pretreated by dilute acid and cellulose solvent-based lignocellulose fractionation: Enzymatic hydrolysis, supramolecular structure, and substrate accessibility.

    PubMed

    Zhu, Zhiguang; Sathitsuksanoh, Noppadon; Vinzant, Todd; Schell, Daniel J; McMillan, James D; Zhang, Y-H Percival

    2009-07-01

    Liberation of fermentable sugars from recalcitrant biomass is among the most costly steps for emerging cellulosic ethanol production. Here we compared two pretreatment methods (dilute acid, DA, and cellulose solvent and organic solvent lignocellulose fractionation, COSLIF) for corn stover. At a high cellulase loading [15 filter paper units (FPUs) or 12.3 mg cellulase per gram of glucan], glucan digestibilities of the corn stover pretreated by DA and COSLIF were 84% at hour 72 and 97% at hour 24, respectively. At a low cellulase loading (5 FPUs per gram of glucan), digestibility remained as high as 93% at hour 24 for the COSLIF-pretreated corn stover but reached only approximately 60% for the DA-pretreated biomass. Quantitative determinations of total substrate accessibility to cellulase (TSAC), cellulose accessibility to cellulase (CAC), and non-cellulose accessibility to cellulase (NCAC) based on adsorption of a non-hydrolytic recombinant protein TGC were measured for the first time. The COSLIF-pretreated corn stover had a CAC of 11.57 m(2)/g, nearly twice that of the DA-pretreated biomass (5.89 m(2)/g). These results, along with scanning electron microscopy images showing dramatic structural differences between the DA- and COSLIF-pretreated samples, suggest that COSLIF treatment disrupts microfibrillar structures within biomass while DA treatment mainly removes hemicellulose. Under the tested conditions COSLIF treatment breaks down lignocellulose structure more extensively than DA treatment, producing a more enzymatically reactive material with a higher CAC accompanied by faster hydrolysis rates and higher enzymatic digestibility.

  17. Comparative Study of Corn Stover Pretreated by Dilute Acid and Cellulose Solvent-Based Lignocellulose Fractionation: Enzymatic Hydrolysis, Supramolecular Structure, and Substrate Accessibility

    SciTech Connect

    Zhu, Z.; Sathitsuksanoh, N.; Vinzant, T.; Schell, D. J.; McMillian, J. D.; Zhang, Y. H. P.

    2009-07-01

    Liberation of fermentable sugars from recalcitrant biomass is among the most costly steps for emerging cellulosic ethanol production. Here we compared two pretreatment methods (dilute acid, DA, and cellulose solvent and organic solvent lignocellulose fractionation, COSLIF) for corn stover. At a high cellulase loading [15 filter paper units (FPUs) or 12.3 mg cellulase per gram of glucan], glucan digestibilities of the corn stover pretreated by DA and COSLIF were 84% at hour 72 and 97% at hour 24, respectively. At a low cellulase loading (5 FPUs per gram of glucan), digestibility remained as high as 93% at hour 24 for the COSLIF-pretreated corn stover but reached only {approx}60% for the DA-pretreated biomass. Quantitative determinations of total substrate accessibility to cellulase (TSAC), cellulose accessibility to cellulase (CAC), and non-cellulose accessibility to cellulase (NCAC) based on adsorption of a non-hydrolytic recombinant protein TGC were measured for the first time. The COSLIF-pretreated corn stover had a CAC of 11.57 m{sup 2}/g, nearly twice that of the DA-pretreated biomass (5.89 m{sup 2}/g). These results, along with scanning electron microscopy images showing dramatic structural differences between the DA- and COSLIF-pretreated samples, suggest that COSLIF treatment disrupts microfibrillar structures within biomass while DA treatment mainly removes hemicellulose. Under the tested conditions COSLIF treatment breaks down lignocellulose structure more extensively than DA treatment, producing a more enzymatically reactive material with a higher CAC accompanied by faster hydrolysis rates and higher enzymatic digestibility.

  18. Evaluation of chlorine dioxide as a supplementary pretreatment reagent for lignocellulosic biomass.

    PubMed

    Acharjee, Tapas C; Jiang, Zhihua; Haynes, Robert Daniel; Lee, Yoon Y

    2017-08-10

    Chlorine dioxide (ClO2) is a bleaching reagent used in paper industry. Two different types of pretreatment methods were investigated incorporating ClO2 as a secondary reagent: (a) alkaline followed by ClO2 treatment; (b) dilute-sulfuric acid followed ClO2 treatment. In these methods, ClO2 treatment has shown little effect on delignification. Scheme-a has shown a significant improvement in enzymatic digestibility of glucan far above that treated by ammonia alone. On the contrary, dilute-acid followed by ClO2 treatment has shown negative effect on the enzymatic hydrolysis. The main factors affecting the enzymatic hydrolysis are the changes of the chemical structure of lignin and its distribution on the biomass surface. ClO2 treatment significantly increases the carboxylic acid content and reduces phenolic groups of lignin, affecting hydrophobicity of lignin and the H-bond induced association between the enzyme and lignin. This collectively led to reduction of unproductive binding of enzyme with lignin, consequently increasing the digestibility. Copyright © 2017 Elsevier Ltd. All rights reserved.

  19. Efficient Degradation of Lignocellulosic Plant Biomass, without Pretreatment, by the Thermophilic Anaerobe “Anaerocellum thermophilum” DSM 6725▿

    PubMed Central

    Yang, Sung-Jae; Kataeva, Irina; Hamilton-Brehm, Scott D.; Engle, Nancy L.; Tschaplinski, Timothy J.; Doeppke, Crissa; Davis, Mark; Westpheling, Janet; Adams, Michael W. W.

    2009-01-01

    Very few cultivated microorganisms can degrade lignocellulosic biomass without chemical pretreatment. We show here that “Anaerocellum thermophilum” DSM 6725, an anaerobic bacterium that grows optimally at 75°C, efficiently utilizes various types of untreated plant biomass, as well as crystalline cellulose and xylan. These include hardwoods such as poplar, low-lignin grasses such as napier and Bermuda grasses, and high-lignin grasses such as switchgrass. The organism did not utilize only the soluble fraction of the untreated biomass, since insoluble plant biomass (as well as cellulose and xylan) obtained after washing at 75°C for 18 h also served as a growth substrate. The predominant end products from all growth substrates were hydrogen, acetate, and lactate. Glucose and cellobiose (on crystalline cellulose) and xylose and xylobiose (on xylan) also accumulated in the growth media during growth on the defined substrates but not during growth on the plant biomass. A. thermophilum DSM 6725 grew well on first- and second-spent biomass derived from poplar and switchgrass, where spent biomass is defined as the insoluble growth substrate recovered after the organism has reached late stationary phase. No evidence was found for the direct attachment of A. thermophilum DSM 6725 to the plant biomass. This organism differs from the closely related strain A. thermophilum Z-1320 in its ability to grow on xylose and pectin. Caldicellulosiruptor saccharolyticus DSM 8903 (optimum growth temperature, 70°C), a close relative of A. thermophilum DSM 6725, grew well on switchgrass but not on poplar, indicating a significant difference in the biomass-degrading abilities of these two otherwise very similar organisms. PMID:19465524

  20. Evaluating the utility of hydrothermolysis pretreatment approaches in enhancing lignocellulosic biomass degradation by the anaerobic fungus Orpinomyces sp. strain C1A.

    PubMed

    Liggenstoffer, Audra S; Youssef, Noha H; Wilkins, Mark R; Elshahed, Mostafa S

    2014-09-01

    Members of the anaerobic fungi (Phylum Neocallimastigomycota) are efficient biomass degraders and represent promising agents for fuel and chemical production from lignocellulosic biomass. Pretreatment of lignocellulosic biomass is considered an unavoidable first step in enzyme-based saccharification schemes, but its necessity in any proposed anaerobic fungi-based schemes is still unclear. Here, we evaluated the effect of hydrothermal pretreatments on the extent of corn stover and switchgrass degradation by an anaerobic fungal isolate, Orpinomyces sp. strain C1A. Using a factorial experimental design, we evaluated the effect of three different temperatures (180, 190, and 200°C) and three hold times (5, 10, and 15min). Pretreated corn stover and switchgrass were more amenable to degradation by strain C1A when compared to untreated biomass, as evident by the higher proportion of plant biomass degraded compared to untreated controls. However, when factoring in the proportion of biomass lost during the pretreatment process (ranging between 25.78 and 58.92% in corn stover and 28.34 and 38.22% in switchgrass), hydrothermolysis provided negligible or negative improvements to the extent of corn stover and switchgrass degradation by strain C1A. Product analysis demonstrated a shift towards higher ethanol and lactate production and lower acetate production associated with increase in pretreatment severity, especially in switchgrass incubations. The results are in stark contrast to the requirement of pretreatment in enzyme-based schemes for biomass saccharification, and their implications on the potential utility of anaerobic fungi in biofuel and biochemical production are discussed.

  1. Thermochemical pretreatment of lignocellulose residues: assessment of the effect on operational conditions and their interactions on the characteristics of leachable fraction.

    PubMed

    Vásquez, Denisse; Contreras, Elsa; Palma, Carolyn; Carvajal, Andrea

    2015-01-01

    Annually, large amounts of agricultural residues are produced in Chile, which can be turned into a good opportunity to diversify the energy matrix. These residues have a slow hydrolysis stage during anaerobic digestion; therefore, the application of a pretreatment seems to be an alternative to improve the process. This work focused on applying a thermochemical pretreatment with NaOH on two lignocellulosic residues. The experiments were performed according to a 2(4) factorial design. The factors studied in a 2(4) factorial design were: temperature (60 and 120 °C), pretreatment time (10 and 30 minutes), NaOH dose (2 and 4%), and residue size (<1 and 1-3 mm for wheat straw; 1-5 and 5-10 mm for corn stover). The analyzed response variables were the solubilization of organic matter, and the biodegradability of the lignocellulose hydrolysate. The statistical analysis of the data allowed the identification of the experimental conditions that maximized solubilization of organic matter and biodegradability. The main results showed that more aggressive experimental conditions could increase the breaking down of the structure; in addition, the time of pretreatment was not significant. Conversely, the less aggressive experimental conditions, regarding regent dosage and downsizing, favored the release of biodegradable organic matter. The main conclusion of this study was the identification of the operational conditions of the thermochemical pretreatment that promote maximum biogas production, which was caused due to the solubilization of a large amount of organic matter, but not because of the increase in biodegradability of the released organic matter.

  2. Asparagus stem as a new lignocellulosic biomass feedstock for anaerobic digestion: increasing hydrolysis rate, methane production and biodegradability by alkaline pretreatment.

    PubMed

    Chen, Xiaohua; Gu, Yu; Zhou, Xuefei; Zhang, Yalei

    2014-07-01

    Recently, anaerobic digestion of lignocellulosic biomass for methane production has attracted considerable attention. However, there is little information regarding methane production from asparagus stem, a typical lignocellulosic biomass, by anaerobic digestion. In this study, alkaline pretreatment of asparagus stem was investigated for its ability to increase hydrolysis rate and methane production and to improve biodegradability (BD). The hydrolysis rate increased with increasing NaOH dose, due to higher removal rates of lignin and hemicelluloses. However, the optimal NaOH dose was 6% (w/w) according to the specific methane production (SMP). Under this condition, the SMP and the technical digestion time of the NaOH-treated asparagus stem were 242.3 mL/g VS and 18 days, which were 38.4% higher and 51.4% shorter than those of the untreated sample, respectively. The BD was improved from 40.1% to 55.4%. These results indicate that alkaline pretreatment could be an efficient method for increasing methane production from asparagus stem. Copyright © 2014 Elsevier Ltd. All rights reserved.

  3. Continuous Ethanol Fermentation of Pretreated Lignocellulosic Biomasses, Waste Biomasses, Molasses and Syrup Using the Anaerobic, Thermophilic Bacterium Thermoanaerobacter italicus Pentocrobe 411.

    PubMed

    Andersen, Rasmus Lund; Jensen, Karen Møller; Mikkelsen, Marie Just

    2015-01-01

    Lignocellosic ethanol production is now at a stage where commercial or semi-commercial plants are coming online and, provided cost effective production can be achieved, lignocellulosic ethanol will become an important part of the world bio economy. However, challenges are still to be overcome throughout the process and particularly for the fermentation of the complex sugar mixtures resulting from the hydrolysis of hemicellulose. Here we describe the continuous fermentation of glucose, xylose and arabinose from non-detoxified pretreated wheat straw, birch, corn cob, sugar cane bagasse, cardboard, mixed bio waste, oil palm empty fruit bunch and frond, sugar cane syrup and sugar cane molasses using the anaerobic, thermophilic bacterium Thermoanaerobacter Pentocrobe 411. All fermentations resulted in close to maximum theoretical ethanol yields of 0.47-0.49 g/g (based on glucose, xylose, and arabinose), volumetric ethanol productivities of 1.2-2.7 g/L/h and a total sugar conversion of 90-99% including glucose, xylose and arabinose. The results solidify the potential of Thermoanaerobacter strains as candidates for lignocellulose bioconversion.

  4. Continuous Ethanol Fermentation of Pretreated Lignocellulosic Biomasses, Waste Biomasses, Molasses and Syrup Using the Anaerobic, Thermophilic Bacterium Thermoanaerobacter italicus Pentocrobe 411

    PubMed Central

    Andersen, Rasmus Lund; Jensen, Karen Møller; Mikkelsen, Marie Just

    2015-01-01

    Lignocellosic ethanol production is now at a stage where commercial or semi-commercial plants are coming online and, provided cost effective production can be achieved, lignocellulosic ethanol will become an important part of the world bio economy. However, challenges are still to be overcome throughout the process and particularly for the fermentation of the complex sugar mixtures resulting from the hydrolysis of hemicellulose. Here we describe the continuous fermentation of glucose, xylose and arabinose from non-detoxified pretreated wheat straw, birch, corn cob, sugar cane bagasse, cardboard, mixed bio waste, oil palm empty fruit bunch and frond, sugar cane syrup and sugar cane molasses using the anaerobic, thermophilic bacterium Thermoanaerobacter Pentocrobe 411. All fermentations resulted in close to maximum theoretical ethanol yields of 0.47–0.49 g/g (based on glucose, xylose, and arabinose), volumetric ethanol productivities of 1.2–2.7 g/L/h and a total sugar conversion of 90–99% including glucose, xylose and arabinose. The results solidify the potential of Thermoanaerobacter strains as candidates for lignocellulose bioconversion. PMID:26295944

  5. Hemicelluloses negatively affect lignocellulose crystallinity for high biomass digestibility under NaOH and H2SO4 pretreatments in Miscanthus

    PubMed Central

    2012-01-01

    Background Lignocellulose is the most abundant biomass on earth. However, biomass recalcitrance has become a major factor affecting biofuel production. Although cellulose crystallinity significantly influences biomass saccharification, little is known about the impact of three major wall polymers on cellulose crystallization. In this study, we selected six typical pairs of Miscanthus samples that presented different cell wall compositions, and then compared their cellulose crystallinity and biomass digestibility after various chemical pretreatments. Results A Miscanthus sample with a high hemicelluloses level was determined to have a relatively low cellulose crystallinity index (CrI) and enhanced biomass digestibility at similar rates after pretreatments of NaOH and H2SO4 with three concentrations. By contrast, a Miscanthus sample with a high cellulose or lignin level showed increased CrI and low biomass saccharification, particularly after H2SO4 pretreatment. Correlation analysis revealed that the cellulose CrI negatively affected biomass digestion. Increased hemicelluloses level by 25% or decreased cellulose and lignin contents by 31% and 37% were also found to result in increased hexose yields by 1.3-times to 2.2-times released from enzymatic hydrolysis after NaOH or H2SO4 pretreatments. The findings indicated that hemicelluloses were the dominant and positive factor, whereas cellulose and lignin had synergistic and negative effects on biomass digestibility. Conclusions Using six pairs of Miscanthus samples with different cell wall compositions, hemicelluloses were revealed to be the dominant factor that positively determined biomass digestibility after pretreatments with NaOH or H2SO4 by negatively affecting cellulose crystallinity. The results suggested potential approaches to the genetic modifications of bioenergy crops. PMID:22883929

  6. Mild alkali-pretreatment effectively extracts guaiacyl-rich lignin for high lignocellulose digestibility coupled with largely diminishing yeast fermentation inhibitors in Miscanthus.

    PubMed

    Li, Ming; Si, Shengli; Hao, Bo; Zha, Yi; Wan, Can; Hong, Shufen; Kang, Yongbo; Jia, Jun; Zhang, Jing; Li, Meng; Zhao, Chunqiao; Tu, Yuanyuan; Zhou, Shiguang; Peng, Liangcai

    2014-10-01

    In this study, various alkali-pretreated lignocellulose enzymatic hydrolyses were evaluated by using three standard pairs of Miscanthus accessions that showed three distinct monolignol (G, S, H) compositions. Mfl26 samples with elevated G-levels exhibited significantly increased hexose yields of up to 1.61-fold compared to paired samples derived from enzymatic hydrolysis, whereas Msa29 samples with high H-levels displayed increased hexose yields of only up to 1.32-fold. In contrast, Mfl30 samples with elevated S-levels showed reduced hexose yields compared to the paired sample of 0.89-0.98 folds at p<0.01. Notably, only the G-rich biomass samples exhibited complete enzymatic hydrolysis under 4% NaOH pretreatment. Furthermore, the G-rich samples showed more effective extraction of lignin-hemicellulose complexes than the S- and H-rich samples upon NaOH pretreatment, resulting in large removal of lignin inhibitors to yeast fermentation. Therefore, this study proposes an optimal approach for minor genetic lignin modification towards cost-effective biomass process in Miscanthus. Copyright © 2014 Elsevier Ltd. All rights reserved.

  7. A novel ionic liquid-tolerant Fusarium oxysporum BN secreting ionic liquid-stable cellulase: consolidated bioprocessing of pretreated lignocellulose containing residual ionic liquid.

    PubMed

    Xu, Jiaxing; Wang, Xinfeng; Hu, Lei; Xia, Jun; Wu, Zhen; Xu, Ning; Dai, Benlin; Wu, Bin

    2015-04-01

    In this study, microbial communities from chemicals polluted microhabitats were cultured with the addition of imidazolium-based ionic liquid (IL) to enrich for IL-tolerant microbes. A strain of Fusarium oxysporum BN producing cellulase from these enrichments was capable of growing in 10% (w/v) 1-ethyl-3-methylimidazolium phosphinate, much higher than the normal IL concentrations in the lignocellulose regenerated from ILs. Cellulase secreted by the strain showed high resistance to ILs based on phosphate and sulfate radicals, evidencing of a high conformational stability in relevant media. Gratifyingly, F. oxysporum BN can directly convert IL-pretreated rice straw to bioethanol via consolidated bioprocessing (I-CBP). At optimum fermentation condition, a maximum ethanol yield of 0.125 g ethanol g(-1) of rice straw was finally obtained, corresponding to 64.2% of the theoretical yield.

  8. Determination of porosity of lignocellulosic biomass before and after pretreatment by using Simons' stain and NMR techniques.

    PubMed

    Meng, Xianzhi; Foston, Marcus; Leisen, Johannes; DeMartini, Jaclyn; Wyman, Charles E; Ragauskas, Arthur J

    2013-09-01

    To further investigate the effect of dilute acid pretreatment (DAP) and steam explosion pretreatment (SE) on the change in cellulose accessibility, several techniques were applied including a Simons' stain (SS) technique along with several NMR methods (i.e., NMR cryoporometry, (1)H spin-lattice (T1) and (1)H spin-spin (T2) relaxometry, and diffusometry). These methods were utilized to probe biomass porosity and thus assess cellulose accessibility on untreated and pretreated Populus. In general, these techniques indicate that pretreated Populus has larger pore size distributions and specific surface area (SSA) when compared to an untreated sample. The SS method revealed that DAP is more effective than SE in terms of the SSA increase, and that DAP increases SSA as a function of pretreatment severity. Relaxometry and diffusion measurements also suggest pore expansion occurs primarily in the first 10 min of DAP.

  9. Evaluation of microwave-assisted pretreatment of lignocellulosic biomass immersed in alkaline glycerol for fermentable sugars production.

    PubMed

    Diaz, Ana Belen; Moretti, Marcia Maria de Souza; Bezerra-Bussoli, Carolina; Carreira Nunes, Christiane da Costa; Blandino, Ana; da Silva, Roberto; Gomes, Eleni

    2015-06-01

    A pretreatment with microwave irradiation was applied to enhance enzyme hydrolysis of corn straw and rice husk immersed in water, aqueous glycerol or alkaline glycerol. Native and pretreated solids underwent enzyme hydrolysis using the extract obtained from the fermentation of Myceliophthora heterothallica, comparing its efficiency with that of the commercial cellulose cocktail Celluclast®. The highest saccharification yields, for both corn straw and rice husk, were attained when biomass was pretreated in alkaline glycerol, method that has not been previously reported in literature. Moreover, FTIR, TG and SEM analysis revealed a more significant modification in the structure of corn straw subjected to this pretreatment. Highest global yields were attained with the crude enzyme extract, which might be the result of its content in a great variety of hydrolytic enzymes, as revealed zymogram analysis. Moreover, its hydrolysis efficiency can be improved by its supplementation with commercial β-glucosidase.

  10. Scale-up study of oxalic acid pretreatment of agricultural lignocellulosic biomass for the production of bioethanol

    Treesearch

    Jae-Won Lee; Carl J. Houtman; Hye-Yun Kim; In-Gyu Choi; Thomas W. Jeffries

    2011-01-01

    Building on our laboratory-scale optimization, oxalic acid was used to pretreat corncobs on the pilotscale. The hydrolysate obtained after washing the pretreated biomass contained 32.55 g/l of xylose, 2.74 g/l of glucose and low concentrations of inhibitors. Ethanol production, using Scheffersomyces stipitis, from this hydrolysate was 10.3 g/l, which approached the...

  11. The Presence of Pretreated Lignocellulosic Solids from Birch during Saccharomyces cerevisiae Fermentations Leads to Increased Tolerance to Inhibitors--A Proteomic Study of the Effects.

    PubMed

    Koppram, Rakesh; Mapelli, Valeria; Albers, Eva; Olsson, Lisbeth

    2016-01-01

    The fermentation performance of Saccharomyces cerevisiae in the cellulose to ethanol conversion process is largely influenced by the components of pretreated biomass. The insoluble solids in pretreated biomass predominantly constitute cellulose, lignin, and -to a lesser extent- hemicellulose. It is important to understand the effects of water-insoluble solids (WIS) on yeast cell physiology and metabolism for the overall process optimization. In the presence of synthetic lignocellulosic inhibitors, we observed a reduced lag phase and enhanced volumetric ethanol productivity by S. cerevisiae CEN.PK 113-7D when the minimal medium was supplemented with WIS of pretreated birch or spruce and glucose as the carbon source. To investigate the underlying molecular reasons for the effects of WIS, we studied the response of WIS at the proteome level in yeast cells in the presence of acetic acid as an inhibitor. Comparisons were made with cells grown in the presence of acetic acid but without WIS in the medium. Altogether, 729 proteins were detected and quantified, of which 246 proteins were significantly up-regulated and 274 proteins were significantly down-regulated with a fold change≥1.2 in the presence of WIS compared to absence of WIS. The cells in the presence of WIS up-regulated several proteins related to cell wall, glycolysis, electron transport chain, oxidative stress response, oxygen and radical detoxification and unfolded protein response; and down-regulated most proteins related to biosynthetic pathways including amino acid, purine, isoprenoid biosynthesis, aminoacyl-tRNA synthetases and pentose phosphate pathway. Overall, the identified differentially regulated proteins may indicate that the likelihood of increased ATP generation in the presence of WIS was used to defend against acetic acid stress at the expense of reduced biomass formation. Although, comparative proteomics of cells with and without WIS in the acetic acid containing medium revealed numerous

  12. Dual effect of soluble materials in pretreated lignocellulose on simultaneous saccharification and co-fermentation process for the bioethanol production.

    PubMed

    Qin, Lei; Li, Xia; Liu, Li; Zhu, Jia-Qing; Guan, Qi-Man; Zhang, Man-Tong; Li, Wen-Chao; Li, Bing-Zhi; Yuan, Ying-Jin

    2017-01-01

    In this study, wash liquors isolated from ethylenediamine and dry dilute acid pretreated corn stover were used to evaluate the effect of soluble materials in pretreated biomass on simultaneous saccharification and co-fermentation (SSCF) for ethanol production, respectively. Both of the wash liquors had different impacts on enzymatic hydrolysis and fermentation. Enzymatic conversions of glucan and xylan monotonically decreased as wash liquor concentration increased. Whereas, with low wash liquor concentrations, xylose consumption rate, cell viability and ethanol yield were maximally stimulated in fermentation without nutrient supplementary. Soluble lignins were found as the key composition which promoted sugars utilization and cell viability without nutrient supplementary. The dual effects of soluble materials on enzymatic hydrolysis and fermentation resulted in the reduction of ethanol yield as soluble materials increased in SSCF.

  13. Profiling and production of hemicellulases by thermophilic fungus Malbranchea flava and the role of xylanases in improved bioconversion of pretreated lignocellulosics to ethanol.

    PubMed

    Sharma, Manju; Mahajan, Chhavi; Bhatti, Manpreet S; Chadha, Bhupinder Singh

    2016-06-01

    This study reports thermophilic fungus Malbranchea flava as a potent source of xylanase and xylan-debranching accessory enzymes. M. flava produced high levels of xylanase on sorghum straw containing solidified culture medium. The optimization of culture conditions for production of hemicellulases was carried out using one factor at a time approach and Box-Behnken design of experiments with casein (%), inoculum age (h) and inoculum level (ml) as process variables and xylanase, β-xylosidase, acetyl esterases and arabinofuranosidase as response variables. The results showed that casein concentration between 3.0 and 3.5 %, inoculum age (56-60 h) and inoculum level (2-2.5 ml) resulted in production of 16,978, 10.0, 67.7 and 3.8 (U/gds) of xylanase, β-xylosidase, acetyl esterase and α-L-arabinofuranosidase, respectively. Under optimized conditions M. flava produced eight functionally diverse xylanases with distinct substrate specificity against different xylan types. The peptide mass fingerprinting of 2-D gel electrophoresis resolved proteins indicated to the presence of cellobiose dehydrogenase and glycosyl hydrolases suggesting the potential of this strain in oxidative and classical cellulase-mediated hydrolysis of lignocellulosics. Addition of xylanase (300 U/g substrate) during saccharification (at 15 % substrate loading) of different pretreated (acid/alkali) substrates (cotton stalks, wheat straw, rice straw, carrot grass) by commercial cellulase (NS28066) resulted in 9-36 % increase in saccharification and subsequent fermentation to ethanol when compared to experiment with commercial enzyme only. High ethanol level 46 (g/l) was achieved with acid pretreated cotton stalk when M. flava xylanase was supplemented as compared to 39 (g/l) with xylanase without xylanase addition.

  14. Enzymatic hydrolysis of various pretreated lignocellulosic substrates and the fermentation of the liberated sugars to ethanol and butanediol

    SciTech Connect

    Saddler, J.N.; Mes-Hartree, M.; Yu, E.K.C.; Brownell, H.H.

    1983-01-01

    Aspen wood and wheat straw were pretreated by exposure to steam at elevated temperatures. Chemical analysis of the substrates revealed that steam explosion differentially decomposed the pentosan component while leaving the glucan portion relatively unchanged. The pretreated residues could be used as substrates for growth of Trichoderma reesei C30 and T. harzianum E58. The cellulase activities detected were in some cases three times as high as those found when Solka Floc was used as the substrate. Culture filtrates of T. harzianum E58 could efficiently hydrolyze the hemicellulose-rich water-soluble fractions. This material was fermented by Klebsiella pneumoniae with 0.4-0.5 g of 2,3-butanediol produced per gram of sugar utilized. Once the steam-exploded residues had been water and alkali extracted, the enzymatically hydrolyzed substrates were readily fermented by Saccharomyces cerevisiae or Zymononas mobilis with values as high as 2% (w/v) ethanol obtained from 5% steam-exploded wood fractions. 30 references, 2 figures, 8 tables.

  15. Effect of lignocellulosic degradation compounds from steam explosion pretreatment on ethanol fermentation by thermotolerant yeast Kluyveromyces marxianus.

    PubMed

    Oliva, Jose Miguel; Sáez, Felicia; Ballesteros, Ignacio; González, Alberto; Negro, Maria José; Manzanares, Paloma; Ballesteros, Mercedes

    2003-01-01

    The filtrate from steam-pretreated poplar was analyzed to identify degradation compounds. The effect of selected compounds on growth and ethanolic fermentation of the thermotolerant yeast strain Kluyveromyces marxianus CECT 10875 was tested. Several fermentations on glucose medium, containing individual inhibitory compounds found in the hydrolysate, were carried out. The degree of inhibition on yeast strain growth and ethanolic fermentation was determined. At concentrations found in the prehy-drolysate, none of the individual compounds significantly affected the fermentation. For all tested compounds, growth was inhibited to a lesser extent than ethanol production. Lower concentrations of catechol (0.96 g/L) and 4-hydroxybenzaldehyde (1.02 g/L) were required to produce the 50% reduction in cell mass in comparison to other tested compounds.

  16. Effects of thermo-chemical pretreatment plus microbial fermentation and enzymatic hydrolysis on saccharification and lignocellulose degradation of corn straw.

    PubMed

    Wang, Ping; Chang, Juan; Yin, Qingqiang; Wang, Erzhu; Zhu, Qun; Song, Andong; Lu, Fushan

    2015-10-01

    In order to increase corn straw degradation, the straw was kept in the combined solution of 15% (w/w) lime supernatant and 2% (w/w) sodium hydroxide with liquid-to-solid ratio of 13:1 (mL/g) at 83.92°C for 6h; and then added with 3% (v/v) H2O2 for reaction at 50°C for 2h; finally cellulase (32.3 FPU/g dry matter) and xylanase (550 U/g dry matter) was added to keep at 50°C for 48 h. The maximal reducing sugars yield (348.77 mg/g) was increased by 126.42% (P<0.05), and the degradation rates of cellulose, hemicellulose and lignin in pretreated corn straw with enzymatic hydrolysis were increased by 40.08%, 45.71% and 52.01%, compared with the native corn straw with enzymatic hydrolysis (P<0.05). The following study indicated that the combined microbial fermentation and enzymatic hydrolysis could further increase straw degradation and reducing sugar yield (442.85 mg/g, P<0.05).

  17. Solid-state fermentation in multi-well plates to assess pretreatment efficiency of rot fungi on lignocellulose biomass

    PubMed Central

    Zhou, Simeng; Raouche, Sana; Grisel, Sacha; Navarro, David; Sigoillot, Jean-Claude; Herpoël-Gimbert, Isabelle

    2015-01-01

    The potential of fungal pretreatment to improve fermentable sugar yields from wheat straw or Miscanthus was investigated. We assessed 63 fungal strains including 53 white-rot and 10 brown-rot fungi belonging to the Basidiomycota phylum in an original 12 day small-scale solid-state fermentation (SSF) experiment using 24-well plates. This method offers the convenience of one-pot processing of samples from SSF to enzymatic hydrolysis. The comparison of the lignocellulolytic activity profiles of white-rot fungi and brown-rot fungi showed different behaviours. The hierarchical clustering according to glucose and reducing sugars released from each biomass after 72 h enzymatic hydrolysis splits the set of fungal strains into three groups: efficient, no-effect and detrimental-effect species. The efficient group contained 17 species belonging to seven white-rot genera and one brown-rot genus. The yield of sugar released increased significantly (max. 62%) compared with non-inoculated controls for both substrates. PMID:26249037

  18. Lignocellulosic sugar management for xylitol and ethanol fermentation with multiple cell recycling by Kluyveromyces marxianus IIPE453.

    PubMed

    Dasgupta, Diptarka; Ghosh, Debashish; Bandhu, Sheetal; Adhikari, Dilip K

    2017-07-01

    Optimum utilization of fermentable sugars from lignocellulosic biomass to deliver multiple products under biorefinery concept has been reported in this work. Alcohol fermentation has been carried out with multiple cell recycling of Kluyveromyces marxianus IIPE453. The yeast utilized xylose-rich fraction from acid and steam treated biomass for cell generation and xylitol production with an average yield of 0.315±0.01g/g while the entire glucose rich saccharified fraction had been fermented to ethanol with high productivity of 0.9±0.08g/L/h. A detailed insight into its genome illustrated the strain's complete set of genes associated with sugar transport and metabolism for high-temperature fermentation. A set flocculation proteins were identified that aided in high cell recovery in successive fermentation cycles to achieve alcohols with high productivity. We have brought biomass derived sugars, yeast cell biomass generation, and ethanol and xylitol fermentation in one platform and validated the overall material balance. 2kg sugarcane bagasse yielded 193.4g yeast cell, and with multiple times cell recycling generated 125.56g xylitol and 289.2g ethanol (366mL). Copyright © 2017 Elsevier GmbH. All rights reserved.

  19. Bioconversion of lignocellulose: inhibitors and detoxification

    PubMed Central

    2013-01-01

    Bioconversion of lignocellulose by microbial fermentation is typically preceded by an acidic thermochemical pretreatment step designed to facilitate enzymatic hydrolysis of cellulose. Substances formed during the pretreatment of the lignocellulosic feedstock inhibit enzymatic hydrolysis as well as microbial fermentation steps. This review focuses on inhibitors from lignocellulosic feedstocks and how conditioning of slurries and hydrolysates can be used to alleviate inhibition problems. Novel developments in the area include chemical in-situ detoxification by using reducing agents, and methods that improve the performance of both enzymatic and microbial biocatalysts. PMID:23356676

  20. Fermentative hydrogen production from agroindustrial lignocellulosic substrates

    PubMed Central

    Reginatto, Valeria; Antônio, Regina Vasconcellos

    2015-01-01

    To achieve economically competitive biological hydrogen production, it is crucial to consider inexpensive materials such as lignocellulosic substrate residues derived from agroindustrial activities. It is possible to use (1) lignocellulosic materials without any type of pretreatment, (2) lignocellulosic materials after a pretreatment step, and (3) lignocellulosic materials hydrolysates originating from a pretreatment step followed by enzymatic hydrolysis. According to the current literature data on fermentative H2 production presented in this review, thermophilic conditions produce H2 in yields approximately 75% higher than those obtained in mesophilic conditions using untreated lignocellulosic substrates. The average H2 production from pretreated material is 3.17 ± 1.79 mmol of H2/g of substrate, which is approximately 50% higher compared with the average yield achieved using untreated materials (2.17 ± 1.84 mmol of H2/g of substrate). Biological pretreatment affords the highest average yield 4.54 ± 1.78 mmol of H2/g of substrate compared with the acid and basic pretreatment - average yields of 2.94 ± 1.85 and 2.41 ± 1.52 mmol of H2/g of substrate, respectively. The average H2 yield from hydrolysates, obtained from a pretreatment step and enzymatic hydrolysis (3.78 ± 1.92 mmol of H2/g), was lower compared with the yield of substrates pretreated by biological methods only, demonstrating that it is important to avoid the formation of inhibitors generated by chemical pretreatments. Based on this review, exploring other microorganisms and optimizing the pretreatment and hydrolysis conditions can make the use of lignocellulosic substrates a sustainable way to produce H2. PMID:26273246

  1. Fermentative hydrogen production from agroindustrial lignocellulosic substrates.

    PubMed

    Reginatto, Valeria; Antônio, Regina Vasconcellos

    2015-06-01

    To achieve economically competitive biological hydrogen production, it is crucial to consider inexpensive materials such as lignocellulosic substrate residues derived from agroindustrial activities. It is possible to use (1) lignocellulosic materials without any type of pretreatment, (2) lignocellulosic materials after a pretreatment step, and (3) lignocellulosic materials hydrolysates originating from a pretreatment step followed by enzymatic hydrolysis. According to the current literature data on fermentative H2 production presented in this review, thermophilic conditions produce H2 in yields approximately 75% higher than those obtained in mesophilic conditions using untreated lignocellulosic substrates. The average H2 production from pretreated material is 3.17 ± 1.79 mmol of H2/g of substrate, which is approximately 50% higher compared with the average yield achieved using untreated materials (2.17 ± 1.84 mmol of H2/g of substrate). Biological pretreatment affords the highest average yield 4.54 ± 1.78 mmol of H2/g of substrate compared with the acid and basic pretreatment - average yields of 2.94 ± 1.85 and 2.41 ± 1.52 mmol of H2/g of substrate, respectively. The average H2 yield from hydrolysates, obtained from a pretreatment step and enzymatic hydrolysis (3.78 ± 1.92 mmol of H2/g), was lower compared with the yield of substrates pretreated by biological methods only, demonstrating that it is important to avoid the formation of inhibitors generated by chemical pretreatments. Based on this review, exploring other microorganisms and optimizing the pretreatment and hydrolysis conditions can make the use of lignocellulosic substrates a sustainable way to produce H2.

  2. Development of next generation biocatalyst for lower-cost ethanol production from lignocellulose

    USDA-ARS?s Scientific Manuscript database

    Economics of fermentation-based biotechnology rely extensively on microbial performance. For renewable ethanol production using lignocellulosic biomass feedstocks, two major technical challenges exist. First, inhibitory compounds liberated from lignocellulosic biomass pretreatment interfere with m...

  3. Recent advances in understanding the role of cellulose accessibility in enzymatic hydrolysis of lignocellulosic substrates.

    PubMed

    Meng, Xianzhi; Ragauskas, Arthur Jonas

    2014-06-01

    Cellulose accessibility has been proposed as a key factor in the efficient bio-conversion of lignocellulosic biomass to fermentable sugars. Factors affecting cellulose accessibility can be divided into direct factors that refer to accessible surface area of cellulose, and indirect factors referring to chemical composition such as lignin/hemicellulose content, and biomass structure-relevant factors (i.e. particle size, porosity). An overview of the current pretreatment technologies special focus on the major mode of action to increase cellulose accessibility as well as multiple techniques that could be used to assess the cellulose accessibility are presented in this review. The appropriate determination of cellulose accessibility before and after pretreatment can assist to understand the effectiveness of a particular pretreatment in overcoming lignocellulosic recalcitrance to improve substrate enzymatic digestibility.

  4. Biohydrogen production from lignocellulosic feedstock.

    PubMed

    Cheng, Chieh-Lun; Lo, Yung-Chung; Lee, Kuo-Shing; Lee, Duu-Jong; Lin, Chiu-Yue; Chang, Jo-Shu

    2011-09-01

    Due to the recent energy crisis and rising concern over climate change, the development of clean alternative energy sources is of significant interest. Biohydrogen produced from cellulosic feedstock, such as second generation feedstock (lignocellulosic biomass) and third generation feedstock (carbohydrate-rich microalgae), is a promising candidate as a clean, CO2-neutral, non-polluting and high efficiency energy carrier to meet the future needs. This article reviews state-of-the-art technology on lignocellulosic biohydrogen production in terms of feedstock pretreatment, saccharification strategy, and fermentation technology. Future developments of integrated biohydrogen processes leading to efficient waste reduction, low CO2 emission and high overall hydrogen yield is discussed.

  5. Lime Pretreatment

    NASA Astrophysics Data System (ADS)

    Sierra, Rocio; Granda, Cesar Benigno; Holtzapple, Mark T.

    Lime pretreatment has proven to be a useful method for selectively reducing the lignin content of lignocellulosic biomass without significant loss in carbohydrates, thus realizing an important increase in biodigestibility. In lime pretreatment, the biomass is pretreated with calcium hydroxide and water under different conditions of temperature and pressure. It can be accomplished in one of three fashions: (1) short-term pretreatment that lasts up to 6 h, requires temperatures of 100-160°C, and can be applied with or without oxygen (pressure ~200 psig); (2) long-term pretreatment taking up to 8 weeks, requiring only 55-65°C, and capable of running with or without air (atmospheric pressure); and (3) simple pretreatment requiring 1 h in boiling water, without air or oxygen. Nonoxidative conditions are effective at low lignin contents (below ~18% lignin), whereas oxidative conditions are required for high lignin contents (above ~18% lignin).

  6. Lime pretreatment.

    PubMed

    Sierra, Rocio; Granda, Cesar Benigno; Holtzapple, Mark T

    2009-01-01

    Lime pretreatment has proven to be a useful method for selectively reducing the lignin content of lignocellulosic biomass without significant loss in carbohydrates, thus realizing an important increase in biodigestibility. In lime pretreatment, the biomass is pretreated with calcium hydroxide and water under different conditions of temperature and pressure. It can be accomplished in one of three fashions: (1) short-term pretreatment that lasts up to 6 h, requires temperatures of 100-160 degrees C, and can be applied with or without oxygen (pressure approximately 200 psig); (2) long-term pretreatment taking up to 8 weeks, requiring only 55-65 degrees C, and capable of running with or without air (atmospheric pressure); and (3) simple pretreatment requiring 1 h in boiling water, without air or oxygen. Nonoxidative conditions are effective at low lignin contents (below approximately 18% lignin), whereas oxidative conditions are required for high lignin contents (above approximately 18% lignin).

  7. Pomalidomide in heavily pretreated refractory multiple myeloma: a case report.

    PubMed

    Palmas, Angelo; Piras, Giovanna; Uras, Antonella; Asproni, Rosanna; Murineddu, Marco; Monne, Maria; Stradoni, Roberta; Latte, Giancarlo

    2017-02-01

    We present the case of a 70-year-old man diagnosed with multiple myeloma in 2008, who after four therapy lines initiated a fifth-line treatment with pomalidomide (4 mg orally, days 1-21 of a 28-day cycle) and low-dose dexamethasone (40 mg weekly orally). The patient was treated with pomalidomide for almost 2 years achieving a complete remission after 12 cycles. Complete remission was maintained for 9 months. This case illustrates the potential of pomalidomide plus low-dose dexamethasone to overcome multiple myeloma refractoriness inducing a quick and very prolonged remission.

  8. Evaluation of alkaline pretreatment temperature on a multi-product basis for the co-production of glucose and hemicellulose based films from lignocellulosic biomass.

    PubMed

    Bahcegul, Erinc; Toraman, Hilal Ezgi; Ozkan, Necati; Bakir, Ufuk

    2012-01-01

    Cotton stalks were subjected to alkaline pretreatment for the co-production of glucose and hemicellulose based films with a multi-product approach. Three pretreatment temperatures (25, 60 and 90 °C) were evaluated for their effects both on the glucose yield and on the properties of hemicellulose based films. Compared to untreated cotton stalks, the glucose yields were enhanced 3.9, 4.1 and 4.2 times for pretreatments conducted at 25, 60 and 90 °C, respectively. The pretreatment temperature of 90 °C was detrimental in terms of film formation. Tensile energy to break values of the films obtained after pretreatments conducted at 25, 60 and 90 °C were 1.1, 0.8, and 0.4 MJ/m3, respectively. The hemicellulosic part of the process, which considers the production of hemicellulose based films, should govern the pretreatment temperature since it was more responsive to the changes in the pretreatment temperature compared to the cellulosic part that accounts for glucose production.

  9. Lignosulfonate-mediated cellulase adsorption: enhanced enzymatic saccharification of lignocellulose through weakening nonproductive binding to lignin

    Treesearch

    Zhaojiang Wang; JY Zhu; Yingjuan Fu; Menghua Qin; Zhiyong Shao; Jungang Jiang; Fang Yang

    2013-01-01

    Thermochemical pretreatment of lignocellulose is crucial to bioconversion in the fields of biorefinery and biofuels. However, the enzyme inhibitors in pretreatment hydrolysate make solid substrate washing and hydrolysate detoxification indispensable prior to enzymatic hydrolysis. Sulfite pretreatment to overcome recalcitrance of lignocelluloses (SPORL) is a relatively...

  10. Lignosulfonate To Enhance Enzymatic Saccharification of Lignocelluloses: Role of Molecular Weight and Substrate Lignin

    Treesearch

    Haifeng Zhou; Hongming Lou; Dongjie Yang; J.Y. Zhu; Xueqing Qiu

    2013-01-01

    This study conducted an investigation of the effect of lignosulfonate (LS) on enzymatic saccharification of lignocelluloses. Two commercial LSs and one laboratory sulfonated kraft lignin were applied to Whatman paper, dilute acid and SPORL (sulfite pretreatment to overcome recalcitrance of lignocelluloses) pretreated aspen, and kraft alkaline and SPORL pretreated...

  11. Fractionating Recalcitrant Lignocellulose at Modest Reaction Conditions

    SciTech Connect

    Zhang, Y.-H. Percival; Ding, Shi-You; Mielenz, Jonathan R; Cui, Jing-Biao; Elander, Richard T.; Laser, Mark; Himmel, Michael; McMillan, James R.; Lynd, L.

    2007-01-01

    Effectively releasing the locked polysaccharides from recalcitrant lignocellulose to fermentable sugars is among the greatest technical and economic barriers to the realization of lignocellulose biorefineries because leading lignocellulose pre-treatment technologies suffer from low sugar yields, and/or severe reaction conditions, and/or high cellulase use, narrow substrate applicability, and high capital investment, etc. A new lignocellulose pre-treatment featuring modest reaction conditions (50 C and atmospheric pressure) was demonstrated to fractionate lignocellulose to amorphous cellulose, hemicellulose, lignin, and acetic acid by using a non-volatile cellulose solvent (concentrated phosphoric acid), a highly volatile organic solvent (acetone), and water. The highest sugar yields after enzymatic hydrolysis were attributed to no sugar degradation during the fractionation and the highest enzymatic cellulose digestibility ({approx}97% in 24 h) during the hydrolysis step at the enzyme loading of 15 filter paper units of cellulase and 60 IU of beta-glucosidase per gram of glucan. Isolation of high-value lignocellulose components (lignin, acetic acid, and hemicellulose) would greatly increase potential revenues of a lignocellulose biorefinery.

  12. Biocatalytic conversion of lignocellulose to platform chemicals.

    PubMed

    Jäger, Gernot; Büchs, Jochen

    2012-09-01

    Naturally occurring lignocellulose can be used as a renewable resource for the sustainable production of platform chemicals that can in turn be converted to valuable fine chemicals, polymers, and fuels. The biocatalytic conversion of lignocellulose is a very promising approach due to its high selectivity, mild conditions, and low exergy loss. However, such biocatalytic processes are still seldom applied at the industrial scale since the single conversion steps (pretreatment, hydrolysis, and fermentation) may exhibit low conversion rates, low efficiencies, or high costs. The biocatalytic conversion of lignocellulose to platform chemicals is reviewed in this work. Structures and production rates of lignocellulose are described, and platform chemicals that may be produced from lignocellulose are summarized. Biocatalytic conversion of lignocellulose is distinguished from conventional non-selective approaches. All essential conversion steps used in biocatalytic approaches (pretreatment, hydrolysis, and fermentation) are reviewed in detail. Finally, potential interactions between these conversion steps are highlighted and the advantages as well as disadvantages of integrated process configurations are elucidated. In conclusion, a comprehensive understanding of the biocatalytic conversion of lignocellulose is provided in this review.

  13. A pilot study on lignocelluloses to ethanol and fish feed using NMMO pretreatment and cultivation with zygomycetes in an air-lift reactor.

    PubMed

    Lennartsson, Patrik R; Niklasson, Claes; Taherzadeh, Mohammad J

    2011-03-01

    A complete process for the production of bioethanol and fungal biomass from spruce and birch was investigated. The process included milling, pretreatment with N-methylmorpholine-N-oxide (NMMO), washing of the pretreated wood, enzymatic hydrolysis, and cultivation of the zygomycetes fungi Mucor indicus. Investigated factors included wood chip size (0.5-16 mm), pretreatment time (1-5h), and scale of the process from bench-scale to 2m high air-lift reactor. Best hydrolysis yields were achieved from wood chips below 2mm after 5h of pretreatment. Ethanol yields (mg/g wood) of 195 and 128 for spruce, and 175 and 136 for birch were achieved from bench-scale and airlift, respectively. Fungal biomass yields (mg/g wood) of 103 and 70 for spruce, and 86 and 66 for birch from bench scale and airlift respectively were simultaneously achieved. NMMO pretreatment and cultivation with M. indicus appear to be a good alternative for ethanol production from birch and spruce.

  14. Grass Lignocellulose

    NASA Astrophysics Data System (ADS)

    Akin, Danny E.

    Grass lignocelluloses are limited in bioconversion by aromatic constituents, which include both lignins and phenolic acids esters. Histochemistry, ultraviolet absorption microspectrophotometry, and response to microorganisms and specific enzymes have been used to determine the significance of aromatics toward recalcitrance. Coniferyl lignin appears to be the most effective limitation to biodegradation, existing in xylem cells of vascular tissues; cell walls with syringyl lignin, for example, leaf sclerenchyma, are less recalcitrant. Esterified phenolic acids, i.e., ferulic and p-coumaric acids, often constitute a major chemical limitation in nonlignified cell walls to biodegradation in grasses, especially warm-season species. Methods to improve biodegradability through modification of aromatics include: plant breeding, use of lignin-degrading white-rot fungi, and addition of esterases. Plant breeding for new cultivars has been especially effective for nutritionally improved forages, for example, bermudagrasses. In laboratory studies, selective white-rot fungi that lack cellulases delignified the lignocellulosic materials and improved fermentation of residual carbohydrates. Phenolic acid esterases released p-coumaric and ferulic acids for potential coproducts, improved the available sugars for fermentation, and improved biodegradation. The separation and removal of the aromatic components for coproducts, while enhancing the availability of sugars for bioconversion, could improve the economics of bioconversion.

  15. Characterization of a thermophilic cellulase from Geobacillus sp. HTA426, an efficient cellulase-producer on alkali pretreated of lignocellulosic biomass.

    PubMed

    Potprommanee, Laddawan; Wang, Xiao-Qin; Han, Ye-Ju; Nyobe, Didonc; Peng, Yen-Ping; Huang, Qing; Liu, Jing-Yong; Liao, Yu-Ling; Chang, Ken-Lin

    2017-01-01

    A themophilic cellulase-producing bacterium was isolated from a hot spring district and identified as Geobacillus sp. HTA426. The cellulase enzyme produced by the Geobacillus sp. HTA426 was purified through ammonium sulfate precipitation and ion exchange chromatography, with the recovery yield and fold purification of 10.14% and 5.12, respectively. The purified cellulase has a molecular weight of 40 kDa. The optimum temperature and pH for carboxymethyl cellulase (CMCase) activity of the purified cellulase were 60°C and pH 7.0, respectively. The enzyme was also stable over a wide temperature range of 50°C to 70°C after 5 h of incubation. Moreover, the strain HTA426 was able to grow and produce cellulase on alkali-treated sugarcane bagasse, rice straw and water hyacinth as carbon sources. Enzymatic hydrolysis of sugarcane bagasse, which was regarded as the most effective carbon source for cellulase production (CMCase activity = 103.67 U/mL), followed by rice straw (74.70 U/mL) and water hyacinth (51.10 U/mL). This strain producing an efficient thermostable cellulose is a potential candidate for developing a more efficient and cost-effective process for converting lignocellulosic biomass into biofuel and other industrial process.

  16. Cost reduction and feedstock diversity for sulfuric acid-free ethanol cooking of lignocellulosic biomass as a pretreatment to enzymatic saccharification.

    PubMed

    Teramoto, Yoshikuni; Lee, Seung-Hwan; Endo, Takashi

    2009-10-01

    We have previously demonstrated that a sulfuric acid-free ethanol (EtOH) cooking treatment enhances the enzymatic digestibility of eucalyptus wood and bagasse flour. In the present study, a reconfigured process that achieves similar performance was developed by identifying possible cost-competitive pretreatments that provide high cellulose-to-glucose conversion during subsequent enzymatic hydrolysis. The series of reconfigurations reduced EtOH usage in the pretreatment by more than 80% in comparison with our previous research. Higher initial pressures and intensive size reduction of the starting material are not required. The reconfigured process was applied to rice straw and Douglas fir, in order to confirm the feasibility of feedstock diversity.

  17. Impact of surfactant assisted acid and alkali pretreatment on lignocellulosic structure of pine foliage and optimization of its saccharification parameters using response surface methodology.

    PubMed

    Pandey, Ajay Kumar; Negi, Sangeeta

    2015-09-01

    In present study, two hybrid methods such as surfactant assisted acid pretreatment (SAAP) and surfactant assisted base pretreatment (SABP) of pine foliage (PF) were found efficient for removal of 59.53 ± 0.76% and 73.47 ± 1.03% lignin, respectively. Assessment of the impact of pretreatment over the structure of PF were studied by scanning electron microscopy, Fourier transform infrared and X-ray diffraction analysis. Parameters for saccharification of SAAP and SABP biomass were optimized by Box-Behnken design method and 0.588 g/g and 0.477 g/g of reducing sugars were obtained, respectively. The ethanol fermentation efficiency of Saccharomyces cerevisiae (NCIM 3288) of hydrolysates was increased by 16.1% and 6.01% in SAAP-PFF and SABP-PFF after detoxification with XAD-4 resin. The mass balance analysis of the process showed that 67.7% and 70.12% cellulose were utilized during SAAP and SABP, respectively. These results indicated that SAAP would be more economic for bioethanol production.

  18. Hydrolysates of lignocellulosic materials for biohydrogen production

    PubMed Central

    Chen, Rong; Wang, Yong-Zhong; Liao, Qiang; Zhu, Xun; Xu, Teng-Fei

    2013-01-01

    Lignocellulosic materials are commonly used in bio-H2 production for the sustainable energy resource development as they are abundant, cheap, renewable and highly biodegradable. In the process of the bio-H2 production, the pretreated lignocellulosic materials are firstly converted to monosaccharides by enzymolysis and then to H2 by fermentation. Since the structures of lignocellulosic materials are rather complex, the hydrolysates vary with the used materials. Even using the same lignocellulosic materials, the hydrolysates also change with different pretreatment methods. It has been shown that the appropriate hydrolysate compositions can dramatically improve the biological activities and bio-H2 production performances. Over the past decades, hydrolysis with respect to different lignocellulosic materials and pretreatments has been widely investigated. Besides, effects of the hydrolysates on the biohydrogen yields have also been examined. In this review, recent studies on hydrolysis as well as their effects on the biohydrogen production performance are summarized. [BMB Reports 2013; 46(5): 244-251] PMID:23710634

  19. Fuel ethanol production from corn stover under optimized dilute phosphoric acid pretreatment and enzymatic hydrolysis

    USDA-ARS?s Scientific Manuscript database

    Ethanol is a renewable oxygenated fuel. Dilute acid pretreatment is a promising pretreatment technology for conversion of lignocellulosic biomass to fuel ethanol. Generation of fermentable sugars from corn stover involves pretreatment and enzymatic saccharification. Pretreatment is crucial as nat...

  20. Process Design and Economics for Biochemical Conversion of Lignocellulosic Biomass to Ethanol: Dilute-Acid Pretreatment and Enzymatic Hydrolysis of Corn Stover

    SciTech Connect

    Humbird, D.; Davis, R.; Tao, L.; Kinchin, C.; Hsu, D.; Aden, A.; Schoen, P.; Lukas, J.; Olthof, B.; Worley, M.; Sexton, D.; Dudgeon, D.

    2011-03-01

    This report describes one potential biochemical ethanol conversion process, conceptually based upon core conversion and process integration research at NREL. The overarching process design converts corn stover to ethanol by dilute-acid pretreatment, enzymatic saccharification, and co-fermentation. Building on design reports published in 2002 and 1999, NREL, together with the subcontractor Harris Group Inc., performed a complete review of the process design and economic model for the biomass-to-ethanol process. This update reflects NREL's current vision of the biochemical ethanol process and includes the latest research in the conversion areas (pretreatment, conditioning, saccharification, and fermentation), optimizations in product recovery, and our latest understanding of the ethanol plant's back end (wastewater and utilities). The conceptual design presented here reports ethanol production economics as determined by 2012 conversion targets and 'nth-plant' project costs and financing. For the biorefinery described here, processing 2,205 dry ton/day at 76% theoretical ethanol yield (79 gal/dry ton), the ethanol selling price is $2.15/gal in 2007$.

  1. Chemical modification of lignocellulosics

    Treesearch

    Roger M. Rowell

    1996-01-01

    Agro-based resources, also referrered to as lignocellulosics, are resources that contain cellulose, hemicelluloses, and lignin. Lignocellulosics include wood, agricultural residues, water plants, grasses, and other plant substances. When considering lignocellulosics as possible engineering materials, there are several very basic concepts that must be considered. First...

  2. Tolerance and adaptive evolution of triacylglycerol-producing Rhodococcus opacus to lignocellulose-derived inhibitors.

    PubMed

    Kurosawa, Kazuhiko; Laser, Josephine; Sinskey, Anthony J

    2015-01-01

    Lignocellulosic biomass has been investigated as a renewable non-food source for production of biofuels. A significant technical challenge to using lignocellulose is the presence of microbial growth inhibitors generated during pretreatment processes. Triacylglycerols (TAGs) are potential precursors for lipid-based biofuel production. Rhodococcus opacus MITXM-61 is an oleaginous bacterium capable of producing large amounts of TAGs on high concentrations of glucose and xylose present in lignocellulosic hydrolysates. However, this strain is sensitive to ligonocellulose-derived inhibitors. To understand the toxic effects of the inhibitors in lignocellulosic hydrolysates, strain MITXM-61 was examined for tolerance toward the potential inhibitors and was subjected to adaptive evolution for the resistance to the inhibitors. We investigated growth-inhibitory effects by potential lignocellulose-derived inhibitors of phenols (lignin, vanillin, 4-hydroxybenzaldehyde (4-HB), syringaldehyde), furans (furfural and 5-hydroxymethyl-2-furaldehyde), and organic acids (levulinic acid, formic acid, and acetic acid) on the growth and TAG production of strain MITXM-61. Phenols and furans exhibited potent inhibitory effects at a concentration of 1 g L(-1), while organic acids had insignificant impacts at concentrations of up to 2 g L(-1). In an attempt to improve the inhibitor tolerance of strain MITXM-61, we evaluated the adaptation of this strain to the potential inhibitors. Adapted mutants were generated on defined agar media containing lignin, 4-HB, and syringaldehyde. Strain MITXM-61(SHL33) with improved multiple resistance of lignin, 4-HB, and syringaldehyde was constructed through adaptive evolution-based strategies. The evolved strain exhibited a two- to threefold increase in resistance to lignin, 4-HB, and syringaldehyde at 50% growth-inhibitory concentrations, compared to the parental strain. When grown in genuine lignocellulosic hydrolysates of corn stover, wheat straw, and

  3. Pretreatment of lignocellulosic material with fungi capable of higher lignin degradation and lower carbohydrate degradation improves substrate acid hydrolysis and the eventual conversion to ethanol.

    PubMed

    Kuhar, Sarika; Nair, Lavanya M; Kuhad, Ramesh Chander

    2008-04-01

    Phanerochaete chrysosporium, Pycnoporus cinnabarinus,and fungal isolates RCK-1 and RCK-3 were tested for their lignin degradation abilities when grown on wheat straw (WS) and Prosopis juliflora (PJ) under solid-state cultivation conditions. Fungal isolate RCK-1 degraded more lignin in WS (12.26% and 22.64%) and PJ (19.30% and 21.97%) and less holocellulose in WS (6.27% and 9.39%) and PJ (3.01% and 4.58%) after 10 and 20 days, respectively, than other fungi tested. Phanerochaete chrysosporium caused higher substrate mass loss and degraded more of holocellulosic content (WS: 55.67%; PJ: 48.89%) than lignin (WS: 18.89%; PJ: 20.20%) after 20 days. The fungal pretreatment of WS and PJ with a high-lignin-degrading and low-holocellulose-degrading fungus (fungal isolate RCK-1) for 10 days resulted in (i) reduction in acid load for hydrolysis of structural polysaccharides (from 3.5% to 2.5% in WS and from 4.5% to 2.5% in PJ), (ii) an increase in the release of fermentable sugars (from 30.27 to 40.82 g L(-1) in WS and from 18.18 to 26.00 g L(-1) in PJ), and (iii) a reduction in fermentation inhibitors (total phenolics) in acid hydrolysate of WS (from 1.31 to 0.63 g L(-1)) and PJ (from 2.05 to 0.80 g L(-1)). Ethanol yield and volumetric productivity from RCK-1-treated WS (0.48 g g(-1) and 0.54 g L(-1) h(-1), respectively) and PJ (0.46 g g(-1) and 0.33 g L(-1) h(-1), respectively) were higher than untreated WS (0.36 g g(-1) and 0.30 g L(-1) h(-1), respectively) and untreated PJ (0.42 g g(-1) and 0.21 g L(-1) h(-1), respectively).

  4. Utilizing Anaerobic Fungi for Two-stage Sugar Extraction and Biofuel Production from Lignocellulosic Biomass.

    PubMed

    Ranganathan, Abhaya; Smith, Olivia P; Youssef, Noha H; Struchtemeyer, Christopher G; Atiyeh, Hasan K; Elshahed, Mostafa S

    2017-01-01

    Lignocellulosic biomass is a vast and underutilized resource for the production of sugars and biofuels. However, the structural complexity of lignocellulosic biomass and the need for multiple pretreatment and enzymatic steps for sugar release renders this process economically challenging. Here, we report a novel approach for direct, single container, exogenous enzyme-free conversion of lignocellulosic biomass to sugars and biofuels using the anaerobic fungal isolate strain C1A. This approach utilizes simple physiological manipulations for timely inhibition and uncoupling of saccharolytic and fermentative capabilities of strain C1A, leading to the accumulation of sugar monomers (glucose and xylose) in the culture medium. The produced sugars, in addition to fungal hyphal lysate, are subsequently converted by Escherichia coli strain K011 to ethanol. Using this approach, we successfully recovered 17.0% (w/w) of alkali-pretreated corn stover (20.0% of its glucan and xylan content) as sugar monomers in the culture media. More importantly, 14.1% of pretreated corn stover (17.1% of glucan and xylan content) was recovered as ethanol at a final concentration of 28.16 mM after the addition of the ethanologenic strain K011. The high ethanol yield obtained is due to its accumulation as a minor fermentation end product by strain C1A during its initial growth phase, the complete conversion of sugars to ethanol by strain K011, and the possible conversion of unspecified substrates in the hyphal lysate of strain C1A to ethanol by strain K011. This study presents a novel, versatile, and exogenous enzyme-free strategy that utilizes a relatively unexplored group of organisms (anaerobic fungi) for direct biofuel production from lignocellulosic biomass.

  5. Utilizing Anaerobic Fungi for Two-stage Sugar Extraction and Biofuel Production from Lignocellulosic Biomass

    PubMed Central

    Ranganathan, Abhaya; Smith, Olivia P.; Youssef, Noha H.; Struchtemeyer, Christopher G.; Atiyeh, Hasan K.; Elshahed, Mostafa S.

    2017-01-01

    Lignocellulosic biomass is a vast and underutilized resource for the production of sugars and biofuels. However, the structural complexity of lignocellulosic biomass and the need for multiple pretreatment and enzymatic steps for sugar release renders this process economically challenging. Here, we report a novel approach for direct, single container, exogenous enzyme-free conversion of lignocellulosic biomass to sugars and biofuels using the anaerobic fungal isolate strain C1A. This approach utilizes simple physiological manipulations for timely inhibition and uncoupling of saccharolytic and fermentative capabilities of strain C1A, leading to the accumulation of sugar monomers (glucose and xylose) in the culture medium. The produced sugars, in addition to fungal hyphal lysate, are subsequently converted by Escherichia coli strain K011 to ethanol. Using this approach, we successfully recovered 17.0% (w/w) of alkali-pretreated corn stover (20.0% of its glucan and xylan content) as sugar monomers in the culture media. More importantly, 14.1% of pretreated corn stover (17.1% of glucan and xylan content) was recovered as ethanol at a final concentration of 28.16 mM after the addition of the ethanologenic strain K011. The high ethanol yield obtained is due to its accumulation as a minor fermentation end product by strain C1A during its initial growth phase, the complete conversion of sugars to ethanol by strain K011, and the possible conversion of unspecified substrates in the hyphal lysate of strain C1A to ethanol by strain K011. This study presents a novel, versatile, and exogenous enzyme-free strategy that utilizes a relatively unexplored group of organisms (anaerobic fungi) for direct biofuel production from lignocellulosic biomass. PMID:28443088

  6. Improved lignocellulose conversion to biofuels with thermophilic bacteria and thermostable enzymes.

    PubMed

    Bhalla, Aditya; Bansal, Namita; Kumar, Sudhir; Bischoff, Kenneth M; Sani, Rajesh K

    2013-01-01

    Second-generation feedstock, especially nonfood lignocellulosic biomass is a potential source for biofuel production. Cost-intensive physical, chemical, biological pretreatment operations and slow enzymatic hydrolysis make the overall process of lignocellulosic conversion into biofuels less economical than available fossil fuels. Lignocellulose conversions carried out at ≤ 50 °C have several limitations. Therefore, this review focuses on the importance of thermophilic bacteria and thermostable enzymes to overcome the limitations of existing lignocellulosic biomass conversion processes. The influence of high temperatures on various existing lignocellulose conversion processes and those that are under development, including separate hydrolysis and fermentation, simultaneous saccharification and fermentation, and extremophilic consolidated bioprocess are also discussed.

  7. Identification of Genes Conferring Tolerance to Lignocellulose-Derived Inhibitors by Functional Selections in Soil Metagenomes

    PubMed Central

    Forsberg, Kevin J.; Patel, Sanket; Witt, Evan; Wang, Bin; Ellison, Tyler D.

    2015-01-01

    The production of fuels or chemicals from lignocellulose currently requires thermochemical pretreatment to release fermentable sugars. These harsh conditions also generate numerous small-molecule inhibitors of microbial growth and fermentation, limiting production. We applied small-insert functional metagenomic selections to discover genes that confer microbial tolerance to these inhibitors, identifying both individual genes and general biological processes associated with tolerance to multiple inhibitory compounds. Having screened over 248 Gb of DNA cloned from 16 diverse soil metagenomes, we describe gain-of-function tolerance against acid, alcohol, and aldehyde inhibitors derived from hemicellulose and lignin, demonstrating that uncultured soil microbial communities hold tremendous genetic potential to address the toxicity of pretreated lignocellulose. We recovered genes previously known to confer tolerance to lignocellulosic inhibitors as well as novel genes that confer tolerance via unknown functions. For instance, we implicated galactose metabolism in overcoming the toxicity of lignin monomers and identified a decarboxylase that confers tolerance to ferulic acid; this enzyme has been shown to catalyze the production of 4-vinyl guaiacol, a valuable precursor to vanillin production. These metagenomic tolerance genes can enable the flexible design of hardy microbial catalysts, customized to withstand inhibitors abundant in specific bioprocessing applications. PMID:26546427

  8. Identification of Genes Conferring Tolerance to Lignocellulose-Derived Inhibitors by Functional Selections in Soil Metagenomes.

    PubMed

    Forsberg, Kevin J; Patel, Sanket; Witt, Evan; Wang, Bin; Ellison, Tyler D; Dantas, Gautam

    2015-11-06

    The production of fuels or chemicals from lignocellulose currently requires thermochemical pretreatment to release fermentable sugars. These harsh conditions also generate numerous small-molecule inhibitors of microbial growth and fermentation, limiting production. We applied small-insert functional metagenomic selections to discover genes that confer microbial tolerance to these inhibitors, identifying both individual genes and general biological processes associated with tolerance to multiple inhibitory compounds. Having screened over 248 Gb of DNA cloned from 16 diverse soil metagenomes, we describe gain-of-function tolerance against acid, alcohol, and aldehyde inhibitors derived from hemicellulose and lignin, demonstrating that uncultured soil microbial communities hold tremendous genetic potential to address the toxicity of pretreated lignocellulose. We recovered genes previously known to confer tolerance to lignocellulosic inhibitors as well as novel genes that confer tolerance via unknown functions. For instance, we implicated galactose metabolism in overcoming the toxicity of lignin monomers and identified a decarboxylase that confers tolerance to ferulic acid; this enzyme has been shown to catalyze the production of 4-vinyl guaiacol, a valuable precursor to vanillin production. These metagenomic tolerance genes can enable the flexible design of hardy microbial catalysts, customized to withstand inhibitors abundant in specific bioprocessing applications.

  9. Ethanol production from lignocellulose

    DOEpatents

    Ingram, Lonnie O.; Wood, Brent E.

    2001-01-01

    This invention presents a method of improving enzymatic degradation of lignocellulose, as in the production of ethanol from lignocellulosic material, through the use of ultrasonic treatment. The invention shows that ultrasonic treatment reduces cellulase requirements by 1/3 to 1/2. With the cost of enzymes being a major problem in the cost-effective production of ethanol from lignocellulosic material, this invention presents a significant improvement over presently available methods.

  10. Cellulose solvent- and organic solvent-based lignocellulose fractionation enabled efficient sugar release from a variety of lignocellulosic feedstocks.

    PubMed

    Sathitsuksanoh, Noppadon; Zhu, Zhiguang; Zhang, Y-H Percival

    2012-08-01

    Developing feedstock-independent biomass pretreatment would be vital to second generation biorefineries that would fully utilize diverse non-food lignocellulosic biomass resources, decrease transportation costs of low energy density feedstock, and conserve natural biodiversity. Cellulose solvent- and organic solvent-based lignocellulose fractionation (COSLIF) was applied to a variety of feedstocks, including Miscanthus, poplar, their mixture, bagasse, wheat straw, and rice straw. Although non-pretreated biomass samples exhibited a large variation in enzymatic digestibility, the COSLIF-pretreated biomass samples exhibited similar high enzymatic glucan digestibilities and fast hydrolysis rates. Glucan digestibilities of most pretreated feedstocks were ∼93% at five filter paper units per gram of glucan. The overall glucose and xylose yields for the Miscanthus:poplar mixture at a weight ratio of 1:2 were 93% and 85%, respectively. These results suggested that COSLIF could be regarded as a feedstock-independent pretreatment suitable for processing diverse feedstocks by adjusting pretreatment residence time only.

  11. pH-Induced Lignin Surface Modification to Reduce Nonspecific Cellulase Binding and Enhance Enzymatic Saccharification of Lignocelluloses

    Treesearch

    Hongming Lou; J.Y. Zhu; Tian Qing Lan; Huranran Lai; Xueqing Qiu

    2013-01-01

    We studied the mechanism of the significant enhancement in the enzymatic saccharification of lignocelluloses at an elevated pH of 5.5–6.0. Four lignin residues with different sulfonic acid contents were isolated from enzymatic hydrolysis of lodgepole pine pretreated by either dilute acid (DA) or sulfite pretreatment to overcome recalcitrance of lignocelluloses (SPORL...

  12. Prehydrolysis of lignocellulose

    DOEpatents

    Torget, Robert W.; Kadam, Kiran L.; Hsu, Teh-An; Philippidis, George P.; Wyman, Charles E.

    1998-01-01

    The invention relates to the prehydrolysis of lignocellulose by passing an acidic or alkaline solution through solid lignocellulosic particles with removal of soluble components as they are formed. The technique permits a less severe combination of pH, temperature and time than conventional prehydrolysis. Furthermore, greater extraction of both hemicellulose and lignin occurs simultaneously in the same reactor and under the same conditions.

  13. Prehydrolysis of lignocellulose

    DOEpatents

    Torget, Robert W.; Kadam, Kiran L.; Hsu, Teh-An; Philippidis, George P.; Wyman, Charles E.

    1996-01-01

    The invention relates to the prehydrolysis of lignocellulose by passing an acidic or alkaline solution through solid lignocellulosic particles with removal of soluble components as they are formed. The technique permits a less severe combination of pH, temperature and time than conventional prehydrolysis. Furthermore, greater extraction of both hemicellulose and lignin occurs simultaneously in the same reactor and under the same conditions.

  14. Prehydrolysis of lignocellulose

    DOEpatents

    Torget, Robert W.; Kadam, Kiran L.; Hsu, Teh-An; Philippidis, George P.; Wyman, Charles E.

    1995-01-01

    The invention relates to the prehydrolysis of lignocellulose by passing an acidic or alkaline solution through solid lignocellulosic particles with removal of soluble components as they are formed. The technique permits a less severe combination of pH, temperature and time than conventional prehydrolysis. Furthermore, greater extraction of both hemicellulose and lignin occurs simultaneously in the same reactor and under the same conditions.

  15. Effects of wet-pressing-induced fiber hornification on enzymatic saccharification of lignocelluloses

    Treesearch

    X.L. Luo; Junyong Zhu; Roland Gleisner; H.Y. Zhan

    2011-01-01

    This article reports the effect of wet-pressing-induced fiber hornification on enzymatic saccharification of lignocelluloses. A wet cellulosic substrate of bleached kraft eucalyptus pulp and two wet sulfite-pretreated lignocellulosic substrates of aspen and lodgepole pine were pressed to various moisture (solids) contents by variation of pressing pressure and pressing...

  16. Lignosulfonate and elevated pH can enhance enzymatic saccharification of lignocelluloses

    Treesearch

    ZJ Wang; TQ Lan; JY Zhu

    2013-01-01

    Nonspecific (nonproductive) binding (adsorption) of cellulase by lignin has been identified as a key barrier to reduce cellulase loading for economical sugar and biofuel production from lignocellulosic biomass. Sulfite Pretreatment to Overcome Recalcitrance of Lignocelluloses (SPORL) is a relatively new process, but demonstrated robust performance for sugar and biofuel...

  17. Evaluations of cellulose accessibilities of lignocelluloses by solute exclusion and protein adsorption techniques

    Treesearch

    Q.Q. Wang; Z. He; Z. Zhu; Y.-H.P. Zhang; Y. Ni; X.L. Luo; J.Y. Zhu

    2012-01-01

    Cellulose accessibilities of a set of hornified lignocellulosic substrates derived by drying the never dried pretreated sample and a set of differently pretreated lodgepople pine substrates, were evaluated using solute exclusion and protein adsorption methods. Direct measurements of cellulase adsorption onto cellulose surface of the set of pretreated substrates were...

  18. Pretreatment methods for bioethanol production.

    PubMed

    Xu, Zhaoyang; Huang, Fang

    2014-09-01

    Lignocellulosic biomass, such as wood, grass, agricultural, and forest residues, are potential resources for the production of bioethanol. The current biochemical process of converting biomass to bioethanol typically consists of three main steps: pretreatment, enzymatic hydrolysis, and fermentation. For this process, pretreatment is probably the most crucial step since it has a large impact on the efficiency of the overall bioconversion. The aim of pretreatment is to disrupt recalcitrant structures of cellulosic biomass to make cellulose more accessible to the enzymes that convert carbohydrate polymers into fermentable sugars. This paper reviews several leading acidic, neutral, and alkaline pretreatments technologies. Different pretreatment methods, including dilute acid pretreatment (DAP), steam explosion pretreatment (SEP), organosolv, liquid hot water (LHW), ammonia fiber expansion (AFEX), soaking in aqueous ammonia (SAA), sodium hydroxide/lime pretreatments, and ozonolysis are intensively introduced and discussed. In this minireview, the key points are focused on the structural changes primarily in cellulose, hemicellulose, and lignin during the above leading pretreatment technologies.

  19. Investigation of adsorption kinetics and isotherm of cellulase and B-Glucosidase on lignocellulosic substrates

    USDA-ARS?s Scientific Manuscript database

    Clear understanding of enzyme adsorption during enzymatic hydrolysis of lignocellulosic biomass is essential to enhance the cost-efficiency of hydrolysis. However, conclusions from literatures often contradicted each other because enzyme adsorption is enzyme, biomass/pretreatment and experimental co...

  20. Molecular mechanisms of yeast tolerance and in situ detoxification of lignocellulose hydrolysates

    USDA-ARS?s Scientific Manuscript database

    Pretreatment of lignocellulose biomass for biofuels production generates inhibitory compounds that interfere with microbial growth and subsequent fermentation. Remediation of the inhibitors by current physical, chemical, and biological abatement means is economically impractical and overcoming the i...

  1. Genomic mechanisms of inhibitor-detoxification for low-cost lignocellulosic bioethanol conversion

    USDA-ARS?s Scientific Manuscript database

    One major challenges of sustainable lignocellulosic biomass conversion to ethanol is to overcome inhibitors generated from biomass pretreatment. Aldehyde inhibitors such as furfural, 5-hydroxymethylfurfural, cinnamaldehyde, phenylacetylaldehyde, and 4-hydroxybenzaldehyde, are common and potent inhi...

  2. Erlotinib pretreatment improves photodynamic therapy of non-small cell lung carcinoma xenografts via multiple mechanisms

    PubMed Central

    Gallagher-Colombo, Shannon M.; Miller, Joann; Cengel, Keith A.; Putt, Mary E.; Vinogradov, Sergei A.; Busch, Theresa M.

    2015-01-01

    Aberrant expression of the epidermal growth factor receptor (EGFR) is a common characteristic of many cancers including non-small cell lung carcinoma (NSCLC), head and neck squamous cell carcinoma, and ovarian cancer. While EGFR is currently a favorite molecular target for treatment of these cancers, inhibition of the receptor with small molecule inhibitors (i.e.- erlotinib) or monoclonal antibodies (i.e.- cetuximab) does not provide long-term therapeutic benefit as standalone treatment. Interestingly, we have found that addition of erlotinib to photodynamic therapy (PDT) can improve treatment response in typically erlotinib-resistant NSCLC tumor xenografts. Ninety-day complete response rates of 63% are achieved when erlotinib is administered in three doses before PDT of H460 human tumor xenografts, compared to 16% after PDT-alone. Similar benefit is found when erlotinib is added to PDT of A549 NCSLC xenografts. Improved response is accompanied by increased vascular shutdown, and erlotinib increases the in vitro cytotoxicity of PDT to endothelial cells. Tumor uptake of the photosensitizer (benzoporphyrin derivative monoacid ring A; BPD) is increased by the in vivo administration of erlotinib; nevertheless, this elevation of BPD levels only partially accounts for the benefit of erlotinib to PDT. Thus, pretreatment with erlotinib augments multiple mechanisms of PDT effect that collectively lead to large improvements in therapeutic efficacy. These data demonstrate that short-duration administration of erlotinib before PDT can greatly improve the responsiveness of even erlotinib-resistant tumors to treatment. Results will inform clinical investigation of EGFR-targeting therapeutics in conjunction with PDT. PMID:26054596

  3. Prehydrolysis of lignocellulose

    DOEpatents

    Torget, R.W.; Kadam, K.L.; Hsu, T.A.; Philippidis, G.P.; Wyman, C.E.

    1996-04-02

    The invention relates to the prehydrolysis of lignocellulose by passing an acidic or alkaline solution through solid lignocellulosic particles with removal of soluble components as they are formed. The technique permits a less severe combination of pH, temperature and time than conventional prehydrolysis. Furthermore, greater extraction of both hemicellulose and lignin occurs simultaneously in the same reactor and under the same conditions. 7 figs.

  4. Prehydrolysis of lignocellulose

    DOEpatents

    Torget, R.W.; Kadam, K.L.; Hsu, T.A.; Philippidis, G.P.; Wyman, C.E.

    1998-01-06

    The invention relates to the prehydrolysis of lignocellulose by passing an acidic or alkaline solution through solid lignocellulosic particles with removal of soluble components as they are formed. The technique permits a less severe combination of pH, temperature and time than conventional prehydrolysis. Furthermore, greater extraction of both hemicellulose and lignin occurs simultaneously in the same reactor and under the same conditions. 7 figs.

  5. Prehydrolysis of lignocellulose

    DOEpatents

    Torget, R.W.; Kadam, K.L.; Hsu, T.A.; Philippidis, G.P.; Wyman, C.E.

    1995-06-13

    The invention relates to the prehydrolysis of lignocellulose by passing an acidic or alkaline solution through solid lignocellulosic particles with removal of soluble components as they are formed. The technique permits a less severe combination of pH, temperature and time than conventional prehydrolysis. Furthermore, greater extraction of both hemicellulose and lignin occurs simultaneously in the same reactor and under the same conditions. 7 figs.

  6. Aqueous ionic liquid pretreatment of straw.

    PubMed

    Fu, Dongbao; Mazza, Giuseppe

    2011-07-01

    Pretreatment is the key to unlock the recalcitrance of lignocellulose for cellulosic biofuels production. Increasing attention has been drawn to ionic liquids (ILs) for pretreatment of lignocellulosic biomass, because this approach has several advantages over conventional methods. However, cost and energy-intensive recycling of the solvents are major constraints preventing ILs from commercial viability. In this work, a mixture of ionic liquid 1-ethyl-3-methylimidazolium acetate and water was demonstrated to be effective for pretreatment of lignocellulosic biomass, evidenced by the removal of lignin and a reduction in cellulose crystallinity. A higher fermentable sugar yield (81%) was obtained than for pure ionic liquid pretreatment under the same conditions (67%). Aqueous ionic liquid pretreatment has the advantages of less usage and easier recycling of ILs, and reduced viscosity. Crown Copyright © 2011. Published by Elsevier Ltd. All rights reserved.

  7. Development of yeast cell factories for consolidated bioprocessing of lignocellulose to bioethanol through cell surface engineering.

    PubMed

    Hasunuma, Tomohisa; Kondo, Akihiko

    2012-01-01

    To build an energy and material secure future, a next generation of renewable fuels produced from lignocellulosic biomass is required. Although lignocellulosic biomass, which represents an abundant, inexpensive and renewable source for bioethanol production, is of great interest as a feedstock, the complicated ethanol production processes involved make the cost of producing bioethanol from it higher compared to corn starch and cane juice. Therefore, consolidated bioprocessing (CBP), which combines enzyme production, saccharification and fermentation in a single step, has gained increased recognition as a potential bioethanol production system. CBP requires a highly engineered microorganism developed for several different process-specific characteristics. The dominant strategy for engineering a CBP biocatalyst is to express multiple components of a cellulolytic system from either fungi or bacteria in the yeast Saccharomyces cerevisiae. The development of recombinant yeast strains displaying cellulases and hemicellulases on the cell surface represents significant progress toward realization of CBP. Regardless of the process used for biomass hydrolysis, CBP-enabling microorganisms encounter a variety of toxic compounds produced during biomass pretreatment that inhibit microbial growth and ethanol yield. Systems biology approaches including disruptome screening, transcriptomics, and metabolomics have been recently exploited to gain insight into the molecular and genetic traits involved in tolerance and adaptation to the fermentation inhibitors. In this review, we focus on recent advances in development of yeast strains with both the ability to directly convert lignocellulosic material to ethanol and tolerance in the harsh environments containing toxic compounds in the presence of ethanol.

  8. Lignocellulose-derived inhibitors improve lipid extraction from wet Rhodococcus opacus cells.

    PubMed

    Kurosawa, Kazuhiko; Anthony Debono, C; Sinskey, Anthony J

    2015-10-01

    Extracting lipids from oleaginous microbial cells in a cost effective and environmentally compatible manner remains a critical challenge in developing manufacturing paradigms for advanced liquid biofuels. In this study, a new approach using microbial growth inhibitors from lignocellulose-derived feedstocks was used to extract lipids efficiently from wet cell mass of the oleaginous bacterium Rhodococcus opacus MITXM-61. Nine common lignocellulose-derived inhibitors for treatment of cells prior to solvent extraction were used and evaluated for their efficiency of lipid extraction from the cells. When the inhibitors were individually examined, formic acid and furfural showed the highest extraction efficiency of lipids from wet cell mass. Multiple extractions of lipids with methanol from wet cell mass pretreated with combined common inhibitors or hardwood hydrolysate comprising lignocellulose-derived inhibitors resulted in lipid recovery of greater than 85% of total lipids, a 1.7-fold increase of lipid extraction as compared to those in the absence of the inhibitors. Copyright © 2015. Published by Elsevier Ltd.

  9. The conversion of lignocellulosics to fermentable sugars - A survey of current research and applications to CELSS

    NASA Technical Reports Server (NTRS)

    Petersen, Gene R.; Baresi, Larry

    1990-01-01

    This report provides an overview options for converting lignocellulosics into fermentable sugars in CELSS. A requirement for pretreatment is shown. Physical-chemical and enzymatic hydrolysis processes for producing fermentable sugars are discussed. At present physical-chemical methods are the simplest and best characterized options, but enzymatic processes will be the likely method of choice in the future. The use of pentose sugars by microorganisms to produce edibles is possible. The use of mycelial food production on pretreated but not hydrolyzed lignocellulosics is also possible. Simple trade-off analyses to regenerate waste lignocellulosics for two pathways are made, one of which is compared to complete oxidation.

  10. The conversion of lignocellulosics to fermentable sugars - A survey of current research and applications to CELSS

    NASA Technical Reports Server (NTRS)

    Petersen, Gene R.; Baresi, Larry

    1990-01-01

    This report provides an overview options for converting lignocellulosics into fermentable sugars in CELSS. A requirement for pretreatment is shown. Physical-chemical and enzymatic hydrolysis processes for producing fermentable sugars are discussed. At present physical-chemical methods are the simplest and best characterized options, but enzymatic processes will be the likely method of choice in the future. The use of pentose sugars by microorganisms to produce edibles is possible. The use of mycelial food production on pretreated but not hydrolyzed lignocellulosics is also possible. Simple trade-off analyses to regenerate waste lignocellulosics for two pathways are made, one of which is compared to complete oxidation.

  11. The application of biotechnology on the enhancing of biogas production from lignocellulosic waste.

    PubMed

    Wei, Suzhen

    2016-12-01

    Anaerobic digestion of lignocellulosic waste is considered to be an efficient way to answer present-day energy crisis and environmental challenges. However, the recalcitrance of lignocellulosic material forms a major obstacle for obtaining maximum biogas production. The use of biological pretreatment and bioaugmentation for enhancing the performance of anaerobic digestion is quite recent and still needs to be investigated. This paper reviews the status and perspectives of recent studies on biotechnology concept and investigates its possible use for enhancing biogas production from lignocellulosic waste with main emphases on biological pretreatment and bioaugmentation techniques.

  12. A review on bioconversion of lignocellulosic biomass to H2: Key challenges and new insights.

    PubMed

    Ren, Nan-Qi; Zhao, Lei; Chen, Chuan; Guo, Wan-Qian; Cao, Guang-Li

    2016-09-01

    With the increasing energy crisis and rising concern over climate change, the development of clean alternative energy sources is of great importance. Biohydrogen produced from lignocellulosic biomass is a promising candidate, because of its positives such as readily available, no harmful emissions, environment friendly, efficient, and renewable. However, obstacles still exist to enable the commercialization of biological hydrogen production from lignocellulosic biomass. Thus the objective of this work is to provide update information about the recent progress on lignocellulosic hydrogen conversion via dark fermentation. In this review, the most important technologies associated with lignocellulosic hydrogen fermentation were covered. Firstly, pretreatment methods for better utilization of lignocellulosic biomass are presented, at the same time, hydrolysis methods assisting to achieve efficient hydrogen fermentation were discussed. Afterwards, issues related to bioprocesses for hydrogen production purposes were presented. Additionally, the paper gave challenges and new insights of lignocellulosic biohydrogen production.

  13. Application of Complex Fluids in Lignocellulose Processing

    NASA Astrophysics Data System (ADS)

    Carrillo Lugo, Carlos A.

    Complex fluids such as emulsions, microemulsions and foams, have been used for different applications due to the multiplicity of properties they possess. In the present work, such fluids are introduced as effective media for processing lignocellulosic biomass. A demonstration of the generic benefits of complex fluids is presented to enhance biomass impregnation, to facilitate pretreatment for fiber deconstruction and to make compatible cellulose fibrils with hydrophobic polymers during composite manufacture. An improved impregnation of woody biomass was accomplished by application of water-continuous microemulsions. Microemulsions with high water content, > 85%, were formulated and wood samples were impregnated by wicking and capillary flooding at atmospheric pressure and temperature. Formulations were designed to effectively impregnate different wood species during shorter times and to a larger extent compared to the single components of the microemulsions (water, oil or surfactant solutions). The viscosity of the microemulsions and their interactions with cell wall constituents in fibers were critical to define the extent of impregnation and solubilization. The relation between composition and formulation variables and the extent of microemulsion penetration in different woody substrates was studied. Formulation variables such as salinity content of the aqueous phase and type of surfactant were elucidated. Likewise, composition variables such as the water-to-oil ratio and surfactant concentration were investigated. These variables affected the characteristics of the microemulsion and determined their effectiveness in wood treatment. Also, the interactions between the surfactant and the substrate had an important contribution in defining microemulsion penetration in the capillary structure of wood. Microemulsions as an alternative pretreatment for the manufacture of cellulose nanofibrils (CNFs) was also studied. Microemulsions were applied to pretreat lignin

  14. Biomass pretreatment: fundamentals toward application.

    PubMed

    Agbor, Valery B; Cicek, Nazim; Sparling, Richard; Berlin, Alex; Levin, David B

    2011-01-01

    Development of sustainable energy systems based on renewable biomass feedstocks is now a global effort. Lignocellulosic biomass contains polymers of cellulose, hemicellulose, and lignin, bound together in a complex structure. Liquid biofuels, such as ethanol, can be made from biomass via fermentation of sugars derived from the cellulose and hemicellulose within lignocellulosic materials, but the biomass must be subjected to pretreatment processes to liberate the sugars needed for fermentation. Production of value-added co-products along-side biofuels through integrated biorefinery processes creates the need for selectivity during pretreatment. This paper presents a survey of biomass pretreatment technologies with emphasis on concepts, mechanism of action and practicability. The advantages and disadvantages, and the potential for industrial applications of different pretreatment technologies are the highlights of this paper. Copyright © 2011 Elsevier Inc. All rights reserved.

  15. Thermostable enzymes in lignocellulose hydrolysis.

    PubMed

    Viikari, Liisa; Alapuranen, Marika; Puranen, Terhi; Vehmaanperä, Jari; Siika-Aho, Matti

    2007-01-01

    Thermostable enzymes offer potential benefits in the hydrolysis of lignocellulosic substrates; higher specific activity decreasing the amount of enzymes, enhanced stability allowing improved hydrolysis performance and increased flexibility with respect to process configurations, all leading to improvement of the overall economy of the process. New thermostable cellulase mixtures were composed of cloned fungal enzymes for hydrolysis experiments. Three thermostable cellulases, identified as the most promising enzymes in their categories (cellobiohydrolase, endoglucanase and beta-glucosidase), were cloned and produced in Trichoderma reesei and mixed to compose a novel mixture of thermostable cellulases. Thermostable xylanase was added to enzyme preparations used on substrates containing residual hemicellulose. The new optimised thermostable enzyme mixtures were evaluated in high temperature hydrolysis experiments on technical steam pretreated raw materials: spruce and corn stover. The hydrolysis temperature could be increased by about 10-15 degrees C, as compared with present commercial Trichoderma enzymes. The same degree of hydrolysis, about 90% of theoretical, measured as individual sugars, could be obtained with the thermostable enzymes at 60 degrees C as with the commercial enzymes at 45 degrees C. Clearly more efficient hydrolysis per assayed FPU unit or per amount of cellobiohydrolase I protein used was obtained. The maximum FPU activity of the novel enzyme mixture was about 25% higher at the optimum temperature at 65 degrees C, as compared with the highest activity of the commercial reference enzyme at 60 degrees C. The results provide a promising basis to produce and formulate improved enzyme products. These products can have high temperature stability in process conditions in the range of 55-60 degrees C (with present industrial products at 45-50 degrees C) and clearly improved specific activity, essentially decreasing the protein dosage required for an

  16. Enhancement in multiple lignolytic enzymes production for optimized lignin degradation and selectivity in fungal pretreatment of sweet sorghum bagasse.

    PubMed

    Mishra, Vartika; Jana, Asim K; Jana, Mithu Maiti; Gupta, Antriksh

    2017-07-01

    The objective of this work was to study the increase in multiple lignolytic enzyme productions through the use of supplements in combination in pretreatment of sweet sorghum bagasse (SSB) by Coriolus versicolor such that enzymes act synergistically to maximize the lignin degradation and selectivity. Enzyme activities were enhanced by metallic salts and phenolic compound supplements in SSF. Supplement of syringic acid increased the activities of LiP, AAO and laccase; gallic acid increased MnP; CuSO4 increased laccase and PPO to improve the lignin degradations and selectivity individually, higher than control. Combination of supplements optimized by RSM increased the production of laccase, LiP, MnP, PPO and AAO by 17.2, 45.5, 3.5, 2.4 and 3.6 folds respectively for synergistic action leading to highest lignin degradation (2.3 folds) and selectivity (7.1 folds). Enzymatic hydrolysis of pretreated SSB yielded ∼2.43 times fermentable sugar. This technique could be widely applied for pretreatment and enzyme productions. Copyright © 2017 Elsevier Ltd. All rights reserved.

  17. Carbon tetrachloride-induced lethality in mouse is prevented by multiple pretreatment with zinc sulfate.

    PubMed

    Yoshioka, Hiroki; Usuda, Haruki; Nonogaki, Tsunemasa; Onosaka, Satomi

    2016-02-01

    Carbon tetrachloride (CCl4) is commonly used as a chemical inducer of experimental liver injury. Several compounds have been demonstrated to attenuate the hepatic damage caused by sublethal doses of CCl4. However, rescue from lethal toxicity of CCl4 has not been reported. In the present study, we evaluated the protective effect of metallothionein (MT), an endogenous scavenger of free radicals, on CCl4-induced lethal toxicity of mice. To induce MT production in male ddY mice, we administered Zn (as ZnSO4) at 50 mg/kg as a once-daily subcutaneous injection for 3 days prior to a single intraperitoneal administration of 4 g/kg CCl4. Animals were observed for mortality every 3 hr for 24 hr after CCl4 injection. Liver damage was assessed by determining (in a subset of these mice) blood levels of alanine aminotransferase (ALT; a marker of liver injury) and liver histopathology at 6 hr after CCl4 injection. Our results showed that three times pretreatment with Zn yielded > 40-fold induction of hepatic MT protein levels compared to control group. Zn pretreatment completely abolished the CCl4-induced mortality of mice. We also found that pretreatment of mice with Zn significantly decreased the ALT levels and reduced the histological liver damage as assessed at 6 hr post-CCl4. These findings suggest that prophylaxis with Zn protects mice from CCl4-induced acute hepatic toxicity and mortality, presumably by induction of radical-scavenging MT.

  18. Fungal biodegradation of lignocelluloses

    Treesearch

    Annele Hatakka; Kenneth E. Hammel

    2010-01-01

    Uncertainties in the basic structures of especially lignin but also other components in lignocellulose make fungal biodegradation studies a challenging task. The following properties are important in terms of microbial or enzymatic attack: (1) lignin polymers have compact structures that are insoluble in water and difficult to penetrate by microbes or enzymes, (2) the...

  19. [Application of process engineering to remove lignocellulose fermentation inhibitors].

    PubMed

    Wang, Lan; Xia, Menglei; Chen, Hongzhang

    2014-05-01

    Fermentation inhibitors are toxic to cells, which is one of the bottlenecks for lignocellulose bio-refinery process. How to remove those inhibitors serves a key role in the bioconversion of lignocellulose. This article reviews the sources and the types of the inhibitors, especially the updated removal strategies including physical methods, chemical methods, biological methods and inhibitor-tolerant strain construction strategies. Based on these, we introduce a new bio-refinery model named "fractional conversion", which reduces the production of inhibitors at pretreatment stage, and a novel in situ detoxification method named "fermentation promoter exploitation technology". This review could provide new research ideas on the removal of fermentation inhibitors.

  20. Dilute oxalic acid pretreatment for biorefining giant reed (Arundo donax L.)

    Treesearch

    Danilo Scordia; Salvatore L. Cosentino; Jae-Won Lee; Thomas W. Jeffries

    2011-01-01

    Biomass pretreatment is essential to overcome recalcitrance of lignocellulose for ethanol production. In the present study we pretreated giant reed (Arundo donax L.), a perennial, rhizomatous lignocellulosic grass with dilute oxalic acid. The effects of temperature (170-190 ºC), acid loading (2-10% w/w) and reaction time (15-40 min) were handled as a single...

  1. Biological pretreatment of corn stover with white-rot fungus for enzymatic hydrolysis and bioethanol production

    USDA-ARS?s Scientific Manuscript database

    Pretreatment, as the first step towards conversion of lignocellulosic feedstocks to biofuels and/or chemicals remains one of the main barriers to commercial success. Typically, harsh methods are used to pretreat lignocellulosic biomass prior to its breakdown to sugars by enzymes, which also result ...

  2. Comparative analysis of the secretomes of Schizophyllum commune and other wood-decay basidiomycetes during solid-state fermentation reveals its unique lignocellulose-degrading enzyme system.

    PubMed

    Zhu, Ning; Liu, Jiawen; Yang, Jinshui; Lin, Yujian; Yang, Yi; Ji, Lei; Li, Meng; Yuan, Hongli

    2016-01-01

    The genome of Schizophyllum commune encodes a diverse repertoire of degradative enzymes for plant cell wall breakdown. Recent comparative genomics study suggests that this wood decayer likely has a mode of biodegradation distinct from the well-established white-rot/brown-rot models. However, much about the extracellular enzyme system secreted by S. commune during lignocellulose deconstruction remains unknown and the underlying mechanism is poorly understood. In this study, extracellular proteins of S. commune colonizing Jerusalem artichoke stalk were analyzed and compared with those of two white-rot fungi Phanerochaete chrysosporium and Ceriporiopsis subvermispora and a brown-rot fungus Gloeophyllum trabeum. Under solid-state fermentation (SSF) conditions, S. commune displayed considerably higher levels of hydrolytic enzyme activities in comparison with those of P. chrysosporium, C. subvermispora and G. trabeum. During biodegradation process, this fungus modified the lignin polymer in a way which was consistent with a hydroxyl radical attack, similar to that of G. trabeum. The crude enzyme cocktail derived from S. commune demonstrated superior performance over a commercial enzyme preparation from Trichoderma longibrachiatum in the hydrolysis of pretreated lignocellulosic biomass at low enzyme loadings. Secretomic analysis revealed that compared with three other fungi, this species produced a higher diversity of carbohydrate-degrading enzymes, especially hemicellulases and pectinases acting on polysaccharide backbones and side chains, and a larger set of enzymes potentially supporting the generation of hydroxyl radicals. In addition, multiple non-hydrolytic proteins implicated in enhancing polysaccharide accessibility were identified in the S. commune secretome, including lytic polysaccharide monooxygenases (LPMOs) and expansin-like proteins. Plant lignocellulose degradation by S. commune involves a hydroxyl radical-mediated mechanism for lignocellulose modification

  3. Plant biotechnology for lignocellulosic biofuel production.

    PubMed

    Li, Quanzi; Song, Jian; Peng, Shaobing; Wang, Jack P; Qu, Guan-Zheng; Sederoff, Ronald R; Chiang, Vincent L

    2014-12-01

    Lignocelluloses from plant cell walls are attractive resources for sustainable biofuel production. However, conversion of lignocellulose to biofuel is more expensive than other current technologies, due to the costs of chemical pretreatment and enzyme hydrolysis for cell wall deconstruction. Recalcitrance of cell walls to deconstruction has been reduced in many plant species by modifying plant cell walls through biotechnology. These results have been achieved by reducing lignin content and altering its composition and structure. Reduction of recalcitrance has also been achieved by manipulating hemicellulose biosynthesis and by overexpression of bacterial enzymes in plants to disrupt linkages in the lignin-carbohydrate complexes. These modified plants often have improved saccharification yield and higher ethanol production. Cell wall-degrading (CWD) enzymes from bacteria and fungi have been expressed at high levels in plants to increase the efficiency of saccharification compared with exogenous addition of cellulolytic enzymes. In planta expression of heat-stable CWD enzymes from bacterial thermophiles has made autohydrolysis possible. Transgenic plants can be engineered to reduce recalcitrance without any yield penalty, indicating that successful cell wall modification can be achieved without impacting cell wall integrity or plant development. A more complete understanding of cell wall formation and structure should greatly improve lignocellulosic feedstocks and reduce the cost of biofuel production. © 2014 Society for Experimental Biology, Association of Applied Biologists and John Wiley & Sons Ltd.

  4. Phenotypic characterization and comparative transcriptomics of evolved Saccharomyces cerevisiae strains with improved tolerance to lignocellulosic derived inhibitors.

    PubMed

    Thompson, Olivia A; Hawkins, Gary M; Gorsich, Steven W; Doran-Peterson, Joy

    2016-01-01

    Lignocellulosic biomass continues to be investigated as a viable source for bioethanol production. However, the pretreatment process generates inhibitory compounds that impair the growth and fermentation performance of microorganisms such as Saccharomyces cerevisiae. Pinewood specifically has been shown to be challenging in obtaining industrially relevant ethanol titers. An industrial S. cerevisiae strain was subjected to directed evolution and adaptation in pretreated pine biomass and resultant strains, GHP1 and GHP4, exhibited improved growth and fermentative ability on pretreated pine in the presence of related inhibitory compounds. A comparative transcriptomic approach was applied to identify and characterize differences in phenotypic stability of evolved strains. Evolved strains displayed different fermentative capabilities with pretreated pine that appear to be influenced by the addition or absence of 13 inhibitory compounds during pre-culturing. GHP4 performance was consistent independent of culturing conditions, while GHP1 performance was dependent on culturing with inhibitors. Comparative transcriptomics revealed 52 genes potentially associated with stress responses to multiple inhibitors simultaneously. Fluorescence microscopy revealed improved cellular integrity of both strains with mitochondria exhibiting resistance to the damaging effects of inhibitors in contrast to the parent. Multiple potentially novel genetic targets have been discovered for understanding stress tolerance through the characterization of our evolved strains. This study specifically examines the synergistic effects of multiple inhibitors and identified targets will guide future studies in remediating effects of inhibitors and further development of robust yeast strains for multiple industrial applications.

  5. Tower reactors for bioconversion of lignocellulosic material

    DOEpatents

    Nguyen, Q.A.

    1999-03-30

    An apparatus is described for enzymatic hydrolysis and fermentation of pretreated lignocellulosic material, in the form of a tower bioreactor, having mixers to achieve intermittent mixing of the material. Precise mixing of the material is important for effective heat and mass transfer requirements without damaging or denaturing the enzymes or fermenting microorganisms. The pretreated material, generally in the form of a slurry, is pumped through the bioreactor, either upwards or downwards, and is mixed periodically as it passes through the mixing zones where the mixers are located. For a thin slurry, alternate mixing can be achieved by a pumping loop which also serves as a heat transfer device. Additional heat transfer takes place through the reactor heat transfer jackets. 5 figs.

  6. Tower reactors for bioconversion of lignocellulosic material

    DOEpatents

    Nguyen, Q.A.

    1998-03-31

    An apparatus is disclosed for enzymatic hydrolysis and fermentation of pretreated lignocellulosic material. The apparatus consists of a tower bioreactor which has mixers to achieve intermittent mixing of the material. Precise mixing of the material is important for effective heat and mass transfer requirements without damaging or denaturing the enzymes or fermenting microorganisms. The pretreated material, generally in the form of a slurry, is pumped through the bioreactor, either upwards or downwards, and is mixed periodically as it passes through the mixing zones where the mixers are located. For a thin slurry, alternate mixing can be achieved by a pumping loop which also serves as a heat transfer device. Additional heat transfer takes place through the reactor heat transfer jackets. 5 figs.

  7. Tower reactors for bioconversion of lignocellulosic material

    DOEpatents

    Nguyen, Quang A.

    1999-01-01

    An apparatus for enzymatic hydrolysis and fermentation of pretreated lignocellulosic material, in the form of a tower bioreactor, having mixers to achieve intermittent mixing of the material. Precise mixing of the material is important for effective heat and mass transfer requirements without damaging or denaturing the enzymes or fermenting microorganisms. The pretreated material, generally in the form of a slurry, is pumped through the bioreactor, either upwards or downwards, and is mixed periodically as it passes through the mixing zones where the mixers are located. For a thin slurry, alternate mixing can be achieved by a pumping loop which also serves as a heat transfer device. Additional heat transfer takes place through the reactor heat transfer jackets.

  8. Tower reactors for bioconversion of lignocellulosic material

    DOEpatents

    Nguyen, Quang A.

    1998-01-01

    An apparatus for enzymatic hydrolysis and fermentation of pretreated lignocellulosic material, in the form of a tower bioreactor, having mixers to achieve intermittent mixing of the material. Precise mixing of the material is important for effective heat and mass transfer requirements without damaging or denaturing the enzymes or fermenting microorganisms. The pretreated material, generally in the form of a slurry, is pumped through the bioreactor, either upwards of downwards, and is mixed periodically as it passes through the mixing zones where the mixers are located. For a thin slurry, alternate mixing can be achieved by a pumping loop which also serves as a heat transfer device. Additional heat transfer takes place through the reactor heat transfer jackets.

  9. Utilization of lignocellulosic polysaccharides

    NASA Astrophysics Data System (ADS)

    Fenske, John James

    Lignocellulosic biomass represents a vast supply of fermentable carbohydrates and functional aromatic compounds. Conversion of lignocellulosics to ethanol and other useful products would be of widespread economical and environmental benefit. Better understanding of the behavior of different lignocellulosic feedstocks in fermentation protocols as well as catalytic activities involved in lignocellulosic depolymerization will further enhance the commercial viability of biomass-to-ethanol conversion processes. The relative toxicity of the combined non-xylose components in prehydrolysates derived from three different lignocellulosic biomass feedstocks (poplar, corn stover and switchgrass, or Panicum virgatum L.) was determined using a Pichia stipits fermentation assay. The relative toxicity of the prehydrolysates, in decreasing order, was poplar-derived prehydrolysates > switchgrass-derived prehydrolysates > corn stover-derived prehydrolysates. Ethanol yields averaged 74%, 83% and 88% of control values for poplar, switchgrass and corn stover prehydrolysates, respectively. Volumetric ethanol productivities (g ethanol lsp{-1} hsp{-1}) averaged 32%, 70% and 102% of control values for poplar, switchgrass and corn stover prehydrolysates, respectively. Ethanol productivities correlated closely with acetate concentrations in the prehydrolysates; however, regression lines correlating acetate concentrations and ethanol productivities were found to be feedstock-dependent. Differences in the relative toxicity of xylose-rich prehydrolysates derived from woody and herbaceous feedstocks are likely due to the relative abundance of a variety of inhibitory compounds, e.g. acetate and aromatic compounds. Fourteen aromatic monomers present in prehydrolysates prepared from corn stover, switchgrass, and poplar were tentatively identified by comparison with published mass spectra. The concentrations of the aromatic monomers totaled 112, 141 and 247 mg(l)sp{-1} for corn stover, switchgrass

  10. Bioconversion of Lignocellulose Materials

    PubMed Central

    Kanmani, P.; Balaji, P.

    2006-01-01

    One of the most economically viable processes for the bioconversion of many lignocellulosic waste is represented by white rot fungi. Phanerochaete chrysosporium is one of the important commercially cultivated fungi which exhibit varying abilities to utilize different lignocellulosic as growth substrate. Examination of the lignocellulolytic enzyme profiles of the two organisms Phanerochaete chrysosporium and Rhizopus stolonifer show this diversity to be reflected in qualitative variation in the major enzymatic determinants (ie cellulase, xylanase, ligninase and etc) required for substrate bioconversion. For example P. chrysosporium which is cultivated on highly lignified substrates such as wood (or) sawdust, produces two extracellular enzymes which have associated with lignin deploymerization. (Mn peroxidase and lignin peroxidase). Conversely Rhizopus stolonifer which prefers high cellulose and low lignin containg substrates produce a family of cellulolytic enzymes including at least cellobiohydrolases and β-glucosidases, but very low level of recognized lignin degrading enzymes. PMID:24039492

  11. Pyrolysis Strategies for Effective Utilization of Lignocellulosic and Algal Biomass

    NASA Astrophysics Data System (ADS)

    Maddi, Balakrishna

    Pyrolysis is a processing technique involving thermal degradation of biomass in the absence of oxygen. The bio-oils obtained following the condensation of the pyrolysis vapors form a convenient starting point for valorizing the major components of lignocellulosic as well as algal biomass feed stocks for the production of fuels and value-added chemicals. Pyrolysis can be implemented on whole biomass or on residues left behind following standard fractionation methods. Microalgae and oil seeds predominantly consist of protein, carbohydrate and triglycerides, whereas lignocellulose is composed of carbohydrates (cellulose and hemicellulose) and lignin. The differences in the major components of these two types of biomass will necessitate different pyrolysis strategies to derive the optimal benefits from the resulting bio-oils. In this thesis, novel pyrolysis strategies were developed that enable efficient utilization of the bio-oils (and/or their vapors) from lignocellulose, algae, as well as oil seed feed stocks. With lignocellulosic feed stocks, pyrolysis of whole biomass as well as the lignin residue left behind following well-established pretreatment and saccharification (i.e., depolymerization of cellulose and hemicellulose to their monomeric-sugars) of the biomass was studied with and without catalysts. Following this, pyrolysis of (lipid-deficient) algae and lignocellulosic feed stocks, under similar reactor conditions, was performed for comparison of product (bio-oil, gas and bio-char) yields and composition. In spite of major differences in component bio-polymers, feedstock properties relevant to thermo-chemical conversions, such as overall C, H and O-content, C/O and H/C molar ratio as well as calorific values, were found to be similar for algae and lignocellulosic material. Bio-oil yields from algae and some lignocellulosic materials were similar; however, algal bio-oils were compositionally different and contained several N-compounds (most likely from

  12. GREET Pretreatment Module

    SciTech Connect

    Adom, Felix K.; Dunn, Jennifer B.; Han, Jeongwoo

    2014-09-01

    A wide range of biofuels and biochemicals can be produced from cellulosic biomass via different pretreatment technologies that yield sugars. Process simulations of dilute acid and ammonia fiber expansion pretreatment processes and subsequent hydrolysis were developed in Aspen Plus for four lignocellulosic feedstocks (corn stover, miscanthus, switchgrass, and poplar). This processing yields sugars that can be subsequently converted to biofuels or biochemical. Material and energy consumption data from Aspen Plus were then compiled in a new Greenhouses Gases, Regulated Emissions, and Energy Use in Transportation (GREETTM) pretreatment module. The module estimates the cradle-to-gate fossil energy consumption (FEC) and greenhouse gas (GHG) emissions associated with producing fermentable sugars. This report documents the data and methodology used to develop this module and the cradle-to-gate FEC and GHG emissions that result from producing fermentable sugars.

  13. Ozone Pretreatment of Wheat Straw and its Effect on Reducing Sugars in Hydrolyzate

    NASA Astrophysics Data System (ADS)

    Gerulová, Kristína; Blinová, Lenka

    2011-01-01

    The aim of this contribution is to measure the effect of the pretreatment of lignocellulosic phytomass utilization for bioethanol production. The first step of bioethanol production from lignocellulosic phytomass is pretreatment of raw material. The next step is hydrolysis, and then the fermentation of sugars follows. The physical (grinding, breaking) and chemical (ozonization) processes were used as pretreatment. Ozone was applied to the aqueous suspension of lignocellulosic phytomass before and during the hydrolysis. Ozone pretreatment did not perform as effectively as expected. The results of study, which are focused on evaluation of reducing sugars are included in this contribution.

  14. Contribution of a family 1 carbohydrate-binding module in thermostable glycoside hydrolase 10 xylanase from Talaromyces cellulolyticus toward synergistic enzymatic hydrolysis of lignocellulose.

    PubMed

    Inoue, Hiroyuki; Kishishita, Seiichiro; Kumagai, Akio; Kataoka, Misumi; Fujii, Tatsuya; Ishikawa, Kazuhiko

    2015-01-01

    Enzymatic removal of hemicellulose components such as xylan is an important factor for maintaining high glucose conversion from lignocelluloses subjected to low-severity pretreatment. Supplementation of xylanase in the cellulase mixture enhances glucose release from pretreated lignocellulose. Filamentous fungi produce multiple xylanases in their cellulase system, and some of them have modular structures consisting of a catalytic domain and a family 1 carbohydrate-binding module (CBM1). However, the role of CBM1 in xylanase in the synergistic hydrolysis of lignocellulose has not been investigated in depth. Thermostable endo-β-1,4-xylanase (Xyl10A) from Talaromyces cellulolyticus, which is recognized as one of the core enzymes in the fungal cellulase system, has a modular structure consisting of a glycoside hydrolase family 10 catalytic domain and CBM1 at the C-terminus separated by a linker region. Three recombinant Xyl10A variants, that is, intact Xyl10A (Xyl10Awt), CBM1-deleted Xyl10A (Xyl10AdC), and CBM1 and linker region-deleted Xyl10A (Xyl10AdLC), were constructed and overexpressed in T. cellulolyticus. Cellulose-binding ability of Xyl10A CBM1 was demonstrated using quartz crystal microbalance with dissipation monitoring. Xyl10AdC and Xyl10AdLC showed relatively high catalytic activities for soluble and insoluble xylan substrates, whereas Xyl10Awt was more effective in xylan hydrolysis of wet disc-mill treated rice straw (WDM-RS). The enzyme mixture of cellulase monocomponents and intact or mutant Xyl10A enhanced the hydrolysis of WDM-RS glucan, with the most efficient synergism found in the interactions with Xyl10Awt. The increased glucan hydrolysis yield exhibited a linear relationship with the xylan hydrolysis yield by each enzyme. This relationship revealed significant hydrolysis of WDM-RS glucan with lower supplementation of Xyl10Awt. Our results suggest that Xyl10A CBM1 has the following two roles in synergistic hydrolysis of lignocellulose by Xyl10A and

  15. Fermentation of lignocellulosic sugars to acetic acid by Moorella thermoacetica.

    PubMed

    Ehsanipour, Mandana; Suko, Azra Vajzovic; Bura, Renata

    2016-06-01

    A systematic study of bioconversion of lignocellulosic sugars to acetic acid by Moorella thermoacetica (strain ATCC 39073) was conducted. Four different water-soluble fractions (hydrolysates) obtained after steam pretreatment of lignocellulosic biomass were selected and fermented to acetic acid in batch fermentations. M. thermoacetica can effectively ferment xylose and glucose in hydrolysates from wheat straw, forest residues, switchgrass, and sugarcane straw to acetic acid. Xylose and glucose were completely utilized, with xylose being consumed first. M. thermoacetica consumed up to 62 % of arabinose, 49 % galactose and 66 % of mannose within 72 h of fermentation in the mixture of lignocellulosic sugars. The highest acetic acid yield was obtained from sugarcane straw hydrolysate, with 71 % of theoretical yield based on total sugars (17 g/L acetic acid from 24 g/L total sugars). The lowest acetic acid yield was observed in forest residues hydrolysate, with 39 % of theoretical yield based on total sugars (18 g/L acetic acid from 49 g/L total sugars). Process derived compounds from steam explosion pretreatment, including 5-hydroxymethylfurfural (0.4 g/L), furfural (0.1 g/L) and total phenolics (3 g/L), did not inhibit microbial growth and acetic acid production yield. This research identified two major factors that adversely affected acetic acid yield in all hydrolysates, especially in forest residues: (i) glucose to xylose ratio and (ii) incomplete consumption of arabinose, galactose and mannose. For efficient bioconversion of lignocellulosic sugars to acetic acid, it is imperative to have an appropriate balance of sugars in a hydrolysate. Hence, the choice of lignocellulosic biomass and steam pretreatment design are fundamental steps for the industrial application of this process.

  16. Process design and evaluation of production of bioethanol and β-lactam antibiotic from lignocellulosic biomass.

    PubMed

    Kim, Sung Bong; Park, Chulhwan; Kim, Seung Wook

    2014-11-01

    To design biorefinery processes producing bioethanol from lignocellulosic biomass with dilute acid pretreatment, biorefinery processes were simulated using the SuperPro Designer program. To improve the efficiency of biomass use and the economics of biorefinery, additional pretreatment processes were designed and evaluated, in which a combined process of dilute acid and aqueous ammonia pretreatments, and a process of waste media containing xylose were used, for the production of 7-aminocephalosporanic acid. Finally, the productivity and economics of the designed processes were compared.

  17. Carfilzomib, lenalidomide, and dexamethasone in patients with heavily-pretreated multiple myeloma: A phase 1 study in Japan.

    PubMed

    Suzuki, Kenshi; Ri, Masaki; Chou, Takaaki; Sugiura, Isamu; Takezako, Naoki; Sunami, Kazutaka; Ishida, Tadao; Izumi, Tohru; Ozaki, Shuji; Shumiya, Yoshihisa; Ota, Kenji; Iida, Shinsuke

    2017-01-16

    This is the first study in which the carfilzomib, lenalidomide, and dexamethasone (KRd) regimen was evaluated in heavily pretreated multiple myeloma. This study is a multicenter, open-label phase 1 study of KRd in Japanese patients with relapsed or refractory multiple myeloma (RRMM). The objectives were to evaluate the safety, tolerability, efficacy and pharmacokinetics. Carfilzomib was administrated intravenously over 10 min on days 1, 2, 8, 9, 15, and 16 of a 28-day cycle. In cycle 1, the dosage for days 1 and 2 was 20 mg/m(2) , followed by 27 mg/m(2) . Lenalidomide and dexamethasone were administered at 25 mg (days 1-21) and 40 mg (days 1, 8, 15, and 22), respectively. Twenty-six patients were enrolled. Patients had received a median of four prior regimens and 88.5% and 61.5% received previous bortezomib and lenalidomide, respectively. High-risk cytogenetics were seen in 53.8% of patients. The overall response rate was 88.5%. A higher rate of hyperglycemia was observed than in a previous carfilzomib monotherapy study, but this was attributed to dexamethasone. Carfilzomib pharmacokinetics were not affected by lenalidomide and dexamethasone. The KRd regimen was well tolerated and showed efficacy in Japanese RRMM patients. This article is protected by copyright. All rights reserved.

  18. Biotechnological strategies to overcome inhibitors in lignocellulose hydrolysates for ethanol production: review.

    PubMed

    Parawira, W; Tekere, M

    2011-03-01

    One of the major challenges faced in commercial production of lignocellulosic bioethanol is the inhibitory compounds generated during the thermo-chemical pre-treatment step of biomass. These inhibitory compounds are toxic to fermenting micro-organisms. The ethanol yield and productivity obtained during fermentation of lignocellulosic hydrolysates is decreased due to the presence of inhibiting compounds, such as weak acids, furans and phenolic compounds formed or released during thermo-chemical pre-treatment step such as acid and steam explosion. This review describes the application and/or effect of biological detoxification (removal of inhibitors before fermentation) or use of bioreduction capability of fermenting yeasts on the fermentability of the hydrolysates. Inhibition of yeast fermentation by the inhibitor compounds in the lignocellulosic hydrolysates can be reduced by treatment with enzymes such as the lignolytic enzymes, for example, laccase and micro-organisms such as Trichoderma reesei, Coniochaeta ligniaria NRRL30616, Trametes versicolor, Pseudomonas putida Fu1, Candida guilliermondii, and Ureibacillus thermosphaericus. Microbial and enzymatic detoxifications of lignocellulosic hydrolysate are mild and more specific in their action. The efficiency of enzymatic process is quite comparable to other physical and chemical methods. Adaptation of the fermentation yeasts to the lignocellulosic hydrolysate prior to fermentation is suggested as an alternative approach to detoxification. Increases in fermentation rate and ethanol yield by adapted micro-organisms to acid pre-treated lignocellulosic hydrolysates have been reported in some studies. Another approach to alleviate the inhibition problem is to use genetic engineering to introduce increased tolerance by Saccharomyces cerevisiae, for example, by overexpressing genes encoding enzymes for resistance against specific inhibitors and altering co-factor balance. Cloning of the laccase gene followed by

  19. Lenalidomide (Revlimid), bortezomib (Velcade) and dexamethasone for heavily pretreated relapsed or refractory multiple myeloma.

    PubMed

    Jimenez-Zepeda, Victor H; Reece, Donna E; Trudel, Suzanne; Chen, Christine; Tiedemann, Rodger; Kukreti, Vishal

    2013-03-01

    The combination of lenalidomide, bortezomib and dexamethasone (RVD) has shown excellent efficacy in patients with relapsed or refractory multiple myeloma (RRMM). The aim of our study was to assess the efficacy and toxicity profile of RVD for patients with advanced RRMM. We retrospectively reviewed the records of all patients with RRMM treated with RVD between March 2009 and December 2011. Thirty patients received ≥ 1 full cycle of RVD. Primary endpoints were overall response rate (ORR), progression-free survival (PFS) and overall survival (OS). After a median of 5 cycles (1-16), a very good partial response (VGPR) was seen in 10%, partial response (PR) in 36.7% and stable disease (SD) in 13.3% (ORR of 46.7%). Disease progression occurred in 21 patients at a median of 3 months (range 1.41-4.59). Eight patients (26%) experienced grade 3/4 adverse events, including anemia, neutropenia, muscle weakness and pneumonia. No patient experienced worsening peripheral neuropathy. Although RVD has been previously shown to be effective in RRMM, the ORR and PFS we observed were affected by very advanced disease status and heavy prior exposure to novel agents. Nevertheless, six of these patients with RRMM experienced a benefit of ≥ 6 months, suggesting synergism of this immunomodulatory derivative/proteasome inhibitor combination and/or re-establishment of drug sensitivity by an emergent myeloma clone.

  20. Hyperthermophilic endoglucanase for in planta lignocellulose conversion

    PubMed Central

    2012-01-01

    Background The enzymatic conversion of lignocellulosic plant biomass into fermentable sugars is a crucial step in the sustainable and environmentally friendly production of biofuels. However, a major drawback of enzymes from mesophilic sources is their suboptimal activity under established pretreatment conditions, e.g. high temperatures, extreme pH values and high salt concentrations. Enzymes from extremophiles are better adapted to these conditions and could be produced by heterologous expression in microbes, or even directly in the plant biomass. Results Here we show that a cellulase gene (sso1354) isolated from the hyperthermophilic archaeon Sulfolobus solfataricus can be expressed in plants, and that the recombinant enzyme is biologically active and exhibits the same properties as the wild type form. Since the enzyme is inactive under normal plant growth conditions, this potentially allows its expression in plants without negative effects on growth and development, and subsequent heat-inducible activation. Furthermore we demonstrate that the recombinant enzyme acts in high concentrations of ionic liquids and can therefore degrade α-cellulose or even complex cell wall preparations under those pretreatment conditions. Conclusion The hyperthermophilic endoglucanase SSO1354 with its unique features is an excellent tool for advanced biomass conversion. Here we demonstrate its expression in planta and the possibility for post harvest activation. Moreover the enzyme is suitable for combined pretreatment and hydrolysis applications. PMID:22928996

  1. Clinical efficacy of daratumumab monotherapy in patients with heavily pretreated relapsed or refractory multiple myeloma

    PubMed Central

    Weiss, Brendan M.; Plesner, Torben; Bahlis, Nizar J.; Belch, Andrew; Lonial, Sagar; Lokhorst, Henk M.; Voorhees, Peter M.; Richardson, Paul G.; Chari, Ajai; Sasser, A. Kate; Axel, Amy; Feng, Huaibao; Uhlar, Clarissa M.; Wang, Jianping; Khan, Imran; Ahmadi, Tahamtan; Nahi, Hareth

    2016-01-01

    The efficacy and favorable safety profile of daratumumab monotherapy in multiple myeloma (MM) was previously reported. Here, we present an updated pooled analysis of 148 patients treated with daratumumab 16 mg/kg. Data were combined from part 2 of a first-in-human phase 1/2 study of patients who relapsed after or were refractory to ≥2 prior therapies and a phase 2 study of patients previously treated with ≥3 prior lines of therapy (including a proteasome inhibitor [PI] and an immunomodulatory drug [IMiD]) or were double refractory. Among the pooled population, patients received a median of 5 prior lines of therapy (range, 2 to 14 prior lines of therapy), and 86.5% were double refractory to a PI and an IMiD. Overall response rate was 31.1%, including 13 very good partial responses, 4 complete responses, and 3 stringent complete responses. The median duration of response was 7.6 months (95% confidence interval [CI], 5.6 to not evaluable [NE]). The median progression-free survival (PFS) and overall survival (OS) were 4.0 months (95% CI, 2.8-5.6 months) and 20.1 months (95% CI, 16.6 months to NE), respectively. When stratified by responders vs stable disease/minimal response vs progressive disease/NE, median PFS was 15.0 months (95% CI, 7.4 months to NE) vs 3.0 months (95% CI, 2.8-3.7 months) vs 0.9 months (95% CI, 0.9-1.0 months), respectively, and median OS was NE (95% CI, NE to NE) vs 18.5 months (95% CI, 15.1-22.4 months) vs 3.7 months (95% CI, 1.7-7.6 months), respectively. No new safety signals were identified. In this pooled data set, daratumumab 16 mg/kg monotherapy demonstrated rapid, deep, and durable responses, with a clinical benefit that extended to patients with stable disease or better. PMID:27216216

  2. Predictive Value of Glycated Hemoglobin and Body Mass Index for Pretreatment Neuropathy in Patients With Multiple Myeloma.

    PubMed

    Lakshman, Arjun; Modi, Manish; Prakash, Gaurav; Malhotra, Pankaj; Khadwal, Alka; Suri, Vikas; Dutta, Pinaki; Jain, Sanjay; Kumari, Savita; Varma, Neelam; Varma, Subhash

    2016-02-01

    Peripheral neuropathy (PN) is detected in up to 62% patients with multiple myeloma (MM) at diagnosis. No specific risk factor for pretreatment neuropathy has been identified. We evaluated 29 sequential patients with MM attending our tertiary care center for peripheral neuropathy at diagnosis using symptoms, clinical examination, and nerve conduction studies (NCSs). Total Neuropathy Score, reduced (TNSr) and Total Neuropathy Score, clinical (TNSc) were calculated, and a score of ≥ 2 in each scale was considered diagnostic of PN. The study was approved by our institutional review board. We found that 51.7% (n = 15) and 17.2% (n = 5) of patients had pretreatment neuropathy by TNSr and TNSc scales, respectively. Higher glycated hemoglobin (HbA1C) (P = .022), higher body mass index (BMI) (P = .008), higher serum creatinine levels (P = .023), and higher blood urea levels (P = .006) were associated with neuropathy by TNSr in univariate analysis. Higher blood urea levels (P = .023), higher serum creatinine levels (P = .003), and higher serum β2-microglobulin levels (P = .013) were associated with neuropathy by TNSc in univariate analysis. Higher HbA1c levels (P = .036; odds ratio [OR], 9.46) and BMI (P = .028; OR, 1.78) were associated with neuropathy by TNSr on binomial logistic regression analysis. Cutoffs of 5.6% (sensitivity, 60%; specificity, 71.4%) and 23.7 kg/m(2) (sensitivity, 80%; specificity, 71.4%) were obtained for HbA1c (area under the curve [AUC], 0.75) and BMI (AUC, 0.79), respectively, on receiver operating characteristic (ROC) curve analysis to predict neuropathy. The combination of HbA1c ≥ 5.6% and BMI ≥ 23.7 kg/m(2) had higher odds of neuropathy by TNSr (OR, 27.0; 95% confidence interval [CI], 2.0-368.4) when compared with either factor alone. Use of TNSr, which incorporates electrophysiological abnormalities in addition to clinical manifestations, improves the detection rate of neuropathy. We found that high HbA1c and high BMI together are risk

  3. Inactivating effects of lignin-derived compounds released during lignocellulosic biomass pretreatment on the endo-glucanase catalyzed hydrolysis of carboxymethylcellulose: A study in continuous stirred ultrafiltration-membrane reactor.

    PubMed

    Cantarella, Maria; Mucciante, Claudia; Cantarella, Laura

    2014-03-01

    This study focusses on the reversible/irreversible damage that selected phenolic compounds, released during steam-explosion pretreatment, mandatory for cellulose accessibility, causes on both stability and activity of a commercial cellulase (half-life=173h) during carboxymethyl-cellulose hydrolysis. Long-term experiments performed in continuous stirred UF-membrane bioreactors, operating at steady-state regime, in controlled operational conditions, allowed evaluating the inactivation-constant in the phenol presence (kd1) and after its removal (kd2) from the reactor feed. p-Hydroxybenzoic acid (1 and 2g L(-1)) are the extreme limits in the inactivating effect with enzyme half-lives 99.02 and 14.15h, respectively. The inactivation reversibility was assessed for vanillic acid, p-hydroxybenzoic acid, syringaldehyde, p-coumaric acid, being kd1>kd2. p-Hydroxybenzaldehyde and protocatechuic acid irreversibly affected cellulase stability increasing its inactivation with kd2>kd1. p-Hydroxybenzaldehyde, 1g L(-1), syringaldehyde, and vanillin, at 2gL(-1), had similar kd1÷kd2. Copyright © 2014 Elsevier Ltd. All rights reserved.

  4. Methods for treating lignocellulosic materials

    DOEpatents

    Jansen, Robert; Gregoire, Claire; Travisano, Philip; Madsen, Lee; Matis, Neta; Har-Tal, Yael Miriam; Eliahu, Shay; Lawson, James Alan; Lapidot, Noa; Eyal, Aharon M.; Bauer, Timothy Allen; McWilliams, Paul; Zviely, Michael; Carden, Adam

    2017-05-16

    The present invention relates to methods of processing lignocellulosic material to obtain hemicellulose sugars, cellulose sugars, lignin, cellulose and other high-value products. Also provided are hemicellulose sugars, cellulose sugars, lignin, cellulose, and other high-value products.

  5. Methods for treating lignocellulosic materials

    DOEpatents

    Jansen, Robert; Gregoire, Claire; Travisano, Philip; Madsen, Lee; Matis, Neta; Har-Tal, Yael Miriam; Eliahu, Shay; Lawson, James Alan; Lapidot, Noa; Burke, Luke; Eyal, Aharon M.; Bauer, Timothy Allen; Sade, Hagit; McWilliams, Paul; Zviely, Michael; Carden, Adam

    2017-04-25

    The present invention relates to methods of processing lignocellulosic material to obtain hemicellulose sugars, cellulose sugars, lignin, cellulose and other high-value products. Also provided are hemicellulose sugars, cellulose sugars, lignin, cellulose, and other high-value products.

  6. Methods for treating lignocellulosic materials

    DOEpatents

    Jansen, Robert; Gregoire, Claire; Travisano, Philip; Madsen, Lee; Matis, Neta; Har-Tal, Yael; Eliahu, Shay; Lawson, James Alan; Lapidot, Noa; Eyal, Aharon M.; Bauer, Timothy Allen; Sade, Hagit; McWilliams, Paul; Zviely, Michael; Carden, Adam

    2016-11-15

    The present invention relates to methods of processing lignocellulosic material to obtain hemicellulose sugars, cellulose sugars, lignin, cellulose and other high-value products. Also provided are hemicellulose sugars, cellulose sugars, lignin, cellulose, and other high-value products.

  7. Robust cellulosic ethanol production from SPORL-pretreated lodgepole pine using an adapted strain Saccharomyces cervisiae without detoxification

    Treesearch

    S. Tian; X.L. Luo; X.S. Yang; J.Y. Zhu

    2010-01-01

    This study reports an ethanol yield of 270 L/ton wood from lodgepole pine pretreated with sulfite pretreatment to overcome recalcitrance of lignocellulose (SPORL) using an adapted strain, Saccharomyces cerevisiae Y5, without detoxification. The enzymatic hydrolysate produced from pretreated cellulosic solids substrate was combined with pretreatment hydrolysate before...

  8. [Anaerobic digestion of lignocellulosic biomass with animal digestion mechanisms].

    PubMed

    Wu, Hao; Zhang, Pan-Yue; Guo, Jian-Bin; Wu, Yong-Jie

    2013-02-01

    Lignocellulosic material is the most abundant renewable resource in the earth. Herbivores and wood-eating insects are highly effective in the digestion of plant cellulose, while anaerobic digestion process simulating animal alimentary tract still remains inefficient. The digestion mechanisms of herbivores and wood-eating insects and the development of anaerobic digestion processes of lignocellulose were reviewed for better understanding of animal digestion mechanisms and their application in design and operation of the anaerobic digestion reactor. Highly effective digestion of lignocellulosic materials in animal digestive system results from the synergistic effect of various digestive enzymes and a series of physical and biochemical reactions. Microbial fermentation system is strongly supported by powerful pretreatment, such as rumination of ruminants, cellulase catalysis and alkali treatment in digestive tract of wood-eating insects. Oxygen concentration gradient along the digestive tract may stimulate the hydrolytic activity of some microorganisms. In addition, the excellent arrangement of solid retention time, digesta flow and end product discharge enhance the animal digestion of wood cellulose. Although anaerobic digestion processes inoculated with rumen microorganisms based rumen digestion mechanisms were developed to treat lignocellulose, the fermentation was more greatly limited by the environmental conditions in the anaerobic digestion reactors than that in rumen or hindgut. Therefore, the anaerobic digestion processes simulating animal digestion mechanisms can effectively enhance the degradation of wood cellulose and other organic solid wastes.

  9. A review of biological delignification and detoxification methods for lignocellulosic bioethanol production.

    PubMed

    Moreno, Antonio D; Ibarra, David; Alvira, Pablo; Tomás-Pejó, Elia; Ballesteros, Mercedes

    2015-01-01

    Future biorefineries will integrate biomass conversion processes to produce fuels, power, heat and value-added chemicals. Due to its low price and wide distribution, lignocellulosic biomass is expected to play an important role toward this goal. Regarding renewable biofuel production, bioethanol from lignocellulosic feedstocks is considered the most feasible option for fossil fuels replacement since these raw materials do not compete with food or feed crops. In the overall process, lignin, the natural barrier of the lignocellulosic biomass, represents an important limiting factor in biomass digestibility. In order to reduce the recalcitrant structure of lignocellulose, biological pretreatments have been promoted as sustainable and environmentally friendly alternatives to traditional physico-chemical technologies, which are expensive and pollute the environment. These approaches include the use of diverse white-rot fungi and/or ligninolytic enzymes, which disrupt lignin polymers and facilitate the bioconversion of the sugar fraction into ethanol. As there is still no suitable biological pretreatment technology ready to scale up in an industrial context, white-rot fungi and/or ligninolytic enzymes have also been proposed to overcome, in a separated or in situ biodetoxification step, the effect of the inhibitors produced by non-biological pretreatments. The present work reviews the latest studies regarding the application of different microorganisms or enzymes as useful and environmentally friendly delignification and detoxification technologies for lignocellulosic biofuel production. This review also points out the main challenges and possible ways to make these technologies a reality for the bioethanol industry.

  10. Methods for degrading lignocellulosic materials

    DOEpatents

    Vlasenko, Elena; Cherry, Joel; Xu, Feng

    2008-04-08

    The present invention relates to methods for degrading a lignocellulosic material, comprising: treating the lignocellulosic material with an effective amount of one or more cellulolytic enzymes in the presence of at least one surfactant selected from the group consisting of a secondary alcohol ethoxylate, fatty alcohol ethoxylate, nonylphenol ethoxylate, tridecyl ethoxylate, and polyoxyethylene ether, wherein the presence of the surfactant increases the degradation of lignocellulosic material compared to the absence of the surfactant. The present invention also relates to methods for producing an organic substance, comprising: (a) saccharifying a lignocellulosic material with an effective amount of one or more cellulolytic enzymes in the presence of at least one surfactant selected from the group consisting of a secondary alcohol ethoxylate, fatty alcohol ethoxylate, nonylphenol ethoxylate, tridecyl ethoxylate, and polyoxyethylene ether, wherein the presence of the surfactant increases the degradation of lignocellulosic material compared to the absence of the surfactant; (b) fermenting the saccharified lignocellulosic material of step (a) with one or more fermentating microoganisms; and (c) recovering the organic substance from the fermentation.

  11. Methods for degrading lignocellulosic materials

    DOEpatents

    Vlasenko, Elena; Cherry, Joel; Xu, Feng

    2011-05-17

    The present invention relates to methods for degrading a lignocellulosic material, comprising: treating the lignocellulosic material with an effective amount of one or more cellulolytic enzymes in the presence of at least one surfactant selected from the group consisting of a secondary alcohol ethoxylate, fatty alcohol ethoxylate, nonylphenol ethoxylate, tridecyl ethoxylate, and polyoxyethylene ether, wherein the presence of the surfactant increases the degradation of lignocellulosic material compared to the absence of the surfactant. The present invention also relates to methods for producing an organic substance, comprising: (a) saccharifying a lignocellulosic material with an effective amount of one or more cellulolytic enzymes in the presence of at least one surfactant selected from the group consisting of a secondary alcohol ethoxylate, fatty alcohol ethoxylate, nonylphenol ethoxylate, tridecyl ethoxylate, and polyoxyethylene ether, wherein the presence of the surfactant increases the degradation of lignocellulosic material compared to the absence of the surfactant; (b) fermenting the saccharified lignocellulosic material of step (a) with one or more fermenting microorganisms; and (c) recovering the organic substance from the fermentation.

  12. Systematic approach to optimize a pretreatment method for ultrasensitive liquid chromatography with tandem mass spectrometry analysis of multiple target compounds in biological samples.

    PubMed

    Togashi, Kazutaka; Mutaguchi, Kuninori; Komuro, Setsuko; Kataoka, Makoto; Yamazaki, Hiroshi; Yamashita, Shinji

    2016-08-01

    In current approaches for new drug development, highly sensitive and robust analytical methods for the determination of test compounds in biological samples are essential. These analytical methods should be optimized for every target compound. However, for biological samples that contain multiple compounds as new drug candidates obtained by cassette dosing tests, it would be preferable to develop a single method that allows the determination of all compounds at once. This study aims to establish a systematic approach that enables a selection of the most appropriate pretreatment method for multiple target compounds without the use of their chemical information. We investigated the retention times of 27 known compounds under different mobile phase conditions and determined the required pretreatment of human plasma samples using several solid-phase and liquid-liquid extractions. From the relationship between retention time and recovery in a principal component analysis, appropriate pretreatments were categorized into several types. Based on the category, we have optimized a pretreatment method for the identification of three calcium channel blockers in human plasma. Plasma concentrations of these drugs in a cassette-dose clinical study at microdose level were successfully determined with a lower limit of quantitation of 0.2 pg/mL for diltiazem, 1 pg/mL for nicardipine, and 2 pg/mL for nifedipine.

  13. Consolidated bioprocessing performance of Thermoanaerobacterium thermosaccharolyticum M18 on fungal pretreated cornstalk for enhanced hydrogen production.

    PubMed

    Zhao, Lei; Cao, Guang-Li; Wang, Ai-Jie; Ren, Hong-Yu; Zhang, Kun; Ren, Nan-Qi

    2014-01-01

    Biological hydrogen production from lignocellulosic biomass shows great potential as a promising alternative to conventional hydrogen production methods, such as electrolysis of water and coal gasification. Currently, most researches on biohydrogen production from lignocellulose concentrate on consolidated bioprocessing, which has the advantages of simpler operation and lower cost over processes featuring dedicated cellulase production. However, the recalcitrance of the lignin structure induces a low cellulase activity, making the carbohydrates in the hetero-matrix more unapproachable. Pretreatment of lignocellulosic biomass is consequently an extremely important step in the commercialization of biohydrogen, and for massive realization of lignocellulosic biomass as alternative fuel feedstock. Thus, development of a pretreatment method which is cost efficient, environmentally benign, and highly efficient for enhanced consolidated bioprocessing of lignocellulosic biomass to hydrogen is essential. In this research, fungal pretreatment was adopted for enhanced hydrogen production by consolidated bioprocessing performance. To confirm the fungal pretreatment efficiency, two typical thermochemical pretreatments were also compared side by side. Results showed that the fungal pretreatment was superior to the other pretreatments in terms of high lignin reduction of up to 35.3% with least holocellulose loss (the value was only 9.5%). Microscopic structure observation combined with Fourier transform infrared spectroscopy (FTIR) analysis further demonstrated that the lignin and crystallinity of lignocellulose were decreased with better holocellulose reservation. Upon fungal pretreatment, the hydrogen yield and hydrogen production rate were 6.8 mmol H2 g(-1) pretreated substrate and 0.89 mmol L(-1) h(-1), respectively, which were 2.9 and 4 times higher than the values obtained for the untreated sample. Results revealed that although all pretreatments could contribute to the

  14. Single-step, single-organism bioethanol production and bioconversion of lignocellulose waste materials by phlebioid fungal species.

    PubMed

    Mattila, Hans; Kuuskeri, Jaana; Lundell, Taina

    2017-02-01

    Ethanol production from non-pretreated lignocellulose was carried out in a consolidated bioprocess with wood-decay fungi of phlebioid Polyporales. Ethanol production was attempted on glucose, spruce wood sawdust and waste core board. Substantial quantities of ethanol were achieved, and isolate Phlebia radiata 0043 produced 5.9g/L of ethanol reaching the yield of 10.4% ethanol from core board lignocellulose substrate. Acidic initial culture conditions (pH 3) induced ethanol fermentation compared to the more neutral environment. Together with bioethanol, the fungi were able to produce organic acids such as oxalate and fumarate, thus broadening their capacity and applicability as efficient organisms to be utilized for bioconversion of various lignocelluloses. In conclusion, fungi of Phlebia grow on, convert and saccharify solid lignocellulose waste materials without pre-treatments resulting in accumulation of ethanol and organic acids. These findings will aid in applying fungal biotechnology for production of biofuels and biocompounds.

  15. Lignocellulosic ethanol production by starch-base industrial yeast under PEG detoxification

    PubMed Central

    Liu, Xiumei; Xu, Wenjuan; Mao, Liaoyuan; Zhang, Chao; Yan, Peifang; Xu, Zhanwei; Zhang, Z. Conrad

    2016-01-01

    Cellulosic ethanol production from lignocellulosic biomass offers a sustainable solution for transition from fossil based fuels to renewable alternatives. However, a few long-standing technical challenges remain to be addressed in the development of an economically viable fermentation process from lignocellulose. Such challenges include the needs to improve yeast tolerance to toxic inhibitory compounds and to achieve high fermentation efficiency with minimum detoxification steps after a simple biomass pretreatment. Here we report an in-situ detoxification strategy by PEG exo-protection of an industrial dry yeast (starch-base). The exo-protected yeast cells displayed remarkably boosted vitality with high tolerance to toxic inhibitory compounds, and with largely improved ethanol productivity from crude hydrolysate derived from a pretreated lignocellulose. The PEG chemical exo-protection makes the industrial S. cerevisiae yeast directly applicable for the production of cellulosic ethanol with substantially improved productivity and yield, without of the need to use genetically modified microorganisms. PMID:26837707

  16. The conversion of lignocellulosics to fermentable sugars: A survey of current research and application to CELSS

    NASA Technical Reports Server (NTRS)

    Petersen, Gene R.; Baresi, Larry

    1990-01-01

    An overview of the options for converting lignocellulosics into fermentable sugars as applied to the Closed Ecological Life Support System (CELSS) is given. A requirement for pretreatment is shown as well as the many available options. At present, physical/chemical methods are the simplest and best characterized options, but enzymatic processes will likely be the method of choice in the future. The use of pentose sugars by microorganisms to produce edibles at levels comparable to conventional plants is shown. The possible use of mycelial food production on pretreated but not hydrolyzed lignocelluloscis is also presented. Simple tradeoff analysis among some of the many possible biological pathways to regeneration of waste lignocellulosics was undertaken. Comparisons with complete oxidation processes were made. It is suggested that the NASA Life Sciences CELSS program maintain relationships with other government agencies involved in lignocellulosic conversions and use their expertise when the actual need for such conversion technology arises rather than develop this expertise within NASA.

  17. Lignocellulosic ethanol production by starch-base industrial yeast under PEG detoxification

    NASA Astrophysics Data System (ADS)

    Liu, Xiumei; Xu, Wenjuan; Mao, Liaoyuan; Zhang, Chao; Yan, Peifang; Xu, Zhanwei; Zhang, Z. Conrad

    2016-02-01

    Cellulosic ethanol production from lignocellulosic biomass offers a sustainable solution for transition from fossil based fuels to renewable alternatives. However, a few long-standing technical challenges remain to be addressed in the development of an economically viable fermentation process from lignocellulose. Such challenges include the needs to improve yeast tolerance to toxic inhibitory compounds and to achieve high fermentation efficiency with minimum detoxification steps after a simple biomass pretreatment. Here we report an in-situ detoxification strategy by PEG exo-protection of an industrial dry yeast (starch-base). The exo-protected yeast cells displayed remarkably boosted vitality with high tolerance to toxic inhibitory compounds, and with largely improved ethanol productivity from crude hydrolysate derived from a pretreated lignocellulose. The PEG chemical exo-protection makes the industrial S. cerevisiae yeast directly applicable for the production of cellulosic ethanol with substantially improved productivity and yield, without of the need to use genetically modified microorganisms.

  18. Feasibilities of consolidated bioprocessing microbes: from pretreatment to biofuel production.

    PubMed

    Parisutham, Vinuselvi; Kim, Tae Hyun; Lee, Sung Kuk

    2014-06-01

    Lignocelluloses are rich sugar treasures, which can be converted to useful commodities such as biofuel with the help of efficient combination of enzymes and microbes. Although several bioprocessing approaches have been proposed, biofuel production from lignocelluloses is limited because of economically infeasible technologies for pretreatment, saccharification and fermentation. Use of consolidated bioprocessing (CBP) microbes is the most promising method for the cost-effective production of biofuels. However, lignocelluloses are obtained from highly diverse environment and hence are heterogeneous in nature. Therefore, it is necessary to develop and integrate tailor-designed pretreatment processes and efficient microbes that can thrive on many different kinds of biomass. In this review, the progress towards the construction of consolidated bioprocessing microbes, which can efficiently convert heterogeneous lignocellulosic biomass to bioenergy, has been discussed; in addition, the potential and constraints of current bioprocessing technologies for cellulosic biofuel production have been discussed.

  19. Comparative Study of SPORL and Dilute Acid Pretreatments of Spruce for Cellulosic Ethanol Production

    USDA-ARS?s Scientific Manuscript database

    The performance of two pretreatment methods, Sulfite Pretreatment to Overcome Recalcitrance of Lignocellulose (SPORL) and Dilute Acid (DA), was compared in pretreating softwood (spruce) for fuel ethanol production under the same conditions of temperature (180°C), time (30 min), sulfuric acid loading...

  20. Comparisons of five Saccharomyces cerevisiae strains for ethanol production from SPORL pretreated lodgepole pine

    Treesearch

    Haifeng Zhou; Tianqing Lan; Bruce S. Dien; Ronald E. Hector; J.Y. Zhu

    2014-01-01

    The performances of five yeast strains under three levels of toxicity were evaluated using hydrolysates from lodgepole pine pretreated by Sulfite Pretreatment to Overcome the Recalcitrance of Lignocelluloses (SPORL). The highest level of toxicity was represented by the whole pretreated biomass slurry, while intermediate toxicity was represented by the...

  1. Comparative study of SPORL and dilute-acid pretreatments of spruce for cellulosic ethanol production

    Treesearch

    L. Shuai; Q. Yang; Junyong Zhu; F.C. Lu; P.J. Weimer; J. Ralph; X.L. Pan

    2010-01-01

    The performance of two pretreatment methods, sulfite pretreatment to overcome recalcitrance of lignocelluloses (SPORL) and dilute acid (DA), was compared in pretreating softwood (spruce) for fuel ethanol production at 180C for 30 min with a sulfuric acid loading of 5% on oven-dry wood and a 5:1 liquor to-wood ratio. SPORL was supplemented with 9% sodium...

  2. Biological pretreatment of corn stover with white-rot fungus for improved enzymatic hydrolysis

    USDA-ARS?s Scientific Manuscript database

    Biological pretreatment of lignocellulosic biomass by white-rot fungus can represent a low-cost and eco-friendly alternative to harsh physical, chemical or physico-chemical pretreatment methods to facilitate enzymatic hydrolysis. However, fungal pretreatment can cause carbohydrate loss and it is, th...

  3. Comparisons of SPORL and dilute acid pretreatments for sugar and ethanol productions from aspen

    Treesearch

    S. Tian; W. Zhu; Roland Gleisner; X.J. Pan; Junyong Zhu

    2011-01-01

    This study reports comparative evaluations of sugar and ethanol production from a native aspen (Populus tremuloides) between sulfite pretreatment to overcome recalcitrance of lignocelluloses (SPORL) and dilute acid (DA) pretreatments. All aqueous pretreatments were carried out in a laboratory wood pulping digester using wood chips at 170°C with a liquid to...

  4. Comparisons of five Saccharomyces cerevisiae strains for ethanol production from SPORL pretreated lodgepole pine

    USDA-ARS?s Scientific Manuscript database

    The performances of 5 yeast strains under three levels of toxicity were evaluated using hydrolysates from lodgepole pine pretreated by Sulfite Pretreatment to Overcome the Recalcitrance of Lignocelluloses (SPORL). The highest level of toxicity was represented by the whole pretreated biomass slurry, ...

  5. Monitoring lignocellulosic bioethanol production processes using Raman spectroscopy.

    PubMed

    Iversen, Jens A; Ahring, Birgitte K

    2014-11-01

    Process control automation in the emerging biorefinery industry may be achieved by applying effective methods for monitoring compound concentrations during the production processes. This study examines the application of Raman spectroscopy with an excitation wavelength of 785nm and an immersion probe for in situ monitoring the progression of pretreatment, hydrolysis and fermentation processes in the production of lignocellulosic ethanol. Raman signals were attenuated by light scattering cells and lignocellulosic particulates, which the quantification method to some degree could correct for by using an internal standard in the spectra. Allowing particulates to settle by using a slow stirring speed further improved results, suggesting that Raman spectroscopy should be used in combination with continuous separation when used to monitor process mixtures with large amounts of particulates. The root mean square error of prediction (RMSE) of ethanol and glucose measured in real-time was determined to be 0.98g/L and 1.91g/L respectively.

  6. [Progress on cellulase and enzymatic hydrolysis of lignocellulosic biomass].

    PubMed

    Fang, Xu; Qin, Yuqi; Li, Xuezhi; Wang, Lushan; Wang, Tianhong; Zhu, Mingtian; Qu, Yinbo

    2010-07-01

    Biofuels and bio-based chemicals from lignocellulosic biomass are sustainable, making them alternatives to petroleum-derived fuels and chemicals to address the challenges of the shortage of crude oil supply and climate change resulted from the overconsumption of petroleum-based products, particularly in China. However, high cost in liberating sugars from lignocellulosic biomass is still the bottleneck of the commercialization of biofuels and bio-based chemicals. In this article, the major components of cellulases and their synergistic role in the hydrolysis of pre-treated biomass is reviewed, followed by how to evaluate the enzymatic hydrolysis. With the elucidation of the underlying mechanism of the conformations of the enzyme molecules and their effectiveness in attacking cellulose substrate, more efficient enzymes are expected to be developed. Using the high production strain Penicillium decumbens, the on-site production of cellulases for cellulose ethanol production is discussed.

  7. Calcium-catalyzed pyrolysis of lignocellulosic biomass components.

    PubMed

    Case, Paige A; Truong, Chi; Wheeler, M Clayton; DeSisto, William J

    2015-09-01

    The present study examines the effect of calcium pretreatment on pyrolysis of individual lignocellulosic compounds. Previous work has demonstrated that the incorporation of calcium compounds with the feedstock prior to pyrolysis has a significant effect on the oxygen content and stability of the resulting oil. The aim of this work was to further explore the chemistry of calcium-catalyzed pyrolysis. Bench-scale pyrolysis of biomass constituents, including lignin, cellulose and xylan is performed and compared to the oils produced from pyrolysis of the same components after calcium pretreatment. The resulting oils were analyzed by quantitative GC-MS and SEC. These analyses, together with data collected from previous work provide evidence which was used to develop proposed reaction pathways for pyrolysis of calcium-pretreatment biomass. Copyright © 2015 Elsevier Ltd. All rights reserved.

  8. Techniques for the evolution of robust Pentose-fermenting yeast for bioconversion of Lignocellulose to Ethanol

    USDA-ARS?s Scientific Manuscript database

    Lignocellulosic biomass is an abundant, renewable feedstock useful for the production of fuel-grade ethanol and other bio-products via the processing steps of pretreatment, enzyme hydrolysis and microbial conversion. Traditional industrial yeasts do not ferment xylose and are not able to grow, survi...

  9. Effects of drying-induced fiber hornification on enzymatic saccharification of lignocelluloses

    Treesearch

    Xiaolin Luo; Junyong Zhu

    2011-01-01

    This study investigated the effect of fiber hornification during drying on lignocellulosic substrate enzymatic saccharification. Two chemically pretreated wood substrates and one commercial bleached kraft hardwood pulp were used. Heat drying at 105 and 150°C and air drying at 50% RH and 23.8°C for different durations were applied to produce substrate...

  10. Bio-Product Recovery from Lignocellulosic Materials Derived from Poultry Manure

    ERIC Educational Resources Information Center

    Champagne, Pascale; Li, Caijian

    2008-01-01

    This study examines the hydrolysis of lignocellulose extracted from poultry manure for the purpose of investigating low-cost feedstocks for ethanol production while providing an alternative solid waste management strategy for agricultural livestock manures. Poultry manure underwent various pretreatments to enhance subsequent enzymatic hydrolysis…

  11. Bio-Product Recovery from Lignocellulosic Materials Derived from Poultry Manure

    ERIC Educational Resources Information Center

    Champagne, Pascale; Li, Caijian

    2008-01-01

    This study examines the hydrolysis of lignocellulose extracted from poultry manure for the purpose of investigating low-cost feedstocks for ethanol production while providing an alternative solid waste management strategy for agricultural livestock manures. Poultry manure underwent various pretreatments to enhance subsequent enzymatic hydrolysis…

  12. Ethanol production from lignocellulosic biomass by recombinant Escherichia coli strain FBR5

    USDA-ARS?s Scientific Manuscript database

    Lignocellulosic biomass, upon pretreatment and enzymatic hydrolysis, generates a mixture of hexose and pentose sugars such as glucose, xylose, arabinose and galactose. Escherichia coli utilizes all these sugars well but it lacks the ability to produce ethanol from them. Recombinant ethanologenic E...

  13. Fungal treated lignocellulosic biomass as ruminant feed ingredient: a review.

    PubMed

    van Kuijk, S J A; Sonnenberg, A S M; Baars, J J P; Hendriks, W H; Cone, J W

    2015-01-01

    In ruminant nutrition, there is an increasing interest for ingredients that do not compete with human nutrition. Ruminants are specialists in digesting carbohydrates in plant cell walls; therefore lignocellulosic biomass has potential in ruminant nutrition. The presence of lignin in biomass, however, limits the effective utilization of cellulose and hemicellulose. Currently, most often chemical and/or physical treatments are used to degrade lignin. White rot fungi are selective lignin degraders and can be a potential alternative to current methods which involve potentially toxic chemicals and expensive equipment. This review provides an overview of research conducted to date on fungal pretreatment of lignocellulosic biomass for ruminant feeds. White rot fungi colonize lignocellulosic biomass, and during colonization produce enzymes, radicals and other small compounds to breakdown lignin. The mechanisms on how these fungi degrade lignin are not fully understood, but fungal strain, the origin of lignocellulose and culture conditions have a major effect on the process. Ceriporiopsis subvermispora and Pleurotus eryngii are the most effective fungi to improve the nutritional value of biomass for ruminant nutrition. However, conclusions on the effectiveness of fungal delignification are difficult to draw due to a lack of standardized culture conditions and information on fungal strains used. Methods of analysis between studies are not uniform for both chemical analysis and in vitro degradation measurements. In vivo studies are limited in number and mostly describing digestibility after mushroom production, when the fungus has degraded cellulose to derive energy for fruit body development. Optimization of fungal pretreatment is required to shorten the process of delignification and make it more selective for lignin. In this respect, future research should focus on optimization of culture conditions and gene expression to obtain a better understanding of the mechanisms

  14. FRACTIONATION OF LIGNOCELLULOSIC BIOMASS FOR FUEL-GRADE ETHANOL PRODUCTION

    SciTech Connect

    F.D. Guffey; R.C. Wingerson

    2002-10-01

    PureVision Technology, Inc. (PureVision) of Fort Lupton, Colorado is developing a process for the conversion of lignocellulosic biomass into fuel-grade ethanol and specialty chemicals in order to enhance national energy security, rural economies, and environmental quality. Lignocellulosic-containing plants are those types of biomass that include wood, agricultural residues, and paper wastes. Lignocellulose is composed of the biopolymers cellulose, hemicellulose, and lignin. Cellulose, a polymer of glucose, is the component in lignocellulose that has potential for the production of fuel-grade ethanol by direct fermentation of the glucose. However, enzymatic hydrolysis of lignocellulose and raw cellulose into glucose is hindered by the presence of lignin. The cellulase enzyme, which hydrolyzes cellulose to glucose, becomes irreversibly bound to lignin. This requires using the enzyme in reagent quantities rather than in catalytic concentration. The extensive use of this enzyme is expensive and adversely affects the economics of ethanol production. PureVision has approached this problem by developing a biomass fractionator to pretreat the lignocellulose to yield a highly pure cellulose fraction. The biomass fractionator is based on sequentially treating the biomass with hot water, hot alkaline solutions, and polishing the cellulose fraction with a wet alkaline oxidation step. In September 2001 PureVision and Western Research Institute (WRI) initiated a jointly sponsored research project with the U.S. Department of Energy (DOE) to evaluate their pretreatment technology, develop an understanding of the chemistry, and provide the data required to design and fabricate a one- to two-ton/day pilot-scale unit. The efforts during the first year of this program completed the design, fabrication, and shakedown of a bench-scale reactor system and evaluated the fractionation of corn stover. The results from the evaluation of corn stover have shown that water hydrolysis prior to

  15. Thermotolerant Yeasts for Bioethanol Production Using Lignocellulosic Substrates

    NASA Astrophysics Data System (ADS)

    Pasha, Chand; Rao, L. Venkateswar

    No other sustainable option for production of transportation fuels can match ethanol made from lignocellulosic biomass with respect to its dramatic environmental, economic, strategic and infrastructure advantages. Substantial progress has been made in advancing biomass ethanol (bioethanol) production technology to the point that it now has commercial potential, and several firms are engaged in the demanding task of introducing first-of-a-kind technology into the marketplace to make bioethanol a reality in existing fuel-blending markets. In order to lower pollution India has a long-term goal to use biofuels (bioethanol and biodiesel). Ethanol may be used either in pure form, or as a blend in petrol in different proportions. Since the cost of raw materials, which can account up to 50 % of the total production cost, is one of the most significant factors affecting the economy of alcohol, nowadays efforts are more concentrated on using cheap and abundant raw materials. Several forms of biomass resources exist (starch or sugar crops, weeds, oil plants, agricultural, forestry and municipal wastes) but of all biomass cellulosic resources represent the most abundant global source. The lignocellulosic materials include agricultural residues, municipal solid wastes (MSW), pulp mill refuse, switchgrass and lawn, garden wastes. Lignocellulosic materials contain two types of polysaccharides, cellulose and hemicellulose, bound together by a third component lignin. The principal elements of the lignocellulosic research include: i) evaluation and characterization of the waste feedstock; ii) pretreatment including initial clean up or dewatering of the feedstock; and iii) development of effective direct conversion bioprocessing to generate ethanol as an end product. Pre-treatment of lignocellulosic materials is a step in which some of the hemicellulose dissolves in water, either as monomeric sugars or as oligomers and polymers. The cellulose cannot be enzymatically hydrolyzed to

  16. Enzymatic hydrolysis of lignocellulosic biomass from Onopordum nervosum.

    PubMed

    Martín, C; Negro, M J; Alfonsel, M; Sáez, R

    1988-07-20

    Some properties of the cellulolytic complex obtained from Trichoderma reesei QM 9414 grown on Solka floc as carbon source and its ability to hydrolyze the lignocellulosic biomass of Onopordum nervosum Boiss were studied. The optimum enzyme activity was found at temperatures between 50 and 55 degrees C and pH ranging from 4.3 to 4.8. Hydrolysis of 4-nitropnenyl-beta-D-glucopyranoside (4-NPG) and cellobiose by the beta-glucosidase of the complex, showed competitive inhibition by glucose with a K(i) value of 0.8 mM for 4-NPG and 2. 56 mM for cellobiose. Enzymatic hydrolysis yield of Onopordum nervosum, evaluated as glucose production after 48 h, showed a threefold increase by pretreating the lignocellulosic substrate with alkali. When the loss of glucose incurred by de pretreatment was taken into account, a 160% increase in the final cellulose to glucose conversion was found to be due to the pretreatment.

  17. Soluble inhibitors/deactivators of cellulase enzymes from lignocellulosic biomass.

    PubMed

    Kim, Youngmi; Ximenes, Eduardo; Mosier, Nathan S; Ladisch, Michael R

    2011-04-07

    Liquid hot water, steam explosion, and dilute acid pretreatments of lignocellulose generate soluble inhibitors which hamper enzymatic hydrolysis as well as fermentation of sugars to ethanol. Toxic and inhibitory compounds will vary with pretreatment and include soluble sugars, furan derivatives (hydroxymethyl fulfural, furfural), organic acids (acetic, formic and, levulinic acid), and phenolic compounds. Their effect is seen when an increase in the concentration of pretreated biomass in a hydrolysis slurry results in decreased cellulose conversion, even though the ratio of enzyme to cellulose is kept constant. We used lignin-free cellulose, Solka Floc, combined with mixtures of soluble components released during pretreatment of wood, to prove that the decrease in the rate and extent of cellulose hydrolysis is due to a combination of enzyme inhibition and deactivation. The causative agents were extracted from wood pretreatment liquid using PEG surfactant, activated charcoal or ethyl acetate and then desorbed, recovered, and added back to a mixture of enzyme and cellulose. At enzyme loadings of either 1 or 25mg protein/g glucan, the most inhibitory components, later identified as phenolics, decreased the rate and extent of cellulose hydrolysis by half due to both inhibition and precipitation of the enzymes. Full enzyme activity occurred when the phenols were removed. Hence detoxification of pretreated woods through phenol removal is expected to reduce enzyme loadings, and therefore reduce enzyme costs, for a given level of cellulose conversion. Copyright © 2011 Elsevier Inc. All rights reserved.

  18. Sonochemistry: what potential for conversion of lignocellulosic biomass into platform chemicals?

    PubMed

    Chatel, Gregory; De Oliveira Vigier, Karine; Jérôme, François

    2014-10-01

    This Review focuses on the use of ultrasound to produce chemicals from lignocellulosic biomass. However, the question about the potential of sonochemistry for valorization/conversion of lignocellulosic biomass into added-value chemicals is rather conceptual. Until now, this technology has been mainly used for the production of low-value chemicals such as biodiesel or as simple method for pretreatment or extraction. According to preliminary studies reported in literature, access to added-value chemicals can be easily and sometimes solely obtained by the use of ultrasound. The design of sonochemical parameters offers many opportunities to develop new eco-friendly and efficient processes. The goal of this Review is to understand why the use of ultrasound is focused rather on pretreatment or extraction of lignocellulosic biomass rather than on the production of chemicals and to understand, through the reported examples, which directions need to be followed to favor strategies based on ultrasound-assisted production of chemicals from lignocellulosic biomass. We believe that ultrasound-assisted processes represent an innovative approach and will create a growing interest in academia but also in the industry in the near future. Based on the examples reported in the literature, we critically discuss how sonochemistry could offer new strategies and give rise to new results in lignocellulosic biomass valorization. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  19. A spatially explicit whole-system model of the lignocellulosic bioethanol supply chain: an assessment of decentralised processing potential.

    PubMed

    Dunnett, Alex J; Adjiman, Claire S; Shah, Nilay

    2008-07-28

    Lignocellulosic bioethanol technologies exhibit significant capacity for performance improvement across the supply chain through the development of high-yielding energy crops, integrated pretreatment, hydrolysis and fermentation technologies and the application of dedicated ethanol pipelines. The impact of such developments on cost-optimal plant location, scale and process composition within multiple plant infrastructures is poorly understood. A combined production and logistics model has been developed to investigate cost-optimal system configurations for a range of technological, system scale, biomass supply and ethanol demand distribution scenarios specific to European agricultural land and population densities. Ethanol production costs for current technologies decrease significantly from $0.71 to $0.58 per litre with increasing economies of scale, up to a maximum single-plant capacity of 550 x 106 l year-1. The development of high-yielding energy crops and consolidated bio-processing realises significant cost reductions, with production costs ranging from $0.33 to $0.36 per litre. Increased feedstock yields result in systems of eight fully integrated plants operating within a 500 x 500 km2 region, each producing between 1.24 and 2.38 x 109 l year-1 of pure ethanol. A limited potential for distributed processing and centralised purification systems is identified, requiring developments in modular, ambient pretreatment and fermentation technologies and the pipeline transport of pure ethanol. The conceptual and mathematical modelling framework developed provides a valuable tool for the assessment and optimisation of the lignocellulosic bioethanol supply chain. In particular, it can provide insight into the optimal configuration of multiple plant systems. This information is invaluable in ensuring (near-)cost-optimal strategic development within the sector at the regional and national scale. The framework is flexible and can thus accommodate a range of processing

  20. A spatially explicit whole-system model of the lignocellulosic bioethanol supply chain: an assessment of decentralised processing potential

    PubMed Central

    Dunnett, Alex J; Adjiman, Claire S; Shah, Nilay

    2008-01-01

    Background Lignocellulosic bioethanol technologies exhibit significant capacity for performance improvement across the supply chain through the development of high-yielding energy crops, integrated pretreatment, hydrolysis and fermentation technologies and the application of dedicated ethanol pipelines. The impact of such developments on cost-optimal plant location, scale and process composition within multiple plant infrastructures is poorly understood. A combined production and logistics model has been developed to investigate cost-optimal system configurations for a range of technological, system scale, biomass supply and ethanol demand distribution scenarios specific to European agricultural land and population densities. Results Ethanol production costs for current technologies decrease significantly from $0.71 to $0.58 per litre with increasing economies of scale, up to a maximum single-plant capacity of 550 × 106 l year-1. The development of high-yielding energy crops and consolidated bio-processing realises significant cost reductions, with production costs ranging from $0.33 to $0.36 per litre. Increased feedstock yields result in systems of eight fully integrated plants operating within a 500 × 500 km2 region, each producing between 1.24 and 2.38 × 109 l year-1 of pure ethanol. A limited potential for distributed processing and centralised purification systems is identified, requiring developments in modular, ambient pretreatment and fermentation technologies and the pipeline transport of pure ethanol. Conclusion The conceptual and mathematical modelling framework developed provides a valuable tool for the assessment and optimisation of the lignocellulosic bioethanol supply chain. In particular, it can provide insight into the optimal configuration of multiple plant systems. This information is invaluable in ensuring (near-)cost-optimal strategic development within the sector at the regional and national scale. The framework is flexible and can thus

  1. Lignocellulosic Biomass Derived Functional Materials: Synthesis and Applications in Biomedical Engineering.

    PubMed

    Zhang, Lei; Peng, Xinwen; Zhong, Linxin; Chua, Weitian; Xiang, Zhihua; Sun, Runcang

    2017-09-18

    The pertinent issue of resources shortage arising from global climate change in the recent years has accentuated the importance of materials that are environmental friendly. Despite the merits of current material like cellulose as the most abundant natural polysaccharide on earth, the incorporation of lignocellulosic biomass has the potential to value-add the recent development of cellulose-derivatives in drug delivery systems. Lignocellulosic biomass, with a hierarchical structure, comprised of cellulose, hemicellulose and lignin. As an excellent substrate that is renewable, biodegradable, biocompatible and chemically accessible for modified materials, lignocellulosic biomass sets forth a myriad of applications. To date, materials derived from lignocellulosic biomass have been extensively explored for new technological development and applications, such as biomedical, green electronics and energy products. In this review, chemical constituents of lignocellulosic biomass are first discussed before we critically examine the potential alternatives in the field of biomedical application. In addition, the pretreatment methods for extracting cellulose, hemicellulose and lignin from lignocellulosic biomass as well as their biological applications including drug delivery, biosensor, tissue engineering etc will be reviewed. It is anticipated there will be an increasing interest and research findings in cellulose, hemicellulose and lignin from natural resources, which help provide important directions for the development in biomedical applications. Copyright© Bentham Science Publishers; For any queries, please email at epub@benthamscience.org.

  2. [Progress in lignocellulose deconstruction by fungi].

    PubMed

    Tian, Chaoguang; Ma, Yanhe

    2010-10-01

    Inefficient degradation of lignocellulose is one of the main barriers for the utilization of renewable plant biomass for biofuel production. The bottleneck of the biorefinery process is the generation of fermentable sugars from complicated biomass polymers. In nature, the main microbes of lignocelluloses deconstruction are fungi. Therefore, elucidating the mechanism of lignocelluloses degradation by fungi is of critical importance for the commercialization of lignocellulosic biofuels. This review focuses on the progress in lignocelluloses degradation pathways in fungi, especially on the advances made by functional genomics studies.

  3. The Effect of Ionic Liquid Pretreatment on the Bioconversion of Tomato Processing Waste to Fermentable Sugars and Biogas.

    PubMed

    Allison, Brittany J; Cádiz, Juan Canales; Karuna, Nardrapee; Jeoh, Tina; Simmons, Christopher W

    2016-08-01

    Tomato pomace is an abundant lignocellulosic waste stream from industrial tomato processing and therefore a potential feedstock for production of renewable biofuels. However, little research has been conducted to determine if pretreatment can enhance release of fermentable sugars from tomato pomace. Ionic liquids (ILs) are an emerging pretreatment technology for lignocellulosic biomass to increase enzymatic digestibility and biofuel yield while utilizing recyclable chemicals with low toxicity. In this study, pretreatment of tomato pomace with the ionic liquid 1-ethyl-3-methylimidazolium acetate ([C2mim][OAc]) was investigated. Changes in pomace enzymatic digestibility were affected by pretreatment time and temperature. Certain pretreatment conditions significantly improved reducing sugar yield and hydrolysis time compared to untreated pomace. Compositional analyses suggested that pretreatment primarily removed water-soluble compounds and enriched for lignocellulose in pomace, with only subtle changes to the composition of the lignocellulose. While tomato pomace was effectively pretreated with [C2mim][OAc] to improve enzymatic digestibility, as of yet, unknown factors in the pomace caused ionic liquid pretreatment to negatively affect anaerobic digestion of pretreated material. This result, which is unique compared to similar studies on IL pretreatment of grasses and woody biomass, highlights the need for additional research to determine how the unique chemical composition of tomato pomace and other lignocellulosic fruit residues may interact with ionic liquids to generate inhibitors for downstream fermentation to biofuels.

  4. Lignocellulose hydrolysis by multienzyme complexes

    USDA-ARS?s Scientific Manuscript database

    Lignocellulosic biomass is the most abundant renewable resource on the planet. Converting this material into a usable fuel is a multi-step process, the rate-limiting step being enzymatic hydrolysis of organic polymers into monomeric sugars. While the substrate can be complex and require a multitud...

  5. Lignocellulose-Adapted Endo-Cellulase Producing Streptomyces Strains for Bioconversion of Cellulose-Based Materials

    PubMed Central

    Ventorino, Valeria; Ionata, Elena; Birolo, Leila; Montella, Salvatore; Marcolongo, Loredana; de Chiaro, Addolorata; Espresso, Francesco; Faraco, Vincenza; Pepe, Olimpia

    2016-01-01

    Twenty-four Actinobacteria strains, isolated from Arundo donax, Eucalyptus camaldulensis and Populus nigra biomass during natural biodegradation and with potential enzymatic activities specific for the degradation of lignocellulosic materials, were identified by a polyphasic approach. All strains belonged to the genus Streptomyces (S.) and in particular, the most highly represented species was Streptomyces argenteolus representing 50% of strains, while 8 strains were identified as Streptomyces flavogriseus (synonym S. flavovirens) and Streptomyces fimicarius (synonyms Streptomyces acrimycini, Streptomyces baarnensis, Streptomyces caviscabies, and Streptomyces flavofuscus), and the other four strains belonged to the species Streptomyces drozdowiczii, Streptomyces rubrogriseus, Streptomyces albolongus, and Streptomyces ambofaciens. Moreover, all Streptomyces strains, tested for endo and exo-cellulase, cellobiase, xylanase, pectinase, ligninase, peroxidase, and laccase activities using qualitative and semi-quantitative methods on solid growth medium, exhibited multiple enzymatic activities (from three to six). The 24 strains were further screened for endo-cellulase activity in liquid growth medium and the four best endo-cellulase producers (S. argenteolus AE58P, S. argenteolus AE710A, S. argenteolus AE82P, and S. argenteolus AP51A) were subjected to partial characterization and their enzymatic crude extracts adopted to perform saccharification experiments on A. donax pretreated biomass. The degree of cellulose and xylan hydrolysis was evaluated by determining the kinetics of glucose and xylose release during 72 h incubation at 50°C from the pretreated biomass in the presence of cellulose degrading enzymes (cellulase and β-glucosidase) and xylan related activities (xylanase and β-xylosidase). The experiments were carried out utilizing the endo-cellulase activities from the selected S. argenteolus strains supplemented with commercial β-gucosidase and xylanase

  6. Lignocellulose-Adapted Endo-Cellulase Producing Streptomyces Strains for Bioconversion of Cellulose-Based Materials.

    PubMed

    Ventorino, Valeria; Ionata, Elena; Birolo, Leila; Montella, Salvatore; Marcolongo, Loredana; de Chiaro, Addolorata; Espresso, Francesco; Faraco, Vincenza; Pepe, Olimpia

    2016-01-01

    Twenty-four Actinobacteria strains, isolated from Arundo donax, Eucalyptus camaldulensis and Populus nigra biomass during natural biodegradation and with potential enzymatic activities specific for the degradation of lignocellulosic materials, were identified by a polyphasic approach. All strains belonged to the genus Streptomyces (S.) and in particular, the most highly represented species was Streptomyces argenteolus representing 50% of strains, while 8 strains were identified as Streptomyces flavogriseus (synonym S. flavovirens) and Streptomyces fimicarius (synonyms Streptomyces acrimycini, Streptomyces baarnensis, Streptomyces caviscabies, and Streptomyces flavofuscus), and the other four strains belonged to the species Streptomyces drozdowiczii, Streptomyces rubrogriseus, Streptomyces albolongus, and Streptomyces ambofaciens. Moreover, all Streptomyces strains, tested for endo and exo-cellulase, cellobiase, xylanase, pectinase, ligninase, peroxidase, and laccase activities using qualitative and semi-quantitative methods on solid growth medium, exhibited multiple enzymatic activities (from three to six). The 24 strains were further screened for endo-cellulase activity in liquid growth medium and the four best endo-cellulase producers (S. argenteolus AE58P, S. argenteolus AE710A, S. argenteolus AE82P, and S. argenteolus AP51A) were subjected to partial characterization and their enzymatic crude extracts adopted to perform saccharification experiments on A. donax pretreated biomass. The degree of cellulose and xylan hydrolysis was evaluated by determining the kinetics of glucose and xylose release during 72 h incubation at 50°C from the pretreated biomass in the presence of cellulose degrading enzymes (cellulase and β-glucosidase) and xylan related activities (xylanase and β-xylosidase). The experiments were carried out utilizing the endo-cellulase activities from the selected S. argenteolus strains supplemented with commercial β-gucosidase and xylanase

  7. Isolation of microorganisms for biological detoxification of lignocellulosic hydrolysates.

    PubMed

    López, M J; Nichols, N N; Dien, B S; Moreno, J; Bothast, R J

    2004-03-01

    Acid pretreatment of lignocellulosic biomass releases furan and phenolic compounds, which are toxic to microorganisms used for subsequent fermentation. In this study, we isolated new microorganisms for depletion of inhibitors in lignocellulosic acid hydrolysates. A sequential enrichment strategy was used to isolate microorganisms from soil. Selection was carried out in a defined mineral medium containing a mixture of ferulic acid (5 mM), 5-hydroxymethylfurfural (5-HMF, 15 mM), and furfural (20 mM) as the carbon and energy sources, followed by an additional transfer into a corn stover hydrolysate (CSH) prepared using dilute acid. Subsequently, based on stable growth on these substrates, six isolates--including five bacteria related to Methylobacterium extorquens, Pseudomonas sp, Flavobacterium indologenes, Acinetobacter sp., Arthrobacter aurescens, and one fungus, Coniochaeta ligniaria--were chosen. All six isolates depleted toxic compounds from defined medium, but only C. ligniaria C8 (NRRL 30616) was effective at eliminating furfural and 5-HMF from CSH. C. ligniaria NRRL 30616 may be useful in developing a bioprocess for inhibitor abatement in the conversion of lignocellulosic biomass to fuels and chemicals.

  8. How does cellulosome composition influence deconstruction of lignocellulosic substrates in Clostridium (Ruminiclostridium) thermocellum DSM 1313?

    PubMed

    Yoav, Shahar; Barak, Yoav; Shamshoum, Melina; Borovok, Ilya; Lamed, Raphael; Dassa, Bareket; Hadar, Yitzhak; Morag, Ely; Bayer, Edward A

    2017-01-01

    Bioethanol production processes involve enzymatic hydrolysis of pretreated lignocellulosic biomass into fermentable sugars. Due to the relatively high cost of enzyme production, the development of potent and cost-effective cellulolytic cocktails is critical for increasing the cost-effectiveness of bioethanol production. In this context, the multi-protein cellulolytic complex of Clostridium (Ruminiclostridium) thermocellum, the cellulosome, was studied here. C. thermocellum is known to assemble cellulosomes of various subunit (enzyme) compositions, in response to the available carbon source. In the current study, different carbon sources were used, and their influence on both cellulosomal composition and the resultant activity was investigated. Glucose, cellobiose, microcrystalline cellulose, alkaline-pretreated switchgrass, alkaline-pretreated corn stover, and dilute acid-pretreated corn stover were used as sole carbon sources in the growth media of C. thermocellum strain DSM 1313. The purified cellulosomes were compared for their activity on selected cellulosic substrates. Interestingly, cellulosomes derived from cells grown on lignocellulosic biomass showed no advantage in hydrolyzing the original carbon source used for their production. Instead, microcrystalline cellulose- and glucose-derived cellulosomes were equal or superior in their capacity to deconstruct lignocellulosic biomass. Mass spectrometry analysis revealed differential composition of catalytic and structural subunits (scaffoldins) in the different cellulosome samples. The most abundant catalytic subunits in all cellulosome types include Cel48S, Cel9K, Cel9Q, Cel9R, and Cel5G. Microcrystalline cellulose- and glucose-derived cellulosome samples showed higher endoglucanase-to-exoglucanase ratios and higher catalytic subunit-per-scaffoldin ratios compared to lignocellulose-derived cellulosome types. The results reported here highlight the finding that cellulosomes derived from cells grown on glucose

  9. Innovative pretreatment strategies for biogas production.

    PubMed

    Patinvoh, Regina J; Osadolor, Osagie A; Chandolias, Konstantinos; Sárvári Horváth, Ilona; Taherzadeh, Mohammad J

    2017-01-01

    Biogas or biomethane is traditionally produced via anaerobic digestion, or recently by thermochemical or a combination of thermochemical and biological processes via syngas (CO and H2) fermentation. However, many of the feedstocks have recalcitrant structure and are difficult to digest (e.g., lignocelluloses or keratins), or they have toxic compounds (such as fruit flavors or high ammonia content), or not digestible at all (e.g., plastics). To overcome these challenges, innovative strategies for enhanced and economically favorable biogas production were proposed in this review. The strategies considered are commonly known physical pretreatment, rapid decompression, autohydrolysis, acid- or alkali pretreatments, solvents (e.g. for lignin or cellulose) pretreatments or leaching, supercritical, oxidative or biological pretreatments, as well as combined gasification and fermentation, integrated biogas production and pretreatment, innovative biogas digester design, co-digestion, and bio-augmentation. Copyright © 2016 Elsevier Ltd. All rights reserved.

  10. Biomass pretreatment

    DOEpatents

    Hennessey, Susan Marie; Friend, Julie; Elander, Richard T; Tucker, III, Melvin P

    2013-05-21

    A method is provided for producing an improved pretreated biomass product for use in saccharification followed by fermentation to produce a target chemical that includes removal of saccharification and or fermentation inhibitors from the pretreated biomass product. Specifically, the pretreated biomass product derived from using the present method has fewer inhibitors of saccharification and/or fermentation without a loss in sugar content.

  11. Using a combined hydrolysis factor to optimize high titer ethanol production from sulfite-pretreated poplar without detoxification

    Treesearch

    Jingzhi Zhang; Feng Gu; J.Y. Zhu; Ronald S. Zalesny Jr.

    2015-01-01

    Sulfite pretreatment to overcome the recalcitrance of lignocelluloses (SPORL) was applied to poplar NE222 chips in a range of chemical loadings, temperatures, and times. The combined hydrolysis factor (CHF) as a pretreatment severity accurately predicted xylan dissolution by SPORL. Good correlations between CHF and pretreated...

  12. Enhancement of lignocellulose-carbon nanotubes composites by lignocellulose grafting.

    PubMed

    Huang, Jintian; Zhang, Shaobo; Zhang, Feiran; Guo, Zhiqing; Jin, Liping; Pan, Yefei; Wang, Yu; Guo, Tongcheng

    2017-03-15

    Lignocellulose (LNC) multi-walled carbon nanotubes (MWCNTs) composites were synthesized by covalently grafting a natural polymer, lignocellulose, onto MWCNTs in an ionic liquid, 1-allyl-3-methylimidazolium chloride (AmimCl). Furthermore, the grafting of LNC facilitated the dispersion of the MWCNTs in AmimCl and MWCNTs/LNC films. The elongation at break and tensile strength of grafted-MWCNTs/LNC films with 3wt% of MWCNTs content were 12.2% and 106.7MPa respectively, which was almost 93.7% and 10.7% higher than those of the pristine MWCNTs/LNC films. This finding clearly revealed that the mechanical properties of grafted-MWCNTs/LNC films were dramatically superior to those of the MWCNTs/LNC films.

  13. Expression of Aspergillus niger CAZymes is determined by compositional changes in wheat straw generated by hydrothermal or ionic liquid pretreatments

    DOE PAGES

    Daly, Paul; van Munster, Jolanda M.; Blythe, Martin J.; ...

    2017-02-07

    The capacity of fungi, such as Aspergillus niger, to degrade lignocellulose is harnessed in biotechnology to generate biofuels and high-value compounds from renewable feedstocks. Most feedstocks are currently pretreated to increase enzymatic digestibility: improving our understanding of the transcriptomic responses of fungi to pretreated lignocellulosic substrates could help to improve the mix of activities and reduce the production costs of commercial lignocellulose saccharifying cocktails. We investigated the responses of A. niger to untreated, ionic liquid and hydrothermally pretreated wheat straw over a 5-day time course using RNA-seq and targeted proteomics. The ionic liquid pretreatment altered the cellulose crystallinity while retainingmore » more of the hemicellulosic sugars than the hydrothermal pretreatment. Ionic liquid pretreatment of straw led to a dynamic induction and repression of genes, which was correlated with the higher levels of pentose sugars saccharified from the ionic liquid-pretreated straw. Hydrothermal pretreatment of straw led to reduced levels of transcripts of genes encoding carbohydrate-active enzymes as well as the derived proteins and enzyme activities. Both pretreatments abolished the expression of a large set of genes encoding pectinolytic enzymes. These reduced levels could be explained by the removal of parts of the lignocellulose by the hydrothermal pretreatment. The time course also facilitated identification of temporally limited gene induction patterns. The presented transcriptomic and biochemical datasets demonstrate that pretreatments caused modifications of the lignocellulose, to both specific structural features as well as the organisation of the overall lignocellulosic structure, that determined A. niger transcript levels. The experimental setup allowed reliable detection of substrate-specific gene expression patterns as well as hitherto non-expressed genes. Our data suggest beneficial effects of using untreated and

  14. Hydrolysis of lignocelluloses by penicillium funiculosum cellulase

    SciTech Connect

    Mishra, C.; Rao, M.; Seeta, R.; Srinivasan, M.C.; Deshpande, V.

    1984-04-01

    Enzymatic hydrolysis of cellulose is a promising method for the conversion of waste cellulose to glucose. During the past few years, the development of this technology has proceeded rapidly, with significant advances made in enzyme production, pretreatment, and hydrolysis. A variety of fungi are reported to produce cellulases but among these Trichoderma reesei and its mutants are powerful producers of cellulases. However, the search for new and possibly better sources of cellulase is continued due to the low levels of beta-glucosidase of T. reesei. Penicillium funiculosum produces a complete cellulase having endo-beta-1,4-glucanase (15-20 U/mL), exo-beta-1,4-glucanase (1.5-2.0 U/mL), and high beta-glucosidase (8-10 U/mL). The saccharification of alkali-treated cotton and bagasse by P. funiculosum enzyme was 70 and 63%, respectively. It was possible to obtain glucose concentration as high as 30% using 50% bagasse. It is of interest that the percent saccharification of cellulosic substrates with the Penicillium enzyme is comparable to that of T. reesei cellulase when the same amount of filter paper activity is used, although the endo-glucanase activity of the latter is two to three times higher. This communication reports the studies on saccharification of lignocelluloses by P. funiculosum cellulase and certain studies on the kinetic aspects. (Refs. 15).

  15. Co-hydrolysis of lignocellulosic biomass for microbial lipid accumulation.

    PubMed

    Ruan, Zhenhua; Zanotti, Michael; Zhong, Yuan; Liao, Wei; Ducey, Chad; Liu, Yan

    2013-04-01

    The herbaceous perennial energy crops miscanthus, giant reed, and switchgrass, along with the annual crop residue corn stover, were evaluated for their bioconversion potential. A co-hydrolysis process, which applied dilute acid pretreatment, directly followed by enzymatic saccharification without detoxification and liquid-solid separation between these two steps was implemented to convert lignocellulose into monomeric sugars (glucose and xylose). A factorial experiment in a randomized block design was employed to optimize the co-hydrolysis process. Under the optimal reaction conditions, corn stover exhibited the greatest total sugar yield (glucose + xylose) at 0.545 g g(-1) dry biomass at 83.3% of the theoretical yield, followed by switch grass (0.44 g g(-1) dry biomass, 65.8% of theoretical yield), giant reed (0.355 g g(-1) dry biomass, 64.7% of theoretical yield), and miscanthus (0.349 g g(-1) dry biomass, 58.1% of theoretical yield). The influence of combined severity factor on the susceptibility of pretreated substrates to enzymatic hydrolysis was clearly discernible, showing that co-hydrolysis is a technically feasible approach to release sugars from lignocellulosic biomass. The oleaginous fungus Mortierella isabellina was selected and applied to the co-hydrolysate mediums to accumulate fungal lipids due to its capability of utilizing both C5 and C6 sugars. Fungal cultivations grown on the co-hydrolysates exhibited comparable cell mass and lipid production to the synthetic medium with pure glucose and xylose. These results elucidated that combining fungal fermentation and co-hydrolysis to accumulate lipids could have the potential to enhance the utilization efficiency of lignocellulosic biomass for advanced biofuels production. Copyright © 2012 Wiley Periodicals, Inc.

  16. Effect of lignocellulosic composition and structure on the bioethanol production from different poplar lines.

    PubMed

    Duan, Xiaojian; Zhang, Changbo; Ju, Xuehai; Li, Qiongcui; Chen, Shouyi; Wang, Jingan; Liu, Zhongqi

    2013-07-01

    Branches from three transgenic poplar lines and their wild type line 107 were used to study the effect of lignocellulosic composition and structure on the production of glucose and ethanol. Experimental results showed that the transgenic line 18-1 had the high cellulose content and amorphous fibril structure. After poplar meals were pretreated with 10% NaOH and a mixture of hydrogen peroxide and acetic acid, their lateral order index decreased significantly. The highest glucose yield in enzymatic hydrolysis and ethanol yield from the substrate of 18-1 was much higher than that from feedstock of 107 by 192.7% and 108.7%, respectively. Scanning electron microscopy images confirmed that lignocellulose from the 18-1 could be destroyed by chemicals more easily than those from other lines. These results demonstrated that changing lignocellulose structure could be more effective on improving the digestibility and enzymatic hydrolysis of poplar biomass than increasing the cellulose content in biomass.

  17. Hydrothermal carbonization of lignocellulosic biomass.

    PubMed

    Xiao, Ling-Ping; Shi, Zheng-Jun; Xu, Feng; Sun, Run-Cang

    2012-08-01

    Hydrothermal carbonization (HTC) is a novel thermochemical conversion process to convert lignocellulosic biomass into value-added products. HTC processes were studied using two different biomass feedstocks: corn stalk and Tamarix ramosissima. The treatment brought an increase of the higher heating values up to 29.2 and 28.4 MJ/kg for corn stalk and T. ramosissima, respectively, corresponding to an increase of 66.8% and 58.3% as compared to those for the raw materials. The resulting lignite-like solid products contained mainly lignin with a high degree of aromatization and a large amount of oxygen-containing groups. Liquid products extracted with ethyl acetate were analyzed by gas chromatography-mass spectrometry. The identified degradation products were phenolic compounds and furan derivatives, which may be desirable feedstocks for biodiesel and chemical production. Based on these results, HTC is considered to be a potential treatment in a lignocellulosic biomass refinery.

  18. Elucidating and alleviating impacts of lignocellulose-derived microbial inhibitors on Clostridium beijerinckii during fermentation of Miscanthus giganteus to butanol.

    PubMed

    Zhang, Yan; Ezeji, Thaddeus Chukwuemeka

    2014-10-01

    Fermentation of liquid hot water (LHW) pretreated Miscanthus giganteus (MG) by Clostridium beijerinckii NCIMB 8052 was investigated towards understanding the toxicity of lignocellulose-derived inhibitors to solventogenic Clostridium species vis-à-vis butanol production. While C. beijerinckii NCIMB 8052 did not grow in undiluted MG hydrolysate-based fermentation medium, supplementation of this medium with Calcium carbonate enabled the growth of C. beijerinckii NCIMB 8052 and production of butanol. Using high-performance liquid chromatography (HPLC) and spectrophotometric assays, LHW-pretreated MG was found to contain lignocellulose-derived microbial inhibitory compounds; some of which were transformed by exponentially growing C. beijerinckii to less inhibitory compounds during fermentation. Contrary to all expectations, the reduction product of furfural, furfuryl alcohol, inhibited butanol production by C. beijerinckii by more than 16 %. Collectively, these results provide new insights into why lignocellulosic biomass hydrolysates are recalcitrant to fermentation to biofuels and chemicals.

  19. Ethanol production from maize silage as lignocellulosic biomass in anaerobically digested and wet-oxidized manure.

    PubMed

    Oleskowicz-Popiel, Piotr; Lisiecki, Przemyslaw; Holm-Nielsen, Jens Bo; Thomsen, Anne Belinda; Thomsen, Mette Hedegaard

    2008-09-01

    In this communication, pretreatment of the anaerobically digested (AD) manure and the application of the pretreated AD manure as liquid medium for the simultaneous saccharification and fermentation (SSF) were described. Furthermore, fermentation of pretreated maize silage and wheat straw was investigated using 2l bioreactors. Wet oxidation performed for 20 min at 121 degrees C was found as the most suitable pretreatment conditions for AD manure. High ammonia concentration and significant amount of macro- and micro-nutrients in the AD manure had a positive influence on the ethanol fermentation. No extra nitrogen source was needed in the fermentation broth. It was shown that the AD manure could successfully substitute process water in SSF of pretreated lignocellulosic fibres. Theoretical ethanol yields of 82% were achieved, giving 30.8 kg ethanol per 100 kg dry mass of maize silage.

  20. Sulfite (SPORL) pretreatment of switchgrass for enzymatic saccharification

    Treesearch

    D.S. Zhang; Q. Yang; J.Y. Zhu; X.J. Pan

    2013-01-01

    SPORL (Sulfite Pretreatment to Overcome Recalcitrance of Lignocellulose) pretreatment was applied to switchgrass and optimized through an experimental design using Response Surface Methodology within the range of temperature (163–197 °C), time (3–37 min), sulfuric acid dosage (0.8–4.2% on switchgrass), and sodium sulfite dosage (0.6–7.4% on switchgrass)....

  1. Screening of lactic acid bacteria for their potential as microbial cell factories for bioconversion of lignocellulosic feedstocks.

    PubMed

    Boguta, Anna Monika; Bringel, Françoise; Martinussen, Jan; Jensen, Peter Ruhdal

    2014-07-05

    The use of fossil carbon sources for fuels and petrochemicals has serious impacts on our environment and is unable to meet the demand in the future. A promising and sustainable alternative is to substitute fossil carbon sources with microbial cell factories converting lignocellulosic biomass into desirable value added products. However, such bioprocesses require availability of suitable and efficient microbial biocatalysts, capable of utilizing C5 sugars and tolerant to inhibitory compounds generated during pretreatment of biomass. In this study, the performance of a collection of lactic acid bacteria was evaluated regarding their properties with respect to the conversion of lignocellulosic feedstocks. The strains were examined for their ability to utilize xylose and arabinose as well as their resistance towards common inhibitors from pretreated lignocellulosic biomass (furan derivatives, phenolic compounds, weak acids). Among 296 tested Lactobacillus and Pediococcus strains, 3 L. pentosus, 1 P. acidilactici and 1 P. pentosaceus isolates were found to be both capable of utilizing xylose and arabinose and highly resistant to the key inhibitors from chemically pretreated lignocellulosic biomass. When tested in broth with commonly found combinations of inhibitors, the selected strains showed merely 4%, 1% and 37% drop in growth rates for sugarcane bagasse, wheat straw and soft wood representatives, respectively, as compared to Escherichia coli MG1655 showing decreased growth rates by 36%, 21% and 90%, respectively, under the same conditions. The study showed that some strains of Lactobacilli and Pediococci have the potential to be used as production platforms for value-added products from pretreated lignocellulosic biomass. Selected Lactobacilli and Pediococci strains were able to tolerate the key inhibitors in higher concentrations compared to E.coli; in addition, as these isolates were also capable of fermenting xylose and arabinose, they constitute good

  2. Screening of lactic acid bacteria for their potential as microbial cell factories for bioconversion of lignocellulosic feedstocks

    PubMed Central

    2014-01-01

    Background The use of fossil carbon sources for fuels and petrochemicals has serious impacts on our environment and is unable to meet the demand in the future. A promising and sustainable alternative is to substitute fossil carbon sources with microbial cell factories converting lignocellulosic biomass into desirable value added products. However, such bioprocesses require availability of suitable and efficient microbial biocatalysts, capable of utilizing C5 sugars and tolerant to inhibitory compounds generated during pretreatment of biomass. In this study, the performance of a collection of lactic acid bacteria was evaluated regarding their properties with respect to the conversion of lignocellulosic feedstocks. The strains were examined for their ability to utilize xylose and arabinose as well as their resistance towards common inhibitors from pretreated lignocellulosic biomass (furan derivatives, phenolic compounds, weak acids). Results Among 296 tested Lactobacillus and Pediococcus strains, 3 L. pentosus, 1 P. acidilactici and 1 P. pentosaceus isolates were found to be both capable of utilizing xylose and arabinose and highly resistant to the key inhibitors from chemically pretreated lignocellulosic biomass. When tested in broth with commonly found combinations of inhibitors, the selected strains showed merely 4%, 1% and 37% drop in growth rates for sugarcane bagasse, wheat straw and soft wood representatives, respectively, as compared to Escherichia coli MG1655 showing decreased growth rates by 36%, 21% and 90%, respectively, under the same conditions. Conclusion The study showed that some strains of Lactobacilli and Pediococci have the potential to be used as production platforms for value-added products from pretreated lignocellulosic biomass. Selected Lactobacilli and Pediococci strains were able to tolerate the key inhibitors in higher concentrations compared to E.coli; in addition, as these isolates were also capable of fermenting xylose and arabinose

  3. Revalorizing lignocellulose for the production of natural pharmaceuticals and other high value bioproducts.

    PubMed

    Zhang, Congqiang; Too, Heng-Phon

    2017-09-11

    Lignocellulose is the most plentiful, renewable natural resource on earth and has been successfully used for the production of biofuels. A significant challenge is to develop cost-effective, environmentally friendly and efficient processes for the conversion of lignocellulose material into suitable substrates for biotransformation. A number of approaches have been explored to convert lignocellulose into sugars, e.g. combining chemical pretreatment and enzymatic hydrolysis. In nature, there are organisms that can biotransform the complex lignocellulose efficiently, such as wood-degrading fungi (brown rot and white rot fungi), bacteria (e.g. Clostridium thermocellum), arthropods (e.g. termite) and certain animals (e.g. ruminant). Here, we highlight recent case studies of the natural degraders and the mechanisms involved, providing new utilities in biotechnology. The sugars produced from such biotransformations can be used in metabolic engineering and synthetic biology for the complete biosynthesis of natural medicine. The unique opportunities in using lignocellulose directly to produce natural drug molecules with either using mushroom and/or 'industrial workhorse' organisms (Escherichia coli and Saccharomyces cerevisiae) will be discussed. Copyright© Bentham Science Publishers; For any queries, please email at epub@benthamscience.org.

  4. Xylose fermentation as a challenge for commercialization of lignocellulosic fuels and chemicals.

    PubMed

    Sànchez Nogué, Violeta; Karhumaa, Kaisa

    2015-04-01

    Fuel ethanol production from lignocellulosic materials is at a level where commercial biofuel production is becoming a reality. The solubilization of the hemicellulose fraction in lignocellulosic-based feedstocks results in a large variety of sugar mixtures including xylose. However, allowing xylose fermentation in yeast that normally is used for fuel ethanol production requires genetic engineering. Moreover, the efficiency of lignocellulosic pretreatment, together with the release and generation of inhibitory compounds in this step, are some of the new challenges faced during second generation ethanol production. Successful advances in all these aspects will improve ethanol yield, productivity and titer, which will reduce the impact on capital and operating costs, leading to the consolidation of the fermentation of lignocellulosic biomass as an economically feasible option for the production of renewable fuels. Therefore the development of yeast strains capable of fermenting a wide variety of sugars in a highly inhibitory environment, while maintaining a high ethanol yield and production rate, is required. This review provides an overview of the current status in the use of xylose-engineered yeast strains and describes the remaining challenges to achieve an efficient deployment of lignocellulosic-based ethanol production.

  5. Efficiencies of acid catalysts in the hydrolysis of lignocellulosic biomass over a range of combined severity factors

    Treesearch

    Jae-Won Lee; Thomas W. Jeffries

    2011-01-01

    Dicarboxylic organic acids have properties that differ from those of sulfuric acid during hydrolysis of lignocellulose. To investigate the effects of different acid catalysts on the hydrolysis and degradation of biomass compounds over a range of thermochemical pretreatments, maleic, oxalic and sulfuric acids were each used at the same combined severity factor (CSF)...

  6. A new source of resistance to 2-furaldehyde from Scheffersomyces (Pichia) stipitis for sustainable lignocellulose-to-biofuel conversion

    USDA-ARS?s Scientific Manuscript database

    Aldehyde inhibitory compounds derived from lignocellulosic biomass pretreatment have been identified as a major class of toxic chemicals that interfere with microbial growth and subsequent fermentation for advanced biofuel production. Development of robust next-generation biocatalyst is a key for a ...

  7. Characterization of microcrystalline cellulose prepared from lignocellulosic materials. Part I. Acid catalyzed hydrolysis.

    PubMed

    Adel, Abeer M; Abd El-Wahab, Zeinab H; Ibrahim, Atef A; Al-Shemy, Mona T

    2010-06-01

    Rice hulls (RH) and bean hulls (BH) were subjected to prehydrolysis treatments, to define the optimum conditions for producing a high percentage of hydrolyzed hemicellulose with a small or moderate degradation of the cellulosic portion. The hydrolysis experiments were performed using hydrochloric and sulfuric acids in concentrations ranging from (0.5 to 5)% (w/w) at 120 degrees C for 90 min and 10% consistency. The effects of different temperatures (80 to 120 degrees C) and time (30 to 120 min) on acid hydrolysis of lignocellulosic materials were recorded. It was found that, the optimum condition to hydrolyze the lignocellulosic materials (RH) and (BH) are 2% (w/w) of mineral acid at 120 degrees C for 90 min and 10% consistency. The cellulose crystallinity index in the different types of lignocellulosic materials with and without acid treatment, were increased from 0.32 to 0.46 in case of RH and from 0.43 to 0.61 in case of BH. Due to the lignin depolymerization during the pretreatment process, the relative absorbency of the methoxyl group and the aromatic rings bands were lowered for the pretreated than the untreated lignocellulosic materials. Also, the band at 1730 cm(-1) which is attributed to carbonyl groups of uronic acids was lowered due the hemicellulose hydrolysis.

  8. In planta expression of hyperthermophilic enzymes as a strategy for accelerated lignocellulosic digestion.

    PubMed

    Mir, Bilal Ahmad; Myburg, Alexander A; Mizrachi, Eshchar; Cowan, Don A

    2017-09-13

    Conversion of lignocellulosic biomass to biofuels and biomaterials suffers from high production costs associated with biomass pretreatment and enzymatic hydrolysis. In-planta expression of lignocellulose-digesting enzymes is a promising approach to reduce these cost elements. However, this approach faces a number of challenges, including auto-hydrolysis of developing cell walls, plant growth and yield penalties, low expression levels and the limited stability of expressed enzymes at the high temperatures generally used for biomass processing to release fermentable sugars. To overcome these challenges we expressed codon-optimized recombinant hyperthermophilic endoglucanase (EG) and xylanase (Xyn) genes in A. thaliana. Transgenic Arabidopsis lines expressing EG and Xyn enzymes at high levels without any obvious plant growth or yield penalties were selected for further analysis. The highest enzyme activities were observed in the dry stems of transgenic lines, indicating that the enzymes were not degraded during stem senescence and storage. Biomass from transgenic lines exhibited improved saccharification efficiency relative to WT control plants. We conclude that the expression of hyperthermophilic enzymes in plants is a promising approach for combining pretreatment and enzymatic hydrolysis processes in lignocellulosic digestion. This study provides a valid foundation for further studies involving in planta co-expression of core and accessory lignocellulose-digesting enzymes.

  9. Efficient sugar release by the cellulose solvent-based lignocellulose fractionation technology and enzymatic cellulose hydrolysis.

    PubMed

    Moxley, Geoffrey; Zhu, Zhiguang; Zhang, Y-H Percival

    2008-09-10

    Efficient liberation of fermentable soluble sugars from lignocellulosic biomass waste not only decreases solid waste handling but also produces value-added biofuels and biobased products. Industrial hemp, a special economic crop, is cultivated for its high-quality fibers and high-value seed oil, but its hollow stalk cords (hurds) are a cellulosic waste. The cellulose-solvent-based lignocellulose fractionation (CSLF) technology has been developed to separate lignocellulose components under modest reaction conditions (Zhang, Y.-H. P.; Ding, S.-Y.; Mielenz, J. R.; Elander, R.; Laser, M.; Himmel, M.; McMillan, J. D.; Lynd, L. R. Biotechnol. Bioeng. 2007, 97 (2), 214- 223). Three pretreatment conditions (acid concentration, reaction temperature, and reaction time) were investigated to treat industrial hemp hurds for a maximal sugar release: a combinatorial result of a maximal retention of solid cellulose and a maximal enzymatic cellulose hydrolysis. At the best treatment condition (84.0% H3PO4 at 50 degrees C for 60 min), the glucan digestibility was 96% at hour 24 at a cellulase loading of 15 filter paper units of cellulase per gram of glucan. The scanning electron microscopic images were presented for the CSLF-pretreated biomass for the first time, suggesting that CSLF can completely destruct the plant cell-wall structure, in a good agreement with the highest enzymatic cellulose digestibility and fastest hydrolysis rate. It was found that phosphoric acid only above a critical concentration (83%) with a sufficient reaction time can efficiently disrupt recalcitrant lignocellulose structures.

  10. Optimization of dilute sulfuric acid pretreatment and enzymatic saccharification of corn stover for efficient ethanol production

    USDA-ARS?s Scientific Manuscript database

    Dilute acid pretreatment is a promising pretreatment technology for conversion of lignocellulosic biomass to fuel ethanol. Corn stover (supplied by a local farmer) used in this study contained 37.0±0.4% cellulose, 31.3±0.6% hemicelluloses, and 17.8±0.2% lignin. Generation of fermentable sugars from ...

  11. Sulfite pretreatment (SPORL) for robust enzymatic saccharification of spruce and red pine

    Treesearch

    J.Y. Zhu; X.J. Pan; G.S. Wang; R. Gleisner

    2009-01-01

    This study established a novel process using sulfite pretreatment to overcome recalcitrance of lignocellulose (SPORL) for robust and efficient bioconversion of softwoods. The process consists of sulfite treatment of wood chips under acidic conditions followed by mechanical size reduction using disk refining. The results indicated that after the SPORL pretreatment of...

  12. Evaluation of various fungal pretreatment of switchgrass for enhanced saccharification and simultaneous enzyme production

    USDA-ARS?s Scientific Manuscript database

    During fungal pretreatment of lignocellulosic biomass for bioethanol production, the treatment effectiveness may vary with different fungal strains in regard to biomass loss, sugar yield, enzyme loading, and co-product yield. In this study, 25 different fungal strains were screened for pretreatment ...

  13. Bendamustine in heavily pre-treated multiple myeloma patients: Results of a retrospective analysis from the Korean Multiple Myeloma Working Party

    PubMed Central

    Kim, Seok Jin; Bang, Soo-Mee; Choi, Yoon Seok; Jo, Deog-Yeon; Kim, Jin Seok; Lee, Hyewon; Eom, Hyeon Seok; Yoon, Dok Hyun; Suh, Cheolwon; Lee, Je-Jung; Hong, Junshik; Lee, Jae Hoon; Koh, Youngil; Kim, Kihyun

    2016-01-01

    Background Bendamustine may be a potential treatment option for patients with myeloma, but little is known about the utility of bendamustine as a salvage treatment, especially in Asian patients. Methods We performed a multicenter retrospective study of patients with relapsed or refractory myeloma who received bendamustine and prednisone. Results The records of 65 heavily pre-treated patients, who had undergone bortezomib and lenalidomide treatment (median number of previous treatments: 5), were analyzed. The median time from diagnosis to bendamustine treatment was 3.8 years, and the median patient age was 63 years (range, 38‒77 yr). The responses to the last treatment before bendamustine were refractory disease (N=52, 80%) or disease progression from partial response (N=13, 20%). Twenty-three patients responded to the treatment, with an overall response rate of 35% (23/65), and the median number of bendamustine treatment cycles was two (range, 1‒5 cycles). The median overall survival after bendamustine treatment was 5.5 months and the overall survival rate in responders to bendamustine was significantly better than that in non-responders (P=0.036). Conclusion Bendamustine may be a potential salvage treatment to extend survival in a select group of heavily pre-treated patients with relapsed or refractory myeloma. PMID:27722131

  14. New Aldehyde Reductase Genes of Saccharomyces cerevisiae Contribute In Situ Detoxification of Lignocellulose-to-Ethanol Conversion Inhibitiors

    USDA-ARS?s Scientific Manuscript database

    Furfural and 5-hydroxymethylfurfural (HMF) are inhibitory compounds commonly encountered during lignocellulose-to-ethanol conversion for cleaner transportation fuels. It is possible to in situ detoxify the aldehyde inhibitors by tolerant ethanologenic yeast strains. Multiple gene-mediated reductio...

  15. Fuel ethanol production from alkaline peroxide pretreated corn stover

    USDA-ARS?s Scientific Manuscript database

    Corn stover (CS) has the potential to serve as an abundant low-cost feedstock for production of fuel ethanol. Due to heterogeneous complexity and recalcitrance of lignocellulosic feedstocks, pretreatment is required to break the lignin seal and/or disrupt the structure of crystalline cellulose to in...

  16. Cellulosic Biomass Pretreatment and Sugar Yields as a Function of Biomass Particle Size

    PubMed Central

    Stavila, Vitalie; Knierim, Bernhard; George, Anthe; Auer, Manfred; Adams, Paul D.; Hadi, Masood Z.

    2014-01-01

    Three lignocellulosic pretreatment techniques (ammonia fiber expansion, dilute acid and ionic liquid) are compared with respect to saccharification efficiency, particle size and biomass composition. In particular, the effects of switchgrass particle size (32–200) on each pretreatment regime are examined. Physical properties of untreated and pretreated samples are characterized using crystallinity, surface accessibility measurements and scanning electron microscopy (SEM) imaging. At every particle size tested, ionic liquid (IL) pretreatment results in greater cell wall disruption, reduced crystallinity, increased accessible surface area, and higher saccharification efficiencies compared with dilute acid and AFEX pretreatments. The advantages of using IL pretreatment are greatest at larger particle sizes (>75 µm). PMID:24971883

  17. Leveraging Genetic-Background Effects in Saccharomyces cerevisiae To Improve Lignocellulosic Hydrolysate Tolerance

    PubMed Central

    Sardi, Maria; Rovinskiy, Nikolay; Zhang, Yaoping

    2016-01-01

    ABSTRACT A major obstacle to sustainable lignocellulosic biofuel production is microbe inhibition by the combinatorial stresses in pretreated plant hydrolysate. Chemical biomass pretreatment releases a suite of toxins that interact with other stressors, including high osmolarity and temperature, which together can have poorly understood synergistic effects on cells. Improving tolerance in industrial strains has been hindered, in part because the mechanisms of tolerance reported in the literature often fail to recapitulate in other strain backgrounds. Here, we explored and then exploited variations in stress tolerance, toxin-induced transcriptomic responses, and fitness effects of gene overexpression in different Saccharomyces cerevisiae (yeast) strains to identify genes and processes linked to tolerance of hydrolysate stressors. Using six different S. cerevisiae strains that together maximized phenotypic and genetic diversity, first we explored transcriptomic differences between resistant and sensitive strains to identify common and strain-specific responses. This comparative analysis implicated primary cellular targets of hydrolysate toxins, secondary effects of defective defense strategies, and mechanisms of tolerance. Dissecting the responses to individual hydrolysate components across strains pointed to synergistic interactions between osmolarity, pH, hydrolysate toxins, and nutrient composition. By characterizing the effects of high-copy gene overexpression in three different strains, we revealed the breadth of the background-specific effects of gene fitness contributions in synthetic hydrolysate. Our approach identified new genes for engineering improved stress tolerance in diverse strains while illuminating the effects of genetic background on molecular mechanisms. IMPORTANCE Recent studies on natural variation within Saccharomyces cerevisiae have uncovered substantial phenotypic diversity. Here, we took advantage of this diversity, using it as a tool to

  18. Leveraging Genetic-Background Effects in Saccharomyces cerevisiae To Improve Lignocellulosic Hydrolysate Tolerance.

    PubMed

    Sardi, Maria; Rovinskiy, Nikolay; Zhang, Yaoping; Gasch, Audrey P

    2016-10-01

    A major obstacle to sustainable lignocellulosic biofuel production is microbe inhibition by the combinatorial stresses in pretreated plant hydrolysate. Chemical biomass pretreatment releases a suite of toxins that interact with other stressors, including high osmolarity and temperature, which together can have poorly understood synergistic effects on cells. Improving tolerance in industrial strains has been hindered, in part because the mechanisms of tolerance reported in the literature often fail to recapitulate in other strain backgrounds. Here, we explored and then exploited variations in stress tolerance, toxin-induced transcriptomic responses, and fitness effects of gene overexpression in different Saccharomyces cerevisiae (yeast) strains to identify genes and processes linked to tolerance of hydrolysate stressors. Using six different S. cerevisiae strains that together maximized phenotypic and genetic diversity, first we explored transcriptomic differences between resistant and sensitive strains to identify common and strain-specific responses. This comparative analysis implicated primary cellular targets of hydrolysate toxins, secondary effects of defective defense strategies, and mechanisms of tolerance. Dissecting the responses to individual hydrolysate components across strains pointed to synergistic interactions between osmolarity, pH, hydrolysate toxins, and nutrient composition. By characterizing the effects of high-copy gene overexpression in three different strains, we revealed the breadth of the background-specific effects of gene fitness contributions in synthetic hydrolysate. Our approach identified new genes for engineering improved stress tolerance in diverse strains while illuminating the effects of genetic background on molecular mechanisms. Recent studies on natural variation within Saccharomyces cerevisiae have uncovered substantial phenotypic diversity. Here, we took advantage of this diversity, using it as a tool to infer the effects of

  19. Lignocellulose Degradation Mechanisms Across the Tree of Life

    DOE PAGES

    Cragg, Simon M.; Beckham, Gregg T.; Bruce, Neil C.; ...

    2015-11-14

    Organisms use diverse mechanisms involving multiple complementary enzymes, particularly glycoside hydrolases (GHs), to deconstruct lignocellulose. Lytic polysaccharide monooxygenases (LPMOs) produced by bacteria and fungi facilitate deconstruction as does the Fenton chemistry of brown-rot fungi. Lignin depolymerisation is achieved by white-rot fungi and certain bacteria, using peroxidases and laccases. Meta-omics is now revealing the complexity of prokaryotic degradative activity in lignocellulose-rich environments. Protists from termite guts and some oomycetes produce multiple lignocellulolytic enzymes. We found that the Lignocellulose-consuming animals secrete some GHs, but most harbour a diverse enzyme-secreting gut microflora in a mutualism that is particularly complex in termites. Shipworms however,more » house GH-secreting and LPMO-secreting bacteria separate from the site of digestion and the isopod Limnoria relies on endogenous enzymes alone. Moreover, the omics revolution is identifying many novel enzymes and paradigms for biomass deconstruction, but more emphasis on function is required, particularly for enzyme cocktails, in which LPMOs may play an important role.« less

  20. Lignocellulose degradation mechanisms across the Tree of Life.

    PubMed

    Cragg, Simon M; Beckham, Gregg T; Bruce, Neil C; Bugg, Timothy D H; Distel, Daniel L; Dupree, Paul; Etxabe, Amaia Green; Goodell, Barry S; Jellison, Jody; McGeehan, John E; McQueen-Mason, Simon J; Schnorr, Kirk; Walton, Paul H; Watts, Joy E M; Zimmer, Martin

    2015-12-01

    Organisms use diverse mechanisms involving multiple complementary enzymes, particularly glycoside hydrolases (GHs), to deconstruct lignocellulose. Lytic polysaccharide monooxygenases (LPMOs) produced by bacteria and fungi facilitate deconstruction as does the Fenton chemistry of brown-rot fungi. Lignin depolymerisation is achieved by white-rot fungi and certain bacteria, using peroxidases and laccases. Meta-omics is now revealing the complexity of prokaryotic degradative activity in lignocellulose-rich environments. Protists from termite guts and some oomycetes produce multiple lignocellulolytic enzymes. Lignocellulose-consuming animals secrete some GHs, but most harbour a diverse enzyme-secreting gut microflora in a mutualism that is particularly complex in termites. Shipworms however, house GH-secreting and LPMO-secreting bacteria separate from the site of digestion and the isopod Limnoria relies on endogenous enzymes alone. The omics revolution is identifying many novel enzymes and paradigms for biomass deconstruction, but more emphasis on function is required, particularly for enzyme cocktails, in which LPMOs may play an important role. Copyright © 2015 The Authors. Published by Elsevier Ltd.. All rights reserved.

  1. Identifying inhibitory effects of lignocellulosic by-products on growth of lactic acid producing micro-organisms using a rapid small-scale screening method.

    PubMed

    van der Pol, Edwin C; Vaessen, Evelien; Weusthuis, Ruud A; Eggink, Gerrit

    2016-06-01

    Sugars obtained from pretreated lignocellulose are interesting as substrate for the production of lactic acid in fermentation processes. However, by-products formed during pretreatment of lignocellulose can inhibit microbial growth. In this study, a small-scale rapid screening method was used to identify inhibitory effects of single and combined by-products on growth of lactic acid producing micro-organisms. The small-scale screening was performed in 48-well plates using 5 bacterial species and 12 by-products. Large differences were observed in inhibitory effects of by-products between different species. Predictions can be made for growth behaviour of different micro-organisms on acid pretreated or alkaline pretreated bagasse substrates using data from the small-scale screening. Both individual and combined inhibition effects were shown to be important parameters to predict growth. Synergy between coumaric acid, formic acid and acetic acid is a key inhibitory parameter in alkaline pretreated lignocellulose, while furfural is a key inhibitor in acid pretreated lignocellulose. Copyright © 2016 Elsevier Ltd. All rights reserved.

  2. Deconstruction of Lignocellulose into Soluble Sugars by Native and Designer Cellulosomes

    PubMed Central

    Moraïs, Sarah; Morag, Ely; Barak, Yoav; Goldman, Dan; Hadar, Yitzhak; Lamed, Raphael; Shoham, Yuval; Wilson, David B.; Bayer, Edward A.

    2012-01-01

    ABSTRACT Lignocellulosic biomass, the most abundant polymer on Earth, is typically composed of three major constituents: cellulose, hemicellulose, and lignin. The crystallinity of cellulose, hydrophobicity of lignin, and encapsulation of cellulose by the lignin-hemicellulose matrix are three major factors that contribute to the observed recalcitrance of lignocellulose. By means of designer cellulosome technology, we can overcome the recalcitrant properties of lignocellulosic substrates and thus increase the level of native enzymatic degradation. In this context, we have integrated six dockerin-bearing cellulases and xylanases from the highly cellulolytic bacterium, Thermobifida fusca, into a chimeric scaffoldin engineered to bear a cellulose-binding module and the appropriate matching cohesin modules. The resultant hexavalent designer cellulosome represents the most elaborate artificial enzyme composite yet constructed, and the fully functional complex achieved enhanced levels (up to 1.6-fold) of degradation of untreated wheat straw compared to those of the wild-type free enzymes. The action of these designer cellulosomes on wheat straw was 33 to 42% as efficient as the natural cellulosomes of Clostridium thermocellum. In contrast, the reduction of substrate complexity by chemical or biological pretreatment of the substrate removed the advantage of the designer cellulosomes, as the free enzymes displayed higher levels of activity, indicating that enzyme proximity between these selected enzymes was less significant on pretreated substrates. Pretreatment of the substrate caused an increase in activity for all the systems, and the native cellulosome completely converted the substrate into soluble saccharides. PMID:23232718

  3. Saccharification of recalcitrant biomass and integration options for lignocellulosic sugars from Catchlight Energy’s sugar process (CLE Sugar)

    PubMed Central

    2013-01-01

    Background Woody biomass is one of the most abundant biomass feedstocks, besides agriculture residuals in the United States. The sustainable harvest residuals and thinnings alone are estimated at about 75 million tons/year. These forest residuals and thinnings could produce the equivalent of 5 billion gallons of lignocellulosic ethanol annually. Softwood biomass is the most recalcitrant biomass in pretreatment before an enzymatic hydrolysis. To utilize the most recalcitrant lignocellulosic materials, an efficient, industrially scalable and cost effective pretreatment method is needed. Results Obtaining a high yield of sugar from recalcitrant biomass generally requires a high severity of pretreatment with aggressive chemistry, followed by extensive conditioning, and large doses of enzymes. Catchlight Energy’s Sugar process, CLE Sugar, uses a low intensity, high throughput variation of bisulfite pulping to pretreat recalcitrant biomass, such as softwood forest residuals. By leveraging well-proven bisulfite technology and the rapid progress of enzyme suppliers, CLE Sugar can achieve a high yield of total biomass carbohydrate conversion to monomeric lignocellulosic sugars. For example, 85.8% of biomass carbohydrates are saccharified for un-debarked Loblolly pine chips (softwood), and 94.0% for debarked maple chips (hardwood). Furan compound formation was 1.29% of biomass feedstock for Loblolly pine and 1.10% for maple. At 17% solids hydrolysis of pretreated softwood, an enzyme dose of 0.075 g Sigma enzyme mixture/g dry pretreated (unwashed) biomass was needed to achieve 8.1% total sugar titer in the hydrolysate and an overall prehydrolysate liquor plus enzymatic hydrolysis conversion yield of 76.6%. At a much lower enzyme dosage of 0.044 g CTec2 enzyme product/g dry (unwashed) pretreated softwood, hydrolysis at 17% solids achieved 9.2% total sugar titer in the hydrolysate with an overall sugar yield of 85.0% in the combined prehydrolysate liquor and enzymatic

  4. Comparison of Ultrasonic and CO2 Laser Pretreatment Methods on Enzyme Digestibility of Corn Stover

    PubMed Central

    Tian, Shuang-Qi; Wang, Zhen-Yu; Fan, Zi-Luan; Zuo, Li-Li

    2012-01-01

    To decrease the cost of bioethanol production, biomass recalcitrance needs to be overcome so that the conversion of biomass to bioethanol becomes more efficient. CO2 laser irradiation can disrupt the lignocellulosic physical structure and reduce the average size of fiber. Analyses with Fourier transform infrared spectroscopy, specific surface area, and the microstructure of corn stover were used to elucidate the enhancement mechanism of the pretreatment process by CO2 laser irradiation. The present work demonstrated that the CO2 laser had potential to enhance the bioconversion efficiency of lignocellulosic waste to renewable bioethanol. The saccharification rate of the CO2 laser pretreatment was significantly higher than ultrasonic pretreatment, and reached 27.75% which was 1.34-fold of that of ultrasonic pretreatment. The results showed the impact of CO2 laser pretreatment on corn stover to be more effective than ultrasonic pretreatment. PMID:22605970

  5. High titer ethanol production from SPORL-pretreated lodgepole pine by simultaneous enzymatic saccharification and combined fermentation

    Treesearch

    T.Q. Lan; Roland Gleisner; J.Y. Zhu; Bruce S. Dien; Ronald E. Hector

    2012-01-01

    Lodgepole wood chips were pretreated by sulfite pretreatment to overcome recalcitrance of lignocelluloses (SPORL) at 25% solids loading and 180 °C for 20 min with sulfuric acid and sodium bisulfite charges of 2.2 and 8 wt/wt% on an oven-dry wood basis, respectively. The pretreated wood chips were disk-milled with pretreatment spent liquor and water, and the...

  6. Enzymatic hydrolysis and characterization of lignocellulosic biomass exposed to electron beam irradiation.

    PubMed

    Karthika, K; Arun, A B; Rekha, P D

    2012-10-01

    Pretreatment of lignocellulosic biomass has been taken up as a global challenge as it comprises a large renewable source of fermentable sugars. In this study, effect of electron beam irradiation (EBI) on a hybrid grass variety investigated as a biomass pretreatment method. Dry biomass samples after characterization were exposed to EBI doses of 0, 75, 150 and 250 kGy. The pretreated biomass samples were enzymatically hydrolyzed using Trichoderma reesei ATCC 26921 cellulase for 144 h. The enzyme loadings were 15 and 30 FPU/g of biomass. The structural changes and degree of crystallinity of the pretreated biomass were studied by FTIR, XRD and SEM analyses. The lignocellulosic biomass sample showed 12.0% extractives, 36.9% cellulose, 28.4% hemicellulose, 11.9% lignin and 8.6% ash. Significant improvements in the reducing sugar and glucose yields were observed in the hydrolysate of EBI pretreated biomass compared to the control. In 250 kGy exposed samples 79% of the final reducing sugar yield was released within 48 h of hydrolysis at an enzyme loading rate of 30FPU/g of biomass. The IR crystallinity index calculated from the FTIR data and degree of crystallinity (XRD) decreased in the EBI treated samples. A significant negative correlation was observed between degree of crystallinity and the glucose yield from enzymatic hydrolysis.

  7. SO2 -catalyzed steam explosion: the effects of different severity on digestibility, accessibility, and crystallinity of lignocellulosic biomass.

    PubMed

    Kang, Yuzhi; Bansal, Prabuddha; Realff, Matthew J; Bommarius, Andreas S

    2013-01-01

    Lignocellulosic biomass is the most promising feedstock for biofuels production. To enhance the efficiency of enzymatic hydrolysis, lignocellulosics needs to be pretreated to lower their recalcitrance. SO(2) -catalyzed steam explosion is an efficient and relatively cost-efficient pretreatment method for softwood. This work investigates the effects of steam explosion severity on the digestibility, accessibility, and crystallinity of Loblolly pine. Higher severity was found to increase the accessibility of the feedstock while also promoting nonselective degradation of carbohydrates. The adsorption behavior of Celluclast® enzymes on steam-exploded Loblolly pine (SELP) can be described by a Langmuir isotherm. Cellulose crystallinity was found to first increase and then decrease with increasing pretreatment severity. A linear relationship between initial hydrolysis rates and crystallinity index (CrI) of pretreated Loblolly pine was found; moreover, a strong correlation between X-ray diffraction intensities and initial rates was confirmed. The findings demonstrate the significance of CrI in enzymatic hydrolysis of pretreated lignocellulosic biomass.

  8. Breakdown of Cell Wall Nanostructure in Dilute Acid Pretreated Biomass

    SciTech Connect

    Pingali, Sai Venkatesh; Urban, Volker S; Heller, William T; McGaughey, Joseph; O'Neill, Hugh Michael; Foston, Marcus B; Myles, Dean A A; Ragauskas, Arthur J; Evans, Barbara R

    2010-01-01

    The generation of bioethanol from lignocellulosic biomass holds great promise for renewable and clean energy production. A better understanding of the complex mechanisms of lignocellulose breakdown during various pretreatment methods is needed to realize this potential in a cost and energy efficient way. Here, we use small-angle neutron scattering (SANS) to characterize morphological changes in switchgrass lignocellulose across molecular to sub-micron length scales resulting from the industrially-relevant dilute acid pretreatment method. Our results demonstrate that dilute acid pretreatment increases the cross-sectional radius of the crystalline cellulose fibril. This change is accompanied by removal of hemicellulose and the formation of Rg ~ 135 lignin aggregates. The structural signature of smooth cell wall surfaces is observed at length scales larger than 1000 , and it remains remarkably invariable during pretreatment. This study elucidates the interplay of the different biomolecular components in the break down process of switchgrass by dilute acid pretreatment. The results are important for the development of efficient strategies of biomass to biofuel conversion.

  9. Radium-223 outcomes after multiple lines of metastatic castration-resistant prostate cancer therapy in clinical practice: implication of pre-treatment spinal epidural disease.

    PubMed

    Spratt, D E; Osborne, J R; Zumsteg, Z S; Rebeiz, K; Leeman, J; Rivera, A; Morris, M J; Zelefsky, M J

    2016-09-01

    Magnetic resonance imaging (MRI) is not routinely performed before initiating radium-223 to document spinal epidural disease. However, radium-223 decays to form α-particles with very short path lengths that may not reach the epidural space. Herein, we investigate the impact of baseline spinal epidural disease on metastatic castration-resistant prostate cancer (mCRPC) patients treated with radium-223. Between October 2013 to December 2014, 41 consecutive mCRPC patients at a large tertiary cancer center were prescribed radium-223 as part of standard of care. 29% of patients had pre-treatment epidural disease (posMRI), 27% had no epidural disease (negMRI), and 44% did not have a baseline MRI (noMRI). All patients had post-treatment spinal imaging. Actuarial survival times were calculated for overall survival (OS), spinal axis radiographic progression-free survival (spinePFS) and epidural progression-free survival (epiPFS) from time of first radium-223 treatment. For patients with posMRI (n=12), noMRI (n=18) and negMRI (n=11) cumulative rates of development or worsening of epidural disease and/or high-grade cord compression at time of last follow-up were 83%, 44% and 9%, respectively (P=0.001). For the posMRI, noMRI and negMRI groups the median OS was 6.3 months, 12.6 months and not reached (P=0.01), the median spinePFS was 3.2 months, 4.8 months and not reached (P=0.01), and the median epiPFS was 3.2 months, 10.4 months and not reached (P=0.001). Completing less than six cycles of radium-223 was significantly associated with worse OS (P<0.0001), spinePFS (P=0.007) and epiPFS (P=0.01). Greater than or equal to twenty osseous lesions pre-treatment was significantly associated with worse spinePFS (P=0.001) and epiPFS (P=0.03). In a heavily pre-treated small cohort, patients with baseline epidural disease frequently progressed to spinal cord compression and early cessation of radium-223 therapy. Studies are needed to determine the optimal timing of radium-223 with other

  10. Enzymatic lignocellulose hydrolysis: Improved cellulase productivity by insoluble solids recycling.

    PubMed

    Weiss, Noah; Börjesson, Johan; Pedersen, Lars Saaby; Meyer, Anne S

    2013-01-21

    It is necessary to develop efficient methods to produce renewable fuels from lignocellulosic biomass. One of the main challenges to the industrialization of lignocellulose conversion processes is the large amount of cellulase enzymes used for the hydrolysis of cellulose. One method for decreasing the amount of enzyme used is to recycle the enzymes. In this study, the recycle of enzymes associated with the insoluble solid fraction after the enzymatic hydrolysis of cellulose was investigated for pretreated corn stover under a variety of recycling conditions. It was found that a significant amount of cellulase activity could be recovered by recycling the insoluble biomass fraction, and the enzyme dosage could be decreased by 30% to achieve the same glucose yields under the most favorable conditions. Enzyme productivity (g glucose produced/g enzyme applied) increased between 30 and 50% by the recycling, depending on the reaction conditions. While increasing the amount of solids recycled increased process performance, the methods applicability was limited by its positive correlation with increasing total solids concentrations, reaction volumes, and lignin content of the insoluble residue. However, increasing amounts of lignin rich residue during the recycle did not negatively impact glucose yields. To take advantage of this effect, the amount of solids recycled should be maximized, based on a given processes ability to deal with higher solids concentrations and volumes. Recycling of enzymes by recycling the insoluble solids fraction was thus shown to be an effective method to decrease enzyme usage, and research should be continued for its industrial application.

  11. Microwave pretreatment of switchgrass for bioethanol production

    NASA Astrophysics Data System (ADS)

    Keshwani, Deepak Radhakrishin

    Lignocellulosic materials are promising alternative feedstocks for bioethanol production. These materials include agricultural residues, cellulosic waste such as newsprint and office paper, logging residues, and herbaceous and woody crops. However, the recalcitrant nature of lignocellulosic biomass necessitates a pretreatment step to improve the yield of fermentable sugars. The overall goal of this dissertation is to expand the current state of knowledge on microwave-based pretreatment of lignocellulosic biomass. Existing research on bioenergy and value-added applications of switchgrass is reviewed in Chapter 2. Switchgrass is an herbaceous energy crop native to North America and has high biomass productivity, potentially low requirements for agricultural inputs and positive environmental impacts. Based on results from test plots, yields in excess of 20 Mg/ha have been reported. Environmental benefits associated with switchgrass include the potential for carbon sequestration, nutrient recovery from run-off, soil remediation and provision of habitats for grassland birds. Published research on pretreatment of switchgrass reported glucose yields ranging from 70-90% and xylose yields ranging from 70-100% after hydrolysis and ethanol yields ranging from 72-92% after fermentation. Other potential value-added uses of switchgrass include gasification, bio-oil production, newsprint production and fiber reinforcement in thermoplastic composites. Research on microwave-based pretreatment of switchgrass and coastal bermudagrass is presented in Chapter 3. Pretreatments were carried out by immersing the biomass in dilute chemical reagents and exposing the slurry to microwave radiation at 250 watts for residence times ranging from 5 to 20 minutes. Preliminary experiments identified alkalis as suitable chemical reagents for microwave-based pretreatment. An evaluation of different alkalis identified sodium hydroxide as the most effective alkali reagent. Under optimum pretreatment

  12. Comprehensive utilization of glycerol from sugarcane bagasse pretreatment to fermentation.

    PubMed

    Jiang, Liqun; Zheng, Anqing; Zhao, Zengli; He, Fang; Li, Haibin

    2015-11-01

    In this study, the effects of glycerol pretreatment on subsequent glycerol fermentation and biomass fast pyrolysis were investigated. The liquid fraction from the pretreatment process was evaluated to be feasible for fermentation by Paenibacillus polymyxa and could be an economic substrate. The pretreated biomass was further utilized to obtain levoglucosan by fast pyrolysis. The pretreated sugarcane bagasse exhibited significantly higher levoglucosan yield (47.70%) than that of un-pretreated sample (11.25%). The promotion could likely be attributed to the effective removal of alkali and alkaline earth metals by glycerol pretreatment. This research developed an economically viable manufacturing paradigm to utilize glycerol comprehensively and enhance the formation of levoglucosan effectively from lignocellulose.

  13. Activation of lignocellulosic biomass for higher sugar yields using aqueous ionic liquid at low severity process conditions.

    PubMed

    Parthasarathi, Ramakrishnan; Sun, Jian; Dutta, Tanmoy; Sun, Ning; Pattathil, Sivakumar; Murthy Konda, N V S N; Peralta, Angelo Gabriel; Simmons, Blake A; Singh, Seema

    2016-01-01

    Concerns around greenhouse gas emissions necessitate the development of sustainable processes for the production of chemicals, materials, and fuels from alternative renewable sources. The lignocellulosic plant cell walls are one of the most abundant sources of carbon for renewable bioenergy production. Certain ionic liquids (ILs) are very effective at disrupting the plant cell walls of lignocellulose, and generate a substrate that is effectively hydrolyzed into fermentable sugars. Conventional ILs are relatively expensive in terms of purchase price, and the most effective imidazolium-based ILs also require energy intensive processing conditions (>140 °C, 3 h) to release >90 % fermentable sugar yields after saccharification. We have developed a highly effective pretreatment technology utilizing the relatively inexpensive IL comprised tetrabutylammonium [TBA](+) and hydroxide [OH](-) ions that generate high glucose yields (~95 %) after pretreatment at very mild processing conditions (50 °C). The efficiency of [TBA][OH] pretreatment of lignocellulose was further studied by analyzing chemical composition, powder X-ray diffraction for cellulose structure, NMR and SEC for lignin dissolution/depolymerization, and glycome profiling for cell wall modifications. Glycome profiling experiments and computational results indicate that removal of the noncellulosic polysaccharides occurs due to the ionic mobility of [TBA][OH] and is the key factor in determining pretreatment efficiency. Process modeling and energy demand analysis suggests that this [TBA][OH] pretreatment could potentially reduce the energy required in the pretreatment unit operation by more than 75 %. By leveraging the benefits of ILs that are effective at very mild processing conditions, such as [TBA][OH], lignocellulosic biomass can be pretreated at similar efficiency as top performing conventional ILs, such as 1-ethyl-3-methylimidazolium acetate [C2C1Im][OAc], but at much lower temperatures, and with

  14. Epidemic based modeling of enzymatic hydrolysis of lignocellulosic biomass.

    PubMed

    Tai, Chao; Arellano, Maria G; Keshwani, Deepak R

    2014-01-01

    An epidemic based model was developed to describe the enzymatic hydrolysis of a lignocellulosic biomass, dilute sulfuric acid pretreated corn stover. The process of substrate getting adsorbed and digested by enzyme was simulated as susceptibles getting infected by viruses and becoming removed and recovered. This model simplified the dynamic enzyme "infection" process and the catalysis of cellulose into a two-parameter controlled, enzyme behavior guided mechanism. Furthermore, the model incorporates the adsorption block by lignin and inhibition effects on cellulose catalysis. The model satisfactorily predicted the enzyme adsorption and hydrolysis, negative role of lignin, and inhibition effects over hydrolysis for a broad range of substrate and enzyme loadings. Sensitivity analysis was performed to evaluate the incorporation of lignin and other inhibition effects. Our model will be a useful tool for evaluating the effects of parameters during hydrolysis and guide a design strategy for continuous hydrolysis and the associated process control.

  15. Lignocellulosic waste valorisation strategy through enzyme and biogas production.

    PubMed

    Wyman, Valentina; Henríquez, Josefa; Palma, Carolyn; Carvajal, Andrea

    2017-09-08

    Lignocellulosic wastes are generally pre-treated to facilitate the hydrolysis stage during the anaerobic digestion process. A process consisting of solid state fermentation carried out by white rot fungi and anaerobic digestion was evaluated on corn stover to produce ligninolytic enzymes and biogas. The enzyme production was quantified every 3d for a month at 30°C, and three fungal strains and two particle sizes of waste were compared. Of the main outcomes, Pleurotus eryngii produced the highest laccase enzyme activity compared with Pleurotus ostreatus and Trametes versicolor. Furthermore, this activity was improved by 16% when copper was used as an enzyme inducer. On the other hand, most of the conditions studied showed a decrease in maximum biogas production compared with untreated waste, the addition of copper decreased biogas production by 20%. Despite the above, Pleurotus eryngii showed promising results allowing a 19% increase of biogas production and high enzyme production values. Copyright © 2017 Elsevier Ltd. All rights reserved.

  16. The fate of lignin during hydrothermal pretreatment

    PubMed Central

    2013-01-01

    Background Effective enzymatic hydrolysis of lignocellulosic biomass benefits from lignin removal, relocation, and/or modification during hydrothermal pretreatment. Phase transition, depolymerization/repolymerization, and solubility effects may all influence these lignin changes. To better understand how lignin is altered, Populus trichocarpa x P. deltoides wood samples and cellulolytic enzyme lignin (CEL) isolated from P. trichocarpa x P. deltoides were subjected to batch and flowthrough pretreatments. The residual solids and liquid hydrolysate were characterized by gel permeation chromatography, heteronuclear single quantum coherence NMR, compositional analysis, and gas chromatography–mass spectrometry. Results Changes in the structure of the solids recovered after the pretreatment of CEL and the production of aromatic monomers point strongly to depolymerization and condensation being primary mechanisms for lignin extraction and redeposition. The differences in lignin removal and phenolic compound production from native P. trichocarpa x P. deltoides and CEL suggested that lignin-carbohydrate interactions increased lignin extraction and the extractability of syringyl groups relative to guaiacyl groups. Conclusions These insights into delignification during hydrothermal pretreatment point to desirable pretreatment strategies and plant modifications. Because depolymerization followed by repolymerization appears to be the dominant mode of lignin modification, limiting the residence time of depolymerized lignin moieties in the bulk liquid phase should reduce lignin content in pretreated biomass. In addition, the increase in lignin removal in the presence of polysaccharides suggests that increasing lignin-carbohydrate cross-links in biomass would increase delignification during pretreatment. PMID:23902789

  17. Examination of lignocellulosic fibers for chemical, thermal, and separations properties: Addressing thermo-chemical stability issues

    NASA Astrophysics Data System (ADS)

    Johnson, Carter David

    Natural fiber-plastic composites incorporate thermoplastic resins with fibrous plant-based materials, sometimes referred to as biomass. Pine wood mill waste has been the traditional source of natural fibrous feedstock. In anticipation of a waste wood shortage other fibrous biomass materials are being investigated as potential supplements or replacements. Perennial grasses, agricultural wastes, and woody biomass are among the potential source materials. As these feedstocks share the basic chemical building blocks; cellulose, hemicellulose, and lignin, they are collectively called lignocellulosics. Initial investigation of a number of lignocellulosic materials, applied to fiber-plastic composite processing and material testing, resulted in varied results, particularly response to processing conditions. Less thermally stable lignocellulosic filler materials were physically changed in observable ways: darkened color and odor. The effect of biomass materials' chemical composition on thermal stability was investigated an experiment involving determination of the chemical composition of seven lignocellulosics: corn hull, corn stover, fescue, pine, soy hull, soy stover, and switchgrass. These materials were also evaluated for thermal stability by thermogravimetric analysis. The results of these determinations indicated that both chemical composition and pretreatment of lignocellulosic materials can have an effect on their thermal stability. A second study was performed to investigate what effect different pretreatment systems have on hybrid poplar, pine, and switchgrass. These materials were treated with hot water, ethanol, and a 2:1 benzene/ethanol mixture for extraction times of: 1, 3, 6, 12, and 24 hours. This factorial experiment demonstrated that both extraction time and medium have an effect on the weight percent of extractives removed from all three material types. The extracted materials generated in the above study were then subjected to an evaluation of thermal

  18. Pervaporation of ethanol from lignocellulosic fermentation broth.

    PubMed

    Gaykawad, Sushil S; Zha, Ying; Punt, Peter J; van Groenestijn, Johan W; van der Wielen, Luuk A M; Straathof, Adrie J J

    2013-02-01

    Pervaporation can be applied in ethanol production from lignocellulosic biomass. Hydrophobic pervaporation, using a commercial PDMS membrane, was employed to concentrate the ethanol produced by fermentation of lignocellulosic hydrolysate. To our knowledge, this is the first report describing this. Pervaporation carried out with three different lignocellulosic fermentation broths reduced the membrane performance by 17-20% as compared to a base case containing only 3 wt.% ethanol in water. The membrane fouling caused by these fermentation broths was irreversible. Solutions containing model lignocellulosic components were tested during pervaporation at the same conditions. A total flux decrease of 12-15%, as compared to the base case, was observed for each component except for furfural. Catechol was found to be most fouling component whereas furfural permeated through the membrane and increased the total flux. The membrane selectivity increased in the presence of fermentation broth but remained unchanged for all selected components.

  19. Ethanol production from lignocellulosic hydrolysates using engineered Saccharomyces cerevisiae harboring xylose isomerase-based pathway.

    PubMed

    Ko, Ja Kyong; Um, Youngsoon; Woo, Han Min; Kim, Kyoung Heon; Lee, Sun-Mi

    2016-06-01

    The efficient co-fermentation of glucose and xylose is necessary for the economically feasible bioethanol production from lignocellulosic biomass. Even with xylose utilizing Saccharomyces cerevisiae, the efficiency of the lignocellulosic ethanol production remains suboptimal mainly due to the low conversion yield of xylose to ethanol. In this study, we evaluated the co-fermentation performances of SXA-R2P-E, a recently engineered isomerase-based xylose utilizing strain, in mixed sugars and in lignocellulosic hydrolysates. In a high-sugar fermentation with 70g/L of glucose and 40g/L of xylose, SXA-R2P-E produced 50g/L of ethanol with an yield of 0.43gethanol/gsugars at 72h. From dilute acid-pretreated hydrolysates of rice straw and hardwood (oak), the strain produced 18-21g/L of ethanol with among the highest yield of 0.43-0.46gethanol/gsugars ever reported. This study shows a highly promising potential of a xylose isomerase-expressing strain as an industrially relevant ethanol producer from lignocellulosic hydrolysates.

  20. Ethanol production from non-detoxified whole slurry of sulfite-pretreated empty fruit bunches at a low cellulase loading

    Treesearch

    Jinlan Cheng; Shao-Yuan Leu; J.Y. Zhu; Thomas W. Jeffries

    2014-01-01

    Sulfite pretreatment to overcome the recalcitrance of lignocelluloses (SPORL) was applied to an empty fruit bunches (EFB) for ethanol production. SPORL facilitated delignification through lignin sulfonation and dissolution of xylan to result in a highly digestible substrate. The pretreated whole slurry was enzymatically saccharified at a solids loading of 18% using a...

  1. Biological pretreatment of corn stover with Phlebia brevispora NRRL-13108 for enhanced enzymatic hydrolysis and efficient ethanol production

    USDA-ARS?s Scientific Manuscript database

    Biological pretreatment of lignocellulosic biomass by white-rot fungus can represent a low-cost and eco-friendly alternative to harsh physical, chemical, or physico-chemical pretreatment methods to facilitate enzymatic hydrolysis. In this work, solid state cultivation of corn stover with Phlebia bre...

  2. Comparison of Dilute Acid and Sulfite Pretreatment for enzymatic Saccharification of Earlywood and Latewood of Douglas Fir

    Treesearch

    Chao Zhang; Xiaochun Lei; C. Tim Scott; J.Y. Zhu; Kecheng Li

    2014-01-01

    This study applied dilute acid (DA) and sulfite pretreatment to overcome the recalcitrance of lignocelluloses (SPORL) to deconstruct earlywood and latewood cell walls of Douglas fir for fermentable sugars production through subsequent enzymatic hydrolysis. DA pretreatment removed almost all the hemicelluloses, while SPORL at initial pH=4.5 (SP-B) removed significant...

  3. Ethanol production from SPORL-pretreated lodgepole pine : preliminary evaluation of mass balance and process energy efficiency

    Treesearch

    Junyong Zhu; Wenyuan Zhu; Patricia OBryan; Bruce S. Dien; Shen Tian; Roland Gleisner; X.J. Pan

    2010-01-01

    Lodgepole pine from forest thinnings is a potential feedstock for ethanol production. In this study, lodgepole pine was converted to ethanol with a yield of 276 L per metric ton of wood or 72% of theoretical yield. The lodgepole pine chips were directly subjected to sulfite pretreatment to overcome recalcitrance of lignocellulose (SPORL) pretreatment and then disk-...

  4. Influence of Retardants to Burning Lignocellulosic Materials

    NASA Astrophysics Data System (ADS)

    Tureková, Ivana; Harangozó, Jozef; Martinka, Jozef

    2011-01-01

    The paper deals with monitoring retardant changes of lignocellulosic materials. Combustion of lignocellulosic materials and fire-technical characteristics are described. In assessing the retarding effect of salt NH4H2PO4, fire-technical characteristics as limiting oxygen index (LOI) were measured, and by using thermoanalytical TG and DSC methods. High-temperature process of cellulose degradation at various flame concentrations was studied.

  5. Effects of enzymatic hydrolysis and ultrasounds pretreatments on corn cob and vine trimming shoots for biogas production.

    PubMed

    Pérez-Rodríguez, N; García-Bernet, D; Domínguez, J M

    2016-12-01

    Due to their lignocellulosic nature, corn cob and vine trimming shoots (VTS) could be valorized by anaerobic digestion for biogas production. To enhance the digestibility of substrates, pretreatments of lignocellulosic materials are recommended. The effect of enzymatic hydrolysis, ultrasounds pretreatments (US) and the combination of both was assayed in lignocellulosic composition, methane, and biogas yields. The pretreatments leaded to a reduction in lignin and an increase in neutral detergent soluble compounds making corn cob and VTS more amendable for biogas conversion. The US were negative for biogas production from both substrates and in particular strongly detrimental for VTS. On the opposite side, the enzymatic hydrolysis was certainly beneficial increasing 59.8% and 14.6% the methane production from VTS and corn cob, respectively. The prior application of US did not potentiate (or not sufficiently) the improvement in the methane production reflected by the enzymatic hydrolysis pretreatment of VTS and corn cob. Copyright © 2016 Elsevier Ltd. All rights reserved.

  6. A review of enzymes and microbes for lignocellulosic biorefinery and the possibility of their application to consolidated bioprocessing technology.

    PubMed

    Hasunuma, Tomohisa; Okazaki, Fumiyoshi; Okai, Naoko; Hara, Kiyotaka Y; Ishii, Jun; Kondo, Akihiko

    2013-05-01

    The biorefinery manufacturing process for producing chemicals and liquid fuels from biomass is a promising approach for securing energy and resources. To establish cost-effective fermentation of lignocellulosic biomass, the consolidation of sacccharification and fermentation processes is a desirable strategy, but requires the development of microorganisms capable of cellulose/hemicellulose hydrolysis and target chemical production. Such an endeavor requires a large number of prerequisites to be realized, including engineering microbial strains with high cellulolytic activity, high product yield, productivities, and titers, ability to use many carbon sources, and resistance to toxic compounds released during the pretreatment of lignocellulosic biomass. Researchers have focused on either engineering naturally cellulolytic microorganisms to improve product-related properties or modifying non-cellulolytic organisms with high product yields to become cellulolytic. This article reviews recent advances in the development of microorganisms for the production of renewable chemicals and advanced biofuels, as well as ethanol, from lignocellulosic materials through consolidated bioprocessing.

  7. Ionic liquid-tolerant microorganisms and microbial communities for lignocellulose conversion to bioproducts.

    PubMed

    Yu, Chaowei; Simmons, Blake A; Singer, Steven W; Thelen, Michael P; VanderGheynst, Jean S

    2016-12-01

    Chemical and physical pretreatment of biomass is a critical step in the conversion of lignocellulose to biofuels and bioproducts. Ionic liquid (IL) pretreatment has attracted significant attention due to the unique ability of certain ILs to solubilize some or all components of the plant cell wall. However, these ILs inhibit not only the enzyme activities but also the growth and productivity of microorganisms used in downstream hydrolysis and fermentation processes. While pretreated biomass can be washed to remove residual IL and reduce inhibition, extensive washing is costly and not feasible in large-scale processes. IL-tolerant microorganisms and microbial communities have been discovered from environmental samples and studies begun to elucidate mechanisms of IL tolerance. The discovery of IL tolerance in environmental microbial communities and individual microbes has lead to the proposal of molecular mechanisms of resistance. In this article, we review recent progress on discovering IL-tolerant microorganisms, identifying metabolic pathways and mechanisms of tolerance, and engineering microorganisms for IL tolerance. Research in these areas will yield new approaches to overcome inhibition in lignocellulosic biomass bioconversion processes and increase opportunities for the use of ILs in biomass pretreatment.

  8. Molecular mechanisms of yeast tolerance and in situ detoxification of lignocellulose hydrolysates.

    PubMed

    Liu, Z Lewis

    2011-05-01

    Pretreatment of lignocellulose biomass for biofuel production generates inhibitory compounds that interfere with microbial growth and subsequent fermentation. Remediation of the inhibitors by current physical, chemical, and biological abatement means is economically impractical, and overcoming the inhibitory effects of lignocellulose hydrolysate poses a significant technical challenge for lower-cost cellulosic ethanol production. Development of tolerant ethanologenic yeast strains has demonstrated the potential of in situ detoxification for numerous aldehyde inhibitors derived from lignocellulose biomass pretreatment and conversion. In the last decade, significant progress has been made in understanding mechanisms of yeast tolerance for tolerant strain development. Enriched genetic backgrounds, enhanced expression, interplays, and global integration of many key genes enable yeast tolerance. Reprogrammed pathways support yeast functions to withstand the inhibitor stress, detoxify the toxic compounds, maintain energy and redox balance, and complete active metabolism for ethanol fermentation. Complex gene interactions and regulatory networks as well as co-regulation are well recognized as involved in yeast adaptation and tolerance. This review presents our current knowledge on mechanisms of the inhibitor detoxification based on molecular studies and genomic-based approaches. Our improved understanding of yeast tolerance and in situ detoxification provide insight into phenotype-genotype relationships, dissection of tolerance mechanisms, and strategies for more tolerant strain development for biofuels applications.

  9. Co-Utilization of Glucose and Xylose for Enhanced Lignocellulosic Ethanol Production with Reverse Membrane Bioreactors

    PubMed Central

    Ishola, Mofoluwake M.; Ylitervo, Päivi; Taherzadeh, Mohammad J.

    2015-01-01

    Integrated permeate channel (IPC) flat sheet membranes were examined for use as a reverse membrane bioreactor (rMBR) for lignocellulosic ethanol production. The fermenting organism, Saccharomyces cerevisiae (T0936), a genetically-modified strain with the ability to ferment xylose, was used inside the rMBR. The rMBR was evaluated for simultaneous glucose and xylose utilization as well as in situ detoxification of furfural and hydroxylmethyl furfural (HMF). The synthetic medium was investigated, after which the pretreated wheat straw was used as a xylose-rich lignocellulosic substrate. The IPC membrane panels were successfully used as the rMBR during the batch fermentations, which lasted for up to eight days without fouling. With the rMBR, complete glucose and xylose utilization, resulting in 86% of the theoretical ethanol yield, was observed with the synthetic medium. Its application with the pretreated wheat straw resulted in complete glucose consumption and 87% xylose utilization; a final ethanol concentration of 30.3 g/L was obtained, which corresponds to 83% of the theoretical yield. Moreover, complete in situ detoxification of furfural and HMF was obtained within 36 h and 60 h, respectively, with the rMBR. The use of the rMBR is a promising technology for large-scale lignocellulosic ethanol production, since it facilitates the co-utilization of glucose and xylose; moreover, the technology would also allow the reuse of the yeast for several batches. PMID:26633530

  10. Identifying inhibitory compounds in lignocellulosic biomass hydrolysates using an exometabolomics approach

    PubMed Central

    2014-01-01

    Background Inhibitors are formed that reduce the fermentation performance of fermenting yeast during the pretreatment process of lignocellulosic biomass. An exometabolomics approach was applied to systematically identify inhibitors in lignocellulosic biomass hydrolysates. Results We studied the composition and fermentability of 24 different biomass hydrolysates. To create diversity, the 24 hydrolysates were prepared from six different biomass types, namely sugar cane bagasse, corn stover, wheat straw, barley straw, willow wood chips and oak sawdust, and with four different pretreatment methods, i.e. dilute acid, mild alkaline, alkaline/peracetic acid and concentrated acid. Their composition and that of fermentation samples generated with these hydrolysates were analyzed with two GC-MS methods. Either ethyl acetate extraction or ethyl chloroformate derivatization was used before conducting GC-MS to prevent sugars are overloaded in the chromatograms, which obscure the detection of less abundant compounds. Using multivariate PLS-2CV and nPLS-2CV data analysis models, potential inhibitors were identified through establishing relationship between fermentability and composition of the hydrolysates. These identified compounds were tested for their effects on the growth of the model yeast, Saccharomyces. cerevisiae CEN.PK 113-7D, confirming that the majority of the identified compounds were indeed inhibitors. Conclusion Inhibitory compounds in lignocellulosic biomass hydrolysates were successfully identified using a non-targeted systematic approach: metabolomics. The identified inhibitors include both known ones, such as furfural, HMF and vanillin, and novel inhibitors, namely sorbic acid and phenylacetaldehyde. PMID:24655423

  11. Identifying inhibitory compounds in lignocellulosic biomass hydrolysates using an exometabolomics approach.

    PubMed

    Zha, Ying; Westerhuis, Johan A; Muilwijk, Bas; Overkamp, Karin M; Nijmeijer, Bernadien M; Coulier, Leon; Smilde, Age K; Punt, Peter J

    2014-03-21

    Inhibitors are formed that reduce the fermentation performance of fermenting yeast during the pretreatment process of lignocellulosic biomass. An exometabolomics approach was applied to systematically identify inhibitors in lignocellulosic biomass hydrolysates. We studied the composition and fermentability of 24 different biomass hydrolysates. To create diversity, the 24 hydrolysates were prepared from six different biomass types, namely sugar cane bagasse, corn stover, wheat straw, barley straw, willow wood chips and oak sawdust, and with four different pretreatment methods, i.e. dilute acid, mild alkaline, alkaline/peracetic acid and concentrated acid. Their composition and that of fermentation samples generated with these hydrolysates were analyzed with two GC-MS methods. Either ethyl acetate extraction or ethyl chloroformate derivatization was used before conducting GC-MS to prevent sugars are overloaded in the chromatograms, which obscure the detection of less abundant compounds. Using multivariate PLS-2CV and nPLS-2CV data analysis models, potential inhibitors were identified through establishing relationship between fermentability and composition of the hydrolysates. These identified compounds were tested for their effects on the growth of the model yeast, Saccharomyces. cerevisiae CEN.PK 113-7D, confirming that the majority of the identified compounds were indeed inhibitors. Inhibitory compounds in lignocellulosic biomass hydrolysates were successfully identified using a non-targeted systematic approach: metabolomics. The identified inhibitors include both known ones, such as furfural, HMF and vanillin, and novel inhibitors, namely sorbic acid and phenylacetaldehyde.

  12. Effect of frequency and reaction time in focused ultrasonic pretreatment of energy cane bagasse for bioethanol production.

    PubMed

    Methrath Liyakathali, Niyaz Ahamed; Muley, Pranjali D; Aita, Giovanna; Boldor, Dorin

    2016-01-01

    Pretreatment of lignocellulosic biomass is a critical steps in bioethanol production. Ultrasonic pretreatment significantly improves cellulose hydrolysis increasing sugar yields, but current system designs have limitations related to efficiency and scalability. This study evaluates the ultrasonic pretreatment of energy cane bagasse in a novel scalable configuration and by maximizing coupling of ultrasound energy to the material via active modulation of frequency. Pretreatment was conducted in 28% ammonia water mixture at a sample:ammonia:water ratio of 1:0.5:8. Process performance was investigated as a function of frequency (20, 20.5, 21kHz), reaction time (30, 45, 60min), temperature, and power levels for multiple combinations of ammonia, water and sample mixture. Results indicated an increased enzymatic digestibility, with maximum glucose yield of 24.29g/100g dry biomass. Theoretical ethanol yields obtained ranged from 6.47 to a maximum of 24.29g/100g dry biomass. Maximum energy attainable was 886.34kJ/100g dry biomass. Copyright © 2015 Elsevier Ltd. All rights reserved.

  13. Bioconversion of lignocellulosic biomass: biochemical and molecular perspectives.

    PubMed

    Kumar, Raj; Singh, Sompal; Singh, Om V

    2008-05-01

    In view of rising prices of crude oil due to increasing fuel demands, the need for alternative sources of bioenergy is expected to increase sharply in the coming years. Among potential alternative bioenergy resources, lignocellulosics have been identified as the prime source of biofuels and other value-added products. Lignocelluloses as agricultural, industrial and forest residuals account for the majority of the total biomass present in the world. To initiate the production of industrially important products from cellulosic biomass, bioconversion of the cellulosic components into fermentable sugars is necessary. A variety of microorganisms including bacteria and fungi may have the ability to degrade the cellulosic biomass to glucose monomers. Bacterial cellulases exist as discrete multi-enzyme complexes, called cellulosomes that consist of multiple subunits. Cellulolytic enzyme systems from the filamentous fungi, especially Trichoderma reesei, contain two exoglucanases or cellobiohydrolases (CBH1 and CBH2), at least four endoglucanases (EG1, EG2, EG3, EG5), and one beta-glucosidase. These enzymes act synergistically to catalyse the hydrolysis of cellulose. Different physical parameters such as pH, temperature, adsorption, chemical factors like nitrogen, phosphorus, presence of phenolic compounds and other inhibitors can critically influence the bioconversion of lignocellulose. The production of cellulases by microbial cells is governed by genetic and biochemical controls including induction, catabolite repression, or end product inhibition. Several efforts have been made to increase the production of cellulases through strain improvement by mutagenesis. Various physical and chemical methods have been used to develop bacterial and fungal strains producing higher amounts of cellulase, all with limited success. Cellulosic bioconversion is a complex process and requires the synergistic action of the three enzymatic components consisting of endoglucanases

  14. Pretreatment of biomass by aqueous ammonia for bioethanol production.

    PubMed

    Kim, Tae Hyun; Gupta, Rajesh; Lee, Y Y

    2009-01-01

    The methods of pretreatment of lignocellulosic biomass using aqueous ammonia are described. The main effect of ammonia treatment of biomass is delignification without significantly affecting the carbohydrate contents. It is a very effective pretreatment method especially for substrates that have low lignin contents such as agricultural residues and herbaceous feedstock. The ammonia-based pretreatment is well suited for simultaneous saccharification and co-fermentation (SSCF) because the treated biomass retains cellulose as well as hemicellulose. It has been demonstrated that overall ethanol yield above 75% of the theoretical maximum on the basis of total carbohydrate is achievable from corn stover pretreated with aqueous ammonia by way of SSCF. There are two different types of pretreatment methods based on aqueous ammonia: (1) high severity, low contact time process (ammonia recycle percolation; ARP), (2) low severity, high treatment time process (soaking in aqueous ammonia; SAA). Both of these methods are described and discussed for their features and effectiveness.

  15. Pretreatment of Biomass by Aqueous Ammonia for Bioethanol Production

    NASA Astrophysics Data System (ADS)

    Kim, Tae Hyun; Gupta, Rajesh; Lee, Y. Y.

    The methods of pretreatment of lignocellulosic biomass using aqueous ammonia are described. The main effect of ammonia treatment of biomass is delignification without significantly affecting the carbohydrate contents. It is a very effective pretreatment method especially for substrates that have low lignin contents such as agricultural residues and herbaceous feedstock. The ammonia-based pretreatment is well suited for simultaneous saccharification and co-fermentation (SSCF) because the treated biomass retains cellulose as well as hemicellulose. It has been demonstrated that overall ethanol yield above 75% of the theoretical maximum on the basis of total carbohydrate is achievable from corn stover pretreated with aqueous ammonia by way of SSCF. There are two different types of pretreatment methods based on aqueous ammonia: (1) high severity, low contact time process (ammonia recycle percolation; ARP), (2) low severity, high treatment time process (soaking in aqueous ammonia; SAA). Both of these methods are described and discussed for their features and effectiveness.

  16. Alkaline twin-screw extrusion pretreatment for fermentable sugar production

    PubMed Central

    2013-01-01

    Background The inevitable depletion of fossil fuels has resulted in an increasing worldwide interest in exploring alternative and sustainable energy sources. Lignocellulose, which is the most abundant biomass on earth, is widely regarded as a promising raw material to produce fuel ethanol. Pretreatment is an essential step to disrupt the recalcitrance of lignocellulosic matrix for enzymatic saccharification and bioethanol production. This paper established an ATSE (alkaline twin-screw extrusion pretreatment) process using a specially designed twin-screw extruder in the presence of alkaline solution to improve the enzymatic hydrolysis efficiency of corn stover for the production of fermentable sugars. Results The ATSE pretreatment was conducted with a biomass/liquid ratio of 1/2 (w/w) at a temperature of 99°C without heating equipment. The results indicated that ATSE pretreatment is effective in improving the enzymatic digestibility of corn stover. Sodium hydroxide loading is more influential factor affecting both sugar yield and lignin degradation than heat preservation time. After ATSE pretreatment under the proper conditions (NaOH loading of 0.06 g/g biomass during ATSE and 1 hour heat preservation after extrusion), 71% lignin removal was achieved and the conversions of glucan and xylan in the pretreated biomass can reach to 83% and 89% respectively via subsequent enzymatic hydrolysis (cellulase loading of 20 FPU/g-biomass and substrate consistency of 2%). About 78% of the original polysaccharides were converted into fermentable sugars. Conclusions With the physicochemical functions in extrusion, the ATSE method can effectively overcome the recalcitrance of lignocellulose for the production of fermentable sugars from corn stover. This process can be considered as a promising pretreatment method due to its relatively low temperature (99°C), high biomass/liquid ratio (1/2) and satisfied total sugar yield (78%), despite further study is needed for process

  17. Alkaline twin-screw extrusion pretreatment for fermentable sugar production.

    PubMed

    Liu, Chao; van der Heide, Evert; Wang, Haisong; Li, Bin; Yu, Guang; Mu, Xindong

    2013-01-01

    The inevitable depletion of fossil fuels has resulted in an increasing worldwide interest in exploring alternative and sustainable energy sources. Lignocellulose, which is the most abundant biomass on earth, is widely regarded as a promising raw material to produce fuel ethanol. Pretreatment is an essential step to disrupt the recalcitrance of lignocellulosic matrix for enzymatic saccharification and bioethanol production. This paper established an ATSE (alkaline twin-screw extrusion pretreatment) process using a specially designed twin-screw extruder in the presence of alkaline solution to improve the enzymatic hydrolysis efficiency of corn stover for the production of fermentable sugars. The ATSE pretreatment was conducted with a biomass/liquid ratio of 1/2 (w/w) at a temperature of 99°C without heating equipment. The results indicated that ATSE pretreatment is effective in improving the enzymatic digestibility of corn stover. Sodium hydroxide loading is more influential factor affecting both sugar yield and lignin degradation than heat preservation time. After ATSE pretreatment under the proper conditions (NaOH loading of 0.06 g/g biomass during ATSE and 1 hour heat preservation after extrusion), 71% lignin removal was achieved and the conversions of glucan and xylan in the pretreated biomass can reach to 83% and 89% respectively via subsequent enzymatic hydrolysis (cellulase loading of 20 FPU/g-biomass and substrate consistency of 2%). About 78% of the original polysaccharides were converted into fermentable sugars. With the physicochemical functions in extrusion, the ATSE method can effectively overcome the recalcitrance of lignocellulose for the production of fermentable sugars from corn stover. This process can be considered as a promising pretreatment method due to its relatively low temperature (99°C), high biomass/liquid ratio (1/2) and satisfied total sugar yield (78%), despite further study is needed for process optimization and cost reduction.

  18. Lignocellulose-based analytical devices: bamboo as an analytical platform for chemical detection

    PubMed Central

    Kuan, Chen-Meng; York, Roger L.; Cheng, Chao-Min

    2015-01-01

    This article describes the development of lignocellulose-based analytical devices (LADs) for rapid bioanalysis in low-resource settings. LADs are constructed using either a single lignocellulose or a hybrid design consisting of multiple types of lignocellulose. LADs are simple, low-cost, easy to use, provide rapid response, and do not require external instrumentation during operation. Here, we demonstrate the implementation of LADs for food and water safety (i.e., nitrite assay in hot-pot soup, bacterial detection in water, and resazurin assay in milk) and urinalysis (i.e., nitrite, urobilinogen, and pH assays in human urine). Notably, we created a unique approach using simple chemicals to achieve sensitivity similar to that of commercially available immunochromatographic strips that is low-cost, and provides on-site, rapid detection, for instance, of Eschericia coli (E. coli) in water. PMID:26686576

  19. Limitations of the NNS assay for reducing sugars from saccharified lignocellulosics. [Trichoderma reesei

    SciTech Connect

    Rivers, D.B.; Gracheck, S.J.; Woodford, L.C.; Emert, G.H.

    1984-07-01

    An evaluation is presented of two DNS (2,4-dinitrosalicylic acid) assay procedures as well as high-performance liquid chromatography (HPLC) and YSI Glucose Analyzer analyses of sugars resulting from enzymatic saccharification of lignocellulosics. Trichoderma reesei was used to produce the cellulase system containing endoglucanase, cellobiohydrolase and cellobiase. Data suggest that the DNS assay can be used as an accurate analytical method for the evaluation of reducing sugars in pure solution as well as in supernatants from enzymatic saccharification if glucose is the sole product. However, only specific assay methods such as HPLC and YSI-type glucose analyzers should be used for the analysis of saccharides produced from the hydrolysis of native or pretreated lignocellulosics since the DNS assay is susceptible to interferences and therefore results in inaccurate analyses.

  20. Direct fungal fermentation of lignocellulosic biomass into itaconic, fumaric, and malic acids: current and future prospects.

    PubMed

    Mondala, Andro H

    2015-04-01

    Various economic and environmental sustainability concerns as well as consumer preference for bio-based products from natural sources have paved the way for the development and expansion of biorefining technologies. These involve the conversion of renewable biomass feedstock to fuels and chemicals using biological systems as alternatives to petroleum-based products. Filamentous fungi possess an expansive portfolio of products including the multifunctional organic acids itaconic, fumaric, and malic acids that have wide-ranging current applications and potentially addressable markets as platform chemicals. However, current bioprocessing technologies for the production of these compounds are mostly based on submerged fermentation, which necessitates physicochemical pretreatment and hydrolysis of lignocellulose biomass to soluble fermentable sugars in liquid media. This review will focus on current research work on fungal production of itaconic, fumaric, and malic acids and perspectives on the potential application of solid-state fungal cultivation techniques for the consolidated hydrolysis and organic acid fermentation of lignocellulosic biomass.

  1. Development of biocatalysts for production of commodity chemicals from lignocellulosic biomass.

    PubMed

    Adsul, M G; Singhvi, M S; Gaikaiwari, S A; Gokhale, D V

    2011-03-01

    Lignocellulosic biomass is recognized as potential sustainable source for production of power, biofuels and variety of commodity chemicals which would potentially add economic value to biomass. Recalcitrance nature of biomass is largely responsible for the high cost of its conversion. Therefore, it is necessary to introduce some cost effective pretreatment processes to make the biomass polysaccharides easily amenable to enzymatic attack to release mixed fermentable sugars. Advancement in systemic biology can provide new tools for the development of such biocatalysts for sustainable production of commodity chemicals from biomass. Integration of functional genomics and system biology approaches may generate efficient microbial systems with new metabolic routes for production of commodity chemicals. This paper provides an overview of the challenges that are faced by the processes converting lignocellulosic biomass to commodity chemicals. The critical factors involved in engineering new microbial biocatalysts are also discussed with more emphasis on commodity chemicals. Copyright © 2011 Elsevier Ltd. All rights reserved.

  2. Simultaneous saccharification, filtration and fermentation (SSFF): a novel method for bioethanol production from lignocellulosic biomass.

    PubMed

    Ishola, Mofoluwake M; Jahandideh, Arash; Haidarian, Behroz; Brandberg, Tomas; Taherzadeh, Mohammad J

    2013-04-01

    Simultaneous saccharification, filtration and fermentation (SSFF) was developed for lignocellulosic ethanol production. In SSFF, pretreated lignocellulosic material is enzymatically hydrolyzed in a reactor, while the suspension is continuously pumped through a cross-flow membrane. The retentate goes back to the hydrolysis vessel, while a clear sugar-rich filtrate continuously perfuses through the fermentation vessel before it is pumped back to the hydrolysis vessel. The capacity and life span of the cross-flow filter module was examined for 4 weeks using enzymatically hydrolyzed slurry, initially with 14.4% suspended solids, without clogging or fouling. An ethanol yield of 85.0% of the theoretical yield was obtained in SSFF and a flocculating strain of Saccharomyces cerevisiae was successfully reused for five cultivations of SSFF. Copyright © 2013 Elsevier Ltd. All rights reserved.

  3. Lignocellulosic agriculture wastes as biomass feedstocks for second-generation bioethanol production: concepts and recent developments.

    PubMed

    Saini, Jitendra Kumar; Saini, Reetu; Tewari, Lakshmi

    2015-08-01

    Production of liquid biofuels, such as bioethanol, has been advocated as a sustainable option to tackle the problems associated with rising crude oil prices, global warming and diminishing petroleum reserves. Second-generation bioethanol is produced from lignocellulosic feedstock by its saccharification, followed by microbial fermentation and product recovery. Agricultural residues generated as wastes during or after processing of agricultural crops are one of such renewable and lignocellulose-rich biomass resources available in huge amounts for bioethanol production. These agricultural residues are converted to bioethanol in several steps which are described here. This review enlightens various steps involved in production of the second-generation bioethanol. Mechanisms and recent advances in pretreatment, cellulases production and second-generation ethanol production processes are described here.

  4. Physico-Chemical Alternatives in Lignocellulosic Materials in Relation to the Kind of Component for Fermenting Purposes

    PubMed Central

    Coz, Alberto; Llano, Tamara; Cifrián, Eva; Viguri, Javier; Maican, Edmond; Sixta, Herbert

    2016-01-01

    The complete bioconversion of the carbohydrate fraction is of great importance for a lignocellulosic-based biorefinery. However, due to the structure of the lignocellulosic materials, and depending basically on the main parameters within the pretreatment steps, numerous byproducts are generated and they act as inhibitors in the fermentation operations. In this sense, the impact of inhibitory compounds derived from lignocellulosic materials is one of the major challenges for a sustainable biomass-to-biofuel and -bioproduct industry. In order to minimise the negative effects of these compounds, numerous methodologies have been tested including physical, chemical, and biological processes. The main physical and chemical treatments have been studied in this work in relation to the lignocellulosic material and the inhibitor in order to point out the best mechanisms for fermenting purposes. In addition, special attention has been made in the case of lignocellulosic hydrolysates obtained by chemical processes with SO2, due to the complex matrix of these materials and the increase in these methodologies in future biorefinery markets. Recommendations of different detoxification methods have been given. PMID:28773700

  5. Production of Biofuel from Waste Lignocellulosic Biomass Materials Based on Energy Saving Viewpoint

    NASA Astrophysics Data System (ADS)

    Takano, Maki; Hoshino, Kazuhiro

    To develop biofuel production from waste lignocellulosic biomass materials the rice straw was selected one of renewable material and the degradation condition about pretreatment and enzymatic hydrolysis to obtain effectively fermentable sugars was investigated. Rice straw was pretreated by five kinds of methods and then the components ratio of rice straw was examined. First, the steam explosion was selected based on the degradability and the requirement energy. In addition, the best suitable combination of two cellulases to effective and economical hydrolyze was determined from the degradability of these pretreated rice straws. In the simultaneous saccharification and fermentation of the steam explosion rice straw by combining cellulase cocktail and a novel fermenting fungus, 13.2 g/L ethanol was able to product for 96 h.

  6. Advances in understanding the surface chemistry of lignocellulosic biomass via time-of-flight secondary ion mass spectrometry

    DOE PAGES

    Tolbert, Allison K.; Ragauskas, Arthur J.

    2016-12-12

    Overcoming the natural recalcitrance of lignocellulosic biomass is necessary in order to efficiently convert biomass into biofuels or biomaterials and many times this requires some type of chemical pretreatment and/or biological treatment. While bulk chemical analysis is the traditional method of determining the impact a treatment has on biomass, the chemistry on the surface of the sample can differ from the bulk chemistry. Specifically, enzymes and microorganisms bind to the surface of the biomass and their efficiency could be greatly impacted by the chemistry of the surface. Therefore, it is important to study and understand the chemistry of the biomassmore » at the surface. Time-of- flight secondary ion mass spectrometry (ToF-SIMS) is a powerful tool that can spectrally and spatially analyze the surface chemistry of a sample. This review discusses the advances in understanding lignocellulosic biomass surface chemistry using the ToF-SIMS by addressing the instrument parameters, biomass sample preparation, and characteristic lignocellulosic ion fragmentation peaks along with their typical location in the plant cell wall. Furthermore, the use of the ToF-SIMS in detecting chemical changes due to chemical pretreatments, microbial treatments, and physical or genetic modifications is discussed along with possible future applications of the instrument in lignocellulosic biomass studies.« less

  7. Comparison of pretreatment methods for rye straw in the second generation biorefinery: effect on cellulose, hemicellulose and lignin recovery.

    PubMed

    Perez-Cantu, Lilia; Schreiber, Andreas; Schütt, Fokko; Saake, Bodo; Kirsch, Christian; Smirnova, Irina

    2013-08-01

    The increasing interest in lignocellulose-based biorefineries boosts the further development of the needed pretreatment methods for preprocessing biomass. There are a large number of different processes that are being investigated; however research is made mostly based on different types of biomass with the same pretreatment or several modifications of the same process for a given type of biomass. In this work a comparison of promising chemical pretreatments using the same biomass was performed. Organosolv (OS), Steam (SE) and Liquid-Hot-Water (LHW) processes were used for the pretreatment of rye straw and the treated solids further enzymatically hydrolyzed. Best results for carbohydrate and lignin yield were found for the OS pretreatment followed close by the LHW and SE with similar results. All of the processes showed satisfactory performance for the pretreatment of lignocellulosic biomass for application in the second generation biorefinery. Copyright © 2013 Elsevier Ltd. All rights reserved.

  8. Lignosulfonate-mediated cellulase adsorption: enhanced enzymatic saccharification of lignocellulose through weakening nonproductive binding to lignin

    PubMed Central

    2013-01-01

    Background Thermochemical pretreatment of lignocellulose is crucial to bioconversion in the fields of biorefinery and biofuels. However, the enzyme inhibitors in pretreatment hydrolysate make solid substrate washing and hydrolysate detoxification indispensable prior to enzymatic hydrolysis. Sulfite pretreatment to overcome recalcitrance of lignocelluloses (SPORL) is a relatively new process, but has demonstrated robust performance for sugar and biofuel production from woody biomass in terms of yield and energy efficiency. This study demonstrated the advantage of SPORL pretreatment whereby the presentation of lignosulfonate (LS) renders the hydrolysate non-inhibitory to cellulase (Cel) due to the formation of lignosulfonate-cellulase complexes (LCCs) which can mediate the Cel adsorption between lignin and cellulose, contrary to the conventional belief that pretreatment hydrolysate inhibits the enzymatic hydrolysis unless detoxified. Results Particular emphasis was made on the formation mechanisms and stability phase of LCCs, the electrostatic interaction between LCCs and lignin, and the redistributed Cel adsorption between lignin and cellulose. The study found that LS, the byproduct of SPORL pretreatment, behaves as a polyelectrolyte to form LCCs with Cel by associating to the oppositely charged groups of protein. Compared to Cel, the zeta potential of LCCs is more negative and adjustable by altering the molar ratio of LS to Cel, and thereby LCCs have the ability to mitigate the nonproductive binding of Cel to lignin because of the enlarged electrostatic repulsion. Experimental results showed that the benefit from the reduced nonproductive binding outweighed the detrimental effects from the inhibitors in pretreatment hydrolysate. Specifically, the glucan conversions of solid substrate from poplar and lodgepole pine were greatly elevated by 25.9% and 31.8%, respectively, with the complete addition of the corresponding hydrolysate. This contradicts the well

  9. Simultaneous saccharification and cofermentation of peracetic acid-pretreated biomass.

    PubMed

    Teixeira, L C; Linden, J C; Schroeder, H A

    2000-01-01

    Previous work in our laboratories has demonstrated the effectiveness of peracetic acid for improving enzymatic digestibility of lignocellulosic materials. The use of dilute alkali solutions as a pre-pretreatment prior to peracetic acid lignin oxidation increased carbohydrate hydrolysis yields in a synergistic as opposed to additive manner. Deacetylation of xylan is easily achieved using dilute alkali solutions under mild conditions. In this article, we evaluate the effectiveness of peracetic acid combined with an alkaline pre-pretreatment through simultaneous saccharification and cofermentation (SSCF) of pretreated hybrid poplar wood and sugar cane bagasse. Respective ethanol yields of 92.8 and 91.9% of theoretical are achieved using 6% NaOH/15% peracetic acid-pretreated substrates and recombinant Zymomonas mobilis CP4/pZB5. Reduction of acetyl groups of the lignocellulosic materials is demonstrated following alkaline pre-pretreatments. Such processing may be helpful in reducing peracetic acid requirements. The influence of deacetylation is more significant in combined pretreatments using lower peracetic acid loadings.

  10. Lignin structural alterations in thermochemical pretreatments with limited delignification

    SciTech Connect

    Pu, Yunqiao; Hu, Fan; Huang, Fang; Ragauskas, Arthur J.

    2015-08-02

    Lignocellulosic biomass has a complex and rigid cell wall structure that makes biomass recalcitrant to biological and chemical degradation. Among the three major structural biopolymers (i.e., cellulose, hemicellulose and lignin) in plant cell walls, lignin is considered the most recalcitrant component and generally plays a negative role in the biochemical conversion of biomass to biofuels. The conversion of biomass to biofuels through a biochemical platform usually requires a pretreatment stage to reduce the recalcitrance. Pretreatment renders compositional and structural changes of biomass with these changes ultimately govern the efficiency of the subsequent enzymatic hydrolysis. Dilute acid, hot water, steam explosion, and ammonia fiber expansion pretreatments are among the leading thermochemical pretreatments with a limited delignification that can reduce biomass recalcitrance. Practical applications of these pretreatment are rapidly developing as illustrated by recent commercial scale cellulosic ethanol plants. While these thermochemical pretreatments generally lead to only a limited delignification and no significant change of lignin content in the pretreated biomass, the lignin transformations that occur during these pretreatments and the roles they play in recalcitrance reduction is an important research aspect. This review highlights recent advances in our understanding of lignin alterations during these limited delignification thermochemical pretreatments, with emphasis on lignin chemical structures, molecular weights, and redistributions in the pretreated biomass.

  11. Lignin structural alterations in thermochemical pretreatments with limited delignification

    DOE PAGES

    Pu, Yunqiao; Hu, Fan; Huang, Fang; ...

    2015-08-02

    Lignocellulosic biomass has a complex and rigid cell wall structure that makes biomass recalcitrant to biological and chemical degradation. Among the three major structural biopolymers (i.e., cellulose, hemicellulose and lignin) in plant cell walls, lignin is considered the most recalcitrant component and generally plays a negative role in the biochemical conversion of biomass to biofuels. The conversion of biomass to biofuels through a biochemical platform usually requires a pretreatment stage to reduce the recalcitrance. Pretreatment renders compositional and structural changes of biomass with these changes ultimately govern the efficiency of the subsequent enzymatic hydrolysis. Dilute acid, hot water, steam explosion,more » and ammonia fiber expansion pretreatments are among the leading thermochemical pretreatments with a limited delignification that can reduce biomass recalcitrance. Practical applications of these pretreatment are rapidly developing as illustrated by recent commercial scale cellulosic ethanol plants. While these thermochemical pretreatments generally lead to only a limited delignification and no significant change of lignin content in the pretreated biomass, the lignin transformations that occur during these pretreatments and the roles they play in recalcitrance reduction is an important research aspect. This review highlights recent advances in our understanding of lignin alterations during these limited delignification thermochemical pretreatments, with emphasis on lignin chemical structures, molecular weights, and redistributions in the pretreated biomass.« less

  12. Acetylation of woody lignocellulose: significance and regulation

    PubMed Central

    Pawar, Prashant Mohan-Anupama; Koutaniemi, Sanna; Tenkanen, Maija; Mellerowicz, Ewa J.

    2013-01-01

    Non-cellulosic cell wall polysaccharides constitute approximately one quarter of usable biomass for human exploitation. In contrast to cellulose, these components are usually substituted by O-acetyl groups, which affect their properties and interactions with other polymers, thus affecting their solubility and extractability. However, details of these interactions are still largely obscure. Moreover, polysaccharide hydrolysis to constituent monosaccharides is hampered by the presence of O-acetyl groups, necessitating either enzymatic (esterase) or chemical de-acetylation, increasing the costs and chemical consumption. Reduction of polysaccharide acetyl content in planta is a way to modify lignocellulose toward improved saccharification. In this review we: (1) summarize literature on lignocellulose acetylation in different tree species, (2) present data and current hypotheses concerning the role of O-acetylation in determining woody lignocellulose properties, (3) describe plant proteins involved in lignocellulose O-acetylation, (4) give examples of microbial enzymes capable to de-acetylate lignocellulose, and (5) discuss prospects for exploiting these enzymes in planta to modify xylan acetylation. PMID:23734153

  13. Effect of non-enzymatic proteins on enzymatic hydrolysis and simultaneous saccharification and fermentation of different lignocellulosic materials.

    PubMed

    Wang, Hui; Kobayashi, Shinichi; Mochidzuki, Kazuhiro

    2015-08-01

    Non-enzymatic proteins were added during hydrolysis of cellulose and simultaneous saccharification and fermentation (SSF) of different biomass materials. Bovine serum albumin (BSA), a model non-enzymatic protein, increased cellulose and xylose conversion efficiency and also enhanced the ethanol yield during SSF of rice straw subjected to varied pretreatments. Corn steep liquor, yeast extract, and peptone also exerted a similar effect as BSA and enhanced the enzymatic hydrolysis of rice straw. Compared to the glucose yields obtained after enzymatic hydrolysis of rice straw in the absence of additives, the glucose yields after 72h of hydrolysis increased by 12.7%, 13.5%, and 13.7% after addition of the corn steep liquor, yeast extract, and peptone, respectively. This study indicated the use of BSA as an alternative to intensive pretreatment of lignocellulosic materials for enhancing enzymatic digestibility. The utilization of non-enzymatic protein additives is promising for application in glucose and ethanol production from lignocellulosic materials.

  14. Using polyvinylpyrrolidone to enhance the enzymatic hydrolysis of lignocelluloses by reducing the cellulase non-productive adsorption on lignin.

    PubMed

    Cai, Cheng; Qiu, Xueqing; Zeng, Meijun; Lin, Meilu; Lin, Xuliang; Lou, Hongming; Zhan, Xuejuan; Pang, Yuxia; Huang, Jinhao; Xie, Lingshan

    2017-03-01

    Polyvinylpyrrolidone (PVP) is an antifouling polymer to resist the adsorption of protein on solid surface. Effects of PVP on the enzymatic hydrolysis of pretreated lignocelluloses and its mechanism were studied. Adding 1g/L of PVP8000, the enzymatic digestibility of eucalyptus pretreated by dilute acid (Eu-DA) was increased from 28.9% to 73.4%, which is stronger than the classic additives, such as PEG, Tween and bovine serum albumin. Compared with PEG4600, the adsorption of PVP8000 on lignin was larger, and the adsorption layer was more stable and hydrophilic. Therefore, PVP8000 reduced 73.1% of the cellulase non-productive adsorption on lignin and enhanced the enzymatic hydrolysis of lignocelluloses greatly. Copyright © 2016 Elsevier Ltd. All rights reserved.

  15. Defined enzyme cocktail from the anaerobic fungus Orpinomyces sp. strain C1A effectively releases sugars from pretreated corn stover and switchgrass

    PubMed Central

    Morrison, Jessica M.; Elshahed, Mostafa S.; Youssef, Noha H.

    2016-01-01

    The anaerobic fungus Orpinomyces strain C1A is capable of growth on various types of lignocellulosic substrates, and harbors an impressive reservoir of carbohydrate active enzymes (CAZymes). Using a minimum enzyme cocktail strategy, we constituted a four-component lignocellulolytic cocktail derived from highly transcribed C1A, and evaluated its efficacy against pretreated corn stover and switchgrass. Hydrolysis yields ranged between 65–77.4%, depending on the lignocellulosic substrate and pretreatment applied. Addition of a highly expressed anaerobic fungal swollenin improved hydrolysis yields by up to 7%. Compared to the commercial cocktail CTec2, these anaerobic fungal cocktails provided comparable or slightly lower hydrolysis yields. Further, the differences in efficacy between commercial and anaerobic cocktails were often only realized after extended (168 hr) incubations. Under certain conditions, the hydrolysis yields of the anaerobic fungal cocktail was slightly superior to that realized by CTec2. We attribute the observed high hydrolysis yields to the high specific activity and affinity of the individual enzymes of the cocktail, as well as the high level of synergy and multi-functionality observed in multiple components. Collectively, this effort provides a novel platform for constructing highly effective enzymes for biofuel production and represents the first lignocellulolytic enzyme cocktail created from anaerobic fungal enzymes. PMID:27381262

  16. Analysis of by-product formation and sugar monomerization in sugarcane bagasse pretreated at pilot plant scale: differences between autohydrolysis, alkaline and acid pretreatment.

    PubMed

    van der Pol, Edwin; Bakker, Rob; van Zeeland, Alniek; Sanchez Garcia, David; Punt, Arjen; Eggink, Gerrit

    2015-04-01

    Sugarcane bagasse is an interesting feedstock for the biobased economy since a large fraction is polymerized sugars. Autohydrolysis, alkaline and acid pretreatment conditions combined with enzyme hydrolysis were used on lignocellulose rich bagasse to acquire monomeric. By-products found after pretreatment included acetic, glycolic and coumaric acid in concentrations up to 40, 21 and 2.5 g/kg dry weight bagasse respectively. Alkaline pretreated material contained up to 45 g/kg bagasse DW of sodium. Acid and autohydrolysis pretreatment results in a furan formation of 14 g/kg and 25 g/kg DW bagasse respectively. Enzyme monomerization efficiencies of pretreated solid material after 72 h were 81% for acid pretreatment, 77% for autohydrolysis and 57% for alkaline pretreatment. Solid material was washed with superheated water to decrease the amount of by-products. Washing decreased organic acid, phenol and furan concentrations in solid material by at least 60%, without a major sugar loss.

  17. Ethanol production with dilute acid hydrolysis using partially dried lignocellulosics

    DOEpatents

    Nguyen, Quang A.; Keller, Fred A.; Tucker, Melvin P.

    2003-12-09

    A process of converting lignocellulosic biomass to ethanol, comprising hydrolyzing lignocellulosic materials by subjecting dried lignocellulosic material in a reactor to a catalyst comprised of a dilute solution of a strong acid and a metal salt to lower the activation energy (i.e., the temperature) of cellulose hydrolysis and ultimately obtain higher sugar yields.

  18. Efficient Eucalypt Cell Wall Deconstruction and Conversion for Sustainable Lignocellulosic Biofuels.

    PubMed

    Healey, Adam L; Lee, David J; Furtado, Agnelo; Simmons, Blake A; Henry, Robert J

    2015-01-01

    In order to meet the world's growing energy demand and reduce the impact of greenhouse gas emissions resulting from fossil fuel combustion, renewable plant-based feedstocks for biofuel production must be considered. The first-generation biofuels, derived from starches of edible feedstocks, such as corn, create competition between food and fuel resources, both for the crop itself and the land on which it is grown. As such, biofuel synthesized from non-edible plant biomass (lignocellulose) generated on marginal agricultural land will help to alleviate this competition. Eucalypts, the broadly defined taxa encompassing over 900 species of Eucalyptus, Corymbia, and Angophora are the most widely planted hardwood tree in the world, harvested mainly for timber, pulp and paper, and biomaterial products. More recently, due to their exceptional growth rate and amenability to grow under a wide range of environmental conditions, eucalypts are a leading option for the development of a sustainable lignocellulosic biofuels. However, efficient conversion of woody biomass into fermentable monomeric sugars is largely dependent on pretreatment of the cell wall, whose formation and complexity lend itself toward natural recalcitrance against its efficient deconstruction. A greater understanding of this complexity within the context of various pretreatments will allow the design of new and effective deconstruction processes for bioenergy production. In this review, we present the various pretreatment options for eucalypts, including research into understanding structure and formation of the eucalypt cell wall.

  19. Efficient Eucalypt Cell Wall Deconstruction and Conversion for Sustainable Lignocellulosic Biofuels

    PubMed Central

    Healey, Adam L.; Lee, David J.; Furtado, Agnelo; Simmons, Blake A.; Henry, Robert J.

    2015-01-01

    In order to meet the world’s growing energy demand and reduce the impact of greenhouse gas emissions resulting from fossil fuel combustion, renewable plant-based feedstocks for biofuel production must be considered. The first-generation biofuels, derived from starches of edible feedstocks, such as corn, create competition between food and fuel resources, both for the crop itself and the land on which it is grown. As such, biofuel synthesized from non-edible plant biomass (lignocellulose) generated on marginal agricultural land will help to alleviate this competition. Eucalypts, the broadly defined taxa encompassing over 900 species of Eucalyptus, Corymbia, and Angophora are the most widely planted hardwood tree in the world, harvested mainly for timber, pulp and paper, and biomaterial products. More recently, due to their exceptional growth rate and amenability to grow under a wide range of environmental conditions, eucalypts are a leading option for the development of a sustainable lignocellulosic biofuels. However, efficient conversion of woody biomass into fermentable monomeric sugars is largely dependent on pretreatment of the cell wall, whose formation and complexity lend itself toward natural recalcitrance against its efficient deconstruction. A greater understanding of this complexity within the context of various pretreatments will allow the design of new and effective deconstruction processes for bioenergy production. In this review, we present the various pretreatment options for eucalypts, including research into understanding structure and formation of the eucalypt cell wall. PMID:26636077

  20. Enhanced lignocellulosic biomass hydrolysis by oxidative lytic polysaccharide monooxygenases (LPMOs) GH61 from Gloeophyllum trabeum.

    PubMed

    Jung, Sera; Song, Younho; Kim, Ho Myeong; Bae, Hyeun-Jong

    2015-09-01

    Lignocellulose is a renewable resource that is extremely abundant, and the complete enzymatic hydrolysis of lignocellulose requires a cocktail containing a variety of enzyme groups that act synergistically. The hydrolysis efficiency can be improved by introducing glycoside hydrolase 61 (GH61), a new enzyme that belongs to the auxiliary activity family 9 (AA9). GH61was isolated from Gloeophyllum trabeum and cleaves the glycosidic bonds on the cellulose surface via oxidation of various carbons. In this study, we investigated the properties of GH61. GtGH61 alone did not exhibit any notable activity, but the synergistic activity of GtGH61 with xylanase (GtXyl10G) or cellulase (GtCel5B) showed efficient bioconversion rates of 56 and 174% in pretreated kenaf (Hibiscus cannabinus L.) and oak (Quercus spp.), respectively. Furthermore, the GtGH61 activity was strongly accelerated in the presence of cobalt Co(2+). Enzyme cocktails (GtXyl10G, GtCel5B, and GtGH61) increased the amount of sugar released by 7 and 6% for pretreated oak and kenaf, respectively, and the addition of Co(2+) stimulated bioconversion by 12 and 11% in pretreated oak and kenaf, respectively. Copyright © 2015 Elsevier Inc. All rights reserved.

  1. Liquefaction of lignocellulose at high-solids concentrations.

    PubMed

    Jørgensen, Henning; Vibe-Pedersen, Jakob; Larsen, Jan; Felby, Claus

    2007-04-01

    To improve process economics of the lignocellulose to ethanol process a reactor system for enzymatic liquefaction and saccharification at high-solids concentrations was developed. The technology is based on free fall mixing employing a horizontally placed drum with a horizontal rotating shaft mounted with paddlers for mixing. Enzymatic liquefaction and saccharification of pretreated wheat straw was tested with up to 40% (w/w) initial DM. In less than 10 h, the structure of the material was changed from intact straw particles (length 1-5 cm) into a paste/liquid that could be pumped. Tests revealed no significant effect of mixing speed in the range 3.3-11.5 rpm on the glucose conversion after 24 h and ethanol yield after subsequent fermentation for 48 h. Low-power inputs for mixing are therefore possible. Liquefaction and saccharification for 96 h using an enzyme loading of 7 FPU/g.DM and 40% DM resulted in a glucose concentration of 86 g/kg. Experiments conducted at 2%-40% (w/w) initial DM revealed that cellulose and hemicellulose conversion decreased almost linearly with increasing DM. Performing the experiments as simultaneous saccharification and fermentation also revealed a decrease in ethanol yield at increasing initial DM. Saccharomyces cerevisiae was capable of fermenting hydrolysates up to 40% DM. The highest ethanol concentration, 48 g/kg, was obtained using 35% (w/w) DM. Liquefaction of biomass with this reactor system unlocks the possibility of 10% (w/w) ethanol in the fermentation broth in future lignocellulose to ethanol plants.

  2. Enzymatic lignocellulose hydrolysis: Improved cellulase productivity by insoluble solids recycling

    PubMed Central

    2013-01-01

    Background It is necessary to develop efficient methods to produce renewable fuels from lignocellulosic biomass. One of the main challenges to the industrialization of lignocellulose conversion processes is the large amount of cellulase enzymes used for the hydrolysis of cellulose. One method for decreasing the amount of enzyme used is to recycle the enzymes. In this study, the recycle of enzymes associated with the insoluble solid fraction after the enzymatic hydrolysis of cellulose was investigated for pretreated corn stover under a variety of recycling conditions. Results It was found that a significant amount of cellulase activity could be recovered by recycling the insoluble biomass fraction, and the enzyme dosage could be decreased by 30% to achieve the same glucose yields under the most favorable conditions. Enzyme productivity (g glucose produced/g enzyme applied) increased between 30 and 50% by the recycling, depending on the reaction conditions. While increasing the amount of solids recycled increased process performance, the methods applicability was limited by its positive correlation with increasing total solids concentrations, reaction volumes, and lignin content of the insoluble residue. However, increasing amounts of lignin rich residue during the recycle did not negatively impact glucose yields. Conclusions To take advantage of this effect, the amount of solids recycled should be maximized, based on a given processes ability to deal with higher solids concentrations and volumes. Recycling of enzymes by recycling the insoluble solids fraction was thus shown to be an effective method to decrease enzyme usage, and research should be continued for its industrial application. PMID:23336604

  3. Lignocellulosic ethanol: Technology design and its impact on process efficiency.

    PubMed

    Paulova, Leona; Patakova, Petra; Branska, Barbora; Rychtera, Mojmir; Melzoch, Karel

    2015-11-01

    This review provides current information on the production of ethanol from lignocellulosic biomass, with the main focus on relationships between process design and efficiency, expressed as ethanol concentration, yield and productivity. In spite of unquestionable advantages of lignocellulosic biomass as a feedstock for ethanol production (availability, price, non-competitiveness with food, waste material), many technological bottlenecks hinder its wide industrial application and competitiveness with 1st generation ethanol production. Among the main technological challenges are the recalcitrant structure of the material, and thus the need for extensive pretreatment (usually physico-chemical followed by enzymatic hydrolysis) to yield fermentable sugars, and a relatively low concentration of monosaccharides in the medium that hinder the achievement of ethanol concentrations comparable with those obtained using 1st generation feedstocks (e.g. corn or molasses). The presence of both pentose and hexose sugars in the fermentation broth, the price of cellulolytic enzymes, and the presence of toxic compounds that can inhibit cellulolytic enzymes and microbial producers of ethanol are major issues. In this review, different process configurations of the main technological steps (enzymatic hydrolysis, fermentation of hexose/and or pentose sugars) are discussed and their efficiencies are compared. The main features, benefits and drawbacks of simultaneous saccharification and fermentation (SSF), simultaneous saccharification and fermentation with delayed inoculation (dSSF), consolidated bioprocesses (CBP) combining production of cellulolytic enzymes, hydrolysis of biomass and fermentation into one step, together with an approach combining utilization of both pentose and hexose sugars are discussed and compared with separate hydrolysis and fermentation (SHF) processes. The impact of individual technological steps on final process efficiency is emphasized and the potential for use

  4. Biodiesel from lignocellulosic biomass--prospects and challenges.

    PubMed

    Yousuf, Abu

    2012-11-01

    Biodiesel can be a potential alternative to petroleum diesel, but its high production cost has impeded its commercialization in most parts of the world. One of the main drivers for the generation and use of biodiesel is energy security, because this fuel can be produced from locally available resources, thereby reducing the dependence on imported oil. Many countries are now trying to produce biodiesel from plant or vegetable oils. However, the consumption of large amounts of vegetable oils for biodiesel production could result in a shortage in edible oils and cause food prices to soar. Alternatively, the use of animal fat, used frying oils, and waste oils from restaurants as feedstock could be a good strategy to reduce the cost. However, these limited resources might not meet the increasing demand for clean, renewable fuels. Therefore, recent research has been focused the use of residual materials as renewable feedstock in order to lower the cost of producing biodiesel. Microbial oils or single cell oils (SCOs), produced by oleaginous microorganisms have been studied as promising alternatives to vegetable or seed oils. Various types of agro-industrial residues have been suggested as prospective nutritional sources for microbial cultures. Since the most abundant residue from agricultural crops is lignocellulosic biomass (LCB), this byproduct has been given top-priority consideration as a source of biomass for producing biodiesel. But the biological transformation of lignocellulosic materials is complicated due to their crystalline structure. So, pretreatment is required before they can be converted into fermentable sugar. This article compares and scrutinizes the extent to which various microbes can accumulate high levels of lipids as functions of the starting materials and the fermentation conditions. Also, the obstacles associated with the use of LCB are described, along with a potentially viable approach for overcoming the obstacles that currently preclude the

  5. Cellulose extraction from Zoysia japonica pretreated by alumina-doped MgO in AMIMCl.

    PubMed

    Liu, Le; Ju, Meiting; Li, Weizun; Jiang, Yang

    2014-11-26

    In this study, alumina-doped MgO was produced as a solid alkali for lignocellulose pretreatment. Pretreatment with alumina-doped MgO disrupted the lignocellulose structure and significantly reduced the lignin content of the Z. japonica. After pretreatment, Z. japonica showed significant solubility in 1-allyl-3-methylimidazolium chloride (AMIMCl). The similar high solubility of pretreated Z. japonica samples by original alumina-doped MgO and used alumina-doped MgO also proved that alumina-doped MgO had strong stability, which can be recycled and used repeatedly. The regenerated cellulose was similar to microcrystalline cellulose according to FTIR and NMR analyses. Compared to microcrystalline cellulose, only the crystallinity of the regenerated cellulose decreased.

  6. Oxidative lime pretreatment of Dacotah switchgrass.

    PubMed

    Falls, Matthew; Sierra-Ramirez, Rocio; Holtzapple, Mark T

    2011-09-01

    Oxidative lime pretreatment increases the enzymatic digestibility of lignocellulosic biomass primarily by removing lignin. In this study, recommended pretreatment conditions (reaction temperature, oxygen pressure, lime loading, and time) were determined for Dacotah switchgrass. Glucan and xylan overall hydrolysis yields (72 h, 15 FPU/g raw glucan) were measured for 105 different reaction conditions involving three different reactor configurations (very short term, short term, and long term). The short-term reactor was the most productive. At the recommended pretreatment condition (120 °C, 6.89 bar O(2), 240 min), it achieved an overall glucan hydrolysis yield of 85.2 g glucan hydrolyzed/100 g raw glucan and an overall xylan yield of 50.1 g xylan hydrolyzed/100 g raw xylan. At this condition, glucan oligomers (1.80 g glucan recovered/100 g glucan in raw biomass) and xylan oligomers (25.20 g xylan recovered/100 g xylan in raw biomass) were recovered from the pretreatment liquor, which compensate for low pretreatment yields.

  7. Evaluation of Relationships between Growth Rate, Tree Size, Lignocellulose Composition, and Enzymatic Saccharification in Interspecific Corymbia Hybrids and Parental Taxa

    PubMed Central

    Healey, Adam L.; Lee, David J.; Lupoi, Jason S.; Papa, Gabriella; Guenther, Joel M.; Corno, Luca; Adani, Fabrizio; Singh, Seema; Simmons, Blake A.; Henry, Robert J.

    2016-01-01

    In order for a lignocellulosic bioenergy feedstock to be considered sustainable, it must possess a high rate of growth to supply biomass for conversion. Despite the desirability of a fast growth rate for industrial application, it is unclear what effect growth rate has on biomass composition or saccharification. We characterized Klason lignin, glucan, and xylan content with response to growth in Corymbia interspecific F1 hybrid families (HF) and parental species Corymbia torelliana and C. citriodora subspecies variegata and measured the effects on enzymatic hydrolysis from hydrothermally pretreated biomass. Analysis of biomass composition within Corymbia populations found similar amounts of Klason lignin content (19.7–21.3%) among parental and hybrid populations, whereas glucan content was clearly distinguished within C. citriodora subspecies variegata (52%) and HF148 (60%) as compared to other populations (28–38%). Multiple linear regression indicates that biomass composition is significantly impacted by tree size measured at the same age, with Klason lignin content increasing with diameter breast height (DBH) (+0.12% per cm DBH increase), and glucan and xylan typically decreasing per DBH cm increase (-0.7 and -0.3%, respectively). Polysaccharide content within C. citriodora subspecies variegata and HF-148 were not significantly affected by tree size. High-throughput enzymatic saccharification of hydrothermally pretreated biomass found significant differences among Corymbia populations for total glucose production from biomass, with parental Corymbia torelliana and hybrids HF-148 and HF-51 generating the highest amounts of glucose (~180 mg/g biomass, respectively), with HF-51 undergoing the most efficient glucan-to-glucose conversion (74%). Based on growth rate, biomass composition, and further optimization of enzymatic saccharification yield, high production Corymbia hybrid trees are potentially suitable for fast-rotation bioenergy or biomaterial production

  8. Evaluation of Relationships between Growth Rate, Tree Size, Lignocellulose Composition, and Enzymatic Saccharification in Interspecific Corymbia Hybrids and Parental Taxa

    DOE PAGES

    Healey, Adam L.; Lee, David J.; Lupoi, Jason S.; ...

    2016-11-18

    In order for a lignocellulosic bioenergy feedstock to be considered sustainable,it must possess a high rate of growth to supply biomass for conversion. Despite the desirability of a fast growth rate for industrial application,it is unclear what effect growth rate has on biomass composition or saccharification. We characterized Klason lignin,glucan,and xylan content with response to growth in Corymbia interspecific F1 hybrid families (HF) and parental species Corymbia torelliana and C. citriodora subspecies variegata and measured the effects on enzymatic hydrolysis from hydrothermally pretreated biomass. Analysis of biomass composition within Corymbia populations found similar amounts of Klason lignin content (19.7–21.3%) amongmore » parental and hybrid populations,whereas glucan content was clearly distinguished within C. citriodora subspecies variegata (52%) and HF148 (60%) as compared to other populations (28–38%). Multiple linear regression indicates that biomass composition is significantly impacted by tree size measured at the same age,with Klason lignin content increasing with diameter breast height (DBH) (+0.12% per cm DBH increase),and glucan and xylan typically decreasing per DBH cm increase (-0.7 and -0.3%,respectively). Polysaccharide content within C. citriodora subspecies variegata and HF-148 were not significantly affected by tree size. High-throughput enzymatic saccharification of hydrothermally pretreated biomass found significant differences among Corymbia populations for total glucose production from biomass,with parental Corymbia torelliana and hybrids HF-148 and HF-51 generating the highest amounts of glucose (~180 mg/g biomass,respectively),with HF-51 undergoing the most efficient glucan-to-glucose conversion (74%). Based on growth rate,biomass composition,and further optimization of enzymatic saccharification yield,high production Corymbia hybrid trees are potentially suitable for fast-rotation bioenergy or biomaterial production.« less

  9. Rapid and accurate determination of the lignin content of lignocellulosic biomass by solid-state NMR.

    PubMed

    Fu, Li; McCallum, Scott A; Miao, Jianjun; Hart, Courtney; Tudryn, Gregory J; Zhang, Fuming; Linhardt, Robert J

    2015-02-01

    Biofuels and biomaterials, produced from lignocellulosic feedstock, require facile access to cellulose and hemicellulose to be competitive with petroleum processing and sugar-based fermentation. Physical-chemical barriers resulting from lignin complicates the hydrolysis biomass into fermentable sugars. Thus, the amount of lignin within a substrate is critical in determining biomass processing. The application of (13)C cross-polarization, magic-angle spinning, and solid-state nuclear magnetic resonance for the direct quantification of lignin content in biomass is examined. Using a standard curve constructed from pristine lignin and cellulose, the lignin content of a biomass sample is accurately determined through direct measurement without chemical or enzymatic pre-treatment.

  10. Ethanol production from poplar wood through enzymatic saccharification and fermentation by dilute acid and SPORL pretreatments

    Treesearch

    Z.J. Wang; J.Y. Zhu; Ronald S. Jr. Zalesny; K.F. Chen

    2012-05-01

    Dilute acid (DA) and Sulfite Pretreatment to Overcome Recalcitrance of Lignocelluloses (SPORL) pretreatments were directly applied to wood chips of four poplar wood samples of different genotypes (hereafter referred to as poplars; Populus tremuloides Michx. ‘native aspen collection’; Populus deltoides Bartr. ex Marsh x Populus nigra L. ‘NE222’ and ‘DN5’; P. nigra x...

  11. Engineering Sugar Utilization and Microbial Tolerance toward Lignocellulose Conversion.

    PubMed

    Nieves, Lizbeth M; Panyon, Larry A; Wang, Xuan

    2015-01-01

    Production of fuels and chemicals through a fermentation-based manufacturing process that uses renewable feedstock such as lignocellulosic biomass is a desirable alternative to petrochemicals. Although it is still in its infancy, synthetic biology offers great potential to overcome the challenges associated with lignocellulose conversion. In this review, we will summarize the identification and optimization of synthetic biological parts used to enhance the utilization of lignocellulose-derived sugars and to increase the biocatalyst tolerance for lignocellulose-derived fermentation inhibitors. We will also discuss the ongoing efforts and future applications of synthetic integrated biological systems used to improve lignocellulose conversion.

  12. Anaerobic digestion of lignocellulosic biomass: challenges and opportunities.

    PubMed

    Sawatdeenarunat, Chayanon; Surendra, K C; Takara, Devin; Oechsner, Hans; Khanal, Samir Kumar

    2015-02-01

    Anaerobic digestion (AD) of lignocellulosic biomass provides an excellent opportunity to convert abundant bioresources into renewable energy. Rumen microorganisms, in contrast to conventional microorganisms, are an effective inoculum for digesting lignocellulosic biomass due to their intrinsic ability to degrade substrate rich in cellulosic fiber. However, there are still several challenges that must be overcome for the efficient digestion of lignocellulosic biomass. Anaerobic biorefinery is an emerging concept that not only generates bioenergy, but also high-value biochemical/products from the same feedstock. This review paper highlights the current status of lignocellulosic biomass digestion and discusses its challenges. The paper also discusses the future research needs of lignocellulosic biomass digestion.

  13. Engineering Sugar Utilization and Microbial Tolerance toward Lignocellulose Conversion

    PubMed Central

    Nieves, Lizbeth M.; Panyon, Larry A.; Wang, Xuan

    2015-01-01

    Production of fuels and chemicals through a fermentation-based manufacturing process that uses renewable feedstock such as lignocellulosic biomass is a desirable alternative to petrochemicals. Although it is still in its infancy, synthetic biology offers great potential to overcome the challenges associated with lignocellulose conversion. In this review, we will summarize the identification and optimization of synthetic biological parts used to enhance the utilization of lignocellulose-derived sugars and to increase the biocatalyst tolerance for lignocellulose-derived fermentation inhibitors. We will also discuss the ongoing efforts and future applications of synthetic integrated biological systems used to improve lignocellulose conversion. PMID:25741507

  14. Effects of SPORL and dilute acid pretreatment on substrate morphology, cell physical and chemical wall structures, and subsequent enzymatic hydrolysis of lodgepole pine

    Treesearch

    Xinping Li; Xiaolin Luo; Kecheng Li; J.Y. Zhu; J. Dennis Fougere; Kimberley Clarke

    2012-01-01

    The effects of pretreatment by dilute acid and sulfite pretreatment to overcome recalcitrance of lignocellulose (SPORL) on substrate morphology, cell wall physical and chemical structures, along with the subsequent enzymatic hydrolysis of lodgepole pine substrate were investigated. FE-SEM and TEM images of substrate structural morphological changes showed that SPORL...

  15. 3D dose reconstruction of pretreatment verification plans using multiple 2D planes from the OCTAVIUS/Seven29 phantom array.

    PubMed

    Calvo, O; Stathakis, S; Gutiérrez, A N; Esquivel, C; Papanikolaou, N

    2012-02-01

    The purpose of this study is to evaluate 3D dose reconstruction of pretreatment verification plans using multiple 2D planes acquired from the OCTAVIUS phantom and the Seven29 detector array. Eight VMAT patient treatment plans of different sites were delivered onto the OCTAVIUS phantom. The plans span a variety of tumor site locations from low to high plan complexity. A patient specific quality assurance (QA) plan was created and delivered for each of the 8 patients using the OCTAVIUS phantom in which the Seven29 detector array was placed. Each plan was delivered four times by rotating the phantom in 45° increments along its longitudinal axis. The treatment plans were delivered using a Novalis Tx with the HD120 MLC. Each of the four corresponding planar doses was exported as a text file for further analysis. An in-house MATLAB code was used to process the planar dose information. A cylindrical geometry-based, linear interpolation method was utilized to generate the measured 3D dose reconstruction. The TPS calculated volumetric dose was exported and compared against the measured reconstructed volumetric dose. Dose difference, dose area histograms (DAH), isodose lines, profiles, 2D and 3D gamma were used for evaluation. The interpolation method shows good agreement (<2%) between the planned dose distributions in the high dose region but shows discrepancies in the low dose region. Horizontal profiles, dose area histograms and isodose lines show good agreement for the sagittal and coronal planes but demonstrate slight discrepancies in the transverse plane. The 3D gamma index average was 92.4% for all patients when a 5%/5 mm gamma passing rate criteria was employed but dropped to <80.1% on average when parameters were reduced to 2%/2 mm. A simple cylindrical geometry-based, linear interpolation method is able to predict good agreement in the high dose region between the reconstructed volumetric dose and the planned volumetric dose. It is important to mention that the

  16. Simultaneous conversion of all cell wall components by oleaginous fungus without chemi-physical pretreatment

    USDA-ARS?s Scientific Manuscript database

    Lignin utilization during biomass conversion has been a major challenge for lignocellulosic biofuel. In particular, the conversion of lignin along with carbohydrate for fungible fuels and chemicals will both improve the overall carbon efficiency and reduce the need for chemical pretreatments. Howeve...

  17. Ethanosolv Pretreatment of Bamboo with Dilute Acid for Efficient Enzymatic Saccharification

    Treesearch

    Zhiqiang Li; Zehui Jiang; Benhua Fei; Zhiyong Cai; Xuejun Pan

    2012-01-01

    Bamboo is a potential lignocellulosic biomass for the production of bioethanol because of its high cellulose and hemicelluloses content. In this research, ethanosolv pretreatment catalyzed by sulfuric acid was studied in order to enhance enzymatic saccharification of moso bamboo. The addition of 2% (w/w on bamboo) sulfuric acid in water or 75% (v/v) ethanol was...

  18. Application of high throughput pretreatment and co-hydrolysis system to thermochemical pretreatment. Part 1: dilute acid.

    PubMed

    Gao, Xiadi; Kumar, Rajeev; DeMartini, Jaclyn D; Li, Hongjia; Wyman, Charles E

    2013-03-01

    Because conventional approaches for evaluating sugar release from the coupled operations of pretreatment and enzymatic hydrolysis are extremely time and material intensive, high throughput (HT) pretreatment and enzymatic hydrolysis systems have become vital for screening large numbers of lignocellulosic biomass samples to identify feedstocks and/or processing conditions that significantly improve performance and lower costs. Because dilute acid pretreatment offers many important advantages in rendering biomass highly susceptible to subsequent enzymatic hydrolysis, a high throughput pretreatment and co-hydrolysis (HTPH) approach was extended to employ dilute acid as a tool to screen for enhanced performance. First, a single-step neutralization and buffering method was developed to allow effective enzymatic hydrolysis of the whole pretreated slurry. Switchgrass and poplar were then pretreated with 0.5% and 1% acid loadings at a 5% solids concentration, the resulting slurry conditioned with the buffering approach, and the entire mixture enzymatically hydrolyzed. The resulting sugar yields demonstrated that single-step neutralizing and buffering was capable of adjusting the pH as needed for enzymatic saccharification, as well as overcoming enzyme inhibition by compounds released in pretreatment. In addition, the effects of pretreatment conditions and biomass types on susceptibility of pretreated substrates to enzymatic conversion were clearly discernible, demonstrating the method to be a useful extension of HTPH systems.

  19. Modification of lignocellulosic materials by laccase

    Treesearch

    William Kenealy; John Klungness; Mandla Tshabalala; Roland Gleisner; Eric Horn; Masood Akhtar; Hilda Zulaica-Villagomez; Gisela Buschle-Diller

    2003-01-01

    Altering the surface properties of pulp can enhance binding, increase paper strength, and decrease the cost of fiber. In this study, we modified lignocellulosic materials (bark and pulp) with laccase and selected substrates to change the nature of the pulp surface. Modified pulps were evaluated by the amount of methylene blue (a cationic dye) that would bind to the...

  20. Semantic text mining support for lignocellulose research

    PubMed Central

    2012-01-01

    Background Biofuels produced from biomass are considered to be promising sustainable alternatives to fossil fuels. The conversion of lignocellulose into fermentable sugars for biofuels production requires the use of enzyme cocktails that can efficiently and economically hydrolyze lignocellulosic biomass. As many fungi naturally break down lignocellulose, the identification and characterization of the enzymes involved is a key challenge in the research and development of biomass-derived products and fuels. One approach to meeting this challenge is to mine the rapidly-expanding repertoire of microbial genomes for enzymes with the appropriate catalytic properties. Results Semantic technologies, including natural language processing, ontologies, semantic Web services and Web-based collaboration tools, promise to support users in handling complex data, thereby facilitating knowledge-intensive tasks. An ongoing challenge is to select the appropriate technologies and combine them in a coherent system that brings measurable improvements to the users. We present our ongoing development of a semantic infrastructure in support of genomics-based lignocellulose research. Part of this effort is the automated curation of knowledge from information on fungal enzymes that is available in the literature and genome resources. Conclusions Working closely with fungal biology researchers who manually curate the existing literature, we developed ontological natural language processing pipelines integrated in a Web-based interface to assist them in two main tasks: mining the literature for relevant knowledge, and at the same time providing rich and semantically linked information. PMID:22595090

  1. Lignocellulosic biomass conversion to ethanol by Saccharomyces

    USDA-ARS?s Scientific Manuscript database

    As interest in alternative energy sources rises, the concept of agriculture as an energy producer has become increasingly attractive (Outlaw et al. 2005). Renewable biomass, including lignocellulosic materials and agricultural residues, are low-cost materials for bioethanol production (Bothast and ...

  2. Semantic text mining support for lignocellulose research.

    PubMed

    Meurs, Marie-Jean; Murphy, Caitlin; Morgenstern, Ingo; Butler, Greg; Powlowski, Justin; Tsang, Adrian; Witte, René

    2012-04-30

    Biofuels produced from biomass are considered to be promising sustainable alternatives to fossil fuels. The conversion of lignocellulose into fermentable sugars for biofuels production requires the use of enzyme cocktails that can efficiently and economically hydrolyze lignocellulosic biomass. As many fungi naturally break down lignocellulose, the identification and characterization of the enzymes involved is a key challenge in the research and development of biomass-derived products and fuels. One approach to meeting this challenge is to mine the rapidly-expanding repertoire of microbial genomes for enzymes with the appropriate catalytic properties. Semantic technologies, including natural language processing, ontologies, semantic Web services and Web-based collaboration tools, promise to support users in handling complex data, thereby facilitating knowledge-intensive tasks. An ongoing challenge is to select the appropriate technologies and combine them in a coherent system that brings measurable improvements to the users. We present our ongoing development of a semantic infrastructure in support of genomics-based lignocellulose research. Part of this effort is the automated curation of knowledge from information on fungal enzymes that is available in the literature and genome resources. Working closely with fungal biology researchers who manually curate the existing literature, we developed ontological natural language processing pipelines integrated in a Web-based interface to assist them in two main tasks: mining the literature for relevant knowledge, and at the same time providing rich and semantically linked information.

  3. Mechanical pretreatment of waste paper for biogas production.

    PubMed

    Rodriguez, C; Alaswad, A; El-Hassan, Z; Olabi, A G

    2017-10-01

    In the anaerobic digestion of lignocellulosic materials such as waste paper, the accessibility of microorganisms to the fermentable sugars is restricted by their complex structure. A mechanical pretreatment with a Hollander beater was assessed in order to reduce the biomass particle size and to increase the feedstock' specific surface area available to the microorganisms, and therefore improve the biogas yield. Pretreatment of paper waste for 60min improves the methane yield by 21%, from a value of 210ml/gVS corresponding to untreated paper waste to 254ml/gVS. 30min pretreatment have no significant effect on the methane yield. A response surface methodology was used to evaluate the effect of the beating time and feedstock/inoculum ratio on the methane yield. An optimum methane yield of 253ml/gVS was achieved at 55min of beating pretreatment and a F/I ratio of 0.3. Copyright © 2017 Elsevier Ltd. All rights reserved.

  4. Effect of chip size on steam explosion pretreatment of softwood.

    PubMed

    Ballesteros, I; Oliva, J M; Navarro, A A; González, A; Carrasco, J; Ballesteros, M

    2000-01-01

    Although considerable progress has been made in technology for converting lignocellulosic biomass into ethanol, substantial opportunities still exist to reduce production costs. In biomass pretreatment, reducing milling power is a technological improvement that will substantially lower production costs for ethanol. Improving sugar yield from hemicellulose hydrolysis would also reduce ethanol production costs. Thus, it would be desirable to test innovative pretreatment conditions to improve the economics by reducing electrical power of the milling stage and by optimizing pretreatment recovery of hemicellulose, as well as to enhance cellulose hydrolysis. The objective of this study was to evaluate the effect of chip size (2-5, 5-8, and 8-12 mm) on steam-explosion pretreatment (190 and 210 degrees C, 4 and 8 min) of softwood (Pinus pinaster).

  5. Theoretical study on interactions between lignocellulose components and ionic liquids

    NASA Astrophysics Data System (ADS)

    Wang, J.; Zhuang, W. C.; Shi, X. Q.; Cao, W. L.

    2017-09-01

    Interactions between lignocellulose and ionic liquids have been studied by designed lignocellulose components models, and their complexes with 1-butyl-3-methylimidazolium chloride. All the structures were optimized by DFT methods and hydrogen bonds within lignocelluloses components, and their complexes with 1-butyl-3-methylimidazolium chloride were investigated by AIM calculations. Our calculated results demonstrate that when dissolved in ionic liquids, the stable intermolecular hydrogen bonds and weak π-stacking interactions between ionic liquids and lignocelluloses components reduce the energy of complex systems, which are advantageous for lignocelluloses components dissolution in ionic liquids. Moreover, there are deformation accrued for both lignocelluloses components and ionic liquids, which may be a prerequisite for lignocelluloses components dissolution in ionic liquids.

  6. Comparison of microwave and conduction-convection heating autohydrolysis pretreatment for bioethanol production.

    PubMed

    Aguilar-Reynosa, Alejandra; Romaní, Aloia; Rodríguez-Jasso, Rosa M; Aguilar, Cristóbal N; Garrote, Gil; Ruiz, Héctor A

    2017-06-20

    This work describes the application of two forms of heating for autohydrolysis pretreatment on isothermal regimen: conduction-convection heating and microwave heating processing using corn stover as raw material for bioethanol production. Pretreatments were performed using different operational conditions: residence time (10-50 min) and temperature (160-200°C) for both pretreatments. Subsequently, the susceptibility of pretreated solids was studied using low enzyme loads, and high substrate loads. The highest conversion was 95.1% for microwave pretreated solids. Also solids pretreated by microwave heating processing showed better ethanol conversion in simultaneous saccharification and fermentation process (92% corresponding to 33.8g/L). Therefore, microwave heating processing is a promising technology in the pretreatment of lignocellulosic materials. Copyright © 2017 Elsevier Ltd. All rights reserved.

  7. Impact of surfactant type for ionic liquid pretreatment on enhancing delignification of rice straw.

    PubMed

    Chang, Ken-Lin; Chen, Xi-Mei; Wang, Xiao-Qin; Han, Ye-Ju; Potprommanee, Laddawan; Liu, Jing-Yong; Liao, Yu-Ling; Ning, Xun-An; Sun, Shui-Yu; Huang, Qing

    2017-03-01

    This work describes an environmentally friendly method for pretreating rice straw by using 1-Allyl-3-methylimidazolium chloride ([AMIM]Cl) as an ionic liquid (IL) assisted by surfactants. The impacts of surfactant type (including nonionic-, anionic-, cationic- and bio-surfactant) on the ionic liquid pretreatment were investigated. The bio-surfactant+IL-pretreated rice straw showed significant lignin removal (26.14%) and exhibited higher cellulose conversion (36.21%) than the untreated (16.16%) rice straw. The cellulose conversion of the rice straw pretreated with bio-surfactant+IL was the highest and the lowest was observed for pretreated with cationic-surfactant+IL. Untreated and pretreated rice straw was thoroughly characterized through SEM and AFM. In conclusion, the results provided an effective and environmental method for pretreating lignocellulosic substrates by using green solvent (ionic liquid) and biodegradable bio-surfactant.

  8. Long term storage of dilute acid pretreated corn stover feedstock and ethanol fermentability evaluation.

    PubMed

    Zhang, Jian; Shao, Shuai; Bao, Jie

    2016-02-01

    This study reported a new solution of lignocellulose feedstock storage based on the distributed pretreatment concept. The dry dilute sulfuric acid pretreatment (DDAP) was conducted on corn stover feedstock, instead of ammonia fiber explosion pretreatment. Then the dry dilute acid pretreated corn stover was stored for three months during summer season with high temperature and humidity. No negative aspects were found on the physical property, composition, hydrolysis yield and ethanol fermentability of the long term stored pretreated corn stover, plus the additional merits including no chemicals recovery operation, anti-microbial contaminant environment from stronger acid and inhibitor contents, as well as the mild and slow hydrolysis in the storage. The new pretreatment method expanded the distributed pretreatment concept of feedstock storage with potential for practical application. Copyright © 2015 Elsevier Ltd. All rights reserved.

  9. Low-energy biomass pretreatment with deep eutectic solvents for bio-butanol production.

    PubMed

    Procentese, Alessandra; Raganati, Francesca; Olivieri, Giuseppe; Russo, Maria Elena; Rehmann, Lars; Marzocchella, Antonio

    2017-11-01

    Waste lettuce leaves - from the "fresh cut vegetable" industry - were pretreated with the deep eutectic solvent (DES) made of choline chloride - glycerol. Reaction time (3-16h) and the operation temperature (80-150°C) were investigated. Enzymatic glucose and xylose yields of 94.9% and 75.0%, respectively were obtained when the biomass was pretreated at 150°C for 16h. Sugars contained in the biomass hydrolysate were fermented in batch cultures of Clostridium acetobutylicum DSMZ 792. The energy consumption and the energy efficiency related to the DES pretreatment were calculated and compared to the most common lignocellulosic pretreatment processes reported in the literature. The DES pretreatment process was characterized by lower energy required (about 28% decrease and 72% decrease) than the NAOH pretreatment and steam explosion process respectively. The Net Energy Ratio (NER) value related to butanol production via DES biomass pretreatment was assessed. Copyright © 2017 Elsevier Ltd. All rights reserved.

  10. Effects of ammonium carbonate pretreatment on the enzymatic digestibility and structural features of rice straw.

    PubMed

    Kim, Ilgook; Lee, Bomi; Song, Dongsu; Han, Jong-In

    2014-08-01

    Rice straw was pretreated with ammonium carbonate ((NH₄)₂CO₃), a major intermediate of ammonia-based carbon capture process, and evaluated for the effects of critical pretreatment parameters including (NH₄)₂CO₃ concentration (5-25%), temperature (60-90°C), and reaction time (4-24 h) on enzymatic digestibility. Pretreatment of rice straw at 80°C for 12 h using 20% (NH₄)₂CO₃ and 1:10 solid to liquid ratio resulted in enzymatic digestibility of 72.2%, which was higher than that pretreated with the same moles of aqueous ammonia. We also investigated physical characteristics of pretreated rice straw, including surface area, pore volume and size, crystallinity, and scanning electron microscopy image. The ammonium carbonate pretreatment process, as a novel pretreatment technique, enhanced enzymatic hydrolysis of lignocellulose by altering structural features. Copyright © 2014 Elsevier Ltd. All rights reserved.

  11. Biogas production and saccharification of Salix pretreated at different steam explosion conditions.

    PubMed

    Horn, Svein J; Estevez, Maria M; Nielsen, Henrik K; Linjordet, Roar; Eijsink, Vincent G H

    2011-09-01

    Different steam explosion conditions were applied to Salix chips and the effect of this pretreatment was evaluated by running both enzymatic hydrolysis and biogas tests. Total enzymatic release of glucose and xylose increased with pretreatment harshness, with maximum values being obtained after pretreatment for 10 min at 210°C. Harsher pretreatment conditions did not increase glucose release, led to degradation of xylose and to formation of furfurals. Samples pretreated at 220 and 230°C initially showed low production of biogas, probably because of inhibitors produced during the pretreatment, but the microbial community was able to adapt and showed high final biogas production. Interestingly, final biogas yields correlated well with sugar yields after enzymatic hydrolysis, suggesting that at least in some cases a 24h enzymatic assay may be developed as a quick method to predict the effects of pretreatment of lignocellulosic biomass on biogas yields.

  12. Adaptation to low pH and lignocellulosic inhibitors resulting in ethanolic fermentation and growth of Saccharomyces cerevisiae

    DOE PAGES

    Narayanan, Venkatachalam; Sànchez i Nogué, Violeta; van Niel, Ed W. J.; ...

    2016-08-26

    Here, lignocellulosic bioethanol from renewable feedstocks using Saccharomyces cerevisiae is a promising alternative to fossil fuels owing to environmental challenges. S. cerevisiae is frequently challenged by bacterial contamination and a combination of lignocellulosic inhibitors formed during the pre-treatment, in terms of growth, ethanol yield and productivity. We investigated the phenotypic robustness of a brewing yeast strain TMB3500 and its ability to adapt to low pH thereby preventing bacterial contamination along with lignocellulosic inhibitors by short-term adaptation and adaptive lab evolution (ALE). The short-term adaptation strategy was used to investigate the inherent ability of strain TMB3500 to activate a robust phenotypemore » involving pre-culturing yeast cells in defined medium with lignocellulosic inhibitors at pH 5.0 until late exponential phase prior to inoculating them in defined media with the same inhibitor cocktail at pH 3.7. Adapted cells were able to grow aerobically, ferment anaerobically (glucose exhaustion by 19 +/- 5 h to yield 0.45 +/- 0.01 g ethanol g glucose-1) and portray significant detoxification of inhibitors at pH 3.7, when compared to non-adapted cells. ALE was performed to investigate whether a stable strain could be developed to grow and ferment at low pH with lignocellulosic inhibitors in a continuous suspension culture. Though a robust population was obtained after 3600 h with an ability to grow and ferment at pH 3.7 with inhibitors, inhibitor robustness was not stable as indicated by the characterisation of the evolved culture possibly due to phenotypic plasticity. With further research, this short-term adaptation and low pH strategy could be successfully applied in lignocellulosic ethanol plants to prevent bacterial contamination.« less

  13. Adaptation to low pH and lignocellulosic inhibitors resulting in ethanolic fermentation and growth of Saccharomyces cerevisiae.

    PubMed

    Narayanan, Venkatachalam; Sànchez I Nogué, Violeta; van Niel, Ed W J; Gorwa-Grauslund, Marie F

    2016-12-01

    Lignocellulosic bioethanol from renewable feedstocks using Saccharomyces cerevisiae is a promising alternative to fossil fuels owing to environmental challenges. S. cerevisiae is frequently challenged by bacterial contamination and a combination of lignocellulosic inhibitors formed during the pre-treatment, in terms of growth, ethanol yield and productivity. We investigated the phenotypic robustness of a brewing yeast strain TMB3500 and its ability to adapt to low pH thereby preventing bacterial contamination along with lignocellulosic inhibitors by short-term adaptation and adaptive lab evolution (ALE). The short-term adaptation strategy was used to investigate the inherent ability of strain TMB3500 to activate a robust phenotype involving pre-culturing yeast cells in defined medium with lignocellulosic inhibitors at pH 5.0 until late exponential phase prior to inoculating them in defined media with the same inhibitor cocktail at pH 3.7. Adapted cells were able to grow aerobically, ferment anaerobically (glucose exhaustion by 19 ± 5 h to yield 0.45 ± 0.01 g ethanol g glucose(-1)) and portray significant detoxification of inhibitors at pH 3.7, when compared to non-adapted cells. ALE was performed to investigate whether a stable strain could be developed to grow and ferment at low pH with lignocellulosic inhibitors in a continuous suspension culture. Though a robust population was obtained after 3600 h with an ability to grow and ferment at pH 3.7 with inhibitors, inhibitor robustness was not stable as indicated by the characterisation of the evolved culture possibly due to phenotypic plasticity. With further research, this short-term adaptation and low pH strategy could be successfully applied in lignocellulosic ethanol plants to prevent bacterial contamination.

  14. Sophorolipid production from lignocellulosic biomass feedstocks

    NASA Astrophysics Data System (ADS)

    Samad, Abdul

    , the yield of SLs was 0.55 g/g carbon (sugars plus oil) for cultures with bagasse hydrolysates. Further, SL production was investigated using sweet sorghum bagasse and corn stover hydrolysates derived from different pretreatment conditions. For the former and latter sugar sources, yellow grease or soybean oil was supplemented at different doses to enhance sophorolipid yield. 14-day batch fermentation on bagasse hydrolysates with 10, 40 and 60 g/L of yellow grease had cell densities of 5.7 g/L, 6.4 g/L and 7.8 g/L, respectively. The study also revealed that the yield of SLs on bagasse hydrolysate decreased from 0.67 to 0.61 and to 0.44 g/g carbon when yellow grease was dosed at 10, 40 and 60 g/L. With aforementioned increasing yellow grease concentration, the residual oil left after 14 days was recorded as 3.2 g/L, 8.5 g/L and 19.9 g/L. For similar experimental conditions, the cell densities observed for corn stover hydrolysate combined with soybean oil at 10, 20 and 40 g/L concentration were 6.1 g/L, 5.9 g/L, and 5.4 g/L respectively. Also, in the same order of oil dose supplemented, the residual oil recovered after 14-day was 8.5 g/L, 8.9 g/L, and 26.9 g/L. Corn stover hydrolysate mixed with the 10, 20 and 40 g/L soybean oil, the SL yield was 0.19, 0.11 and 0.09 g/g carbon. Overall, both hydrolysates supported cell growth and sophorolipid production. The results from this research show that hydrolysates derived from the different lignocellulosic biomass feedstocks can be utilized by C. bombicola to achieve substantial yields of SLs. Based upon the results revealed by several batch-stage experiments, it can be stated that there is great potential for scaling up and industrial scale production of these high value products in future.

  15. Low-heat alkaline pretreatment of biomass for dairy anaerobic codigestion.

    PubMed

    Jin, Guang; Bierma, Tom

    2014-01-01

    In this research, low-heat alkaline pretreatment was evaluated to determine the extent to which urban landscape waste (yard waste), corn stover, and switchgrass could be codigested under conditions typical of US farm-based anaerobic digestion (AD). Waste heat from combined heat and power (CHP) units associated with AD could make such pretreatment economical. Short-term batch digestion studies and 8-week continuous-feed studies were used to screen and evaluate various pretreatment conditions. Results indicate that maple and oak leaves did not digest well, even with pretreatment. Pretreatment did improve digestion of corn leaves and stalks as well as switchgrass. However, these materials also digested reasonably well even without pretreatment. No digester operational problems were observed during continuous-feed studies of intermittently stirred bench top digesters, but optimal levels of alkali, temperature, and pretreatment time may be specific to the feedstock, particle size, and digester loading rate. Results suggest that some common lignocellulosic biomass materials, such as corn stover and switchgrass, could be successfully codigested in many existing farm-based digesters. Interestingly, without pretreatment, switchgrass digestion improved over 20-fold when digested with seed culture from a dairy digester compared to seed culture from a municipal digester, suggesting that culture acclimation could be as important as pretreatment in improving digestion of specific lignocellulosic feedstocks.

  16. Green Processing of Lignocellulosic Biomass and Its Derivatives in Deep Eutectic Solvents.

    PubMed

    Tang, Xing; Zuo, Miao; Li, Zheng; Liu, Huai; Xiong, Caixia; Zeng, Xianhai; Sun, Yong; Hu, Lei; Liu, Shijie; Lei, Tingzhou; Lin, Lu

    2017-07-10

    The scientific community has been seeking cost-competitive and green solvents with good dissolving capacity for the valorization of lignocellulosic biomass. At this point, deep eutectic solvents (DESs) are currently emerging as a new class of promising solvents that are generally liquid eutectic mixtures formed by self-association (or hydrogen-bonding interaction) of two or three components. DESs are attractive solvents for the fractionation (or pretreatment) of lignocellulose and the valorization of lignin, owing to the high solubility of lignin in DESs. DESs are also employed as effective media for the modification of cellulose to afford functionalized cellulosic materials, such as cellulose nanocrystals. More interestingly, biomassderived carbohydrates, such as fructose, can be used as one of the constituents of DESs and then dehydrated to 5-hydroxymethylfurfural in high yield. In this review, a comprehensive summary of recent contribution of DESs to the processing of lignocellulosic biomass and its derivatives is provided. Moreover, further discussion about the challenges of the application of DESs in biomass processing is presented. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  17. Evolutionary engineering of Saccharomyces cerevisiae for enhanced tolerance to hydrolysates of lignocellulosic biomass.

    PubMed

    Almario, María P; Reyes, Luis H; Kao, Katy C

    2013-10-01

    Lignocellulosic biomass has become an important feedstock to mitigate current ethical and economical concerns related to the bio-based production of fuels and chemicals. During the pre-treatment and hydrolysis of the lignocellulosic biomass, a complex mixture of sugars and inhibitors are formed. The inhibitors interfere with microbial growth and product yields. This study uses an adaptive laboratory evolution method called visualizing evolution in real-time (VERT) to uncover the molecular mechanisms associated with tolerance to hydrolysates of lignocellulosic biomass in Saccharomyces cerevisiae. VERT enables a more rational scheme for isolating adaptive mutants for characterization and molecular analyses. Subsequent growth kinetic analyses of the mutants in individual and combinations of common inhibitors present in hydrolysates (acetic acid, furfural, and hydroxymethylfurfural) showed differential levels of resistance to different inhibitors, with enhanced growth rates up to 57%, 12%, 22%, and 24% in hydrolysates, acetic acid, HMF and furfural, respectively. Interestingly, some of the adaptive mutants exhibited reduced fitness in the presence of individual inhibitors, but showed enhanced fitness in the presence of combinations of inhibitors compared to the parental strains. Transcriptomic analysis revealed different mechanisms for resistance to hydrolysates and a potential cross adaptation between oxidative stress and hydrolysates tolerance in several of the mutants.

  18. Utilization of selected biorenewable resources: solubilization of lignocellulosics and conjugation of soybean oil

    SciTech Connect

    Oshel, Reed E.

    2007-01-01

    In recent years, concern has risen over the use of fossil fuels due to their contribution to global warming, and to our dependence on imports of petroleum from nations that could pose a threat to national security. As a result, it has become increasingly important to develop technologies to replace fossil fuel based products with biorenewable alternatives. In this thesis nearly quantitative solubilization of lignocellulosic materials using phosphite esters has been realized, and is presented as a potential pretreatment for production of fermentable sugars for use in manufacturing commodity chemicals, specifically ethanol. Water solubilization of lignocellulosics using phosphite esters will enhance digestibility by disrupting the lignocellulose structure, changing cellulose morphology, and cleaving some glycosidic bonds. In a second project, soybean oil, which contains un-conjugated polyunsaturated fatty acid esters, is isomerized into oil containing conjugated polyunsaturates. The process is carried out under photochemical conditions using iodine as a catalyst in a hexanes solution to achieve 99% conjugation. The resulting conjugated soybean oil is demonstrated to have enhanced drying properties for use in alkyd resins.

  19. Catalytic fast pyrolysis of lignocellulosic biomass.

    PubMed

    Liu, Changjun; Wang, Huamin; Karim, Ayman M; Sun, Junming; Wang, Yong

    2014-11-21

    Increasing energy demand, especially in the transportation sector, and soaring CO2 emissions necessitate the exploitation of renewable sources of energy. Despite the large variety of new energy carriers, liquid hydrocarbon still appears to be the most attractive and feasible form of transportation fuel taking into account the energy density, stability and existing infrastructure. Biomass is an abundant, renewable source of energy; however, utilizing it in a cost-effective way is still a substantial challenge. Lignocellulose is composed of three major biopolymers, namely cellulose, hemicellulose and lignin. Fast pyrolysis of biomass is recognized as an efficient and feasible process to selectively convert lignocellulose into a liquid fuel-bio-oil. However bio-oil from fast pyrolysis contains a large amount of oxygen, distributed in hundreds of oxygenates. These oxygenates are the cause of many negative properties, such as low heating value, high corrosiveness, high viscosity, and instability; they also greatly limit the application of bio-oil particularly as transportation fuel. Hydrocarbons derived from biomass are most attractive because of their high energy density and compatibility with the existing infrastructure. Thus, converting lignocellulose into transportation fuels via catalytic fast pyrolysis has attracted much attention. Many studies related to catalytic fast pyrolysis of biomass have been published. The main challenge of this process is the development of active and stable catalysts that can deal with a large variety of decomposition intermediates from lignocellulose. This review starts with the current understanding of the chemistry in fast pyrolysis of lignocellulose and focuses on the development of catalysts in catalytic fast pyrolysis. Recent progress in the experimental studies on catalytic fast pyrolysis of biomass is also summarized with the emphasis on bio-oil yields and quality.

  20. Catalytic fast pyrolysis of lignocellulosic biomass

    SciTech Connect

    Liu, Changjun; Wang, Huamin; Karim, Ayman M.; Sun, Junming; Wang, Yong

    2014-11-21

    Increasing energy demand, especially in the transportation sector, and soaring CO2 emissions necessitate the exploitation of renewable sources of energy. Despite the large variety of new energy Q3 carriers, liquid hydrocarbon still appears to be the most attractive and feasible form of transportation fuel taking into account the energy density, stability and existing infrastructure. Biomass is an abundant, renewable source of energy; however, utilizing it in a cost-effective way is still a substantial challenge. Lignocellulose is composed of three major biopolymers, namely cellulose, hemicellulose and lignin. Fast pyrolysis of biomass is recognized as an efficient and feasible process to selectively convert lignocellulose into a liquid fuel—bio-oil. However bio-oil from fast pyrolysis contains a large amount of oxygen, distributed in hundreds of oxygenates. These oxygenates are the cause of many negative properties, such as low heating values, high corrosiveness, high viscosity, and instability; they also greatly Q4 limit the application of bio-oil particularly as transportation fuel. Hydrocarbons derived from biomass are most attractive because of their high energy density and compatibility with the existing infrastructure. Thus, converting lignocellulose into transportation fuels via catalytic fast pyrolysis has attracted much attention. Many studies related to catalytic fast pyrolysis of biomass have been published. The main challenge of this process is the development of active and stable catalysts that can deal with a large variety of decomposition intermediates from lignocellulose. This review starts with the current understanding of the chemistry in fast pyrolysis of lignocellulose and focuses on the development of catalysts in catalytic fast pyrolysis. Recent progress in the experimental studies on catalytic fast pyrolysis of biomass is also summarized with the emphasis on bio-oil yields and quality.

  1. Combination of high solids loading pretreatment and ethanol fermentation of whole slurry of pretreated rice straw to obtain high ethanol titers and yields.

    PubMed

    Jung, Young Hoon; Park, Hyun Min; Kim, Dong Hyun; Park, Yong-Cheol; Seo, Jin-Ho; Kim, Kyoung Heon

    2015-12-01

    In cellulosic ethanol production using lignocellulose, an increase in biomass solids loading during the pretreatment process significantly affects the final ethanol titer and the production cost. In this study, pretreatment using rice straw at high solids loading (20% (w/v)) was evaluated, using maleic acid as a catalyst. After pretreatment at optimal conditions of 190°C, 20 min, and 0.2% or 5% (w/v) maleic acid, the highest enzymatic digestibility obtained was over 80%. Simultaneous saccharification and fermentation (SSF) of the whole slurry of pretreated rice straw in the presence of activated carbon to separate inhibitory compounds generated a high ethanol yield of 62.8%, based on the initial glucan in unpretreated rice straw. These findings suggest that high solids loading pretreatment using maleic acid and SSF of the whole slurry of pretreated rice straw can be combined to improve the process economics of ethanol production. Copyright © 2015 Elsevier Ltd. All rights reserved.

  2. Development of a system for characterizing biomass quality of lignocellulosic feedstocks for biochemical conversion

    NASA Astrophysics Data System (ADS)

    Murphy, Patrick Thomas

    The purpose of this research was twofold: (i) to develop a system for screening lignocellulosic biomass feedstocks for biochemical conversion to biofuels and (ii) to evaluate brown midrib corn stover as feedstock for ethanol production. In the first study (Chapter 2), we investigated the potential of corn stover from bm1-4 hybrids for increased ethanol production and reduced pretreatment intensity compared to corn stover from the isogenic normal hybrid. Corn stover from hybrid W64A X A619 and respective isogenic bm hybrids was pretreated by aqueous ammonia steeping using ammonium hydroxide concentrations from 0 to 30%, by weight, and the resulting residues underwent simultaneous saccharification and cofermentation (SSCF) to ethanol. Dry matter (DM) digested by SSCF increased with increasing ammonium hydroxide concentration across all genotypes (P>0.0001) from 277 g kg-1 DM in the control to 439 g kg-1 DM in the 30% ammonium hydroxide pretreatment. The bm corn stover materials averaged 373 g kg-1 DM of DM digested by SSCF compared with 335 g kg-1 DM for the normal corn stover (P<0.0001). Of the bm mutations, bm3 had (i) the greatest effect on cell-wall carbohydrate hydrolysis of corn stover, (ii) the lowest initial cell-wall carbohydrate concentration, (iii) the lowest dry matter remaining after pretreatment, and (iv) the highest amount of monosaccharides released during enzymatic hydrolysis. However, bm corn stover did not reduce the severity of aqueous ammonia steeping pretreatment needed to maximize DM hydrolysis during SSCF compared with normal corn stover. In the remaining studies (Chapters 3 thru 5), a system for analyzing the quality of lignocellulosic biomass feedstocks for biochemical conversion to biofuels (i.e., pretreatment, enzymatic hydrolysis, and fermentation) was developed. To accomplish this, a carbohydrate availability model was developed to characterize feedstock quality. The model partitions carbohydrates within a feedstock material into

  3. Strong cellulase inhibitors from the hydrothermal pretreatment of wheat straw

    PubMed Central

    2013-01-01

    Background The use of the enzymatic hydrolysis of lignocellulose with subsequent fermentation to ethanol provides a green alternative for the production of transportation fuels. Because of its recalcitrant nature, the lignocellulosic biomass must be pretreated before enzymatic hydrolysis. However, the pretreatment often results in the formation of compounds that are inhibitory for the enzymes or fermenting organism. Although well recognized, little quantitative information on the inhibition of individual cellulase components by identified inhibitors is available. Results Strong cellulase inhibitors were separated from the liquid fraction of the hydrothermal pretreatment of wheat straw. HPLC and mass-spectroscopy analyses confirmed that the inhibitors were oligosaccharides (inhibitory oligosaccharides, IOS) with a degree of polymerization from 7 to 16. The IOS are composed of a mixture of xylo- (XOS) and gluco-oligosaccharides (GOS). We propose that XOS and GOS are the fragments of the xylan backbone and mixed-linkage β-glucans, respectively. The IOS were approximately 100 times stronger inhibitors for Trichoderma reesei cellobiohydrolases (CBHs) than cellobiose, which is one of the strongest inhibitors of these enzymes reported to date. Inhibition of endoglucanases (EGs) by IOS was weaker than that of CBHs. Most of the tested cellulases and hemicellulases were able to slowly degrade IOS and reduce the inhibitory power of the liquid fraction to some extent. The most efficient single enzyme component here was T. reesei EG TrCel7B. Although reduced by the enzyme treatment, the residual inhibitory power of IOS and the liquid fraction was strong enough to silence the major component of the T. reesei cellulase system, CBH TrCel7A. Conclusions The cellulase inhibitors described here may be responsible for the poor yields from the enzymatic conversion of the whole slurries from lignocellulose pretreatment under conditions that do not favor complete degradation of

  4. Aqueous Ionic Liquids and Deep Eutectic Solvents for Cellulosic Biomass Pretreatment and Saccharification.

    PubMed

    Xia, Shuqian; Baker, Gary A; Li, Hao; Ravula, Sudhir; Zhao, Hua

    2014-01-01

    Ionic liquids (ILs) have proven effective solvents for pretreating lignocellulose, leading to the fast saccharification of cellulose and hemicellulose. However, the high current cost of most ILs remains a major barrier to commercializing this recent approach at a practical scale. As a strategic detour, aqueous solutions of ILs are also being explored as less costly alternatives to neat ILs for cellulose pretreatment. However, limited studies on a few select IL systems are known and there remains no systematic survey of various ILs, eluding an in-depth understanding of pretreatment mechanisms afforded by aqueous IL systems. As a step toward filling this gap, this study presents results for Avicel cellulose pretreatment by neat and aqueous solutions (1.0 and 2.0 M) of 20 different ILs and three deep eutectic solvents, correlating enzymatic hydrolysis rates of pretreated cellulose with various IL properties such as hydrogen-bond basicity, polarity, Hofmeister ranking, and hydrophobicity. The pretreatment efficiencies of neat ILs may be loosely correlated to the hydrogen-bond basicity of the constituent anion and IL polarity; however, the pretreatment efficacies for aqueous ILs are more complicated and cannot be simply related to any single IL property. Several aqueous IL systems have been identified as effective alternatives to neat ILs in lignocellulose pretreatment. In particular, this study reveals that aqueous solutions of 1-butyl-3-methylimidazolium methanesulfonate ([BMIM][MeSO3]) are effective for pretreating switchgrass (Panicum virgatum), resulting in fast saccharification of both cellulose and hemicellulose. An integrated analysis afforded by X-ray diffraction, scanning electron microscopy, thermogravimetric analysis and cellulase adsorption isotherm of lignocellulose samples is further used to deliver a more complete view of the structural changes attending aqueous IL pretreatment.

  5. Aqueous Ionic Liquids and Deep Eutectic Solvents for Cellulosic Biomass Pretreatment and Saccharification

    PubMed Central

    Xia, Shuqian; Baker, Gary A.; Li, Hao; Ravula, Sudhir; Zhao, Hua

    2014-01-01

    Ionic liquids (ILs) have proven effective solvents for pretreating lignocellulose, leading to the fast saccharification of cellulose and hemicellulose. However, the high current cost of most ILs remains a major barrier to commercializing this recent approach at a practical scale. As a strategic detour, aqueous solutions of ILs are also being explored as less costly alternatives to neat ILs for cellulose pretreatment. However, limited studies on a few select IL systems are known and there remains no systematic survey of various ILs, eluding an in-depth understanding of pretreatment mechanisms afforded by aqueous IL systems. As a step toward filling this gap, this study presents results for Avicel cellulose pretreatment by neat and aqueous solutions (1.0 and 2.0 M) of 20 different ILs and three deep eutectic solvents, correlating enzymatic hydrolysis rates of pretreated cellulose with various IL properties such as hydrogen-bond basicity, polarity, Hofmeister ranking, and hydrophobicity. The pretreatment efficiencies of neat ILs may be loosely correlated to the hydrogen-bond basicity of the constituent anion and IL polarity; however, the pretreatment efficacies for aqueous ILs are more complicated and cannot be simply related to any single IL property. Several aqueous IL systems have been identified as effective alternatives to neat ILs in lignocellulose pretreatment. In particular, this study reveals that aqueous solutions of 1-butyl-3-methylimidazolium methanesulfonate ([BMIM][MeSO3]) are effective for pretreating switchgrass (Panicum virgatum), resulting in fast saccharification of both cellulose and hemicellulose. An integrated analysis afforded by X-ray diffraction, scanning electron microscopy, thermogravimetric analysis and cellulase adsorption isotherm of lignocellulose samples is further used to deliver a more complete view of the structural changes attending aqueous IL pretreatment. PMID:24729865

  6. Microbial inhibitors: formation and effects on acetone-butanol-ethanol fermentation of lignocellulosic biomass.

    PubMed

    Baral, Nawa Raj; Shah, Ajay

    2014-11-01

    Biobutanol is a promising biofuel due to the close resemblance of its fuel properties to gasoline, and it is produced via acetone-butanol-ethanol (ABE) fermentation using Clostridium species. However, lignin in the crystalline structure of the lignin-cellulose-hemicellulose biomass complex is not readily consumed by the Clostridium; thus, pretreatment is required to degrade this complex. During pretreatment, some fractions of cellulose and hemicellulose are converted into fermentable sugars, which are further converted to ABE. However, a major setback resulting from common pretreatment processes is the formation of sugar and lignin degradation compounds, including weak acids, furan derivatives, and phenolic compounds, which have inhibitory effects on the Clostridium. In addition, butanol concentration above 13 g/L in the fermentation broth is itself toxic to most Clostridium strain(s). This review summarizes the current state-of-the-art knowledge on the formation of microbial inhibitors during the most common lignocellulosic biomass pretreatment processes. Metabolic effects of inhibitors and their impacts on ABE production, as well as potential solutions for reducing inhibitor formation, such as optimizing pretreatment process parameters, using inhibitor tolerant strain(s) with high butanol yield ability, continuously recovering butanol during ABE fermentation, and adopting consolidated bioprocessing, are also discussed.

  7. Production of a generic microbial feedstock for lignocellulose biorefineries through sequential bioprocessing.

    PubMed

    Chang, Chen-Wei; Webb, Colin

    2017-03-01

    Lignocellulosic materials, mostly from agricultural and forestry residues, provide a potential renewable resource for sustainable biorefineries. Reducing sugars can be produced only after a pre-treatment stage, which normally involves chemicals but can be biological. In this case, two steps are usually necessary: solid-state cultivation of fungi for deconstruction, followed by enzymatic hydrolysis using cellulolytic enzymes. In this research, the utilisation of solid-state bioprocessing using the fungus Trichoderma longibrachiatum was implemented as a simultaneous microbial pretreatment and in-situ enzyme production method for fungal autolysis and further enzyme hydrolysis of fermented solids. Suspending the fermented solids in water at 50°C led to the highest hydrolysis yields of 226mg/g reducing sugar and 7.7mg/g free amino nitrogen (FAN). The resultant feedstock was shown to be suitable for the production of various products including ethanol.

  8. Fuzzy logic feedback control for fed-batch enzymatic hydrolysis of lignocellulosic biomass.

    PubMed

    Tai, Chao; Voltan, Diego S; Keshwani, Deepak R; Meyer, George E; Kuhar, Pankaj S

    2016-06-01

    A fuzzy logic feedback control system was developed for process monitoring and feeding control in fed-batch enzymatic hydrolysis of a lignocellulosic biomass, dilute acid-pretreated corn stover. Digested glucose from hydrolysis reaction was assigned as input while doser feeding time and speed of pretreated biomass were responses from fuzzy logic control system. Membership functions for these three variables and rule-base were created based on batch hydrolysis data. The system response was first tested in LabVIEW environment then the performance was evaluated through real-time hydrolysis reaction. The feeding operations were determined timely by fuzzy logic control system and efficient responses were shown to plateau phases during hydrolysis. Feeding of proper amount of cellulose and maintaining solids content was well balanced. Fuzzy logic proved to be a robust and effective online feeding control tool for fed-batch enzymatic hydrolysis.

  9. Bioconversion potential of Trichoderma viride HN1 cellulase for a lignocellulosic biomass Saccharum spontaneum.

    PubMed

    Iqtedar, Mehwish; Nadeem, Mohammad; Naeem, Hira; Abdullah, Roheena; Naz, Shagufta; Qurat ul Ain Syed; Kaleem, Afshan

    2015-01-01

    The industrialisation of lignocellulose conversion is impeded by expensive cellulase enzymes required for saccharification in bioethanol production. Current research undertakes cellulase production from pretreated Saccharum spontaneum through Trichoderma viride HN1 under submerged fermentation conditions. Pretreatment of substrate with 2% NaOH resulted in 88% delignification. Maximum cellulase production (2603 ± 16.39 U/mL/min carboxymethyl cellulase and 1393 ± 25.55 U/mL/min FPase) was achieved at 6% substrate at pH 5.0, with 5% inoculum, incubated at 35°C for 120 h of fermentation period. Addition of surfactant, Tween 80 and metal ion Mn(+2), significantly enhanced cellulase yield. This study accounts proficient cellulase yield through process optimisation by exploiting cheaper substrate to escalate their commercial endeavour.

  10. Comparative lipid production by oleaginous yeasts in hydrolyzates of lignocellulosic biomass and process strategy for high titers.

    PubMed

    Slininger, Patricia J; Dien, Bruce S; Kurtzman, Cletus P; Moser, Bryan R; Bakota, Erica L; Thompson, Stephanie R; O'Bryan, Patricia J; Cotta, Michael A; Balan, Venkatesh; Jin, Mingjie; Sousa, Leonardo da Costa; Dale, Bruce E

    2016-08-01

    Oleaginous yeasts can convert sugars to lipids with fatty acid profiles similar to those of vegetable oils, making them attractive for production of biodiesel. Lignocellulosic biomass is an attractive source of sugars for yeast lipid production because it is abundant, potentially low cost, and renewable. However, lignocellulosic hydrolyzates are laden with byproducts which inhibit microbial growth and metabolism. With the goal of identifying oleaginous yeast strains able to convert plant biomass to lipids, we screened 32 strains from the ARS Culture Collection, Peoria, IL to identify four robust strains able to produce high lipid concentrations from both acid and base-pretreated biomass. The screening was arranged in two tiers using undetoxified enzyme hydrolyzates of ammonia fiber expansion (AFEX)-pretreated cornstover as the primary screening medium and acid-pretreated switch grass as the secondary screening medium applied to strains passing the primary screen. Hydrolyzates were prepared at ∼18-20% solids loading to provide ∼110 g/L sugars at ∼56:39:5 mass ratio glucose:xylose:arabinose. A two stage process boosting the molar C:N ratio from 60 to well above 400 in undetoxified switchgrass hydrolyzate was optimized with respect to nitrogen source, C:N, and carbon loading. Using this process three strains were able to consume acetic acid and nearly all available sugars to accumulate 50-65% of cell biomass as lipid (w/w), to produce 25-30 g/L lipid at 0.12-0.22 g/L/h and 0.13-0.15 g/g or 39-45% of the theoretical yield at pH 6 and 7, a performance unprecedented in lignocellulosic hydrolyzates. Three of the top strains have not previously been reported for the bioconversion of lignocellulose to lipids. The successful identification and development of top-performing lipid-producing yeast in lignocellulose hydrolyzates is expected to advance the economic feasibility of high quality biodiesel and jet fuels from renewable biomass, expanding the market

  11. Predictive models of biohydrogen and biomethane production based on the compositional and structural features of lignocellulosic materials.

    PubMed

    Monlau, Florian; Sambusiti, Cecilia; Barakat, Abdellatif; Guo, Xin Mei; Latrille, Eric; Trably, Eric; Steyer, Jean-Philippe; Carrere, Hélène

    2012-11-06

    In an integrated biorefinery concept, biological hydrogen and methane production from lignocellulosic substrates appears to be one of the most promising alternatives to produce energy from renewable sources. However, lignocellulosic substrates present compositional and structural features that can limit their conversion into biohydrogen and methane. In this study, biohydrogen and methane potentials of 20 lignocellulosic residues were evaluated. Compositional (lignin, cellulose, hemicelluloses, total uronic acids, proteins, and soluble sugars) as well as structural features (crystallinity) were determined for each substrate. Two predictive partial least square (PLS) models were built to determine which compositional and structural parameters affected biohydrogen or methane production from lignocellulosic substrates, among proteins, total uronic acids, soluble sugars, crystalline cellulose, amorphous holocelluloses, and lignin. Only soluble sugars had a significant positive effect on biohydrogen production. Besides, methane potentials correlated negatively to the lignin contents and, to a lower extent, crystalline cellulose showed also a negative impact, whereas soluble sugars, proteins, and amorphous hemicelluloses showed a positive impact. These findings will help to develop further pretreatment strategies for enhancing both biohydrogen and methane production.

  12. Final Report on Development of Thermoanaerobacterium saccharolyticum for the conversion of lignocellulose to ethanol

    SciTech Connect

    Herring, Christopher D.; Kenealy, William R.; Shaw, A. Joe; Raman, Babu; Tschaplinski, Timothy J.; Brown, Steven D.; Davison, Brian H.; Covalla, Sean F.; Sillers, W. Ryan; Xu, Haowen; Tsakraklides, Vasiliki; Hogsett, David A.

    2012-01-24

    This project addressed the need for economical technology for the conversion of lignocellulosic biomass to fuels, specifically the conversion of pretreated hardwood to ethanol. The technology developed is a set of strains of the bacterium Thermoanaerobacterium saccharolyticum and an associated fermentation process for pretreated hardwood. Tools for genetic engineering and analysis of the organism were developed, including a markerless mutation method, a complete genome sequence and a set of gene expression profiles that show the activity of its genes under a variety of conditions relevant to lignocellulose conversion. Improved strains were generated by selection and genetic engineering to be able to produce higher amounts of ethanol (up to 70 g/L) and to be able to better tolerate inhibitory compounds from pretreated hardwood. Analysis of these strains has generated useful insight into the genetic basis for desired properties of biofuel producing organisms. Fermentation conditions were tested and optimized to achieve ethanol production targets established in the original project proposal. The approach proposed was to add cellulase enzymes to the fermentation, a method called Simultaneous Saccharification and Fermentation (SSF). We had reason to think SSF would be an efficient approach because the optimal temperature and pH for the enzymes and bacterium are very close. Unfortunately, we discovered that commercially available cellulases are inactivated in thermophilic SSF by a combination of low redox potential and ethanol. Despite this, progress was made against the fermentation targets using bacterial cellulases. Thermoanaerobacterium saccharolyticum may still prove to be a commercially viable technology should cellulase enzyme issues be addressed. Moreover, the organism was demonstrated to produce ethanol at approximately theoretical yield from oligomeric hemicellulose extracts, an ability that may prove to be uniquely valuable in pretreatment configurations in

  13. Current Challenges in Commercially Producing Biofuels from Lignocellulosic Biomass

    PubMed Central

    Balan, Venkatesh

    2014-01-01

    Biofuels that are produced from biobased materials are a good alternative to petroleum based fuels. They offer several benefits to society and the environment. Producing second generation biofuels is even more challenging than producing first generation biofuels due the complexity of the biomass and issues related to producing, harvesting, and transporting less dense biomass to centralized biorefineries. In addition to this logistic challenge, other challenges with respect to processing steps in converting biomass to liquid transportation fuel like pretreatment, hydrolysis, microbial fermentation, and fuel separation still exist and are discussed in this review. The possible coproducts that could be produced in the biorefinery and their importance to reduce the processing cost of biofuel are discussed. About $1 billion was spent in the year 2012 by the government agencies in US to meet the mandate to replace 30% existing liquid transportation fuels by 2022 which is 36 billion gallons/year. Other countries in the world have set their own targets to replace petroleum fuel by biofuels. Because of the challenges listed in this review and lack of government policies to create the demand for biofuels, it may take more time for the lignocellulosic biofuels to hit the market place than previously projected. PMID:25937989

  14. Development of Lignocellulosic Biorefinery Technologies: Recent Advances and Current Challenges

    SciTech Connect

    Amore, Antonella; Ciesielski, Peter N.; Lin, Chien-Yuan; Salvachua, Davinia; Sanchez i Nogue, Violeta

    2016-06-06

    Recent developments of the biorefinery concept are described within this review, which focuses on the efforts required to make the lignocellulosic biorefinery a sustainable and economically viable reality. Despite the major research and development endeavours directed towards this goal over the past several decades, the integrated production of biofuel and other bio-based products still needs to be optimized from both technical and economical perspectives. This review will highlight recent progress towards the optimization of the major biorefinery processes, including biomass pretreatment and fractionation, saccharification of sugars, and conversion of sugars and lignin into fuels and chemical precursors. In addition, advances in genetic modification of biomass structure and composition for the purpose of enhancing the efficacy of conversion processes, which is emerging as a powerful tool for tailoring biomass fated for the biorefinery, will be overviewed. The continual improvement of these processes and their integration in the format of a modern biorefinery is paving the way for a sustainable bio-economy which will displace large portions of petroleum-derived fuels and chemicals with renewable substitutes.

  15. Development of Lignocellulosic Biorefinery Technologies: Recent Advances and Current Challenges

    SciTech Connect

    Amore, Antonella; Ciesielski, Peter N.; Lin, Chien-Yuan; Salvachua, Davinia; Sanchez i Nogue, Violeta

    2016-06-06

    We describe some recent developments of the biorefinery concept within this review, which focuses on the efforts required to make the lignocellulosic biorefinery a sustainable and economically viable reality. In spite of the major research and development endeavours directed towards this goal over the past several decades, the integrated production of biofuel and other bio-based products still needs to be optimized from both technical and economical perspectives. This review will highlight recent progress towards the optimization of the major biorefinery processes, including biomass pretreatment and fractionation, saccharification of sugars, and conversion of sugars and lignin into fuels and chemical precursors. Additionally, advances in genetic modification of biomass structure and composition for the purpose of enhancing the efficacy of conversion processes, which is emerging as a powerful tool for tailoring biomass fated for the biorefinery, will be overviewed. The continual improvement of these processes and their integration in the format of a modern biorefinery is paving the way for a sustainable bio-economy which will displace large portions of petroleum-derived fuels and chemicals with renewable substitutes.

  16. Current Challenges in Commercially Producing Biofuels from Lignocellulosic Biomass

    DOE PAGES

    Balan, Venkatesh

    2014-01-01

    Biofuels that are produced from biobased materials are a good alternative to petroleum based fuels. They offer several benefits to society and the environment. Producing second generation biofuels is even more challenging than producing first generation biofuels due the complexity of the biomass and issues related to producing, harvesting, and transporting less dense biomass to centralized biorefineries. In addition to this logistic challenge, other challenges with respect to processing steps in converting biomass to liquid transportation fuel like pretreatment, hydrolysis, microbial fermentation, and fuel separation still exist and are discussed in this review. The possible coproducts that could be producedmore » in the biorefinery and their importance to reduce the processing cost of biofuel are discussed. About $1 billion was spent in the year 2012 by the government agencies in US to meet the mandate to replace 30% existing liquid transportation fuels by 2022 which is 36 billion gallons/year. Other countries in the world have set their own targets to replace petroleum fuel by biofuels. Because of the challenges listed in this review and lack of government policies to create the demand for biofuels, it may take more time for the lignocellulosic biofuels to hit the market place than previously projected.« less

  17. Development of Lignocellulosic Biorefinery Technologies: Recent Advances and Current Challenges

    DOE PAGES

    Amore, Antonella; Ciesielski, Peter N.; Lin, Chien-Yuan; ...

    2016-06-06

    We describe some recent developments of the biorefinery concept within this review, which focuses on the efforts required to make the lignocellulosic biorefinery a sustainable and economically viable reality. In spite of the major research and development endeavours directed towards this goal over the past several decades, the integrated production of biofuel and other bio-based products still needs to be optimized from both technical and economical perspectives. This review will highlight recent progress towards the optimization of the major biorefinery processes, including biomass pretreatment and fractionation, saccharification of sugars, and conversion of sugars and lignin into fuels and chemical precursors.more » Additionally, advances in genetic modification of biomass structure and composition for the purpose of enhancing the efficacy of conversion processes, which is emerging as a powerful tool for tailoring biomass fated for the biorefinery, will be overviewed. The continual improvement of these processes and their integration in the format of a modern biorefinery is paving the way for a sustainable bio-economy which will displace large portions of petroleum-derived fuels and chemicals with renewable substitutes.« less

  18. Life cycle evaluation of emerging lignocellulosic ethanol conversion technologies.

    PubMed

    Spatari, Sabrina; Bagley, David M; MacLean, Heather L

    2010-01-01

    Lignocellulosic ethanol holds promise for addressing climate change and energy security issues associated with personal transportation through lowering the fuel mixes' carbon intensity and petroleum demand. We compare the technological features and life cycle environmental impacts of near- and mid-term ethanol bioconversion technologies in the United States. Key uncertainties in the major processes: pre-treatment, hydrolysis, and fermentation are evaluated. The potential to reduce fossil energy use and greenhouse gas (GHG) emissions varies among bioconversion processes, although all options studied are considerably more attractive than gasoline. Anticipated future performance is found to be considerably more attractive than that published in the literature as being achieved to date. Electricity co-product credits are important in characterizing the GHG impacts of different ethanol production pathways; however, in the absence of near-term liquid transportation fuel alternatives to gasoline, optimizing ethanol facilities to produce ethanol (as opposed to co-products) is important for reducing the carbon intensity of the road transportation sector and for energy security.

  19. Using Populus as a lignocellulosic feedstock for bioethanol.

    PubMed

    Porth, Ilga; El-Kassaby, Yousry A

    2015-04-01

    Populus species along with species from the sister genus Salix will provide valuable feedstock resources for advanced second-generation biofuels. Their inherent fast growth characteristics can particularly be exploited for short rotation management, a time and energy saving cultivation alternative for lignocellulosic feedstock supply. Salicaceae possess inherent cell wall characteristics with favorable cellulose to lignin ratios for utilization as bioethanol crop. We review economically important traits relevant for intensively managed biofuel crop plantations, genomic and phenotypic resources available for Populus, breeding strategies for forest trees dedicated to bioenergy provision, and bioprocesses and downstream applications related to opportunities using Salicaceae as a renewable resource. Challenges need to be resolved for every single step of the conversion process chain, i.e., starting from tree domestication for improved performance as a bioenergy crop, bioconversion process, policy development for land use changes associated with advanced biofuels, and harvest and supply logistics associated with industrial-scale biorefinery plants using Populus as feedstock. Significant hurdles towards cost and energy efficiency, environmental friendliness, and yield maximization with regards to biomass pretreatment, saccharification, and fermentation of celluloses and the sustainability of biorefineries as a whole still need to be overcome.

  20. Improve the Anaerobic Biodegradability by Copretreatment of Thermal Alkali and Steam Explosion of Lignocellulosic Waste

    PubMed Central

    Siddhu, Muhammad Abdul Hanan; Li, Jianghao; Zhang, Jiafu; Huang, Yan; Wang, Wen; Chen, Chang; Liu, Guangqing

    2016-01-01

    Effective alteration of the recalcitrance properties like crystallization of cellulose, lignin shield, and interlinking of lignocellulosic biomass is an ideal way to utilize the full-scale potential for biofuel production. This study exhibited three different pretreatment effects to enhance the digestibility of corn stover (CS) for methane production. In this context, steam explosion (SE) and thermal potassium hydroxide (KOH-60°C) treated CS produced the maximal methane yield of 217.5 and 243.1 mL/gvs, which were 40.0% and 56.4% more than untreated CS (155.4 mL/gvs), respectively. Copretreatment of thermal potassium hydroxide and steam explosion (CPTPS) treated CS was highly significant among all treatments and improved 88.46% (292.9 mL/gvs) methane yield compared with untreated CS. Besides, CPTPS also achieved the highest biodegradability up to 68.90%. Three kinetic models very well simulated dynamics of methane production yield. Moreover, scanning electron microscopy (SEM), Fourier transform infrared (FTIR), and X-ray diffraction (XRD) analyses declared the most effective changes in physicochemical properties after CPTPS pretreatment. Thus, CPTPS might be a promising approach to deconstructing the recalcitrance of lignocellulosic structure to improve the biodegradability for AD. PMID:27200370

  1. Improve the Anaerobic Biodegradability by Copretreatment of Thermal Alkali and Steam Explosion of Lignocellulosic Waste.

    PubMed

    Siddhu, Muhammad Abdul Hanan; Li, Jianghao; Zhang, Jiafu; Huang, Yan; Wang, Wen; Chen, Chang; Liu, Guangqing

    2016-01-01

    Effective alteration of the recalcitrance properties like crystallization of cellulose, lignin shield, and interlinking of lignocellulosic biomass is an ideal way to utilize the full-scale potential for biofuel production. This study exhibited three different pretreatment effects to enhance the digestibility of corn stover (CS) for methane production. In this context, steam explosion (SE) and thermal potassium hydroxide (KOH-60°C) treated CS produced the maximal methane yield of 217.5 and 243.1 mL/gvs, which were 40.0% and 56.4% more than untreated CS (155.4 mL/gvs), respectively. Copretreatment of thermal potassium hydroxide and steam explosion (CPTPS) treated CS was highly significant among all treatments and improved 88.46% (292.9 mL/gvs) methane yield compared with untreated CS. Besides, CPTPS also achieved the highest biodegradability up to 68.90%. Three kinetic models very well simulated dynamics of methane production yield. Moreover, scanning electron microscopy (SEM), Fourier transform infrared (FTIR), and X-ray diffraction (XRD) analyses declared the most effective changes in physicochemical properties after CPTPS pretreatment. Thus, CPTPS might be a promising approach to deconstructing the recalcitrance of lignocellulosic structure to improve the biodegradability for AD.

  2. Dilute acid pretreatment and enzymatic hydrolysis of sorghum biomass for sugar recovery--a statistical approach.

    PubMed

    Akanksha, Karthik; Prasad, Arjun; Sukumaran, Rajeev K; Nampoothiri, Madhavan; Pandey, Ashok; Rao, S S; Parameswaran, Binod

    2014-11-01

    Sorghum is one of the commercially feasible lignocellulosic biomass and has a great potential of being sustainable feedstock for renewable energy. As with any lignocellulosic biomass, sorghum also requires pretreatment which increases its susceptibility to hydrolysis by enzymes for generating sugars which can be further fermented to alcohol. In the present study, sorghum biomass was evaluated for deriving maximum fermentable sugars by optimizing various pretreatment parameters using statistical optimization methods. Pretreatment studies were done with H2SO4, followed by enzymatic saccharification. The efficiency of the process was evaluated on the basis of production of the total reducing sugars released during the process. Compositional analysis was done for native as well as pretreated biomass and compared. The biomass pretreated with the optimized conditions could yield 0.408 g of reducing sugars /g of pretreated biomass upon enzymatic hydrolysis. The cellulose content in the solid portion obtained after pretreatment using optimised conditions was found to be increased by 43.37% with lesser production of inhibitors in acid pretreated liquor.

  3. Perspective and prospective of pretreatment of corn straw for butanol production.

    PubMed

    Baral, Nawa Raj; Li, Jiangzheng; Jha, Ajay Kumar

    2014-01-01

    Corn straw, lignocellulosic biomass, is a potential substrate for microbial production of bio-butanol. Bio-butanol is a superior second generation biofuel among its kinds. Present researches are focused on the selection of butanol tolerant clostridium strain(s) to optimize butanol yield in the fermentation broth because of toxicity of bio-butanol to the clostridium strain(s) itself. However, whatever the type of the strain(s) used, pretreatment process always affects not only the total sugar yield before fermentation but also the performance and growth of microbes during fermentation due to the formation of hydroxyl-methyl furfural, furfural and phenolic compounds. In addition, the lignocellulosic biomasses also resist physical and biological attacks. Thus, selection of best pretreatment process and its parameters is crucial. In this context, worldwide research efforts are increased in past 12 years and researchers are tried to identify the best pretreatment method, pretreatment conditions for the actual biomass. In this review, effect of particle size, status of most common pretreatment method and enzymatic hydrolysis particularly for corn straw as a substrate is presented. This paper also highlights crucial parameters necessary to consider during most common pretreatment processes such as hydrothermal, steam explosion, ammonia explosion, sulfuric acid, and sodium hydroxide pretreatment. Moreover, the prospective of pretreatment methods and challenges is discussed.

  4. Microwave-based alkali pretreatment of switchgrass and coastal bermudagrass for bioethanol production.

    PubMed

    Keshwani, Deepak R; Cheng, Jay J

    2010-01-01

    Switchgrass and coastal bermudagrass are promising lignocellulosic feedstocks for bioethanol production. However, pretreatment of lignocelluloses is required to improve production of fermentable sugars from enzymatic hydrolysis. Microwave-based alkali pretreatment of switchgrass and coastal bermudagrass was investigated in this study. Pretreatments were carried out by immersing the biomass in dilute alkali reagents and exposing the slurry to microwave radiation at 250 W for residence times ranging from 5 to 20 min. Simons' stain method was used to quantify changes in biomass porosity as a result of the pretreatment. Pretreatments were evaluated based on yields of total reducing sugars, glucose, and xylose. An evaluation of different alkalis identified sodium hydroxide as the most effective alkali reagent for microwave-based pretreatment of switchgrass and coastal bermudagrass. 82% glucose and 63% xylose yields were achieved for switchgrass and 87% glucose and 59% xylose yields were achieved for coastal bermudagrass following enzymatic hydrolysis of biomass pretreated under optimal conditions. Dielectric properties for dilute sodium hydroxide solutions were measured and compared with solid losses, lignin reduction, and reducing sugar levels in hydrolyzates. Results indicate that dielectric loss tangent of alkali solutions is a potential indicator of the severity of microwave-based pretreatments.

  5. Improving enzymatic hydrolysis of corn stover pretreated by ethylene glycol-perchloric acid-water mixture.

    PubMed

    He, Yu-Cai; Liu, Feng; Gong, Lei; Lu, Ting; Ding, Yun; Zhang, Dan-Ping; Qing, Qing; Zhang, Yue

    2015-02-01

    To improve the enzymatic saccharification of lignocellulosic biomass, a mixture of ethylene glycol-HClO4-water (88.8:1.2:10, w/w/w) was used for pretreating corn stover in this study. After the optimization in oil-bath system, the optimum pretreatment temperature and time were 130 °C and 30 min, respectively. After the saccharification of 10 g/L pretreated corn stover for 48 h, the saccharification rate was obtained in the yield of 77.4 %. To decrease pretreatment temperature and shorten pretreatment time, ethylene glycol-HClO4-water (88.8:1.2:10, w/w/w) media under microwave irradiation was employed to pretreat corn stover effectively at 100 °C and 200 W for 5 min. Finally, the recovered hydrolyzates containing glucose obtained from the enzymatic hydrolysis of pretreated corn stovers could be fermented into ethanol efficiently. These results would be helpful for developing a cost-effective pretreatment combined with enzymatic saccharification of cellulosic materials for the production of lignocellulosic ethanol.

  6. Ethanolic fermentation of pentoses in lignocellulose hydrolysates

    SciTech Connect

    Hahn-Haegerdal, B.; Linden, T.; Senac, T.; Skoog, K.

    1991-12-31

    In the fermentation of lignocellulose hydrolysates to ethanol, two major problems are encountered: the fermentation of the pentose sugar xylose, and the presence of microbial inhibitors. Xylose can be directly fermented with yeasts; such as Pachysolen tannophilus, Candida shehatae, and Pichia stipis, or by isomerization of xylose to xylulose with the enzyme glucose (xylose) isomerase, and subsequent fermentation with bakers yeast, Saccharomyces cerevisiae. The direct fermentation requires low, carefully controlled oxygenation, as well as the removal of inhibitors. Also, the xylose-fermenting yeasts have a limited ethanol tolerance. The combined isomerization and fermentation with XI and S. cerevisiae gives yields and productivities comparable to those obtained in hexose fermentations without oxygenation and removal of inhibitors. However, the enzyme is not very stable in a lignocellulose hydrolysate, and S. cerevisiae has a poorly developed pentose phosphate shunt. Different strategies involving strain adaptation, and protein and genetic engineering adopted to overcome these different obstacles, are discussed.

  7. Ethanol Fermentation of Various Pretreated and Hydrolyzed Substrates at Low Initial pH

    NASA Astrophysics Data System (ADS)

    Kádár, Zsófia; Maltha, San Feng; Szengyel, Zsolt; Réczey, Kati; de Laat, Wim

    Lignocellulosic materials represent an abundant feedstock for bioethanol production. Because of their complex structure pretreatment is necessary to make it accessible for enzymatic attack. Steam pretreatment with or without acid catalysts seems to be one of the most promising techniques, which has already been applied for large variety of lignocellulosics in order to improve enzymatic digestibility. During this process a range of toxic compounds (lignin and sugar degradation products) are formed which inhibit ethanol fermentation. In this study, the toxicity of hemicellulose hydrolysates obtained in the steam pretreatment of spruce, willow, and corn stover were investigated in ethanol fermentation tests using a yeast strain, which has been previously reported to have a resistance to inhibitory compounds generated during steam pretreatment. To overcome bacterial contamination, fermentations were carried out at low initial pH. The fermentability of hemicellulose hydrolysates of pretreated lignocellulosic substrates at low pH gave promising results with the economically profitable final 5 vol% ethanol concentration corresponding to 85% of theoretical. Adaptation experiments have shown that inhibitor tolerance of yeast strain can be improved by subsequent transfer of the yeast to inhibitory medium.

  8. Ethanol fermentation of various pretreated and hydrolyzed substrates at low initial pH.

    PubMed

    Kádár, Zsófia; Maltha, San Feng; Szengyel, Zsolt; Réczey, Kati; de Laat, Wim

    2007-04-01

    Lignocellulosic materials represent an abundant feedstock for bioethanol production. Because of their complex structure pretreatment is necessary to make it accessible for enzymatic attack. Steam pretreatment with or without acid catalysts seems to be one of the most promising techniques, which has already been applied for large variety of lignocellulosics in order to improve enzymatic digestibility. During this process a range of toxic compounds (lignin and sugar degradation products) are formed which inhibit ethanol fermentation. In this study, the toxicity of hemicellulose hydrolysates obtained in the steam pretreatment of spruce, willow, and corn stover were investigated in ethanol fermentation tests using a yeast strain, which has been previously reported to have a resistance to inhibitory compounds generated during steam pretreatment. To overcome bacterial contamination, fermentations were carried out at low initial pH. The fermentability of hemicellulose hydrolysates of pretreated lignocellulosic substrates at low pH gave promising results with the economically profitable final 5 vol% ethanol concentration corresponding to 85% of theoretical. Adaptation experiments have shown that inhibitor tolerance of yeast strain can be improved by subsequent transfer of the yeast to inhibitory medium.

  9. Profiling microbial lignocellulose degradation and utilization by emergent omics technologies

    SciTech Connect

    Rosnow, Joshua J.; Anderson, Lindsey N.; Nair, Reji N.; Baker, Erin S.; Wright, Aaron T.

    2016-07-20

    The use of plant materials to generate renewable biofuels and other high-value chemicals is the sustainable and preferable option, but will require considerable improvements to increase the rate and efficiency of lignocellulose depolymerization. This review highlights novel and emergent technologies that are being developed and deployed to characterize the process of lignocellulose degradation. The review will also illustrate how microbial communities deconstruct and metabolize lignocellulose by identifying the necessary genes and enzyme activities along with the reaction products. These technologies include multi-omic measurements, cell sorting and isolation, nuclear magnetic resonance spectroscopy (NMR), activity-based protein profiling, and direct measurement of enzyme activity. The recalcitrant nature of lignocellulose necessitates the need to characterize the methods microbes employ to deconstruct lignocellulose to inform new strategies on how to greatly improve biofuel conversion processes. New technologies are yielding important insights into microbial functions and strategies employed to degrade lignocellulose, providing a mechanistic blueprint to advance biofuel production.

  10. Simultaneous saccharification and fermentation of fungal pretreated cornstalk for hydrogen production using Thermoanaerobacterium thermosaccharolyticum W16.

    PubMed

    Zhao, Lei; Cao, Guang-Li; Wang, Ai-Jie; Guo, Wan-Qian; Ren, Hong-Yu; Ren, Nan-Qi

    2013-10-01

    In this research, environmentally friendly fungal pretreatment was first adopted for deconstruction of cornstalk. Then the fungal-pretreated cornstalk was employed to produce hydrogen in simultaneous saccharification and fermentation (SSF) using crude enzyme from Trichoderma viride and Thermoanaerobacterium thermosaccharolyticum W16. The influence of various factors including substrate concentration, initial pH, and enzyme loading on hydrogen production were evaluated. The highest hydrogen yield of 89.3 ml/g-cornstalk was obtained with an initial pH 6.5, 0.75% substrate concentration, and 34 FPU/g cellulose. Compared the result with SSF of physical or chemical pretreated lignocellulosic materials, this research suggested an economic and efficient way for hydrogen production from lignocellulosic biomass. Copyright © 2013 Elsevier Ltd. All rights reserved.

  11. Deconstruction of lignocellulosic biomass to fuels and chemicals.

    PubMed

    Chundawat, Shishir P S; Beckham, Gregg T; Himmel, Michael E; Dale, Bruce E

    2011-01-01

    Plants represent a vast, renewable resource and are well suited to provide sustainably for humankind's transportation fuel needs. To produce infrastructure-compatible fuels from biomass, two challenges remain: overcoming plant cell wall recalcitrance to extract sugar and phenolic intermediates, and reduction of oxygenated intermediates to fuel molecules. To compete with fossil-based fuels, two primary routes to deconstruct cell walls are under development, namely biochemical and thermochemical conversion. Here, we focus on overcoming recalcitrance with biochemical conversion, which uses low-severity thermochemical pretreatment followed by enzymatic hydrolysis to produce soluble sugars. Many challenges remain, including understanding how pretreatments affect the physicochemical nature of heterogeneous cell walls; determination of how enzymes deconstruct the cell wall effectively with the aim of designing superior catalysts; and resolution of issues associated with the co-optimization of pretreatment, enzymatic hydrolysis, and fermentation. Here, we highlight some of the scientific challenges and open questions with a particular focus on problems across multiple length scales.

  12. Engineering microbial surfaces to degrade lignocellulosic biomass

    PubMed Central

    Huang, Grace L; Anderson, Timothy D; Clubb, Robert T

    2014-01-01

    Renewable lignocellulosic plant biomass is a promising feedstock from which to produce biofuels, chemicals, and materials. One approach to cost-effectively exploit this resource is to use consolidating bioprocessing (CBP) microbes that directly convert lignocellulose into valuable end products. Because many promising CBP-enabling microbes are non-cellulolytic, recent work has sought to engineer them to display multi-cellulase containing minicellulosomes that hydrolyze biomass more efficiently than isolated enzymes. In this review, we discuss progress in engineering the surfaces of the model microorganisms: Bacillus subtilis, Escherichia coli, and Saccharomyces cerevisiae. We compare the distinct approaches used to display cellulases and minicellulosomes, as well as their surface enzyme densities and cellulolytic activities. Thus far, minicellulosomes have only been grafted onto the surfaces of B. subtilis and S. cerevisiae, suggesting that the absence of an outer membrane in fungi and Gram-positive bacteria may make their surfaces better suited for displaying the elaborate multi-enzyme complexes needed to efficiently degrade lignocellulose. PMID:24430239

  13. Fungal Bioconversion of Lignocellulosic Residues; Opportunities & Perspectives

    PubMed Central

    Dashtban, Mehdi; Schraft, Heidi; Qin, Wensheng

    2009-01-01

    The development of alternative energy technology is critically important because of the rising prices of crude oil, security issues regarding the oil supply, and environmental issues such as global warming and air pollution. Bioconversion of biomass has significant advantages over other alternative energy strategies because biomass is the most abundant and also the most renewable biomaterial on our planet. Bioconversion of lignocellulosic residues is initiated primarily by microorganisms such as fungi and bacteria which are capable of degrading lignocellulolytic materials. Fungi such as Trichoderma reesei and Aspergillus niger produce large amounts of extracellular cellulolytic enzymes, whereas bacterial and a few anaerobic fungal strains mostly produce cellulolytic enzymes in a complex called cellulosome, which is associated with the cell wall. In filamentous fungi, cellulolytic enzymes including endoglucanases, cellobiohydrolases (exoglucanases) and β-glucosidases work efficiently on cellulolytic residues in a synergistic manner. In addition to cellulolytic/hemicellulolytic activities, higher fungi such as basidiomycetes (e.g. Phanerochaete chrysosporium) have unique oxidative systems which together with ligninolytic enzymes are responsible for lignocellulose degradation. This review gives an overview of different fungal lignocellulolytic enzymatic systems including extracellular and cellulosome-associated in aerobic and anaerobic fungi, respectively. In addition, oxidative lignocellulose-degradation mechanisms of higher fungi are discussed. Moreover, this paper reviews the current status of the technology for bioconversion of biomass by fungi, with focus on mutagenesis, co-culturing and heterologous gene expression attempts to improve fungal lignocellulolytic activities to create robust fungal strains. PMID:19774110

  14. Fungal bioconversion of lignocellulosic residues; opportunities & perspectives.

    PubMed

    Dashtban, Mehdi; Schraft, Heidi; Qin, Wensheng

    2009-09-04

    The development of alternative energy technology is critically important because of the rising prices of crude oil, security issues regarding the oil supply, and environmental issues such as global warming and air pollution. Bioconversion of biomass has significant advantages over other alternative energy strategies because biomass is the most abundant and also the most renewable biomaterial on our planet. Bioconversion of lignocellulosic residues is initiated primarily by microorganisms such as fungi and bacteria which are capable of degrading lignocellulolytic materials. Fungi such as Trichoderma reesei and Aspergillus niger produce large amounts of extracellular cellulolytic enzymes, whereas bacterial and a few anaerobic fungal strains mostly produce cellulolytic enzymes in a complex called cellulosome, which is associated with the cell wall. In filamentous fungi, cellulolytic enzymes including endoglucanases, cellobiohydrolases (exoglucanases) and beta-glucosidases work efficiently on cellulolytic residues in a synergistic manner. In addition to cellulolytic/hemicellulolytic activities, higher fungi such as basidiomycetes (e.g. Phanerochaete chrysosporium) have unique oxidative systems which together with ligninolytic enzymes are responsible for lignocellulose degradation. This review gives an overview of different fungal lignocellulolytic enzymatic systems including extracellular and cellulosome-associated in aerobic and anaerobic fungi, respectively. In addition, oxidative lignocellulose-degradation mechanisms of higher fungi are discussed. Moreover, this paper reviews the current status of the technology for bioconversion of biomass by fungi, with focus on mutagenesis, co-culturing and heterologous gene expression attempts to improve fungal lignocellulolytic activities to create robust fungal strains.

  15. Sequential acid-/alkali-pretreatment of empty palm fruit bunch fiber.

    PubMed

    Kim, Seonghun; Park, Jang Min; Seo, Jeong-Woo; Kim, Chul Ho

    2012-04-01

    Pretreatment processes are key technologies for generating fermentable sugars based on lignocellulosic biomass. In this study, we developed a novel method for empty palm fruit bunch fiber (EPFBF) using sequential pretreatment with dilute acid and then alkali. Dilute sulfuric acid was used in the first step, which removed 90% of the hemicellulose and 32% of the lignin, but left most of the cellulose under the optimum pretreatment condition. Sodium hydroxide was then applied in the second step, which extracted lignin effectively with a 70% delignification yield, partially disrupting the ordered fibrils of the EPFBF and thus enhancing the enzyme digestibility of the cellulose. The sequentially pretreated biomass consisted of 82% cellulose, less than 1% hemicellulose, and 30% lignin content afterward. The pretreated biomasses morphologically revealed rough, porous, and irregularly ordered surfaces for enhancing enzyme digestibility. These results indicate that the sequentially acid/alkali-pretreated EPFBF could be broadly useful as a novel biomass. Copyright © 2012 Elsevier Ltd. All rights reserved.

  16. Pretreatment combining ultrasound and sodium percarbonate under mild conditions for efficient degradation of corn stover.

    PubMed

    Nakashima, Kazunori; Ebi, Yuuki; Kubo, Masaki; Shibasaki-Kitakawa, Naomi; Yonemoto, Toshikuni

    2016-03-01

    Ultrasound (US) can be used to disrupt microcrystalline cellulose to give nanofibers via ultrasonic cavitation. Sodium percarbonate (SP), consisting of sodium carbonate and hydrogen peroxide, generates highly reactive radicals, which cause oxidative delignification. Here, we describe a novel pretreatment technique using a combination of US and SP (US-SP) for the efficient saccharification of cellulose and hemicellulose in lignocellulosic corn stover. Although US-SP pretreatment was conducted under mild condition (i.e., at room temperature and atmospheric pressure), the pretreatment greatly increased lignin removal and cellulose digestibility. We also determined the optimum US-SP treatment conditions, such as ultrasonic power output, pretreatment time, pretreatment temperature, and SP concentration for an efficient cellulose saccharification. Moreover, xylose could be effectively recovered from US-SP pretreated biomass without the formation of microbial inhibitor furfural.

  17. Improving methane production from digested manure biofibers by mechanical and thermal alkaline pretreatment.

    PubMed

    Tsapekos, P; Kougias, Panagiotis G; Frison, A; Raga, R; Angelidaki, I

    2016-09-01

    Animal manure digestion is associated with limited methane production, due to the high content in fibers, which are hardly degradable lignocellulosic compounds. In this study, different mechanical and thermal alkaline pretreatment methods were applied to partially degradable fibers, separated from the effluent stream of biogas reactors. Batch and continuous experiments were conducted to evaluate the efficiency of these pretreatments. In batch experiments, the mechanical pretreatment improved the degradability up to 45%. Even higher efficiency was shown by applying thermal alkaline pretreatments, enhancing fibers degradability by more than 4-fold. In continuous experiments, the thermal alkaline pretreatment, using 6% NaOH at 55°C was proven to be the most efficient pretreatment method as the methane production was increased by 26%. The findings demonstrated that the methane production of the biogas plants can be increased by further exploiting the fraction of the digested manure fibers which are discarded in the post-storage tank.

  18. Enhanced enzymatic hydrolysis and structural features of corn stover by FeCl3 pretreatment.

    PubMed

    Liu, Li; Sun, Junshe; Li, Min; Wang, Shuhao; Pei, Haisheng; Zhang, Jingsheng

    2009-12-01

    Corn stover was pretreated with FeCl(3) to remove almost all of the hemicellulose present and then hydrolyzed with cellulase and beta-glucosidase to produce glucose. Enzymatic hydrolysis of corn stover that had been pretreated with FeCl(3) at 160 degrees C for 20 min resulted in an optimum yield of 98.0%. This yield was significantly higher than that of untreated corn stover (22.8%). FeCl(3) pretreatment apparently damaged the surface of corn stover and significantly increased the enzymatic digestibility, as evidenced by SEM and XRD analysis data. FTIR analysis indicated that FeCl(3) pretreatment could disrupt almost all the ether linkages and some ester linkages between lignin and carbohydrates but had no effect on delignification. The FeCl(3) pretreatment technique, as a novel pretreatment method, enhances enzymatic hydrolysis of lignocellulosic biomass by destructing chemical composition and altering structural features.

  19. Processes for converting lignocellulosics to reduced acid pyrolysis oil

    DOEpatents

    Kocal, Joseph Anthony; Brandvold, Timothy A

    2015-01-06

    Processes for producing reduced acid lignocellulosic-derived pyrolysis oil are provided. In a process, lignocellulosic material is fed to a heating zone. A basic solid catalyst is delivered to the heating zone. The lignocellulosic material is pyrolyzed in the presence of the basic solid catalyst in the heating zone to create pyrolysis gases. The oxygen in the pyrolysis gases is catalytically converted to separable species in the heating zone. The pyrolysis gases are removed from the heating zone and are liquefied to form the reduced acid lignocellulosic-derived pyrolysis oil.

  20. Efficient biomass pretreatment using ionic liquids derived from lignin and hemicellulose.

    PubMed

    Socha, Aaron M; Parthasarathi, Ramakrishnan; Shi, Jian; Pattathil, Sivakumar; Whyte, Dorian; Bergeron, Maxime; George, Anthe; Tran, Kim; Stavila, Vitalie; Venkatachalam, Sivasankari; Hahn, Michael G; Simmons, Blake A; Singh, Seema

    2014-09-02

    Ionic liquids (ILs), solvents composed entirely of paired ions, have been used in a variety of process chemistry and renewable energy applications. Imidazolium-based ILs effectively dissolve biomass and represent a remarkable platform for biomass pretreatment. Although efficient, imidazolium cations are expensive and thus limited in their large-scale industrial deployment. To replace imidazolium-based ILs with those derived from renewable sources, we synthesized a series of tertiary amine-based ILs from aromatic aldehydes derived from lignin and hemicellulose, the major by-products of lignocellulosic biofuel production. Compositional analysis of switchgrass pretreated with ILs derived from vanillin, p-anisaldehyde, and furfural confirmed their efficacy. Enzymatic hydrolysis of pretreated switchgrass allowed for direct comparison of sugar yields and lignin removal between biomass-derived ILs and 1-ethyl-3-methylimidazolium acetate. Although the rate of cellulose hydrolysis for switchgrass pretreated with biomass-derived ILs was slightly slower than that of 1-ethyl-3-methylimidazolium acetate, 90-95% glucose and 70-75% xylose yields were obtained for these samples after 72-h incubation. Molecular modeling was used to compare IL solvent parameters with experimentally obtained compositional analysis data. Effective pretreatment of lignocellulose was further investigated by powder X-ray diffraction and glycome profiling of switchgrass cell walls. These studies showed different cellulose structural changes and differences in hemicellulose epitopes between switchgrass pretreatments with the aforementioned ILs. Our concept of deriving ILs from lignocellulosic biomass shows significant potential for the realization of a "closed-loop" process for future lignocellulosic biorefineries and has far-reaching economic impacts for other IL-based process technology currently using ILs synthesized from petroleum sources.

  1. Efficient biomass pretreatment using ionic liquids derived from lignin and hemicellulose

    PubMed Central

    Socha, Aaron M.; Parthasarathi, Ramakrishnan; Shi, Jian; Pattathil, Sivakumar; Whyte, Dorian; Bergeron, Maxime; George, Anthe; Tran, Kim; Stavila, Vitalie; Venkatachalam, Sivasankari; Hahn, Michael G.; Simmons, Blake A.; Singh, Seema

    2014-01-01

    Ionic liquids (ILs), solvents composed entirely of paired ions, have been used in a variety of process chemistry and renewable energy applications. Imidazolium-based ILs effectively dissolve biomass and represent a remarkable platform for biomass pretreatment. Although efficient, imidazolium cations are expensive and thus limited in their large-scale industrial deployment. To replace imidazolium-based ILs with those derived from renewable sources, we synthesized a series of tertiary amine-based ILs from aromatic aldehydes derived from lignin and hemicellulose, the major by-products of lignocellulosic biofuel production. Compositional analysis of switchgrass pretreated with ILs derived from vanillin, p-anisaldehyde, and furfural confirmed their efficacy. Enzymatic hydrolysis of pretreated switchgrass allowed for direct comparison of sugar yields and lignin removal between biomass-derived ILs and 1-ethyl-3-methylimidazolium acetate. Although the rate of cellulose hydrolysis for switchgrass pretreated with biomass-derived ILs was slightly slower than that of 1-ethyl-3-methylimidazolium acetate, 90–95% glucose and 70–75% xylose yields were obtained for these samples after 72-h incubation. Molecular modeling was used to compare IL solvent parameters with experimentally obtained compositional analysis data. Effective pretreatment of lignocellulose was further investigated by powder X-ray diffraction and glycome profiling of switchgrass cell walls. These studies showed different cellulose structural changes and differences in hemicellulose epitopes between switchgrass pretreatments with the aforementioned ILs. Our concept of deriving ILs from lignocellulosic biomass shows significant potential for the realization of a “closed-loop” process for future lignocellulosic biorefineries and has far-reaching economic impacts for other IL-based process technology currently using ILs synthesized from petroleum sources. PMID:25136131

  2. Hydrolysis and fractionation of lignocellulosic biomass

    DOEpatents

    Torget, Robert W.; Padukone, Nandan; Hatzis, Christos; Wyman, Charles E.

    2000-01-01

    A multi-function process is described for the hydrolysis and fractionation of lignocellulosic biomass to separate hemicellulosic sugars from other biomass components such as extractives and proteins; a portion of the solubilized lignin; cellulose; glucose derived from cellulose; and insoluble lignin from said biomass comprising one or more of the following: optionally, as function 1, introducing a dilute acid of pH 1.0-5.0 into a continual shrinking bed reactor containing a lignocellulosic biomass material at a temperature of about 94 to about 160.degree. C. for a period of about 10 to about 120 minutes at a volumetric flow rate of about 1 to about 5 reactor volumes to effect solubilization of extractives, lignin, and protein by keeping the solid to liquid ratio constant throughout the solubilization process; as function 2, introducing a dilute acid of pH 1.0-5.0, either as virgin acid or an acidic stream from another function, into a continual shrinking bed reactor containing either fresh biomass or the partially fractionated lignocellulosic biomass material from function 1 at a temperature of about 94-220.degree. C. for a period of about 10 to about 60 minutes at a volumetric flow rate of about 1 to about 5 reactor volumes to effect solubilization of hemicellulosic sugars, semisoluble sugars and other compounds, and amorphous glucans by keeping the solid to liquid ratio constant throughout the solubilization process; as function 3, optionally, introducing a dilute acid of pH 1.0-5.0 either as virgin acid or an acidic stream from another function, into a continual shrinking bed reactor containing the partially fractionated lignocellulosic biomass material from function 2 at a temperature of about 180-280.degree. C. for a period of about 10 to about 60 minutes at a volumetric flow rate of 1 to about 5 reactor volumes to effect solubilization of cellulosic sugars by keeping the solid to liquid ratio constant throughout the solubilization process; and as function 4

  3. Microwave irradiation--A green and efficient way to pretreat biomass.

    PubMed

    Li, Hongqiang; Qu, Yongshui; Yang, Yongqing; Chang, Senlin; Xu, Jian

    2016-01-01

    As a non-traditional heating way, microwave irradiation (MWI) has long been used for lignocellulose pretreatment with the advent of commercial microwave oven since the 1970s. MWI pretreatment using MWI as heating source is similar to other pretreatment methods. Although MWI pretreatment solves some problems caused by other pretreatment methods, such as low heating rate and thermal efficiency, uneven heating, it brings some new challenges such as reaction vessel selection and pretreatment process design. Over 30 years of development, researchers have achieved good pretreatment performance with MWI which has been applied gradually from laboratory scale to pilot-scale. It should be noted that MWI pretreatment is facing some problems: high cost of pretreatment, short of large-scale equipment, the non-thermal effects in pretreatment is still controversial. If MWI pretreatment reaction mechanism could be further clarified and large-scale industrialized reactor be designed, MWI pretreatment might be widely used in biorefinery. Copyright © 2015 Elsevier Ltd. All rights reserved.

  4. Reducing biomass recalcitrance via mild sodium carbonate pretreatment.

    PubMed

    Mirmohamadsadeghi, Safoora; Chen, Zhu; Wan, Caixia

    2016-06-01

    This study examined the effects of mild sodium carbonate (Na2CO3) pretreatment on enzymatic hydrolysis of different feedstocks (i.e., corn stover, Miscanthus, and switchgrass). The results showed that sodium carbonate pretreatment markedly enhanced the sugar yields of the tested biomass feedstocks. The pretreated corn stover, Miscanthus, and switchgrass gave the glucose yields of 95.1%, 62.3%, and 81.3%, respectively, after enzymatic hydrolysis. The above glucose yields of pretreated feedstocks were 2-4 times that of untreated ones. The pretreatment also enhanced the xylose yields, 4 times for corn stover and 20 times for both Miscanthus and switchgrass. Sodium carbonate pretreatment removed 40-59% lignin from the tested feedstocks while preserving most of cellulose (<5% cellulose loss). Corn stover appeared to be least resistant to breakdown by Na2CO3 and enzymatic hydrolysis. Our study indicated that mild sodium carbonate pretreatment was effective for reducing biomass recalcitrance and subsequently improving the digestibility of lignocellulosic biomass. Copyright © 2016 Elsevier Ltd. All rights reserved.

  5. Recovery of monosaccharides from lignocellulosic hydrolysates by ion exclusion chromatography.

    PubMed

    Lodi, Gabriele; Pellegrini, Laura Annamaria; Aliverti, Alessandro; Rivas Torres, Beatriz; Bernardi, Marco; Morbidelli, Massimo; Storti, Giuseppe

    2017-05-05

    The production of sugars from lignocellulosic biomass is the key to a sustainable, renewable chemical industry. Glucose, xylose and other monosaccharides can be easily produced by hydrolyzing cellulose and hemicellulose, the primary polysaccharides in biomass. However, the hydrolysis of biomass generates byproducts that, together with the mineral acid normally added in the hydrolysis step, have to be removed before the downstream conversion processes. In this work, the recovery of monosaccharides from lignocellulosic hydrolysates by means of Ion Exclusion Chromatography (IEC) has been studied. The analyzed process relies on new pretreatment and hydrolysis steps, involving the neutralization of the hydrolysate with sodium hydroxide. The adsorption behavior of the main components involved in the separation has been experimentally investigated. Pulse tests at the high loading encountered in preparative conditions have been performed for a selected group of model components found in the hydrolysates. For all the electrolytes, the retention volume fraction was always between the interparticle porosity and the total column porosity, confirming that ion exclusion was the dominant retention mechanism. On the other hand, sugars eluted before the total column porosity, indicating partial steric exclusion from the resin pores. This observation was then confirmed by size-exclusion experiments with polyethylene glycol standards, from which the distribution coefficient of the studied sugars has been determined. The comparison between the elution profiles of the same sugars in pure form and as a mixture present in the hydrolysate showed differences in both peak shape and retention times. Therefore, an investigation of the influence of the main electrolytes contained in the hydrolysates on sugars adsorption has been performed through the pulse on a plateau method. The electrolytes were found to enhance the sugars retention by promoting their adsorption onto the resin. However

  6. Precultivation of Bacillus coagulans DSM2314 in the presence of furfural decreases inhibitory effects of lignocellulosic by-products during L(+)-lactic acid fermentation.

    PubMed

    van der Pol, Edwin; Springer, Jan; Vriesendorp, Bastienne; Weusthuis, Ruud; Eggink, Gerrit

    2016-12-01

    By-products resulting from thermo-chemical pretreatment of lignocellulose can inhibit fermentation of lignocellulosic sugars to lactic acid. Furfural is such a by-product, which is formed during acid pretreatment of lignocellulose. pH-controlled fermentations with 1 L starting volume, containing YP medium and a mixture of lignocellulosic by-products, were inoculated with precultures of Bacillus coagulans DSM2314 to which 1 g/L furfural was added. The addition of furfural to precultures resulted in an increase in L(+)-lactic acid productivity by a factor 2 to 1.39 g/L/h, an increase in lactic acid production from 54 to 71 g and an increase in conversion yields of sugar to lactic acid from 68 to 88 % W/W in subsequent fermentations. The improved performance was not caused by furfural consumption or conversion, indicating that the cells acquired a higher tolerance towards this by-product. The improvement coincided with a significant elongation of B. coagulans cells. Via RNA-Seq analysis, an upregulation of pathways involved in the synthesis of cell wall components such as bacillosamine, peptidoglycan and spermidine was observed in elongated cells. Furthermore, the gene SigB and genes promoted by SigB, such as NhaX and YsnF, were upregulated in the presence of furfural. These genes are involved in stress responses in bacilli.

  7. Pretreatment Technology Plan

    SciTech Connect

    Barker, S.A.; Thornhill, C.K.; Holton, L.K. Jr.

    1993-03-01

    This technology plan presents a strategy for the identification, evaluation, and development of technologies for the pretreatment of radioactive wastes stored in underground storage tanks at the Hanford Site. This strategy includes deployment of facilities and process development schedules to support the other program elements. This document also presents schedule information for alternative pretreatment systems: (1) the reference pretreatment technology development system, (2) an enhanced pretreatment technology development system, and (3) alternative pretreatment technology development systems.

  8. Assessing pretreatment reactor scaling through empirical analysis

    DOE PAGES

    Lischeske, James J.; Crawford, Nathan C.; Kuhn, Erik; ...

    2016-10-10

    Pretreatment is a critical step in the biochemical conversion of lignocellulosic biomass to fuels and chemicals. Due to the complexity of the physicochemical transformations involved, predictively scaling up technology from bench- to pilot-scale is difficult. This study examines how pretreatment effectiveness under nominally similar reaction conditions is influenced by pretreatment reactor design and scale using four different pretreatment reaction systems ranging from a 3 g batch reactor to a 10 dry-ton/d continuous reactor. The reactor systems examined were an Automated Solvent Extractor (ASE), Steam Explosion Reactor (SER), ZipperClave(R) reactor (ZCR), and Large Continuous Horizontal-Screw Reactor (LHR). To our knowledge, thismore » is the first such study performed on pretreatment reactors across a range of reaction conditions (time and temperature) and at different reactor scales. The comparative pretreatment performance results obtained for each reactor system were used to develop response surface models for total xylose yield after pretreatment and total sugar yield after pretreatment followed by enzymatic hydrolysis. Near- and very-near-optimal regions were defined as the set of conditions that the model identified as producing yields within one and two standard deviations of the optimum yield. Optimal conditions identified in the smallest-scale system (the ASE) were within the near-optimal region of the largest scale reactor system evaluated. A reaction severity factor modeling approach was shown to inadequately describe the optimal conditions in the ASE, incorrectly identifying a large set of sub-optimal conditions (as defined by the RSM) as optimal. The maximum total sugar yields for the ASE and LHR were 95%, while 89% was the optimum observed in the ZipperClave. The optimum condition identified using the automated and less costly to operate ASE system was within the very-near-optimal space for the total xylose yield of both the ZCR and the LHR, and

  9. Assessing pretreatment reactor scaling through empirical analysis

    SciTech Connect

    Lischeske, James J.; Crawford, Nathan C.; Kuhn, Erik; Nagle, Nicholas J.; Schell, Daniel J.; Tucker, Melvin P.; McMillan, James D.; Wolfrum, Edward J.

    2016-10-10

    Pretreatment is a critical step in the biochemical conversion of lignocellulosic biomass to fuels and chemicals. Due to the complexity of the physicochemical transformations involved, predictively scaling up technology from bench- to pilot-scale is difficult. This study examines how pretreatment effectiveness under nominally similar reaction conditions is influenced by pretreatment reactor design and scale using four different pretreatment reaction systems ranging from a 3 g batch reactor to a 10 dry-ton/d continuous reactor. The reactor systems examined were an Automated Solvent Extractor (ASE), Steam Explosion Reactor (SER), ZipperClave(R) reactor (ZCR), and Large Continuous Horizontal-Screw Reactor (LHR). To our knowledge, this is the first such study performed on pretreatment reactors across a range of reaction conditions (time and temperature) and at different reactor scales. The comparative pretreatment performance results obtained for each reactor system were used to develop response surface models for total xylose yield after pretreatment and total sugar yield after pretreatment followed by enzymatic hydrolysis. Near- and very-near-optimal regions were defined as the set of conditions that the model identified as producing yields within one and two standard deviations of the optimum yield. Optimal conditions identified in the smallest-scale system (the ASE) were within the near-optimal region of the largest scale reactor system evaluated. A reaction severity factor modeling approach was shown to inadequately describe the optimal conditions in the ASE, incorrectly identifying a large set of sub-optimal conditions (as defined by the RSM) as optimal. The maximum total sugar yields for the ASE and LHR were 95%, while 89% was the optimum observed in the ZipperClave. The optimum condition identified using the automated and less costly to operate ASE system was within the very-near-optimal space for the total xylose yield of both the ZCR and the LHR, and was

  10. Correlation analysis of enzyme activities and deconstruction of ammonia-pretreated switchgrass by bacterial-fungal communities.

    PubMed

    Jain, Abhiney; Bediako, Sandra H; Henson, J Michael

    2016-10-01

    The mixed microbial communities that occur naturally on lignocellulosic feedstocks can provide feedstock-specific enzyme mixtures to saccharify lignocelluloses. Bacterial-fungal communities were enriched from switchgrass bales to deconstruct ammonia-pretreated switchgrass (DSG). Correlation analysis was carried out to elucidate the relationship between microbial decomposition of DSG by these communities, enzymatic activities produced and enzymatic saccharification of DSG using these enzyme mixtures. Results of the analysis showed that β-glucosidase and xylosidase activities limited the extent of microbial deconstruction and enzymatic saccharification of DSG. The results also underlined the importance of ligninase activity for the enzymatic saccharification of pretreated lignocellulosic feedstock. The bacterial-fungal communities developed in this research can be used to produce enzyme mixtures to deconstruct DSG, and the results from the correlation analysis can be used to optimize these enzyme mixtures for efficient saccharification of DSG to produce second-generation biofuels.

  11. Pretreatment of paper tube residuals for improved biogas production.

    PubMed

    Teghammar, Anna; Yngvesson, Johan; Lundin, Magnus; Taherzadeh, Mohammad J; Horváth, Ilona Sárvári

    2010-02-01

    Paper tube residuals, which are lignocellulosic wastes, have been studied as substrate for biogas (methane) production. Steam explosion and nonexplosive hydrothermal pretreatment, in combination with sodium hydroxide and/or hydrogen peroxide, have been used to improve the biogas production. The treatment conditions of temperature, time and addition of NaOH and H(2)O(2) were statistically evaluated for methane production. Explosive pretreatment was more successful than the nonexplosive method, and gave the best results at 220 degrees C, 10 min, with addition of both 2% NaOH and 2% H(2)O(2). Digestion of the pretreated materials at these conditions yielded 493 N ml/g VS methane which was 107% more than the untreated materials. In addition, the initial digestion rate was improved by 132% compared to the untreated samples. The addition of NaOH was, besides the explosion effect, the most important factor to improve the biogas production.

  12. Mandarin peel wastes pretreatment with steam explosion for bioethanol production.

    PubMed

    Boluda-Aguilar, María; García-Vidal, Lidia; González-Castañeda, Fayiny Del Pilar; López-Gómez, Antonio

    2010-05-01

    The mandarin (Citrus reticulata L.) citrus peel wastes (MCPW) were studied for bioethanol production, obtaining also as co-products: d-limonene, galacturonic acid, and citrus pulp pellets (CPP). The steam explosion pretreatment was analysed at pilot plant level to decrease the hydrolytic enzymes requirements and to separate and recover the d-limonene. The effect of steam explosion on MCPW lignocellulosic composition was analyzed by means thermogravimetric analysis. The d-limonene contents and their influence on ethanol production have been also studied, while concentration of sugars, galacturonic acid and ethanol have been analysed to measure the saccharification and fermentation (HF and SSF) processes efficiency obtained by MCPW steam explosion pretreatment. Ethanol contents of 50-60L/1000kg raw MCPW can be obtained and CPP yields can be regulated by means the control of enzymes dose and the steam explosion pretreatment which can significantly reduce the enzymes requirements. Copyright 2009 Elsevier Ltd. All rights reserved.

  13. The effect of Pleurotus ostreatus arabinofuranosidase and its evolved variant in lignocellulosic biomasses conversion.

    PubMed

    Marcolongo, Loredana; Ionata, Elena; La Cara, Francesco; Amore, Antonella; Giacobbe, Simona; Pepe, Olimpia; Faraco, Vincenza

    2014-11-01

    The fungal arabinofuranosidase from Pleurotus ostreatus PoAbf recombinantly expressed in Pichia pastoris rPoAbf and its evolved variant rPoAbf F435Y/Y446F were tested for their effectiveness to enhance the enzymatic saccharification of three lignocellulosic biomasses, namely Arundo donax, corn cobs and brewer's spent grains (BSG), after chemical or chemical-physical pretreatment. All the raw materials were subjected to an alkaline pretreatment by soaking in aqueous ammonia solution whilst the biomass from A. donax was also pretreated by steam explosion. The capability of the wild-type and mutant rPoAbf to increase the fermentable sugars recovery was assessed by using these enzymes in combination with different (hemi)cellulolytic activities. These enzymatic mixtures were either entirely of commercial origin or contained the cellulase from Streptomyces sp. G12 CelStrep recombinantly expressed in Escherichia coli in substitution to the commercial counterparts. The addition of the arabinofuranosidases from P. ostreatus improved the hydrolytic efficiency of the commercial enzymatic cocktails on all the pretreated biomasses. The best results were obtained using the rPoAbf evolved variant and are represented by increases of the xylose recovery up to 56.4%. These data clearly highlight the important role of the accessory hemicellulolytic activities to optimize the xylan bioconversion yields. Copyright © 2014 Elsevier Inc. All rights reserved.

  14. Biochemical methane potential tests of different autoclaved and microwaved lignocellulosic organic fractions of municipal solid waste.

    PubMed

    Pecorini, Isabella; Baldi, Francesco; Carnevale, Ennio Antonio; Corti, Andrea

    2016-10-01

    The aim of this research was to enhance the anaerobic biodegradability and methane production of two synthetic Organic Fractions of Municipal Solid Waste with different lignocellulosic contents by assessing microwave and autoclave pre-treatments. Biochemical Methane Potential assays were performed for 21days. Changes in the soluble fractions of the organic matter (measured by soluble chemical oxygen demand, carbohydrates and proteins), the first order hydrolysis constant kh and the cumulated methane production at 21days were used to evaluate the efficiency of microwaving and autoclaving pretreatments on substrates solubilization and anaerobic digestion. Microwave treatment led to a methane production increase of 8.5% for both the tested organic fractions while autoclave treatment had an increase ranging from 1.0% to 4.4%. Results showed an increase of the soluble fraction after pre-treatments for both the synthetic organic fractions. Soluble chemical oxygen demand observed significant increases for pretreated substrates (up to 219.8%). In this regard, the mediocre results of methane's production led to the conclusion that autoclaving and microwaving resulted in the hydrolysis of a significant fraction of non-biodegradable organic substances recalcitrant to anaerobic digestion. Copyright © 2016 Elsevier Ltd. All rights reserved.

  15. Rapid optimization of enzyme mixtures for deconstruction of diverse pretreatment/biomass feedstock combinations

    PubMed Central

    2010-01-01

    Background Enzymes for plant cell wall deconstruction are a major cost in the production of ethanol from lignocellulosic biomass. The goal of this research was to develop optimized synthetic mixtures of enzymes for multiple pretreatment/substrate combinations using our high-throughput biomass digestion platform, GENPLAT, which combines robotic liquid handling, statistical experimental design and automated Glc and Xyl assays. Proportions of six core fungal enzymes (CBH1, CBH2, EG1, β-glucosidase, a GH10 endo-β1,4-xylanase, and β-xylosidase) were optimized at a fixed enzyme loading of 15 mg/g glucan for release of Glc and Xyl from all combinations of five biomass feedstocks (corn stover, switchgrass, Miscanthus, dried distillers' grains plus solubles [DDGS] and poplar) subjected to three alkaline pretreatments (AFEX, dilute base [0.25% NaOH] and alkaline peroxide [AP]). A 16-component mixture comprising the core set plus 10 accessory enzymes was optimized for three pretreatment/substrate combinations. Results were compared to the performance of two commercial enzymes (Accellerase 1000 and Spezyme CP) at the same protein loadings. Results When analyzed with GENPLAT, corn stover gave the highest yields of Glc with commercial enzymes and with the core set with all pretreatments, whereas corn stover, switchgrass and Miscanthus gave comparable Xyl yields. With commercial enzymes and with the core set, yields of Glc and Xyl were highest for grass stovers pretreated by AP compared to AFEX or dilute base. Corn stover, switchgrass and DDGS pretreated with AFEX and digested with the core set required a higher proportion of endo-β1,4-xylanase (EX3) and a lower proportion of endo-β1,4-glucanase (EG1) compared to the same materials pretreated with dilute base or AP. An optimized enzyme mixture containing 16 components (by addition of α-glucuronidase, a GH11 endoxylanase [EX2], Cel5A, Cel61A, Cip1, Cip2, β-mannanase, amyloglucosidase, α-arabinosidase, and Cel12A to the

  16. Whole slurry saccharification and fermentation of maleic acid-pretreated rice straw for ethanol production.

    PubMed

    Jung, Young Hoon; Park, Hyun Min; Kim, Kyoung Heon

    2015-09-01

    We evaluated the feasibility of whole slurry (pretreated lignocellulose) saccharification and fermentation for producing ethanol from maleic acid-pretreated rice straw. The optimized conditions for pretreatment were to treat rice straw at a high temperature (190 °C) with 1 % (w/v) maleic acid for a short duration (3 min ramping to 190 °C and 3 min holding at 190 °C). Enzymatic digestibility (based on theoretical glucose yield) of cellulose in the pretreated rice straw was 91.5 %. Whole slurry saccharification and fermentation of pretreated rice straw resulted in 83.2 % final yield of ethanol based on the initial quantity of glucan in untreated rice straw. These findings indicate that maleic acid pretreatment results in a high yield of ethanol from fermentation of whole slurry even without conditioning or detoxification of the slurry. Additionally, the separation of solids and liquid is not required; therefore, the economics of cellulosic ethanol fuel production are significantly improved. We also demonstrated whole slurry saccharification and fermentation of pretreated lignocellulose, which has rarely been reported.

  17. Correlating physical changes and enhanced enzymatic saccharification of pine flour pretreated by Ν-Methylmorpholine-Ν-oxide

    Treesearch

    Ye Liu; Qixin Zhong; Siqun Wang; Zhiyong Cai

    2011-01-01

    Pretreatment of lignocellulosic biomass by Ν-methylmorpholine-Ν-oxide (NMMO), a solvent used in the textile industry to dissolve cellulose for production of regenerated cellulose fibers, was observed to enhance significantly enzymatic saccharification and fermentation. The enhancement was speculated to have been caused by reduced cellulose crystallinity...

  18. Effect of Hot-Pressing Temperature on the Subsequent Enzymatic Saccharification and Fermentation Performance of SPORL Pretreated Forest Biomass

    Treesearch

    Jingzhi Zhang; Andrea Laguna; Craig Clemons; Michael P. Wolcott; Rolland Gleisner; J.Y. Zhu; Xu Zhang

    2015-01-01

    Methods to increase the energy density ofbiofuel feedstock for shipment are important towards improving supply chain efficiency in upstream processes. Towards this end, densified pretreated lignocellulosic biomass was produced using hot-pressing. The effects offiber hornification induced by hot-pressing on enzymatic digestibilities of lodgepolepine and poplar NE222...

  19. Using low temperature to balance enzymatic saccharification and furan formation during SPORL pretreatment of Douglas-fir

    Treesearch

    C. Zhang; C.J. Houtman; J.Y. Zhu

    2014-01-01

    tComparing analytical results for Sulfite Pretreatment to Overcome the Recalcitrance of Lignocelluloses(SPORL) of Douglas-fir (Pseudotsuga menziesii) at two different temperatures shows that the apparentactivation energy of sugar degradation is higher than that of hemicellulose hydrolysis, approximately161 kJ/mole versus 100 kJ/mole. Thus, one can...

  20. Phenotypic selection of a wild Saccharomyces cerevisiae strain for simultaneous saccharification and co-fermentation of AFEX pretreated corn stover

    Treesearch

    Mingie Jin; Cory Sarks; Christa Gunawan; Benjamin D. Bice; Shane P. Simonett; Ragothaman Avanasi Narasimhan; Laura B. Willis; Bruce E. Dale; Venkatesh Balan; Trey K. Sato

    2013-01-01

    Simultaneous saccharification and co-fermentation (SSCF) process involves enzymatic hydrolysis of pretreated lignocellulosic biomass and fermentation of glucose and xylose in one bioreactor. The optimal temperatures for enzymatic hydrolysis are higher than the standard fermentation temperature of ethanologenic Saccharomyces cerevisiae. Moreover,...