1
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De PS, Theilmann J, Raguin A. A detailed sensitivity analysis identifies the key factors influencing the enzymatic saccharification of lignocellulosic biomass. Comput Struct Biotechnol J 2024; 23:1005-1015. [PMID: 38420218 PMCID: PMC10900831 DOI: 10.1016/j.csbj.2024.01.006] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2023] [Revised: 01/09/2024] [Accepted: 01/14/2024] [Indexed: 03/02/2024] Open
Abstract
Corn stover is the most abundant form of crop residue that can serve as a source of lignocellulosic biomass in biorefinery approaches, for instance for the production of bioethanol. In such biorefinery processes, the constituent polysaccharide biopolymers are typically broken down into simple monomeric sugars by enzymatic saccharification, for further downstream fermentation into bioethanol. However, the recalcitrance of this material to enzymatic saccharification invokes the need for innovative pre-treatment methods to increase sugar conversion yield. Here, we focus on experimental glucose conversion time-courses for corn stover lignocellulose that has been pre-treated with different acid-catalysed processes and intensities. We identify the key parameters that determine enzymatic saccharification dynamics by performing a Sobol's sensitivity analysis on the comparison between the simulation results from our complex stochastic biophysical model, and the experimental data that we accurately reproduce. We find that the parameters relating to cellulose crystallinity and those associated with the cellobiohydrolase activity are predominantly driving the enzymatic saccharification dynamics. We confirm our computational results using mathematical calculations for a purely cellulosic substrate. On the one hand, having identified that only five parameters drastically influence the saccharification dynamics allows us to reduce the dimensionality of the parameter space (from nineteen to five parameters), which we expect will significantly speed up our fitting algorithm for comparison of experimental and simulated saccharification time-courses. On the other hand, these parameters directly highlight key targets for experimental endeavours in the optimisation of pre-treatment and saccharification conditions. Finally, this systematic and two-fold theoretical study, based on both mathematical and computational approaches, provides experimentalists with key insights that will support them in rationalising their complex experimental results.
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Affiliation(s)
- Partho Sakha De
- Institute for Computational Cell Biology, Heinrich Heine University, Universitätsstr. 1, Düsseldorf, 40225, NRW, Germany
- Bioeconomy Science Center (BioSC), c/o Forschungszentrum Jülich, Jülich, 52425, NRW, Germany
| | - Jasmin Theilmann
- Institute for Computational Cell Biology, Heinrich Heine University, Universitätsstr. 1, Düsseldorf, 40225, NRW, Germany
| | - Adélaïde Raguin
- Institute for Computational Cell Biology, Heinrich Heine University, Universitätsstr. 1, Düsseldorf, 40225, NRW, Germany
- Bioeconomy Science Center (BioSC), c/o Forschungszentrum Jülich, Jülich, 52425, NRW, Germany
- Cluster of Excellence on Plant Sciences (CEPLAS), Heinrich Heine University, Universitätsstr. 1, Düsseldorf, 40225, NRW, Germany
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2
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Takada M, Okazaki Y, Kajita S, Kawamoto H, Sagawa T. Fractionation of beech wood cell walls into digestible cellulose-rich residues and photoluminescent lignin-rich precipitates via semi-flow hot-compressed water treatment with 2-naphthol. RSC Adv 2024; 14:20660-20667. [PMID: 38952928 PMCID: PMC11215400 DOI: 10.1039/d4ra03094j] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2024] [Accepted: 06/20/2024] [Indexed: 07/03/2024] Open
Abstract
Utilization of cell wall components of woody biomass has attracted attention as alternatives for fossil fuels towards a sustainable society. A semi-flow hydrothermal treatment was used to fractionate the beech (Fagus crenata) wood into cellulose-rich residues and lignin-rich precipitates. The enzymatic saccharification of the cellulose component in the residue was enhanced significantly because the preferential delignification from the secondary wall increased enzyme accessibility. Meanwhile, the precipitated lignin was soluble in organic solvent and exhibited clear photoluminescence (PL) according to the chromophore distances. Furthermore, the carbocation scavenger, 2-naphthol, was impregnated into the beech wood to inhibit the lignin re-condensation reaction. As a result, the digestibility of the cellulose component in the residue increased because unproductive enzymatic binding of lignin and lignin re-condensation were both suppressed. In addition, the PL intensity of the precipitates was significantly enhanced, indicating that 2-naphthol bound to the lignin molecules influenced the PL properties. Overall, fractionation using a semi-flow hydrothermal treatment efficiently uses both polysaccharides and lignin, especially the impregnation of 2-naphthol provided advantages for both saccharides and lignin. Monosaccharides can be converted into valuable products via a sugar platform, and the lignin precipitates exhibit useful PL properties that give them significant potential as a feedstock for numerous valuable materials, such as fluorescence reagents and spectral conversion agents. The results presented herein provide insights that are crucial for the comprehensive utilization of cell wall components for sustainable biorefinery systems.
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Affiliation(s)
- Masatsugu Takada
- Graduate School of Bio-Applications and Systems Engineering (BASE), Tokyo University of Agriculture and Technology 2-24-16, Nakacho Koganeishi Tokyo 184-8588 Japan
| | - Yutaka Okazaki
- Graduate School of Energy Science, Kyoto University Yoshida-Honmachi, Sakyo-ku Kyoto 606-8501 Japan
| | - Shinya Kajita
- Graduate School of Bio-Applications and Systems Engineering (BASE), Tokyo University of Agriculture and Technology 2-24-16, Nakacho Koganeishi Tokyo 184-8588 Japan
| | - Haruo Kawamoto
- Graduate School of Energy Science, Kyoto University Yoshida-Honmachi, Sakyo-ku Kyoto 606-8501 Japan
| | - Takashi Sagawa
- Graduate School of Energy Science, Kyoto University Yoshida-Honmachi, Sakyo-ku Kyoto 606-8501 Japan
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3
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Haddis DZ, Chae M, Asomaning J, Bressler DC. Evaluation of steam explosion pretreatment on the cellulose nanocrystals (CNCs) yield from poplar wood. Carbohydr Polym 2024; 323:121460. [PMID: 37940318 DOI: 10.1016/j.carbpol.2023.121460] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2023] [Revised: 10/02/2023] [Accepted: 10/03/2023] [Indexed: 11/10/2023]
Abstract
The high sulfuric acid concentration used in the hydrolysis of cellulose to isolate cellulose nanocrystals (CNCs) leads to low yields due to the dissolution of both amorphous and semi-crystalline cellulose. The present study explored the use of steam explosion pretreatment before acid hydrolysis to enhance the crystallization of semi-crystalline/ non-crystalline cellulose and generating new CNC precursors with poplar wood as feedstock. The crystallinity of steam exploded poplar wood increased 1.3-fold compared to untreated poplar wood. Consequently, the overall yield of CNCs of steam exploded poplar wood increased 2.5-fold compared to untreated poplar wood. Moreover, the steam explosion pretreatment did not affect the quality of the CNCs with regard to the crystal size, crystallinity, and colloidal stability. Whereas the thermal stability of the CNCs increased due to the steam explosion pretreatment. This study demonstrates a simple and scalable pretreatment step that can significantly improve the CNCs yield from the acid hydrolysis step thereby improving the overall economics and commercial viability.
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Affiliation(s)
- Dagem Zekaryas Haddis
- Department of Agricultural, Food and Nutritional Science, University of Alberta, Edmonton, AB T6G 2P5, Canada
| | - Michael Chae
- Department of Agricultural, Food and Nutritional Science, University of Alberta, Edmonton, AB T6G 2P5, Canada
| | - Justice Asomaning
- Department of Agricultural, Food and Nutritional Science, University of Alberta, Edmonton, AB T6G 2P5, Canada
| | - David C Bressler
- Department of Agricultural, Food and Nutritional Science, University of Alberta, Edmonton, AB T6G 2P5, Canada.
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4
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De PS, Glass T, Stein M, Spitzlei T, Raguin A. PREDIG: Web application to model and predict the enzymatic saccharification of plant cell wall. Comput Struct Biotechnol J 2023; 21:5463-5475. [PMID: 38022701 PMCID: PMC10663758 DOI: 10.1016/j.csbj.2023.09.026] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2023] [Revised: 09/21/2023] [Accepted: 09/22/2023] [Indexed: 12/01/2023] Open
Abstract
Enzymatic digestion of lignocellulosic plant biomass is a key step in bio-refinery approaches for the production of biofuels and other valuable chemicals. However, the recalcitrance of this material in conjunction with its variability and heterogeneity strongly hampers the economic viability and profitability of biofuel production. To complement both academic and industrial experimental research in the field, we designed an advanced web application that encapsulates our in-house developed complex biophysical model of enzymatic plant cell wall degradation. PREDIG (https://predig.cs.hhu.de/) is a user-friendly, free, and fully open-source web application that allows the user to perform in silico experiments. Specifically, it uses a Gillespie algorithm to run stochastic simulations of the enzymatic saccharification of a lignocellulose microfibril, at the mesoscale, in three dimensions. Such simulations can for instance be used to test the action of distinct enzyme cocktails on the substrate. Additionally, PREDIG can fit the model parameters to uploaded experimental time-course data, thereby returning values that are intrinsically difficult to measure experimentally. This gives the user the possibility to learn which factors quantitatively explain the recalcitrance to saccharification of their specific biomass material.
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Affiliation(s)
- Partho Sakha De
- Institute for Computational Cell Biology, Computer Science department, Heinrich Heine University, Düsseldorf, 40225, Germany
- Bioeconomy Science Center (BioSC), c/o Forschungszentrum Jülich, Jülich, 52425, Germany
| | - Torben Glass
- Institute for Computational Cell Biology, Computer Science department, Heinrich Heine University, Düsseldorf, 40225, Germany
- Bioeconomy Science Center (BioSC), c/o Forschungszentrum Jülich, Jülich, 52425, Germany
| | - Merle Stein
- Institute for Computational Cell Biology, Computer Science department, Heinrich Heine University, Düsseldorf, 40225, Germany
- Cluster of Excellence on Plant Sciences (CEPLAS), Heinrich Heine University, Düsseldorf, 40225, Germany
| | - Thomas Spitzlei
- Institute for Computational Cell Biology, Computer Science department, Heinrich Heine University, Düsseldorf, 40225, Germany
| | - Adélaïde Raguin
- Institute for Computational Cell Biology, Computer Science department, Heinrich Heine University, Düsseldorf, 40225, Germany
- Bioeconomy Science Center (BioSC), c/o Forschungszentrum Jülich, Jülich, 52425, Germany
- Cluster of Excellence on Plant Sciences (CEPLAS), Heinrich Heine University, Düsseldorf, 40225, Germany
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5
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Wu J, Ebadian M, Kim KH, Kim CS, Saddler J. The use of steam pretreatment to enhance pellet durability and the enzyme-mediated hydrolysis of pellets to fermentable sugars. BIORESOURCE TECHNOLOGY 2022; 347:126731. [PMID: 35074465 DOI: 10.1016/j.biortech.2022.126731] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/10/2021] [Revised: 01/13/2022] [Accepted: 01/15/2022] [Indexed: 06/14/2023]
Abstract
Although densified wood pellets are an attractive biomass feedstock for bioenergy and biofuels production, partly due to their ease of transport, their friability and hygroscopic nature (attraction of moisture) have proven problematic in terms of storage and handling. Pre-steaming the biomass was shown to reduce the need for size reduction, significantly increasing pellet durability by relocating the plant cell wall lignin to the fibre surface and consequently enhancing binding between particles. Although steam pretreatment has been shown to facilitate enzyme-mediated hydrolysis of biomass, by increasing cellulose accessibility, drying and pelletization partially impeded enzymatic hydrolysis. However, the incorporation of alkaline deacetylation or neutral sulfonation step prior to pre-steaming was shown to mitigate many of the negative effects of drying. Although drying and pelletization did not significantly impact the redistribution of lignin, a mild mechanical refining step was shown to further enhance the hydrolysis of the cellulose component of the pelletized biomass.
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Affiliation(s)
- Jie Wu
- Forest Products Biotechnology/Bioenergy Group, Department of Wood Science, Faculty of Forestry, University of British Columbia, 2424 Main Mall, Vancouver BC V6T 1Z4, Canada
| | - Mahmood Ebadian
- Forest Products Biotechnology/Bioenergy Group, Department of Wood Science, Faculty of Forestry, University of British Columbia, 2424 Main Mall, Vancouver BC V6T 1Z4, Canada
| | - Kwang Ho Kim
- Clean Energy Research Center, Korea Institute of Science and Technology, Seoul 02792, Republic of Korea
| | - Chang Soo Kim
- Clean Energy Research Center, Korea Institute of Science and Technology, Seoul 02792, Republic of Korea
| | - Jack Saddler
- Forest Products Biotechnology/Bioenergy Group, Department of Wood Science, Faculty of Forestry, University of British Columbia, 2424 Main Mall, Vancouver BC V6T 1Z4, Canada.
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6
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Behle E, Raguin A. Stochastic model of lignocellulosic material saccharification. PLoS Comput Biol 2021; 17:e1009262. [PMID: 34516546 PMCID: PMC8460048 DOI: 10.1371/journal.pcbi.1009262] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2021] [Revised: 09/23/2021] [Accepted: 07/09/2021] [Indexed: 12/03/2022] Open
Abstract
The processing of agricultural wastes towards extraction of renewable resources is recently being considered as a promising alternative to conventional biofuel production. The degradation of agricultural residues is a complex chemical process that is currently time intensive and costly. Various pre-treatment methods are being investigated to determine the subsequent modification of the material and the main obstacles in increasing the enzymatic saccharification. In this study, we present a computational model that complements the experimental approaches. We decipher how the three-dimensional structure of the substrate impacts the saccharification dynamics. We model a cell wall microfibril composed of cellulose and surrounded by hemicellulose and lignin, with various relative abundances and arrangements. This substrate is subjected to digestion by different cocktails of well characterized enzymes. The saccharification dynamics is simulated in silico using a stochastic procedure based on a Gillespie algorithm. As we additionally implement a fitting procedure that optimizes the parameters of the simulation runs, we are able to reproduce experimental saccharification time courses for corn stover. Our model highlights the synergistic action of enzymes, and confirms the linear decrease of sugar conversion when either lignin content or crystallinity of the substrate increases. Importantly, we show that considering the crystallinity of cellulose in addition to the substrate composition is essential to interpret experimental saccharification data. Finally, our findings support the hypothesis of xylan being partially crystalline. Leftover wastes generated by agriculture, such as inedible leaves and stalks of plants, represent an abundant and unexploited raw material that contains energy in the form of sugar polymers. Their breakdown and processing into bio-ethanol is recently being considered as a promising candidate for renewable fuel production. However, it is still poorly understood, how the microscopic structure and composition of plant waste materials impact their enzymatic digestion. Various experimental pre-processing methods are currently being tested to determine their effect on the material composition and structure, and the sugar conversion. In this study, we present a computational model to complement such experimental approaches. We simulate a microscopic plant fragment typically found in plant waste materials, whose structure and composition can be tailored. This fragment is then subjected to enzymatic digestion, whose dynamics is tracked in silico. The model reproduces experimentally observed time courses for plant fragments of known composition. It additionally provides new hypotheses for interpreting complex experimental results.
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Affiliation(s)
- Eric Behle
- Department of Biology, Cluster of Excellence on Plant Sciences, Institute of Quantitative and Theoretical Biology, Heinrich-Heine University, Düsseldorf, Germany
| | - Adélaïde Raguin
- Department of Biology, Cluster of Excellence on Plant Sciences, Institute of Quantitative and Theoretical Biology, Heinrich-Heine University, Düsseldorf, Germany
- * E-mail:
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7
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Ji G, Xu L, Lyu Q, Liu Y, Gong X, Li X, Yan Z. Poly-γ-glutamic acid production by simultaneous saccharification and fermentation using corn straw and its fertilizer synergistic effect evaluation. Bioprocess Biosyst Eng 2021; 44:2181-2191. [PMID: 34086133 DOI: 10.1007/s00449-021-02593-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2021] [Accepted: 05/25/2021] [Indexed: 10/21/2022]
Abstract
Agricultural wastes rich in lignocellulosic biomass have been used in the production of poly-γ-glutamic acid (γ-PGA) through separate hydrolysis and fermentation (SHF), but this process is complicated and generates a lot of wastes. In order to find a simpler and greener way to produce γ-PGA using agricultural wastes, this study attempted to establish simultaneous saccharification and fermentation (SSF) with citric acid-pretreated corn straw. The possibility of Bacillus amyloliquefaciens JX-6 using corn straw as substrate to synthesize γ-PGA was validated, and the results showed that increasing the proportion of glucose in the substrate could improve the γ-PGA yield. Based on these preliminary results, the corn straw was pretreated using citric acid. Then, the liquid fraction (xylan-rich) was used for cultivation of seed culture, and the solid fraction (glucan-rich) was used as the substrate for SSF. In a 10-L fermenter, the maximum cumulative γ-PGA concentration in batch and fed-batch SSF were 5.08 ± 0.78 g/L and 10.78 ± 0.32 g/L, respectively. Moreover, the product from SSF without γ-PGA extraction was used as a fertilizer synergist, increasing the yield of pepper by 13.46% (P < 0.05). Our study greatly simplified the production steps of γ-PGA, and each step achieved zero emission as far as possible. The SSF process for γ-PGA production provided a simple and green way for lignocellulose biorefinery and sustainable cultivation in agriculture.
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Affiliation(s)
- Gaosheng Ji
- CAS Key Laboratory of Environmental and Applied Microbiology, Environmental Microbiology Key Laboratory of Sichuan Province, Chengdu Institute of Biology, Chinese Academy of Sciences, Chengdu, 610041, People's Republic of China.,University of Chinese Academy of Sciences, Beijing, 100049, China
| | - Lishan Xu
- CAS Key Laboratory of Environmental and Applied Microbiology, Environmental Microbiology Key Laboratory of Sichuan Province, Chengdu Institute of Biology, Chinese Academy of Sciences, Chengdu, 610041, People's Republic of China
| | - Qingyang Lyu
- CAS Key Laboratory of Environmental and Applied Microbiology, Environmental Microbiology Key Laboratory of Sichuan Province, Chengdu Institute of Biology, Chinese Academy of Sciences, Chengdu, 610041, People's Republic of China
| | - Yang Liu
- CAS Key Laboratory of Environmental and Applied Microbiology, Environmental Microbiology Key Laboratory of Sichuan Province, Chengdu Institute of Biology, Chinese Academy of Sciences, Chengdu, 610041, People's Republic of China
| | - Xuefeng Gong
- Institute of Horticulture, Sichuan Academy of Agricultural Sciences, Chengdu, 610066, China
| | - Xudong Li
- CAS Key Laboratory of Environmental and Applied Microbiology, Environmental Microbiology Key Laboratory of Sichuan Province, Chengdu Institute of Biology, Chinese Academy of Sciences, Chengdu, 610041, People's Republic of China
| | - Zhiying Yan
- CAS Key Laboratory of Environmental and Applied Microbiology, Environmental Microbiology Key Laboratory of Sichuan Province, Chengdu Institute of Biology, Chinese Academy of Sciences, Chengdu, 610041, People's Republic of China.
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8
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Pascoli DU, Suko A, Gustafson R, Gough HL, Bura R. Novel ethanol production using biomass preprocessing to increase ethanol yield and reduce overall costs. BIOTECHNOLOGY FOR BIOFUELS 2021; 14:9. [PMID: 33413532 PMCID: PMC7789555 DOI: 10.1186/s13068-020-01839-0] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 04/10/2020] [Accepted: 11/24/2020] [Indexed: 06/12/2023]
Abstract
BACKGROUND Ethanol biorefineries need to lower their overall production costs to become economically feasible. Two strategies to achieve this are to reduce costs using cheaper feedstocks or to increase the ethanol production yield. Low-cost feedstocks usually have high non-structural components (NSC) content; therefore, a new process is necessary to accommodate these feedstocks and overcome the negative effects of NSC. This study developed a novel ethanol biorefinery process including a biomass preprocessing step that enabled the use of lower-cost feedstocks while improving ethanol production without detoxification (overliming). Two types of poplar feedstocks were used, low-quality whole-tree chips (WTC) and high-quality clean pulp chips (CPC), to determine if the proposed process is effective while using feedstocks with different NSC contents. RESULTS Technical assessment showed that acidic preprocessing increased the monomeric sugar recovery of WTC from 73.2% (untreated) to 87.5% due to reduced buffering capacity of poplar, improved sugar solubilization during pretreatment, and better enzymatic hydrolysis conversion. Preprocessing alone significantly improved the fermentability of the liquid fraction from 1-2% to 49-56% for both feedstocks while overliming improved it to 45%. Consequently, it was proposed that preprocessing can substitute for the detoxification step. The economic assessment revealed that using poplar WTC via the new process increased annual ethanol production of 10.5 million liters when compared to using CPC via overliming (base case scenario). Also, savings in total operating costs were about $10 million per year when using cheaper poplar WTC instead of CPC, and using recycled water for preprocessing lowered its total operating costs by 45-fold. CONCLUSIONS The novel process developed in this study was successful in increasing ethanol production while decreasing overall costs, thus facilitating the feasibility of lignocellulosic ethanol biorefineries. Key factors to achieving this outcome included substituting overliming by preprocessing, enabling the use of lower-quality feedstock, increasing monomeric sugar recovery and ethanol fermentation yield, and using recycled water for preprocessing. In addition, preprocessing enabled the implementation of an evaporator-combustor downstream design, resulting in a low-loading waste stream that can be treated in a wastewater treatment plant with a simple configuration.
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Affiliation(s)
- Danielle Uchimura Pascoli
- School of Environmental and Forest Sciences, University of Washington, Box 352100, Seattle, WA 98195-2100 USA
| | - Azra Suko
- School of Environmental and Forest Sciences, University of Washington, Box 352100, Seattle, WA 98195-2100 USA
| | - Rick Gustafson
- School of Environmental and Forest Sciences, University of Washington, Box 352100, Seattle, WA 98195-2100 USA
| | - Heidi L. Gough
- School of Environmental and Forest Sciences, University of Washington, Box 352100, Seattle, WA 98195-2100 USA
| | - Renata Bura
- School of Environmental and Forest Sciences, University of Washington, Box 352100, Seattle, WA 98195-2100 USA
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Pires Nogueira D, Ferreira Rosa PR, Aparecida Seolatto A, Galeano Suarez CA, Ferreira Freitas F. Saccharification of Orange Bagasse Pre-treated with Calcium Hydroxide using an enzymatic blend Diluted Hydrochloric Acid. REVISTA ION 2019. [DOI: 10.18273/revion.v32n1-2018007] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
Abstract
Enzymatic and dilute acid processes were applied to study the orange bagasse hydrolysis. The moisture, ashes, lignin, cellulose, and hemicellulose contents, of the orange peels, were quantified. The xylanase and cellulase enzymes activities were quantified, as well as their optimum pH and temperatures. The pre dried orange peel biomass was pre-treated with calcium hydroxide, at preestablished conditions. The hydrolysis followed a central composite factorial 2³ design. The cellulase activity was 28.05x10-6 FPU (Filter Paper Units)/m3, the optimum pH was 4.8 and the temperature was 60°C. The results for xylanase were an activity of 199.58x10-3 U/Kg, pH 5.2, and temperature 50°C. The acid hydrolysis TRS (total reducing sugars) values varied from (9.328±0.68 mg)*10-3 TRS per Kg of biomass to (30.15±0.31)*10-3 mg TRS per Kg biomass, the most significant factor was the temperature and the least the time. The enzymatic hydrolysis TRS values varied from (77.33±3.82)*10-3 mg TRS per Kg biomass to (99.66±0.62)*10-3 mg TRS per Kg biomass, the most significant factor was the concentration of cellulase and the least the xylanase concentration.
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10
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Pires Nogueira D, Ferreira Rosa PR, Aparecida Seolatto A, Galeano Suarez CA, Ferreira Freitas F. Saccharification of Orange Bagasse Pre-treated with Calcium Hydroxide using an enzymatic blend Diluted Hydrochloric Acid. REVISTA ION 2019. [DOI: 10.18273/revion.v32n1-2019007] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
Abstract
Enzymatic and dilute acid processes were applied to study the orange bagasse hydrolysis. The moisture, ashes, lignin, cellulose, and hemicellulose contents, of the orange peels, were quantified. The xylanase and cellulase enzymes activities were quantified, as well as their optimum pH and temperatures. The pre dried orange peel biomass was pre-treated with calcium hydroxide, at preestablished conditions. The hydrolysis followed a central composite factorial 2³ design. The cellulase activity was 28.05x10-6 FPU (Filter Paper Units)/m3, the optimum pH was 4.8 and the temperature was 60°C. The results for xylanase were an activity of 199.58x10-3 U/Kg, pH 5.2, and temperature 50°C. The acid hydrolysis TRS (total reducing sugars) values varied from (9.328±0.68 mg)*10-3 TRS per Kg of biomass to (30.15±0.31)*10-3 mg TRS per Kg biomass, the most significant factor was the temperature and the least the time. The enzymatic hydrolysis TRS values varied from (77.33±3.82)*10-3 mg TRS per Kg biomass to (99.66±0.62)*10-3 mg TRS per Kg biomass, the most significant factor was the concentration of cellulase and the least the xylanase concentration.
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11
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Takada M, Chandra RP, Saddler JN. The influence of lignin migration and relocation during steam pretreatment on the enzymatic hydrolysis of softwood and corn stover biomass substrates. Biotechnol Bioeng 2019; 116:2864-2873. [DOI: 10.1002/bit.27137] [Citation(s) in RCA: 29] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2019] [Revised: 07/23/2019] [Accepted: 08/04/2019] [Indexed: 11/07/2022]
Affiliation(s)
- Masatsugu Takada
- Forest Products Biotechnology/Bioenergy Group, Department of Wood Science, Faculty of ForestryUniversity of British Columbia Vancouver BC Canada
| | - Richard P. Chandra
- Forest Products Biotechnology/Bioenergy Group, Department of Wood Science, Faculty of ForestryUniversity of British Columbia Vancouver BC Canada
| | - John N. Saddler
- Forest Products Biotechnology/Bioenergy Group, Department of Wood Science, Faculty of ForestryUniversity of British Columbia Vancouver BC Canada
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12
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Pires-Nogueira D, Ferreira-Rosa PR, Seolatto AA, Galeano-Suarez CA, Ferreira-Freitas F. Saccharification of Orange Bagasse Pre-treated with Calcium Hydroxide using an enzymatic blendDiluted Hydrochloric Acid. REVISTA ION 2019. [DOI: 10.18273/10.18273/revion.v32n1-2019007] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
Abstract
Enzymatic and dilute acid processes were applied to study the orange bagasse hydrolysis. The moisture, ashes, lignin, cellulose, and hemicellulose contents, of the orange peels, were quantified. The xylanase and cellulase enzymes activities were quantified, as well as their optimum pH and temperatures. The pre dried orange peel biomass was pre-treated with calcium hydroxide, at preestablished conditions. The hydrolysis followed a central composite factorial 2³ design. The cellulase activity was 28.05x10-6 FPU (Filter Paper Units)/m3, the optimum pH was 4.8 and the temperature was 60°C. The results for xylanase were an activity of 199.58x10-3 U/Kg, pH 5.2, and temperature 50°C. The acid hydrolysis TRS (total reducing sugars) values varied from (9.328±0.68 mg)*10-3 TRS per Kg of biomass to (30.15±0.31)*10-3 mg TRS per Kg biomass, the most significant factor was the temperature and the least the time. The enzymatic hydrolysis TRS values varied from (77.33±3.82)*10-3 mg TRS per Kg biomass to (99.66±0.62)*10-3 mg TRS per Kg biomass, the most significant factor was the concentration of cellulase and the least the xylanase concentration
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13
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Wang Y, Gong X, Hu X, Zhou N. Lignin monomer in steam explosion assist chemical treated cotton stalk affects sugar release. BIORESOURCE TECHNOLOGY 2019; 276:343-348. [PMID: 30641333 DOI: 10.1016/j.biortech.2019.01.008] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/28/2018] [Revised: 01/02/2019] [Accepted: 01/03/2019] [Indexed: 05/12/2023]
Abstract
In this study, the fermentable sugar released from cotton stalk (CS), which were pretreated by instant catapult steam explosion (SE) combined with different concentrations of strong monobasic acid (HCl), weak monobasic acid (CH3COOH), strong monobasic alkali (NaOH) and weak monobasic alkali (NH3·H2O), followed by hydrolysis in cellulase/xylanase mixed enzyme solutions, were comparably investigated. The highest yield of 73.22% of fermentable sugar yield was obtained in SE-2.4 MPa-5%NH3·H2O treated CS substrates, which was 5.14 times higher than that from enzymatic hydrolysis (EH) of raw CS. Furthermore, evaluation of monolignins content (H, G, S) in different CS samples suggested that substrates rich in guaiacyl (G) and syringyl (S) would generate a higher efficiency of enzymatic saccharification. Therefore, the slight genetic modification of monolignins for cotton stalk might be a potential way to enhance biomass degradation and transformation.
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Affiliation(s)
- Ya Wang
- Key Laboratory for Green Processing of Chemical Engineering of Xinjiang Bingtuan, School of Chemistry and Chemical Engineering, Shihezi University, Shihezi, China
| | - Xiaowu Gong
- Key Laboratory for Green Processing of Chemical Engineering of Xinjiang Bingtuan, School of Chemistry and Chemical Engineering, Shihezi University, Shihezi, China
| | - Xiaona Hu
- Key Laboratory for Green Processing of Chemical Engineering of Xinjiang Bingtuan, School of Chemistry and Chemical Engineering, Shihezi University, Shihezi, China
| | - Na Zhou
- Key Laboratory for Green Processing of Chemical Engineering of Xinjiang Bingtuan, School of Chemistry and Chemical Engineering, Shihezi University, Shihezi, China.
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14
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Dong M, Wang S, Xu F, Wang J, Yang N, Li Q, Chen J, Li W. Pretreatment of sweet sorghum straw and its enzymatic digestion: insight into the structural changes and visualization of hydrolysis process. BIOTECHNOLOGY FOR BIOFUELS 2019; 12:276. [PMID: 31768194 PMCID: PMC6874820 DOI: 10.1186/s13068-019-1613-6] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/02/2019] [Accepted: 11/10/2019] [Indexed: 05/03/2023]
Abstract
BACKGROUND The efficient utilization of lignocellulosic biomass for biofuel production has received increasing attention. Previous studies have investigated the pretreatment process of biomass, but the detailed enzymatic hydrolysis process of pretreated biomass remains largely unclear. Thus, this study investigated the pretreatment efficiency of dilute alkali, acid, hydrogen peroxide and its ultimate effects on enzymatic hydrolysis. Furthermore, to better understand the enzymatic digestion process of alkali-pretreated sweet sorghum straw (SSS), multimodal microscopy techniques were used to visualize the enzymatic hydrolysis process. RESULT After pretreatment with alkali, an enzymatic hydrolysis efficiency of 86.44% was obtained, which increased by 99.54% compared to the untreated straw (43.23%). The FTIR, XRD and SEM characterization revealed a sequence of microstructural changes occurring in plant cell walls after pretreatment, including the destruction of lignin-polysaccharide interactions, the increase of porosity and crystallinity, and reduction of recalcitrance. During the course of hydrolysis, the cellulase dissolved the cell walls in the same manner and the digestion firstly occurred from the middle of cell walls and then toward the cell wall corners. The CLSM coupled with fluorescent labeling demonstrated that the sclerenchyma cells and vascular bundles in natural SSS were highly lignified, which caused the nonproductive bindings of cellulase on lignin. However, the efficient delignification significantly increased the accessibility and digestibility of cellulase to biomass, thereby improving the saccharification efficiency. CONCLUSION This work will be helpful in investigating the biomass pretreatment and its structural characterization. In addition, the visualization results of the enzymatic hydrolysis process of pretreated lignocellulose could be used for guidance to explore the lignocellulosic biomass processing and large-scale biofuel production.
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Affiliation(s)
- Miaoyin Dong
- Institute of Modern Physics, Chinese Academy of Sciences, 509 Nanchang Rd., Lanzhou, 730000 Gansu People’s Republic of China
- College of Life Sciences, University of Chinese Academy of Sciences, No. 19A Yuquan Road, Beijing, 100049 People’s Republic of China
| | - Shuyang Wang
- Institute of Modern Physics, Chinese Academy of Sciences, 509 Nanchang Rd., Lanzhou, 730000 Gansu People’s Republic of China
- Institute of Biology, Gansu Academy of Sciences, 197 Dingxi South Rd., Lanzhou, 730000 Gansu People’s Republic of China
- College of Life Sciences, University of Chinese Academy of Sciences, No. 19A Yuquan Road, Beijing, 100049 People’s Republic of China
| | - Fuqiang Xu
- Institute of Modern Physics, Chinese Academy of Sciences, 509 Nanchang Rd., Lanzhou, 730000 Gansu People’s Republic of China
- College of Life Sciences, University of Chinese Academy of Sciences, No. 19A Yuquan Road, Beijing, 100049 People’s Republic of China
| | - Junkai Wang
- College of Physics and Electronic Engineering, Northwest Normal University, Anning Rd., Lanzhou, 730000 Gansu People’s Republic of China
| | - Ning Yang
- College of Life Sciences, Northwest Normal University, Anning Rd., Lanzhou, 730000 Gansu People’s Republic of China
| | - Qiaoqiao Li
- Institute of Modern Physics, Chinese Academy of Sciences, 509 Nanchang Rd., Lanzhou, 730000 Gansu People’s Republic of China
- College of Life Sciences, University of Chinese Academy of Sciences, No. 19A Yuquan Road, Beijing, 100049 People’s Republic of China
| | - Jihong Chen
- Institute of Modern Physics, Chinese Academy of Sciences, 509 Nanchang Rd., Lanzhou, 730000 Gansu People’s Republic of China
- College of Life Sciences, University of Chinese Academy of Sciences, No. 19A Yuquan Road, Beijing, 100049 People’s Republic of China
| | - Wenjian Li
- Institute of Modern Physics, Chinese Academy of Sciences, 509 Nanchang Rd., Lanzhou, 730000 Gansu People’s Republic of China
- College of Life Sciences, University of Chinese Academy of Sciences, No. 19A Yuquan Road, Beijing, 100049 People’s Republic of China
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15
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Xin D, Chen X, Wen P, Zhang J. Insight into the role of α-arabinofuranosidase in biomass hydrolysis: cellulose digestibility and inhibition by xylooligomers. BIOTECHNOLOGY FOR BIOFUELS 2019; 12:64. [PMID: 30949240 PMCID: PMC6429694 DOI: 10.1186/s13068-019-1412-0] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/09/2018] [Accepted: 03/15/2019] [Indexed: 05/05/2023]
Abstract
BACKGROUND α-l-Arabinofuranosidase (ARA), a debranching enzyme that can remove arabinose substituents from arabinoxylan and arabinoxylooligomers (AXOS), promotes the hydrolysis of the arabinoxylan fraction of biomass; however, the impact of ARA on the overall digestibility of cellulose is controversial. In this study, we investigated the effects of the addition of ARA on cellulase hydrolytic action. RESULTS We found that approximately 15% of the xylan was converted into AXOS during the hydrolysis of aqueous ammonia-pretreated corn stover and that this AXOS fraction was approximately 12% substituted with arabinose. The addition of ARA removes a portion of the arabinose decoration, but the resulting less-substituted AXOS inhibited cellulase action much more effectively; showing an increase of 45.7%. Kinetic experiments revealed that AXOS with a lower degree of arabinose substitution showed stronger affinity for the active site of cellobiohydrolase, which could be the mechanism of increased inhibition. CONCLUSIONS Our findings strongly suggest that the ratio of ARA and other xylanases should be carefully selected to avoid the strong inhibition caused by the less-substituted AXOS during the hydrolysis of arabinoxylan-containing biomass. This study advances our understanding of the inhibitory mechanism of xylooligomers and provides critical new insights into the relationship of ARA addition and cellulose digestibility.
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Affiliation(s)
- Donglin Xin
- College of Forestry, Northwest A&F University, 3 Taicheng Road, Yangling, 712100 Shaanxi China
| | - Xiang Chen
- College of Forestry, Northwest A&F University, 3 Taicheng Road, Yangling, 712100 Shaanxi China
| | - Peiyao Wen
- College of Forestry, Northwest A&F University, 3 Taicheng Road, Yangling, 712100 Shaanxi China
| | - Junhua Zhang
- College of Forestry, Northwest A&F University, 3 Taicheng Road, Yangling, 712100 Shaanxi China
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16
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Zhuo R, Yu H, Qin X, Ni H, Jiang Z, Ma F, Zhang X. Heterologous expression and characterization of a xylanase and xylosidase from white rot fungi and their application in synergistic hydrolysis of lignocellulose. CHEMOSPHERE 2018; 212:24-33. [PMID: 30138852 DOI: 10.1016/j.chemosphere.2018.08.062] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/16/2018] [Revised: 08/04/2018] [Accepted: 08/13/2018] [Indexed: 05/10/2023]
Abstract
Endo-xylanase and β-xylosidase are the major enzymes for hemicellulose hydrolysis, which play a significant role in biomass conversion. In our previous work, the white-rot fungi Pleurotus ostreatus HAUCC 162 and Irpex lacteus CD2 were demonstrated to have strong ability in lignocellulose degradation, and the related lignin degradation enzymes were characterized. However, little was known about their hemicellulases. In this work, a novel endo-1, 4-xylanase and a β-xylosidase from Pleurotus ostreatus HAUCC 162 and Irpex lacteus CD2 were heterologously expressed and characterized. The optima of pH and temperature were 5.0 and 55 °C for rXyn162, and 6.5 and 30 °C for rXylCD2. rXyn162 showed high tolerance to metal ions such as Ca2+, Cr3+, Zn2+, Na+, and Al3+. The recombinant rXyn162 and rXylCD2 exhibited synergistic hydrolysis of oat spelts xylan and sodium hydroxide pretreated cornstalk (SHPC), where the degree of synergy (DS) was 2.26 for SHPC hydrolysis. MALDI-TOF-MS and HPLC analysis showed that xylooligosaccharides (XOS) with small degrees of polymerization (DP2-DP4) were the major XOS hydrolyzate during SHPC degradation by rXyn162 and rXylCD2. In addition, rXyn162 and rXylCD2 could efficiently improve the hydrolysis of SHPC by commercial cellulase. The present study suggested the potential application of rXyn162 and rXylCD2 in the field of biomass pretreatment and biofuel production.
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Affiliation(s)
- Rui Zhuo
- Key Laboratory of Molecular Biophysics of MOE, College of Life Science and Technology, Huazhong University of Science and Technology, Wuhan 430074, PR China; College of Biology, Hunan University, Changsha 410082, PR China
| | - Hongbo Yu
- Key Laboratory of Molecular Biophysics of MOE, College of Life Science and Technology, Huazhong University of Science and Technology, Wuhan 430074, PR China
| | - Xing Qin
- Key Laboratory of Molecular Biophysics of MOE, College of Life Science and Technology, Huazhong University of Science and Technology, Wuhan 430074, PR China
| | - Haoxiang Ni
- Key Laboratory of Molecular Biophysics of MOE, College of Life Science and Technology, Huazhong University of Science and Technology, Wuhan 430074, PR China
| | - Zhen Jiang
- Key Laboratory of Molecular Biophysics of MOE, College of Life Science and Technology, Huazhong University of Science and Technology, Wuhan 430074, PR China
| | - Fuying Ma
- Key Laboratory of Molecular Biophysics of MOE, College of Life Science and Technology, Huazhong University of Science and Technology, Wuhan 430074, PR China.
| | - Xiaoyu Zhang
- Key Laboratory of Molecular Biophysics of MOE, College of Life Science and Technology, Huazhong University of Science and Technology, Wuhan 430074, PR China.
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17
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Donev E, Gandla ML, Jönsson LJ, Mellerowicz EJ. Engineering Non-cellulosic Polysaccharides of Wood for the Biorefinery. FRONTIERS IN PLANT SCIENCE 2018; 9:1537. [PMID: 30405672 PMCID: PMC6206411 DOI: 10.3389/fpls.2018.01537] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/13/2018] [Accepted: 09/28/2018] [Indexed: 05/10/2023]
Abstract
Non-cellulosic polysaccharides constitute approximately one third of usable woody biomass for human exploitation. In contrast to cellulose, these substances are composed of several different types of unit monosaccharides and their backbones are substituted by various groups. Their structural diversity and recent examples of their modification in transgenic plants and mutants suggest they can be targeted for improving wood-processing properties, thereby facilitating conversion of wood in a biorefinery setting. Critical knowledge on their structure-function relationship is slowly emerging, although our understanding of molecular interactions responsible for observed phenomena is still incomplete. This review: (1) provides an overview of structural features of major non-cellulosic polysaccharides of wood, (2) describes the fate of non-cellulosic polysaccharides during biorefinery processing, (3) shows how the non-cellulosic polysaccharides impact lignocellulose processing focused on yields of either sugars or polymers, and (4) discusses outlooks for the improvement of tree species for biorefinery by modifying the structure of non-cellulosic polysaccharides.
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Affiliation(s)
- Evgeniy Donev
- Department of Forest Genetics and Plant Physiology, Swedish University of Agricultural Sciences, Umeå, Sweden
| | | | | | - Ewa J. Mellerowicz
- Department of Forest Genetics and Plant Physiology, Swedish University of Agricultural Sciences, Umeå, Sweden
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18
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Yuan Z, Li G, Hegg EL. Enhancement of sugar recovery and ethanol production from wheat straw through alkaline pre-extraction followed by steam pretreatment. BIORESOURCE TECHNOLOGY 2018; 266:194-202. [PMID: 29982039 DOI: 10.1016/j.biortech.2018.06.065] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/30/2018] [Revised: 06/19/2018] [Accepted: 06/20/2018] [Indexed: 06/08/2023]
Abstract
To improve sugar recovery and ethanol production from wheat straw, a sequential two-stage pretreatment process combining alkaline pre-extraction and acid catalyzed steam treatment was investigated. The results showed that alkaline pre-extraction using 8% (w/w) sodium hydroxide at 80 °C for 90 min followed by steam pretreatment with 3% (w/w) sulfur dioxide at 151 °C for 16 min was sufficient to prepare a substrate that could be efficiently hydrolyzed at high solid loadings. Moreover, alkaline pre-extraction reduced the process severity of steam pretreatment and decreased the generation of inhibitory compounds. During enzymatic hydrolysis, increasing solid loading decreased the yield of monomeric sugars. Enzymatic hydrolysis at 25% (w/v) solid loading, the yields of approximately 80% of glucose and 65% of xylose could be reached with an enzyme dosage of 25 mg protein/g glucan. Following fermentation of hydrolysate with sugar concentration of approximately 120 g/L, an ethanol concentration of 54.5 g/L was achieved.
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Affiliation(s)
- Zhaoyang Yuan
- Department of Biochemistry & Molecular Biology, Michigan State University, 603 Wilson Road, East Lansing, MI 48824, USA
| | - Guodong Li
- State Key Laboratory of Biobased Material and Green Papermaking, Qilu University of Technology, Shandong Academy of Sciences, Jinan 250353, China.
| | - Eric L Hegg
- Department of Biochemistry & Molecular Biology, Michigan State University, 603 Wilson Road, East Lansing, MI 48824, USA
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19
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Vargas R, Vecchietti A. Modeling the Thermochemical Pretreatment of Eucalyptus globulus for Bioethanol Production. Ind Eng Chem Res 2018. [DOI: 10.1021/acs.iecr.8b02706] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/28/2022]
Affiliation(s)
- Rafael Vargas
- INGAR - CONICET - UTN Avellaneda 3657, Santa Fe 3000, Argentina
| | - Aldo Vecchietti
- INGAR - CONICET - UTN Avellaneda 3657, Santa Fe 3000, Argentina
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20
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Syaftika N, Matsumura Y. Comparative study of hydrothermal pretreatment for rice straw and its corresponding mixture of cellulose, xylan, and lignin. BIORESOURCE TECHNOLOGY 2018; 255:1-6. [PMID: 29414153 DOI: 10.1016/j.biortech.2018.01.085] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/22/2017] [Revised: 01/17/2018] [Accepted: 01/18/2018] [Indexed: 05/15/2023]
Abstract
We herein investigated the effect of hemicellulose and lignin on the hydrothermal pretreatment of lignocellulosic biomass for glucose production from cellulose in terms of structural cross-linking between cellulose and the above components. A comparison was made between the hydrothermal pretreatment of biomass and a mixture containing the individual model compounds in the same composition ratio. Thus, rice straw biomass and the mixture containing cellulose, xylan, and lignin were treated in an autoclave reactor at temperatures between 150 and 250 °C for 30 min. The obtained products were then subjected to enzymatic hydrolysis. Interestingly, different results were obtained for the two samples, as the presence of cross-linking between cellulose and lignin in the original biomass sample affected the efficiency of hydrothermal pretreatment. A model was therefore proposed to account for the obtained result in accordance with previous knowledge regarding the behavior of these compounds under hydrothermal conditions.
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Affiliation(s)
- Novi Syaftika
- Department of Mechanical Sciences and Engineering, Hiroshima University, Kagamiyama 1-4-1, Higashi-Hiroshima, Hiroshima 739-8527, Japan
| | - Yukihiko Matsumura
- Department of Mechanical Sciences and Engineering, Hiroshima University, Kagamiyama 1-4-1, Higashi-Hiroshima, Hiroshima 739-8527, Japan.
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21
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Malgas S, Chandra R, Van Dyk JS, Saddler JN, Pletschke BI. Formulation of an optimized synergistic enzyme cocktail, HoloMix, for effective degradation of various pre-treated hardwoods. BIORESOURCE TECHNOLOGY 2017; 245:52-65. [PMID: 28892706 DOI: 10.1016/j.biortech.2017.08.186] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/21/2017] [Revised: 08/25/2017] [Accepted: 08/29/2017] [Indexed: 06/07/2023]
Abstract
In this study, two selected hardwoods were subjected to sodium chlorite delignification and steam explosion, and the impact of pre-treatments on synergistic enzymatic saccharification evaluated. A cellulolytic core-set, CelMix, and a xylanolytic core-set, XynMix, optimised for glucose and xylose release, respectively, were used to formulate HoloMix cocktail for optimal saccharification of various pre-treated hardwoods. For delignified biomass, the optimized HoloMix consisted of 75%:25% protein dosage, CelMix: XynMix, while for untreated and steam exploded biomass the HoloMix consisted of 93.75%:6.25% protein dosage. Saccharification by HoloMix (27.5mgprotein/gbiomass) for 24h achieved 70-100% sugar yields. Pre-treatment of the hardwoods (especially those with a higher proportion of lignin) with a laccase, improved saccharification by HoloMix. This study provided insights into enzymatic hydrolysis of various pre-treated hardwood substrates and showed the same lignocellulolytic cocktail comparable to/if not better than commercial enzyme preparations can be used to efficiently hydrolyse different hardwood species.
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Affiliation(s)
- S Malgas
- Enzyme Science Programme (ESP), Department of Biochemistry and Microbiology, Rhodes University, Grahamstown 6140, Eastern Cape, South Africa
| | - R Chandra
- Forest Products Biotechnology Group, University of British Columbia, 2424 Main Mall, Vancouver, British Columbia V6T1Z4, Canada
| | - J S Van Dyk
- Forest Products Biotechnology Group, University of British Columbia, 2424 Main Mall, Vancouver, British Columbia V6T1Z4, Canada
| | - J N Saddler
- Forest Products Biotechnology Group, University of British Columbia, 2424 Main Mall, Vancouver, British Columbia V6T1Z4, Canada
| | - B I Pletschke
- Enzyme Science Programme (ESP), Department of Biochemistry and Microbiology, Rhodes University, Grahamstown 6140, Eastern Cape, South Africa.
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22
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Zhou S, Runge T, Karlen SD, Ralph J, Gonzales‐Vigil E, Mansfield SD. Chemical Pulping Advantages of Zip-lignin Hybrid Poplar. CHEMSUSCHEM 2017; 10:3565-3573. [PMID: 28768066 PMCID: PMC5697620 DOI: 10.1002/cssc.201701317] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/21/2017] [Revised: 07/27/2017] [Indexed: 05/05/2023]
Abstract
Hybrid poplar genetically engineered to possess chemically labile ester linkages in its lignin backbone (zip-lignin hybrid poplar) was examined to determine if the strategic lignin modifications would enhance chemical pulping efficiencies. Kraft pulping of zip-lignin and wild-type hybrid poplar was performed in lab-scale reactors under conditions of varying severity by altering time, temperature and chemical charge. The resulting pulps were analyzed for yield, residual lignin content, and cellulose DP (degree of polymerization), as well as changes in carbohydrates and lignin structure. Statistical models of pulping were created, and the pulp bleaching and physical properties evaluated. Under identical cooking conditions, compared to wild-type, the zip-lignin hybrid poplar showed extended delignification, confirming the zip-lignin effect. Additionally, yield and carbohydrate content of the ensuing pulps were slightly elevated, as was the cellulose DP for zip-lignin poplar pulp, although differences in residual lignin between zip-lignin and wild-type poplar were not detected. Statistical prediction models facilitated comparisons between pulping conditions that resulted in identical delignification, with the zip-lignin poplar needing milder cooking conditions and resulting in higher pulp yield (up to 1.41 % gain). Bleaching and physical properties were subsequently equivalent between the samples with slight chemical savings realized in the zip-lignin samples due to the enhanced delignification.
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Affiliation(s)
- Shengfei Zhou
- Department of Biological System EngineeringUniversity of Wisconsin-MadisonMadisonWI53706USA
| | - Troy Runge
- Department of Biological System EngineeringUniversity of Wisconsin-MadisonMadisonWI53706USA
| | - Steven D. Karlen
- Department of Biochemistry, DOE Great Lakes Bioenergy Research CenterWisconsin Energy InstituteUniversity of Wisconsin-MadisonMadisonWI53706USA
| | - John Ralph
- Department of Biochemistry, DOE Great Lakes Bioenergy Research CenterWisconsin Energy InstituteUniversity of Wisconsin-MadisonMadisonWI53706USA
| | | | - Shawn D. Mansfield
- Department of Wood ScienceUniversity of British ColumbiaVancouverBCV6T 1Z4Canada
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23
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Malgas S, Thoresen M, van Dyk JS, Pletschke BI. Time dependence of enzyme synergism during the degradation of model and natural lignocellulosic substrates. Enzyme Microb Technol 2017; 103:1-11. [DOI: 10.1016/j.enzmictec.2017.04.007] [Citation(s) in RCA: 36] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2016] [Revised: 04/18/2017] [Accepted: 04/21/2017] [Indexed: 10/19/2022]
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24
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Arslan B, Egerton K, Zhang X, Abu-Lail NI. Effects of the Surface Morphology and Conformations of Lignocellulosic Biomass Biopolymers on Their Nanoscale Interactions with Hydrophobic Self-Assembled Monolayers. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2017; 33:6857-6868. [PMID: 28617601 DOI: 10.1021/acs.langmuir.7b01470] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/09/2023]
Abstract
The effects of the morphology and conformations of the surface biopolymers present on lignocellulosic biomass as well as their steric hindrance on enzymatic adsorption to biomass surfaces remain elusive. In a step to better understand these effects, nanoscale steric forces between a model surface that represents the hydrophobic residues of a cellulase enzyme and a set of reference lignocellulosic substrates were measured using atomic force microscopy (AFM) in liquid media. The reference substrates investigated were prepared by kraft, sulfite, and organosolv pulping pretreatment methods and varied in their surface lignin, xylan, and acetone extractives' contents. Measured steric forces were quantified through fitting to a model developed to describe polyelectrolytes brushes in terms of a brush thickness and a brush grafting density. Our data indicated that cellulose microfibrils extend from the microfibril matrix leading to a long-range steric repulsion and low attractive forces to the hydrophobic model of the enzyme, suggesting that steric hindering can be a possible mechanism for nonproductive binding of enzymes to cellulose. When the amount of xylan increased in the absence of lignin, steric repulsions between the hydrophobic model of the enzyme, and biomass biopolymers decreased as a result of collapsed cellulose microfibrils and adhesion forces increased. This suggests that leaving a small amount of xylan after biomass pretreatment can help improve enzymatic binding to cellulose. Irrespective of the type of lignin present on biomass, grafting densities increased and brush thicknesses decreased compared to those of lignin-free substrates. When compared to lignin-free substrates, lignin-containing substrates had higher attractive forces and lower steric repulsive forces. In addition, AFM images of the reference substrates in the wet and dry states showed that lignin precipitates on the biomass surface where kraft lignin had the highest particle size leading to a limited accessibility of the enzyme to the cellulose in biomass. When the effects of lignin precipitate size, the adhesion force, and steric forces on nonproductive enzymatic binding were all considered, our results indicate that organosolv pretreatment should be the treatment of choice to minimize enzymatic nonproductive binding to lignin.
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Affiliation(s)
- Baran Arslan
- Gene and Linda Voiland School of Chemical Engineering and Bioengineering, Washington State University , Pullman, Washington 99164-6515, United States
| | - Kirstin Egerton
- Gene and Linda Voiland School of Chemical Engineering and Bioengineering, Washington State University , Pullman, Washington 99164-6515, United States
| | - Xiao Zhang
- Gene and Linda Voiland School of Chemical Engineering and Bioengineering, Bioproducts' Science and Engineering Laboratory, Washington State University , Richland, Washington 99354-1670, United States
| | - Nehal I Abu-Lail
- Gene and Linda Voiland School of Chemical Engineering and Bioengineering, Washington State University , Pullman, Washington 99164-6515, United States
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25
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Tang Y, Dou X, Hu J, Jiang J, Saddler JN. Lignin Sulfonation and SO2 Addition Enhance the Hydrolyzability of Deacetylated and Then Steam-Pretreated Poplar with Reduced Inhibitor Formation. Appl Biochem Biotechnol 2017; 184:264-277. [DOI: 10.1007/s12010-017-2545-x] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2017] [Accepted: 06/20/2017] [Indexed: 12/01/2022]
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26
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Enhanced delignification of steam-pretreated poplar by a bacterial laccase. Sci Rep 2017; 7:42121. [PMID: 28169340 PMCID: PMC5294454 DOI: 10.1038/srep42121] [Citation(s) in RCA: 35] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2016] [Accepted: 01/05/2017] [Indexed: 11/09/2022] Open
Abstract
The recalcitrance of woody biomass, particularly its lignin component, hinders its sustainable transformation to fuels and biomaterials. Although the recent discovery of several bacterial ligninases promises the development of novel biocatalysts, these enzymes have largely been characterized using model substrates: direct evidence for their action on biomass is lacking. Herein, we report the delignification of woody biomass by a small laccase (sLac) from Amycolatopsis sp. 75iv3. Incubation of steam-pretreated poplar (SPP) with sLac enhanced the release of acid-precipitable polymeric lignin (APPL) by ~6-fold, and reduced the amount of acid-soluble lignin by ~15%. NMR spectrometry revealed that the APPL was significantly syringyl-enriched relative to the original material (~16:1 vs. ~3:1), and that sLac preferentially oxidized syringyl units and altered interunit linkage distributions. sLac's substrate preference among monoaryls was also consistent with this observation. In addition, sLac treatment reduced the molar mass of the APPL by over 50%, as determined by gel-permeation chromatography coupled with multi-angle light scattering. Finally, sLac acted synergistically with a commercial cellulase cocktail to increase glucose production from SPP ~8%. Overall, this study establishes the lignolytic activity of sLac on woody biomass and highlights the biocatalytic potential of bacterial enzymes.
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Tian D, Chandra RP, Lee JS, Lu C, Saddler JN. A comparison of various lignin-extraction methods to enhance the accessibility and ease of enzymatic hydrolysis of the cellulosic component of steam-pretreated poplar. BIOTECHNOLOGY FOR BIOFUELS 2017; 10:157. [PMID: 28649276 PMCID: PMC5477284 DOI: 10.1186/s13068-017-0846-5] [Citation(s) in RCA: 59] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/02/2023]
Abstract
BACKGROUND Current single-stage delignification-pretreatment technologies to overcome lignocellulosic biomass recalcitrance are usually achieved at the expense of compromising the recovery of the polysaccharide components, particularly the hemicellulose fraction. One way to enhance overall sugar recovery is to tailor an efficient two-stage pretreatment that can pre-extract the more labile hemicellulose component before subjecting the cellulose-rich residual material to a second-stage delignification process. Previous work had shown that a mild steam pretreatment could recover >65% of the hemicellulose from poplar while limiting the acid-catalysed condensation of lignin. This potentially allowed for subsequent lignin extraction using various lignin solvents to produce a more accessible cellulosic substrate. RESULTS A two-stage approach using steam and/or solvent pretreatment was assessed for its ability to separate hemicellulose and lignin from poplar wood chips while providing a cellulose-rich fraction that could be readily hydrolysed by cellulase enzymes. An initial steam-pretreatment stage was performed over a range of temperatures (160-200 °C) using an equivalent severity factor of 3.6. A higher steam temperature of 190 °C applied over a shorter residence time of 10 min effectively solubilized and recovered 75% of the hemicellulose while enhancing the ability of various solvents [deep eutectic solvent (DES), ethanol organosolv, soda/anthraquinone (soda/AQ) or a hydrotrope] to extract lignin in a second stage. When the second-stage treatments were compared, the mild DES treatment (lactic acid and betaine) at 130 °C, removed comparable amounts of lignin with higher selectivity than did the soda/AQ and organosolv pretreatments at 170 °C. However, the cellulose-rich substrates obtained after the second-stage organosolv and soda/AQ pretreatments showed the highest cellulose accessibility, as measured by the Simon's staining technique. They were also the most susceptible to subsequent enzymatic hydrolysis. CONCLUSIONS The second-stage pretreatments varied in their ability to solubilize and extract the lignin component of steam-pretreated poplar while enhancing the enzymatic hydrolysis of the resulting cellulose-rich residual fractions. Although DES extraction was more selective in extracting lignin from the steam-pretreated substrates, the organosolv and soda/AQ post treatments disrupted the cellulose structure to a greater extent while enhancing the ease of enzymatic hydrolysis. Graphical abstractEffective hemicellulose removal via steam pretreatment followed by subsequent lignin extraction under acidic, alkaline or solvolytic conditions results in a highly accessible, more readily hydrolysed cellulose fraction.
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Affiliation(s)
- Dong Tian
- Forest Products Biotechnology/Bioenergy Group, Department of Wood Science, Faculty of Forestry, University of British Columbia, 2424 Main Mall, Vancouver, BC V6T 1Z4 Canada
- State Key Laboratory of Polymer Materials Engineering, Polymer Research Institute of Sichuan University, Chengdu, 610065 China
| | - Richard P. Chandra
- Forest Products Biotechnology/Bioenergy Group, Department of Wood Science, Faculty of Forestry, University of British Columbia, 2424 Main Mall, Vancouver, BC V6T 1Z4 Canada
| | - Jin-Suk Lee
- Clean Fuel Department, Korea Institute of Energy Research, Jeongeup, Jeonbuk 580-185 South Korea
| | - Canhui Lu
- State Key Laboratory of Polymer Materials Engineering, Polymer Research Institute of Sichuan University, Chengdu, 610065 China
| | - Jack N. Saddler
- Forest Products Biotechnology/Bioenergy Group, Department of Wood Science, Faculty of Forestry, University of British Columbia, 2424 Main Mall, Vancouver, BC V6T 1Z4 Canada
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Wang X, Li K, Yang M, Zhang J. Hydrolyzability of xylan after adsorption on cellulose: Exploration of xylan limitation on enzymatic hydrolysis of cellulose. Carbohydr Polym 2016; 148:362-70. [PMID: 27185150 DOI: 10.1016/j.carbpol.2016.04.069] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2015] [Revised: 03/20/2016] [Accepted: 04/17/2016] [Indexed: 11/19/2022]
Abstract
During pretreatment of lignocellulosic materials, the dissolved xylan would re-adsorb on cellulose, and then inhibits the cellulose hydrolysis by cellulases. However, the hydrolyzability of xylan adsorbed on cellulose is not clear. In this work, the adsorption behavior of xylans on celluloses and the hydrolysis of adsorbed xylan by xylanase (XYL) were investigated. The results indicated that the adsorption of beechwood xylan (BWX) and oat spelt xylan (OSX) on Avicel was conformed to Langmuir-type adsorption isotherm. Higher ion strength increased the adsorption of BWX on Avicel, but not that of OSX. Both BWX and OSX adsorbed on Avicel and corn stover after dilute acid pretreatment (CS-DA) could be hydrolyzed by XYL. Compared to OSX, BWX adsorbed on cellulosic materials could be more easily hydrolyzed by XYL. Thus, supplementation of XYL could hydrolyze the xylan adsorbed on cellulose and potentially improved hydrolysis efficiency of lignocelluloses.
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Affiliation(s)
- Xiao Wang
- College of Forestry, Northwest A&F University, 3 Taicheng Road, Yangling 712100, China
| | - Kena Li
- College of Forestry, Northwest A&F University, 3 Taicheng Road, Yangling 712100, China
| | - Ming Yang
- College of Forestry, Northwest A&F University, 3 Taicheng Road, Yangling 712100, China
| | - Junhua Zhang
- College of Forestry, Northwest A&F University, 3 Taicheng Road, Yangling 712100, China.
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Suko AV, Bura R. Enhanced Xylitol and Ethanol Yields by Fermentation Inhibitors in Steam-Pretreated Lignocellulosic Biomass. Ind Biotechnol (New Rochelle N Y) 2016. [DOI: 10.1089/ind.2015.0026] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Affiliation(s)
- Azra Vajzovic Suko
- University of Washington, School of Environmental and Forest Sciences, Seattle, WA
| | - Renata Bura
- University of Washington, School of Environmental and Forest Sciences, Seattle, WA
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Dou C, Ewanick S, Bura R, Gustafson R. Post-treatment mechanical refining as a method to improve overall sugar recovery of steam pretreated hybrid poplar. BIORESOURCE TECHNOLOGY 2016; 207:157-165. [PMID: 26881333 DOI: 10.1016/j.biortech.2016.01.076] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/10/2015] [Revised: 01/22/2016] [Accepted: 01/22/2016] [Indexed: 06/05/2023]
Abstract
This study investigates the effect of mechanical refining to improve the sugar yield from biomass processed under a wide range of steam pretreatment conditions. Hybrid poplar chips were steam pretreated using six different conditions with or without SO2. The resulting water insoluble fractions were subjected to mechanical refining. After refining, poplar pretreated at 205°C for 10min without SO2 obtained a 32% improvement in enzymatic hydrolysis and achieved similar overall monomeric sugar recovery (539kg/tonne) to samples pretreated with SO2. Refining did not improve hydrolyzability of samples pretreated at more severe conditions, nor did it improve the overall sugar recovery. By maximizing overall sugar recovery, refining could partially decouple the pretreatment from other unit operations, and enable the use of low temperature, non-sulfur pretreatment conditions. The study demonstrates the possibility of using post-treatment refining to accommodate potential pretreatment process upsets without sacrificing sugar yields.
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Affiliation(s)
- Chang Dou
- Biofuels and Bioproducts Laboratory, School of Environmental and Forest Sciences, University of Washington, Seattle, WA 98115, USA
| | - Shannon Ewanick
- Biofuels and Bioproducts Laboratory, School of Environmental and Forest Sciences, University of Washington, Seattle, WA 98115, USA
| | - Renata Bura
- Biofuels and Bioproducts Laboratory, School of Environmental and Forest Sciences, University of Washington, Seattle, WA 98115, USA.
| | - Rick Gustafson
- Biofuels and Bioproducts Laboratory, School of Environmental and Forest Sciences, University of Washington, Seattle, WA 98115, USA
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31
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Haque MA, Barman DN, Kim MK, Yun HD, Cho KM. Cogon grass (Imperata cylindrica), a potential biomass candidate for bioethanol: cell wall structural changes enhancing hydrolysis in a mild alkali pretreatment regime. JOURNAL OF THE SCIENCE OF FOOD AND AGRICULTURE 2016; 96:1790-1797. [PMID: 26041026 DOI: 10.1002/jsfa.7288] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/06/2015] [Revised: 05/16/2015] [Accepted: 05/30/2015] [Indexed: 06/04/2023]
Abstract
BACKGROUND Imperata cylindrica is being considered as a biomass candidate for bioethanol. This work aimed to evaluate a mild alkali pretreatment effect on the Imperata recalcitrant structure. Therefore, varied concentrations of NaOH (0, 7.5, 15, 20, and 25 g L(-1) ) were applied as treatments to Imperata at 105 °C for 10 min. RESULTS Scanning electron microscopy, atomic force microscopy, and Fourier transform infrared spectroscopy studies revealed that 20 to 25 g L(-1) NaOH-treated Imperata exposed amorphous cellulose on surface granules composed of lignin, waxes, and partly hemicelluloses were abolished due to the comprehensive disruption of the linkages between lignin and carbohydrates. The cellulose crystalline index was increased with 7.5 to 20 g L(-1) NaOH treatments and reduced with a 25 g L(-1) NaOH treatment. In fact, the cellulose content in solids increased with the increasing NaOH concentration and was estimated to be 720 and 740 g kg(-1) for the 20 and 25 g L(-1) NaOH treatments, respectively. The yield of the reducing sugar was obtained 805 and 813 mg g(-1) from 20 and 25 g L(-1) NaOH-treated Imperata, respectively. CONCLUSION Considering the cost of pretreatment, the 20 g L(-1) NaOH treatment is judged to be effective for disrupting Imperata recalcitrance in this pretreatment regime.
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Affiliation(s)
- Md Azizul Haque
- Division of Applied Life Science (BK21 Program), Gyeongsang National University, Chinju 660-701, Republic of Korea
- Dept of Food Science, Gyeongnam National University of Science and Technology, Jinju 660-758, Republic of Korea
| | - Dhirendra Nath Barman
- Division of Applied Life Science (BK21 Program), Gyeongsang National University, Chinju 660-701, Republic of Korea
| | - Min Keun Kim
- Gyeongsangnam-do Agricultural Research and Extension Service, Jinju 660-758, Republic of Korea
| | - Han Dae Yun
- Division of Applied Life Science (BK21 Program), Gyeongsang National University, Chinju 660-701, Republic of Korea
- Research Institute of Agriculture and Life Science, Gyeongsang National University, Chinju, 660-701, Republic of Korea
| | - Kye Man Cho
- Dept of Food Science, Gyeongnam National University of Science and Technology, Jinju 660-758, Republic of Korea
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32
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Khatri V, Hébert-Ouellet Y, Meddeb-Mouelhi F, Beauregard M. Specific tracking of xylan using fluorescent-tagged carbohydrate-binding module 15 as molecular probe. BIOTECHNOLOGY FOR BIOFUELS 2016; 9:74. [PMID: 27019671 PMCID: PMC4807533 DOI: 10.1186/s13068-016-0486-1] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/02/2015] [Accepted: 03/14/2016] [Indexed: 05/18/2023]
Abstract
BACKGROUND Xylan has been identified as a physical barrier which limits cellulose accessibility by covering the outer surface of fibers and interfibrillar space. Therefore, tracking xylan is a prerequisite for understanding and optimizing lignocellulosic biomass processes. RESULTS In this study, we developed a novel xylan tracking approach using a two-domain probe called OC15 which consists of a fusion of Cellvibrio japonicus carbohydrate-binding domain 15 with the fluorescent protein mOrange2. The new probe specifically binds to xylan with an affinity similar to that of CBM15. The sensitivity of the OC15-xylan detection approach was compared to that of standard methods such as X-ray photoelectron spectroscopy (XPS) and chemical composition analysis (NREL/TP-510-42618). All three approaches were used to analyze the variations of xylan content of kraft pulp fibers. XPS, which allows for surface analysis of fibers, did not clearly indicate changes in xylan content. Chemical composition analysis responded to the changes in xylan content, but did not give any specific information related to the fibers surface. Interestingly, only the OC15 probe enabled the highly sensitive detection of xylan variations at the surface of kraft pulp fibers. At variance with the other methods, the OC15 probe can be used in a high throughput format. CONCLUSIONS We developed a rapid and high throughput approach for the detection of changes in xylan exposure at the surface of paper fibers. The introduction of this method into the lignocellulosic biomass-based industries should revolutionize the understanding and optimization of most wood biomass processes.
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Affiliation(s)
- Vinay Khatri
- />Centre de recherche sur les matériaux lignocellulosiques, Université du Québec à Trois-Rivières, C.P. 500, Trois-Rivières, QC G9A 5H7 Canada
- />PROTEO, Université Laval, Quebec, QC G1V 4G2 Canada
| | - Yannick Hébert-Ouellet
- />Centre de recherche sur les matériaux lignocellulosiques, Université du Québec à Trois-Rivières, C.P. 500, Trois-Rivières, QC G9A 5H7 Canada
- />PROTEO, Université Laval, Quebec, QC G1V 4G2 Canada
| | - Fatma Meddeb-Mouelhi
- />Centre de recherche sur les matériaux lignocellulosiques, Université du Québec à Trois-Rivières, C.P. 500, Trois-Rivières, QC G9A 5H7 Canada
- />PROTEO, Université Laval, Quebec, QC G1V 4G2 Canada
- />Buckman North America, Vaudreuil-Dorion, QC J7V 5V5 Canada
| | - Marc Beauregard
- />Centre de recherche sur les matériaux lignocellulosiques, Université du Québec à Trois-Rivières, C.P. 500, Trois-Rivières, QC G9A 5H7 Canada
- />PROTEO, Université Laval, Quebec, QC G1V 4G2 Canada
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33
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Chandra RP, Chu Q, Hu J, Zhong N, Lin M, Lee JS, Saddler J. The influence of lignin on steam pretreatment and mechanical pulping of poplar to achieve high sugar recovery and ease of enzymatic hydrolysis. BIORESOURCE TECHNOLOGY 2016; 199:135-141. [PMID: 26391968 DOI: 10.1016/j.biortech.2015.09.019] [Citation(s) in RCA: 40] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/09/2015] [Revised: 08/31/2015] [Accepted: 09/01/2015] [Indexed: 05/05/2023]
Abstract
With the goal of enhancing overall carbohydrate recovery and reducing enzyme loading refiner mechanical pulping and steam pretreatment (210°C, 5 min) were used to pretreat poplar wood chips. Neutral sulphonation post-treatment indicated that, although the lignin present in the steam pretreated substrate was less reactive, the cellulose-rich, water insoluble component was more accessible to cellulases and Simons stain. This was likely due to lignin relocation as the relative surface lignin measured by X-ray photoelectron spectroscopy increased from 0.4 to 0.8. The integration of sulphite directly into steam pretreatment resulted in the solubilisation of 60% of the lignin while more than 80% of the carbohydrate present in the original substrate was recovered in the water insoluble fraction after Na2CO3 addition. More than 80% of the sugars present in the original cellulose and xylan could be recovered after 48 h using an enzyme loading of 20 mg protein/g cellulose at a 10% substrate concentration.
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Affiliation(s)
- Richard P Chandra
- Forest Products Biotechnology/Bioenergy Group, University of British Columbia, Faculty of Forestry, British Columbia, Canada
| | - QiuLu Chu
- Forest Products Biotechnology/Bioenergy Group, University of British Columbia, Faculty of Forestry, British Columbia, Canada
| | - Jinguang Hu
- Forest Products Biotechnology/Bioenergy Group, University of British Columbia, Faculty of Forestry, British Columbia, Canada
| | - Na Zhong
- Forest Products Biotechnology/Bioenergy Group, University of British Columbia, Faculty of Forestry, British Columbia, Canada
| | - Mandy Lin
- Forest Products Biotechnology/Bioenergy Group, University of British Columbia, Faculty of Forestry, British Columbia, Canada
| | - Jin-Suk Lee
- Clean Fuel Department, Korea Institute of Energy Research, Jeongeup, Jeonbuk 580-185, South Korea
| | - Jack Saddler
- Forest Products Biotechnology/Bioenergy Group, University of British Columbia, Faculty of Forestry, British Columbia, Canada
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34
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Liu ZH, Chen HZ. Xylose production from corn stover biomass by steam explosion combined with enzymatic digestibility. BIORESOURCE TECHNOLOGY 2015; 193:345-56. [PMID: 26143002 DOI: 10.1016/j.biortech.2015.06.114] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/14/2015] [Revised: 06/20/2015] [Accepted: 06/22/2015] [Indexed: 05/26/2023]
Abstract
A novel conversion process using steam explosion combined with enzymatic digestibility was exploited to increase sugar yield. Results showed that glucan and xylan recovery decreased with the increase of holding temperature and residence time in SE, respectively, while glucan and xylan conversion exhibited an opposite trend. The optimal conditions of steam explosion were 160 °C and 48 min, under which glucan and xylan recovery was 93.4% and 71.6%, respectively. Glucan and xylan conversion at 18% solid loading by periodic peristalsis increased by 3.4-5.8% and 4.5-6.2%, respectively, compared with that by water baths shaker. In the whole process, glucose, xylose and total sugar yield reached to 77.3%, 62.8% and 72.3%, respectively. The yield of hydroxymethyl furfural, furfural and lignin-derived products was 6.3 × 10(-2), 7.5 × 10(-2) and less than 3.7 × 10(-2) g/100 g feedstock, respectively. This novel conversion process increased sugar recovery, reduced degradation products formation, improved digestibility efficiency, and hence increased sugar yield.
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Affiliation(s)
- Zhi-Hua Liu
- State Key Laboratory of Biochemical Engineering, Institute of Process Engineering, Chinese Academy of Sciences, Beijing, China; University of Chinese Academy of Sciences, Beijing, China
| | - Hong-Zhang Chen
- State Key Laboratory of Biochemical Engineering, Institute of Process Engineering, Chinese Academy of Sciences, Beijing, China.
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35
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Papoutsakis ET. Reassessing the Progress in the Production of Advanced Biofuels in the Current Competitive Environment and Beyond: What Are the Successes and Where Progress Eludes Us and Why. Ind Eng Chem Res 2015. [DOI: 10.1021/acs.iecr.5b01695] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Affiliation(s)
- Eleftherios T. Papoutsakis
- Molecular Biotechnology Laboratory, Department of Chemical & Biomolecular Engineering, Department of Biological Sciences & the Delaware Biotechnology Institute, University of Delaware, Newark, Delaware 19711, United States
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36
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Hu J, Chandra R, Arantes V, Gourlay K, Susan van Dyk J, Saddler JN. The addition of accessory enzymes enhances the hydrolytic performance of cellulase enzymes at high solid loadings. BIORESOURCE TECHNOLOGY 2015; 186:149-153. [PMID: 25812819 DOI: 10.1016/j.biortech.2015.03.055] [Citation(s) in RCA: 104] [Impact Index Per Article: 11.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/14/2015] [Revised: 03/09/2015] [Accepted: 03/10/2015] [Indexed: 05/05/2023]
Abstract
The pretreatment process used and the nature of the biomass feedstock will influence the role that accessory enzymes can play in synergistically interacting with cellulases to effectively deconstruct the substrate. The work reported here assessed the possible boosting effects of the xylanase and lytic polysaccharide monooxygenase (AA9, formerly known as GH61) on the hydrolytic potential of cellulase enzyme mixtures during hydrolysis of steam pretreated poplar and corn stover at high (10-20% w/v) substrate concentrations. A higher proportion of xylanase was required when the substrate had a relatively high xylan content and at high substrate concentrations. In contrast, a relatively small amount of AA9 (about 2 mg/g cellulose) was enough, regardless of the nature or concentration of the substrate. The overall protein loading required to achieve effective hydrolysis of high concentrations of pretreated biomass substrates could be substantially reduced by optimizing the ratio of enzymes in the "cellulase" mixture.
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Affiliation(s)
- Jinguang Hu
- Forest Products Biotechnology and Bioenergy Group, University of British Columbia, Vancouver, BC, Canada
| | - Richard Chandra
- Forest Products Biotechnology and Bioenergy Group, University of British Columbia, Vancouver, BC, Canada
| | - Valdeir Arantes
- Forest Products Biotechnology and Bioenergy Group, University of British Columbia, Vancouver, BC, Canada
| | - Keith Gourlay
- Forest Products Biotechnology and Bioenergy Group, University of British Columbia, Vancouver, BC, Canada
| | - J Susan van Dyk
- Forest Products Biotechnology and Bioenergy Group, University of British Columbia, Vancouver, BC, Canada
| | - Jack N Saddler
- Forest Products Biotechnology and Bioenergy Group, University of British Columbia, Vancouver, BC, Canada.
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37
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Chandra RP, Arantes V, Saddler J. Steam pretreatment of agricultural residues facilitates hemicellulose recovery while enhancing enzyme accessibility to cellulose. BIORESOURCE TECHNOLOGY 2015; 185:302-7. [PMID: 25780906 DOI: 10.1016/j.biortech.2015.02.106] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/13/2015] [Revised: 02/25/2015] [Accepted: 02/26/2015] [Indexed: 05/11/2023]
Abstract
The origins of lignocellulosic biomass and the pretreatment used to enhance enzyme accessibility to the cellulosic component are known to be strongly influenced by various substrate characteristics. To assess the impact that fibre properties might have on enzymatic hydrolysis, seven agricultural residues were characterised before and after steam pretreatment using a single pretreatment condition (190°C, 5min, 3% SO2) previously shown to enhance fractionation and hydrolysis of the cellulosic component of corn stover. When the fibre length, width and coarseness, viscosity, water retention value and cellulose crystallinity were monitored, no clear correlation was observed between any single substrate characteristic and the substrate's ease of enzymatic hydrolysis. However, the amount of hemicellulose that was solubilised during pretreatment correlated (r(2)=0.98) with the effectiveness of enzyme hydrolysis of each pretreated substrate. Simons's staining, to measure the cellulose accessibility, showed good correlation (r(2)=0.83) with hemicellulose removal and the extent of enzymatic hydrolysis.
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Affiliation(s)
- Richard P Chandra
- Forest Products Biotechnology/Bioenergy Group, University of British Columbia, Faculty of Forestry, British Columbia, Canada
| | - Valdeir Arantes
- Lorena School of Engineering, University of São Paulo, Brazil
| | - Jack Saddler
- Forest Products Biotechnology/Bioenergy Group, University of British Columbia, Faculty of Forestry, British Columbia, Canada.
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Vancov T, Schneider RCS, Palmer J, McIntosh S, Stuetz R. Potential use of feedlot cattle manure for bioethanol production. BIORESOURCE TECHNOLOGY 2015; 183:120-128. [PMID: 25727759 DOI: 10.1016/j.biortech.2015.02.027] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/15/2014] [Revised: 02/03/2015] [Accepted: 02/07/2015] [Indexed: 06/04/2023]
Abstract
This paper reports on processing options for the conversion of feedlot cattle manures into composite sugars for ethanol fermentation. Small-scale anaerobic digestion trials revealed that the process significantly reduces the content of glucan and xylan (ca. 70%) without effecting lignin. Moreover, anaerobic digestate (AD) fibres were poor substrates for cellulase (Cellic® CTec 2) saccharification, generating a maximum combined sugar yield of ca. 12% per original dry weight. Dilute acid pretreatment and enzyme saccharification of raw manures significantly improved total sugar recoveries, totalling 264 mg/g (79% theoretical). This was attained when manures were pretreated with 2.5% H2SO4 for 90 min at 121°C and saccharified with 50 FPU CTec 2/g glucan. Saccharomyces cerevisiae efficiently fermented crude hydrolysates within 6 h, yielding 7.3 g/L ethanol, representing glucose to ethanol conversion rate of 70%. With further developments (i.e., fermentation of xylose), this process could deliver greater yields, reinforcing its potential as a biofuel feedstock.
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Affiliation(s)
- T Vancov
- NSW Department of Primary Industries, Wollongbar Primary Industries Institute, NSW, Australia.
| | - R C S Schneider
- Chemistry and Physics Department, University of Santa Cruz do Sul, 2293 Avenida Independência, Santa Cruz do Sul 96815-900, RS, Brazil
| | - J Palmer
- NSW Department of Primary Industries, Wollongbar Primary Industries Institute, NSW, Australia
| | - S McIntosh
- NSW Department of Primary Industries, Wollongbar Primary Industries Institute, NSW, Australia
| | - R Stuetz
- School of Civil and Environmental Engineering, University of New South Wales, NSW, Australia
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39
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Inoue H, Kishishita S, Kumagai A, Kataoka M, Fujii T, Ishikawa K. Contribution of a family 1 carbohydrate-binding module in thermostable glycoside hydrolase 10 xylanase from Talaromyces cellulolyticus toward synergistic enzymatic hydrolysis of lignocellulose. BIOTECHNOLOGY FOR BIOFUELS 2015; 8:77. [PMID: 26000036 PMCID: PMC4440266 DOI: 10.1186/s13068-015-0259-2] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/17/2015] [Accepted: 04/29/2015] [Indexed: 05/10/2023]
Abstract
BACKGROUND 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. RESULTS 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. CONCLUSIONS Our results suggest that Xyl10A CBM1 has the following two roles in synergistic hydrolysis of lignocellulose by Xyl10A and cellulases: enhancement of lignocellulosic xylan hydrolysis by binding to cellulose, and the efficient removal of xylan obstacles that interrupt the cellulase activity (because of similar binding target of CBM1). The combination of CBM-containing cellulases and xylanases in a fugal cellulase system could contribute to reduction of the enzyme loading in the hydrolysis of pretreated lignocelluloses.
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Affiliation(s)
- Hiroyuki Inoue
- Research Institute for Sustainable Chemistry, National Institute of Advanced Industrial Science and Technology (AIST), 3-11-32 Kagamiyama, Higashi-Hiroshima, Hiroshima 739-0046 Japan
| | - Seiichiro Kishishita
- Research Institute for Sustainable Chemistry, National Institute of Advanced Industrial Science and Technology (AIST), 3-11-32 Kagamiyama, Higashi-Hiroshima, Hiroshima 739-0046 Japan
| | - Akio Kumagai
- Research Institute for Sustainable Chemistry, National Institute of Advanced Industrial Science and Technology (AIST), 3-11-32 Kagamiyama, Higashi-Hiroshima, Hiroshima 739-0046 Japan
| | - Misumi Kataoka
- Research Institute for Sustainable Chemistry, National Institute of Advanced Industrial Science and Technology (AIST), 3-11-32 Kagamiyama, Higashi-Hiroshima, Hiroshima 739-0046 Japan
| | - Tatsuya Fujii
- Research Institute for Sustainable Chemistry, National Institute of Advanced Industrial Science and Technology (AIST), 3-11-32 Kagamiyama, Higashi-Hiroshima, Hiroshima 739-0046 Japan
| | - Kazuhiko Ishikawa
- Research Institute for Sustainable Chemistry, National Institute of Advanced Industrial Science and Technology (AIST), 3-11-32 Kagamiyama, Higashi-Hiroshima, Hiroshima 739-0046 Japan
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Singh J, Suhag M, Dhaka A. Augmented digestion of lignocellulose by steam explosion, acid and alkaline pretreatment methods: a review. Carbohydr Polym 2014; 117:624-631. [PMID: 25498680 DOI: 10.1016/j.carbpol.2014.10.012] [Citation(s) in RCA: 167] [Impact Index Per Article: 16.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2013] [Revised: 10/02/2014] [Accepted: 10/05/2014] [Indexed: 10/24/2022]
Abstract
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.
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Affiliation(s)
- Joginder Singh
- Laboratory of Environmental Biotechnology, Department of Botany, A. I. Jat H. M. College, Rohtak 124001, Haryana, India.
| | - Meenakshi Suhag
- Institute of Environmental Studies, Kurukshetra University, Kurukshetra 136119, Haryana, India.
| | - Anil Dhaka
- PNRS Government College, Rohtak 124001, Haryana, India.
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Impact of Xylan on Synergistic Effects of Xylanases and Cellulases in Enzymatic Hydrolysis of Lignocelluloses. Appl Biochem Biotechnol 2014; 174:1393-1402. [DOI: 10.1007/s12010-014-1140-7] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2014] [Accepted: 08/01/2014] [Indexed: 10/24/2022]
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Alkali Pretreatment of Wheat Straw (Triticum aestivum) at Boiling Temperature for Producing a Bioethanol Precursor. Biosci Biotechnol Biochem 2014; 76:2201-7. [DOI: 10.1271/bbb.120480] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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Fungal Beta-glucosidases: a bottleneck in industrial use of lignocellulosic materials. Biomolecules 2013; 3:612-31. [PMID: 24970184 PMCID: PMC4030957 DOI: 10.3390/biom3030612] [Citation(s) in RCA: 161] [Impact Index Per Article: 14.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2013] [Revised: 08/17/2013] [Accepted: 08/20/2013] [Indexed: 12/16/2022] Open
Abstract
Profitable biomass conversion processes are highly dependent on the use of efficient enzymes for lignocellulose degradation. Among the cellulose degrading enzymes, beta-glucosidases are essential for efficient hydrolysis of cellulosic biomass as they relieve the inhibition of the cellobiohydrolases and endoglucanases by reducing cellobiose accumulation. In this review, we discuss the important role beta-glucosidases play in complex biomass hydrolysis and how they create a bottleneck in industrial use of lignocellulosic materials. An efficient beta-glucosidase facilitates hydrolysis at specified process conditions, and key points to consider in this respect are hydrolysis rate, inhibitors, and stability. Product inhibition impairing yields, thermal inactivation of enzymes, and the high cost of enzyme production are the main obstacles to commercial cellulose hydrolysis. Therefore, this sets the stage in the search for better alternatives to the currently available enzyme preparations either by improving known or screening for new beta-glucosidases.
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Hu J, Arantes V, Pribowo A, Saddler JN. The synergistic action of accessory enzymes enhances the hydrolytic potential of a "cellulase mixture" but is highly substrate specific. BIOTECHNOLOGY FOR BIOFUELS 2013; 6:112. [PMID: 23915398 PMCID: PMC3750293 DOI: 10.1186/1754-6834-6-112] [Citation(s) in RCA: 133] [Impact Index Per Article: 12.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/20/2013] [Accepted: 08/02/2013] [Indexed: 05/05/2023]
Abstract
BACKGROUND Currently, the amount of protein/enzyme required to achieve effective cellulose hydrolysis is still too high. One way to reduce the amount of protein/enzyme required is to formulate a more efficient enzyme cocktail by adding so-called accessory enzymes such as xylanase, lytic polysaccharide monooxygenase (AA9, formerly known as GH61), etc., to the cellulase mixture. Previous work has shown the strong synergism that can occur between cellulase and xylanase mixtures during the hydrolysis of steam pretreated corn stover, requiring lower protein loading to achieve effective hydrolysis. However, relatively high loadings of xylanases were required. When family 10 and 11 endo-xylanases and family 5 xyloglucanase were supplemented to a commercial cellulase mixture varying degrees of improved hydrolysis over a range of pretreated, lignocellulosic substrates were observed. RESULTS The potential synergistic interactions between cellulase monocomponents and hemicellulases from family 10 and 11 endo-xylanases (GH10 EX and GH11 EX) and family 5 xyloglucanase (GH5 XG), during hydrolysis of various steam pretreated lignocellulosic substrates, were assessed. It was apparent that the hydrolytic activity of cellulase monocomponents was enhanced by the addition of accessory enzymes although the "boosting" effect was highly substrate specific. The GH10 EX and GH5 XG both exhibited broad substrate specificity and showed strong synergistic interaction with the cellulases when added individually. The GH10 EX was more effective on steam pretreated agriculture residues and hardwood substrates whereas GH5 XG addition was more effective on softwood substrates. The synergistic interaction between GH10 EX and GH5 XG when added together further enhanced the hydrolytic activity of the cellulase enzymes over a range of pretreated lignocellulosic substrates. GH10 EX addition could also stimulate further cellulose hydrolysis when added to the hydrolysis reactions when the rate of hydrolysis had levelled off. CONCLUSIONS Endo-xylanases and xyloglucanases interacted synergistically with cellulases to improve the hydrolysis of a range of pretreated lignocellulosic substrates. However, the extent of improved hydrolysis was highly substrate dependent. It appears that those accessory enzymes, such as GH10 EX and GH5 XG, with broader substrate specificities promoted the greatest improvements in the hydrolytic performance of the cellulase mixture on all of the pretreated biomass substrates.
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Affiliation(s)
- Jinguang Hu
- Forestry Products Biotechnology/Bioenergy Group, Wood Science Department, University of British Columbia, 2424 Main Mall, Vancouver, BC V6T 1Z4, Canada
| | - Valdeir Arantes
- Forestry Products Biotechnology/Bioenergy Group, Wood Science Department, University of British Columbia, 2424 Main Mall, Vancouver, BC V6T 1Z4, Canada
| | - Amadeus Pribowo
- Forestry Products Biotechnology/Bioenergy Group, Wood Science Department, University of British Columbia, 2424 Main Mall, Vancouver, BC V6T 1Z4, Canada
| | - Jack N Saddler
- Forestry Products Biotechnology/Bioenergy Group, Wood Science Department, University of British Columbia, 2424 Main Mall, Vancouver, BC V6T 1Z4, Canada
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Lacayo CI, Hwang MS, Ding SY, Thelen MP. Lignin depletion enhances the digestibility of cellulose in cultured xylem cells. PLoS One 2013; 8:e68266. [PMID: 23874568 PMCID: PMC3715489 DOI: 10.1371/journal.pone.0068266] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2012] [Accepted: 05/23/2013] [Indexed: 01/15/2023] Open
Abstract
Plant lignocellulose constitutes an abundant and sustainable source of polysaccharides that can be converted into biofuels. However, the enzymatic digestion of native plant cell walls is inefficient, presenting a considerable barrier to cost-effective biofuel production. In addition to the insolubility of cellulose and hemicellulose, the tight association of lignin with these polysaccharides intensifies the problem of cell wall recalcitrance. To determine the extent to which lignin influences the enzymatic digestion of cellulose, specifically in secondary walls that contain the majority of cellulose and lignin in plants, we used a model system consisting of cultured xylem cells from Zinniaelegans. Rather than using purified cell wall substrates or plant tissue, we have applied this system to study cell wall degradation because it predominantly consists of homogeneous populations of single cells exhibiting large deposits of lignocellulose. We depleted lignin in these cells by treating with an oxidative chemical or by inhibiting lignin biosynthesis, and then examined the resulting cellulose digestibility and accessibility using a fluorescent cellulose-binding probe. Following cellulase digestion, we measured a significant decrease in relative cellulose content in lignin-depleted cells, whereas cells with intact lignin remained essentially unaltered. We also observed a significant increase in probe binding after lignin depletion, indicating that decreased lignin levels improve cellulose accessibility. These results indicate that lignin depletion considerably enhances the digestibility of cellulose in the cell wall by increasing the susceptibility of cellulose to enzymatic attack. Although other wall components are likely to contribute, our quantitative study exploits cultured Zinnia xylem cells to demonstrate the dominant influence of lignin on the enzymatic digestion of the cell wall. This system is simple enough for quantitative image analysis, but realistic enough to capture the natural complexity of lignocellulose in the plant cell wall. Consequently, these cells represent a suitable model for analyzing native lignocellulose degradation.
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Affiliation(s)
- Catherine I. Lacayo
- Physical & Life Sciences Directorate, Lawrence Livermore National Laboratory, Livermore, California, United States of America
| | - Mona S. Hwang
- Physical & Life Sciences Directorate, Lawrence Livermore National Laboratory, Livermore, California, United States of America
| | - Shi-You Ding
- Chemical and Biosciences Center, National Renewable Energy Laboratory, Golden, Colorado, United States of America
| | - Michael P. Thelen
- Physical & Life Sciences Directorate, Lawrence Livermore National Laboratory, Livermore, California, United States of America
- * E-mail:
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Lim WS, Lee JW. Influence of pretreatment condition on the fermentable sugar production and enzymatic hydrolysis of dilute acid-pretreated mixed softwood. BIORESOURCE TECHNOLOGY 2013; 140:306-311. [PMID: 23708848 DOI: 10.1016/j.biortech.2013.04.103] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/22/2013] [Revised: 04/25/2013] [Accepted: 04/26/2013] [Indexed: 06/02/2023]
Abstract
In this study, the effects of different acid catalysts and pretreatment factors on the hydrolysis of mixed softwood were investigated over a range of thermochemical pretreatments. Maleic, oxalic, and sulfuric acids were each used, under different pretreatment conditions. The most influential factor for fermentable sugar production in the dicarboxylic acid pretreatment of softwood was the pH. Reaction temperature was the next significant factor. However, during sulfuric acid pretreatment, fermentable sugar production was more dependent on reaction temperature, than time or pH. Enzymatic hydrolysis yields differed, depending on acid catalyst and pretreatment factor, regardless of lignin content in pretreated biomass. The highest enzymatic hydrolysis yield was found following maleic acid pretreatment, which reached 61.23%. The trend in enzymatic hydrolysis yields that were detected concomitantly with pretreatment condition or type of acid catalyst was closely related to the fermentable sugar production in the hydrolysate.
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Affiliation(s)
- Woo-Seok Lim
- Department of Forest Products and Technology, BK21 Program, Chonnam National University, Gwangju 500-757, Republic of Korea
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Lim WS, Kim JY, Kim HY, Choi JW, Choi IG, Lee JW. Structural properties of pretreated biomass from different acid pretreatments and their effects on simultaneous saccharification and ethanol fermentation. BIORESOURCE TECHNOLOGY 2013; 139:214-219. [PMID: 23665216 DOI: 10.1016/j.biortech.2013.04.009] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/22/2013] [Revised: 04/03/2013] [Accepted: 04/03/2013] [Indexed: 06/02/2023]
Abstract
The aim of this study was to investigate the effects of different acid pretreatments on the hydrolysis of biomass and ethanol production. Maleic, oxalic, and sulfuric acids were used individually as catalysts. The fermentable sugar concentration in hydrolysate was high at more than 30 g/L, which obtained at the dicarboxylic acid pretreatment. On the structural change of pretreated biomass, the S/G ratio ranged from 1.7 to 2.0, which was lower than that of raw material. The amount of phenolic OH group was significantly increased by acid pretreatment, which ranged 17.5-32.8%, compared to 4.7% of the raw material. The amounts of phenolic OH group in lignin sensitively affected simultaneous saccharification and fermentation. The maleic acid pretreated biomass, which included 17.5% of the phenolic OH group, was very effective for attaining high glucose yields and ethanol yield, after simultaneous saccharification and fermentation. At the same time, the highest ethanol yield was 0.48.
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Affiliation(s)
- Woo-Seok Lim
- Department of Forest Products and Technology, Chonnam National University, 77 Yongbong-ro, Buk-gu, Gwangju 500-757, Republic of Korea
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Jin Y, Huang T, Geng W, Yang L. Comparison of sodium carbonate pretreatment for enzymatic hydrolysis of wheat straw stem and leaf to produce fermentable sugars. BIORESOURCE TECHNOLOGY 2013; 137:294-301. [PMID: 23587832 DOI: 10.1016/j.biortech.2013.03.140] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/28/2012] [Revised: 03/18/2013] [Accepted: 03/20/2013] [Indexed: 05/18/2023]
Abstract
The specific characteristics of biomass structure and chemical composition of straw stem and leaf may result in different behavior of pretreatment and enzymatic hydrolysis. In this work, sodium carbonate (SC) was employed as a pretreatment to improve the enzymatic digestibility of wheat straw. The chemical composition and enzymatic hydrolysis of wheat straw stem and leaf (sheath included) were investigated comparatively. Most of the polysaccharides are kept in the solid fractions after SC pretreatment, while the stem has better delignification selectivity than leaf at high temperature. The enzymatic hydrolysis efficiency of wheat straw leaf is significantly higher than that of stem. The maximum total sugar yield from SC pretreated leaf was about 16% higher than stem. The results show that sodium carbonate is of great potential to be used as a pretreatment for the production of bioethanol from straw handling waste in a straw pulp mill with a low feedstock cost.
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Affiliation(s)
- Yongcan Jin
- Jiangsu Provincial Key Laboratory of Pulp and Paper Science and Technology, Nanjing Forestry University, Nanjing 210037, China.
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Holopainen-Mantila U, Marjamaa K, Merali Z, Käsper A, de Bot P, Jääskeläinen AS, Waldron K, Kruus K, Tamminen T. Impact of hydrothermal pre-treatment to chemical composition, enzymatic digestibility and spatial distribution of cell wall polymers. BIORESOURCE TECHNOLOGY 2013; 138:156-62. [PMID: 23612175 DOI: 10.1016/j.biortech.2013.03.152] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/15/2013] [Revised: 03/21/2013] [Accepted: 03/22/2013] [Indexed: 05/08/2023]
Abstract
The effect of hydrothermal pretreatment on chemical composition, microscopic structure and enzymatic digestibility of wheat straw was studied. Wheat straw was pretreated with increasing severity to obtain series of samples with altered chemistry and structure. The hydrothermal pretreatment caused solubilisation of arabinoxylan and phenolic acids and their dimers in a temperature dependent manner with minor effects on the cellulose and Klason lignin content. In the cell wall level, the pretreatment intensified staining of cellulose and relocalised xylan in the cell walls. The distribution, properties and content of the cell wall phenolic compounds was altered as observed with phloroglucinol and autofluorescence imaging. In the enzymatic hydrolysis, the highest yields were obtained from the samples with a low xylan and diferulate content. On the cell wall structural level, the sample with the highest digestibility was observed to have intensified cellulose staining, possibly reflecting the increased accessibility of cellulose.
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50
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Pribowo AY, Hu J, Arantes V, Saddler JN. The development and use of an ELISA-based method to follow the distribution of cellulase monocomponents during the hydrolysis of pretreated corn stover. BIOTECHNOLOGY FOR BIOFUELS 2013; 6:80. [PMID: 23687947 PMCID: PMC3666928 DOI: 10.1186/1754-6834-6-80] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/06/2013] [Accepted: 05/10/2013] [Indexed: 05/11/2023]
Abstract
BACKGROUND It is widely recognised that fast, effective hydrolysis of pretreated lignocellulosic substrates requires the synergistic action of multiple types of hydrolytic and some non-hydrolytic proteins. However, due to the complexity of the enzyme mixture, the enzymes interaction with and interference from the substrate and a lack of specific methods to follow the distribution of individual enzymes during hydrolysis, most of enzyme-substrate interaction studies have used purified enzymes and pure cellulose model substrates. As the enzymes present in a typical "cellulase mixture" need to work cooperatively to achieve effective hydrolysis, the action of one enzyme is likely to influence the behaviour of others. The action of the enzymes will be further influenced by the nature of the lignocellulosic substrate. Therefore, it would be beneficial if a method could be developed that allowed us to follow some of the individual enzymes present in a cellulase mixture during hydrolysis of more commercially realistic biomass substrates. RESULTS A high throughput immunoassay that could quantitatively and specifically follow individual cellulase enzymes during hydrolysis was developed. Using monoclonal and polyclonal antibodies (MAb and PAb, respectively), a double-antibody sandwich enzyme-linked immunosorbent assay (ELISA) was developed to specifically quantify cellulase enzymes from Trichoderma reesei: cellobiohydrolase I (Cel7A), cellobiohydrolase II (Cel6A), and endoglucanase I (Cel7B). The interference from substrate materials present in lignocellulosic supernatants could be minimized by dilution. CONCLUSION A double-antibody sandwich ELISA was able to detect and quantify individual enzymes when present in cellulase mixtures. The assay was sensitive over a range of relatively low enzyme concentration (0 - 1 μg/ml), provided the enzymes were first pH adjusted and heat treated to increase their antigenicity. The immunoassay was employed to quantitatively monitor the adsorption of cellulase monocomponents, Cel7A, Cel6A, and Cel7B, that were present in both Celluclast and Accellerase 1000, during the hydrolysis of steam-pretreated corn stover (SPCS). All three enzymes exhibited different individual adsorption profiles. The specific and quantitative adsorption profiles observed with the ELISA method were in agreement with earlier work where more labour intensive enzyme assay techniques were used.
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Affiliation(s)
- Amadeus Y Pribowo
- Forest Products Biotechnology/Bioenergy Group, University of British Columbia, 2424 Main Mall, Vancouver, British Columbia, V6T1Z4, Canada
| | - Jinguang Hu
- Forest Products Biotechnology/Bioenergy Group, University of British Columbia, 2424 Main Mall, Vancouver, British Columbia, V6T1Z4, Canada
| | - Valdeir Arantes
- Forest Products Biotechnology/Bioenergy Group, University of British Columbia, 2424 Main Mall, Vancouver, British Columbia, V6T1Z4, Canada
| | - Jack N Saddler
- Forest Products Biotechnology/Bioenergy Group, University of British Columbia, 2424 Main Mall, Vancouver, British Columbia, V6T1Z4, Canada
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