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Rueckel M, Janson S, Solbak A, Fickler A. Spatial activity mapping of ß-mannanase on soybean seeds. Sci Rep 2024; 14:1037. [PMID: 38200142 PMCID: PMC10781726 DOI: 10.1038/s41598-024-51494-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2023] [Accepted: 01/05/2024] [Indexed: 01/12/2024] Open
Abstract
For farm animals the supplementation of exogenous enzymes, like ß-mannanase, to soybean-based diets is beneficial to improve feed digestibility. In order to unravel the effect of ß-mannanase on soybean meal's cell structure, a novel imaging concept was developed which allows visualizing the spatial activity pattern of ß-mannanase with high sensitivity by fluorescence microscopy before any visible degradation of the cellular structure occurs. It is based on fluorescence labeling of newly formed reducing ends of ß-mannanase-hydrolyzed polysaccharides after the native reducing ends of all polysaccharides present were chemically reduced. It was revealed that ß-mannanase is not only active at the cell wall but also at previously unknown sites, like the middle lamella and, most prominently, at an intracellular matrix enclosing the protein storage vacuoles. Based on these findings it can be hypothesized that the evaluated ß-mannanase can degrade the enclosing matrix of encapsulated proteins and the cell wall structure and thereby improves efficiency of feed utilization.
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Affiliation(s)
- Markus Rueckel
- BASF SE, Carl-Bosch-Straße 38, 67056, Ludwigshafen, Germany.
| | - Sven Janson
- BASF SE, Carl-Bosch-Straße 38, 67056, Ludwigshafen, Germany
| | - Arne Solbak
- BASF Enzymes LLC, 3550 John Hopkins Court, San Diego, CA, 92121, USA
| | - Anna Fickler
- BASF SE, Carl-Bosch-Straße 38, 67056, Ludwigshafen, Germany
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2
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Xue H, Qin R, Liu Y, Yuan L, Li G. An aggregated understanding of the influence of aqueous ammonia pretreatment on the physical deconstruction of cell walls in sugar beet pulp. Bioprocess Biosyst Eng 2023; 46:1427-1435. [PMID: 37490146 DOI: 10.1007/s00449-023-02908-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2023] [Accepted: 07/10/2023] [Indexed: 07/26/2023]
Abstract
The underlying interplay between physicochemical property and enzymatic hydrolysis of cellulose still remains unclear. The impacts of matrix glycan composition of sugar beet pulp (SBP) on physical structure and saccharification efficiency were emphasized. The results showed that aqueous ammonia (AA) pretreatment could remove the non-cellulosic polysaccharides and destroy the linkage between the pectin and lignin. The cellulose supramolecule was changed significantly after AA pretreatment, in terms of the decline in hardness, gumminess, springiness, thickness and degree of polymerization. Furthermore, vascular cell was exposed and degraded. The highest reducing sugar yield of 355.06 mg/g was obtained from the pretreated SBP (80 °C) with enzyme loading of 30 U/g, which was 1.01 times higher than that of the untreated SBP. This research also supported the idea that recognizing and precisely removing the primary epitopes in cell walls might be an ideal strategy to accomplish the improved enzymatic hydrolysis through mild pretreatment.
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Affiliation(s)
- Huiting Xue
- Inner Mongolia Engineering Technology Research Center of Germplasm Resources Conservation and Utilization, School of Life Sciences, Inner Mongolia University, Hohhot, 010070, People's Republic of China
- College of Basic Medicine, Inner Mongolia Medical University, Hohhot, 010070, People's Republic of China
| | - Renjie Qin
- Inner Mongolia Engineering Technology Research Center of Germplasm Resources Conservation and Utilization, School of Life Sciences, Inner Mongolia University, Hohhot, 010070, People's Republic of China
| | - Yang Liu
- Inner Mongolia Engineering Technology Research Center of Germplasm Resources Conservation and Utilization, School of Life Sciences, Inner Mongolia University, Hohhot, 010070, People's Republic of China
| | - Lin Yuan
- Inner Mongolia Engineering Technology Research Center of Germplasm Resources Conservation and Utilization, School of Life Sciences, Inner Mongolia University, Hohhot, 010070, People's Republic of China
| | - Guanhua Li
- Inner Mongolia Engineering Technology Research Center of Germplasm Resources Conservation and Utilization, School of Life Sciences, Inner Mongolia University, Hohhot, 010070, People's Republic of China.
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3
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Removal of RhB from water by Fe-modified hydrochar and biochar – An experimental evaluation supported by genetic programming. J Mol Liq 2023. [DOI: 10.1016/j.molliq.2022.120971] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
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Sun Q, Chen WJ, Pang B, Sun Z, Lam SS, Sonne C, Yuan TQ. Ultrastructural change in lignocellulosic biomass during hydrothermal pretreatment. BIORESOURCE TECHNOLOGY 2021; 341:125807. [PMID: 34474237 DOI: 10.1016/j.biortech.2021.125807] [Citation(s) in RCA: 24] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/17/2021] [Revised: 08/13/2021] [Accepted: 08/15/2021] [Indexed: 06/13/2023]
Abstract
In recent years, visualization and characterization of lignocellulose at different scales elucidate the modifications of its ultrastructural and chemical features during hydrothermal pretreatment which include degradation and dissolving of hemicelluloses, swelling and partial hydrolysis of cellulose, melting and redepositing a part of lignin in the surface. As a result, cell walls are swollen, deformed and de-laminated from the adjacent layer, lead to a range of revealed droplets that appear on and within cell walls. Moreover, the certain extent morphological changes significantly promote the downstream processing steps, especially for enzymatic hydrolysis and anaerobic fermentation to bioethanol by increasing the contact area with enzymes. However, the formation of pseudo-lignin hinders the accessibility of cellulase to cellulose, which decreases the efficiency of enzymatic hydrolysis. This review is intended to bridge the gap between the microstructure studies and value-added applications of lignocellulose while inspiring more research prospects to enhance the hydrothermal pretreatment process.
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Affiliation(s)
- Qian Sun
- Beijing Key Laboratory of Lignocellulosic Chemistry, Beijing Forestry University, No.35 Tsinghua East Road, Beijing 100083, PR China
| | - Wei-Jing Chen
- Beijing Key Laboratory of Lignocellulosic Chemistry, Beijing Forestry University, No.35 Tsinghua East Road, Beijing 100083, PR China
| | - Bo Pang
- Beijing Key Laboratory of Lignocellulosic Chemistry, Beijing Forestry University, No.35 Tsinghua East Road, Beijing 100083, PR China
| | - Zhuohua Sun
- Beijing Key Laboratory of Lignocellulosic Chemistry, Beijing Forestry University, No.35 Tsinghua East Road, Beijing 100083, PR China
| | - Su Shiung Lam
- Pyrolysis Technology Research Group, Institute of Tropical Aquaculture and Fisheries (Akuatrop), Universiti Malaysia Terengganu, 21030 Kuala Nerus, Terengganu, Malaysia
| | - Christian Sonne
- Department of Bioscience, Arctic Research Centre (ARC), Aarhus University, Frederiksborgvej 399, PO Box 358, DK-4000, Roskilde, Denmark
| | - Tong-Qi Yuan
- Beijing Key Laboratory of Lignocellulosic Chemistry, Beijing Forestry University, No.35 Tsinghua East Road, Beijing 100083, PR China.
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5
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Abstract
In this study, a waste of biorefinery—lignin—is investigated as an anticorrosion coating on stainless steel. Corrosion behavior of two lignin types (hardwood beech and softwood spruce) was studied by electrochemical measurements (linear sweep voltammetry, open circuit potential, potentiostatic polarization, cyclic potentiodynamic polarization, and electrochemical impedance measurements) during exposure to simulated body fluid (SBF) or phosphate buffer (PBS). Results from linear sweep voltammetry of lignin-coated samples, in particular, demonstrated a reduction in corrosion current density between 1 and 3 orders of magnitude cf. blank stainless steel. Furthermore, results from cross cut adhesion tests on lignin-coated samples demonstrated that the best possible adhesion (grade 0) of ISO 2409 standard was achieved for the investigated novel coatings. Such findings suggest that lignin materials could transform the field of organic coatings towards more sustainable alternatives by replacing non-renewable polymer coatings.
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Action of lytic polysaccharide monooxygenase on plant tissue is governed by cellular type. Sci Rep 2017; 7:17792. [PMID: 29259205 PMCID: PMC5736606 DOI: 10.1038/s41598-017-17938-2] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2017] [Accepted: 11/28/2017] [Indexed: 11/08/2022] Open
Abstract
Lignocellulosic biomass bioconversion is hampered by the structural and chemical complexity of the network created by cellulose, hemicellulose and lignin. Biological conversion of lignocellulose involves synergistic action of a large array of enzymes including the recently discovered lytic polysaccharide monooxygenases (LPMOs) that perform oxidative cleavage of cellulose. Using in situ imaging by synchrotron UV fluorescence, we have shown that the addition of AA9 LPMO (from Podospora anserina) to cellulases cocktail improves the progression of enzymes in delignified Miscanthus x giganteus as observed at tissular levels. In situ chemical monitoring of cell wall modifications performed by synchrotron infrared spectroscopy during enzymatic hydrolysis demonstrated that the boosting effect of the AA9 LPMO was dependent on the cellular type indicating contrasted recalcitrance levels in plant tissues. Our study provides a useful strategy for investigating enzyme dynamics and activity in plant cell wall to improve enzymatic cocktails aimed at expanding lignocelluloses biorefinery.
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Donaldson L, Vaidya A. Visualising recalcitrance by colocalisation of cellulase, lignin and cellulose in pretreated pine biomass using fluorescence microscopy. Sci Rep 2017; 7:44386. [PMID: 28281670 PMCID: PMC5345003 DOI: 10.1038/srep44386] [Citation(s) in RCA: 31] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2016] [Accepted: 02/07/2017] [Indexed: 11/08/2022] Open
Abstract
Mapping the location of bound cellulase enzymes provides information on the micro-scale distribution of amenable and recalcitrant sites in pretreated woody biomass for biofuel applications. The interaction of a fluorescently labelled cellulase enzyme cocktail with steam-exploded pine (SEW) was quantified using confocal microscopy. The spatial distribution of Dylight labelled cellulase was quantified relative to lignin (autofluorescence) and cellulose (Congo red staining) by measuring their colocalisation using Pearson correlations. Correlations were greater in cellulose-rich secondary cell walls compared to lignin-rich middle lamella but with significant variations among individual biomass particles. The distribution of cellulose in the pretreated biomass accounted for 30% of the variation in the distribution of enzyme after correcting for the correlation between lignin and cellulose. For the first time, colocalisation analysis was able to quantify the spatial distribution of amenable and recalcitrant sites in relation to the histochemistry of cellulose and lignin. This study will contribute to understanding the role of pretreatment in enzymatic hydrolysis of recalcitrant softwood biomass.
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Affiliation(s)
- Lloyd Donaldson
- Scion, 49 Sala Street, Private Bag 3020, Rotorua 3010, New Zealand
| | - Alankar Vaidya
- Scion, 49 Sala Street, Private Bag 3020, Rotorua 3010, New Zealand
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Crowe JD, Feringa N, Pattathil S, Merritt B, Foster C, Dines D, Ong RG, Hodge DB. Identification of developmental stage and anatomical fraction contributions to cell wall recalcitrance in switchgrass. BIOTECHNOLOGY FOR BIOFUELS 2017; 10:184. [PMID: 28725264 PMCID: PMC5512841 DOI: 10.1186/s13068-017-0870-5] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/26/2017] [Accepted: 07/06/2017] [Indexed: 05/08/2023]
Abstract
BACKGROUND Heterogeneity within herbaceous biomass can present important challenges for processing feedstocks to cellulosic biofuels. Alterations to cell wall composition and organization during plant growth represent major contributions to heterogeneity within a single species or cultivar. To address this challenge, the focus of this study was to characterize the relationship between composition and properties of the plant cell wall and cell wall response to deconstruction by NaOH pretreatment and enzymatic hydrolysis for anatomical fractions (stem internodes, leaf sheaths, and leaf blades) within switchgrass at various tissue maturities as assessed by differing internode. RESULTS Substantial differences in both cell wall composition and response to deconstruction were observed as a function of anatomical fraction and tissue maturity. Notably, lignin content increased with tissue maturity concurrently with decreasing ferulate content across all three anatomical fractions. Stem internodes exhibited the highest lignin content as well as the lowest hydrolysis yields, which were inversely correlated to lignin content. Confocal microscopy was used to demonstrate that removal of cell wall aromatics (i.e., lignins and hydroxycinnamates) by NaOH pretreatment was non-uniform across diverse cell types. Non-cellulosic polysaccharides were linked to differences in cell wall response to deconstruction in lower lignin fractions. Specifically, leaf sheath and leaf blade were found to have higher contents of substituted glucuronoarabinoxylans and pectic polysaccharides. Glycome profiling demonstrated that xylan and pectic polysaccharide extractability varied with stem internode maturity, with more mature internodes requiring harsher chemical extractions to remove comparable glycan abundances relative to less mature internodes. While enzymatic hydrolysis was performed on extractives-free biomass, extractible sugars (i.e., starch and sucrose) comprised a significant portion of total dry weight particularly in stem internodes, and may provide an opportunity for recovery during processing. CONCLUSIONS Cell wall structural differences within a single plant can play a significant role in feedstock properties and have the potential to be exploited for improving biomass processability during a biorefining process. The results from this work demonstrate that cell wall lignin content, while generally exhibiting a negative correlation with enzymatic hydrolysis yields, is not the sole contributor to cell wall recalcitrance across diverse anatomical fractions within switchgrass.
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Affiliation(s)
- Jacob D. Crowe
- Department of Chemical Engineering and Materials Science, Michigan State University, East Lansing, MI USA
| | - Nicholas Feringa
- Department of Chemical Engineering and Materials Science, Michigan State University, East Lansing, MI USA
| | - Sivakumar Pattathil
- Complex Carbohydrate Research Center, University of Georgia, Athens, GA USA
- Bioenergy Science Center, Oak Ridge National Laboratory, Oak Ridge, TN USA
| | - Brian Merritt
- Complex Carbohydrate Research Center, University of Georgia, Athens, GA USA
| | - Cliff Foster
- DOE-Great Lakes Bioenergy Research Center, Michigan State University, East Lansing, MI USA
| | - Dayna Dines
- DOE-Great Lakes Bioenergy Research Center, Michigan State University, East Lansing, MI USA
| | - Rebecca G. Ong
- Department of Chemical Engineering, Michigan Technological University, Houghton, MI USA
| | - David B. Hodge
- Department of Chemical Engineering and Materials Science, Michigan State University, East Lansing, MI USA
- DOE-Great Lakes Bioenergy Research Center, Michigan State University, East Lansing, MI USA
- Department of Biosystems & Agricultural Engineering, Michigan State University, East Lansing, MI USA
- Department of Civil, Environmental and Natural Resources Engineering, Luleå University of Technology, Luleå, Sweden
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9
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Jiang B, Wang W, Gu F, Cao T, Jin Y. Comparison of the substrate enzymatic digestibility and lignin structure of wheat straw stems and leaves pretreated by green liquor. BIORESOURCE TECHNOLOGY 2016; 199:181-187. [PMID: 26342786 DOI: 10.1016/j.biortech.2015.08.104] [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: 07/24/2015] [Revised: 08/18/2015] [Accepted: 08/19/2015] [Indexed: 06/05/2023]
Abstract
In this work, the substrate enzymatic digestibility (SED) and the lignin structure of green liquor (GL) pretreated wheat straw stems and leaves were investigated. Compared with wheat straw stems, leaves showed higher delignification selectivity in GL pretreatment and higher SED in enzymatic hydrolysis. Wet chemical analysis indicated that, characterized with lower content of syringyl units and less β-O-4 linkages, leaf lignin is structurally different from stem lignin. After GL pretreatment, the drops of both nitrobenzene oxidation and ozonation products yield of leaves were obviously higher than those of stems, which means that more β-O-4 linkages of leaf lignin were broken than that of stem lignin. The SED of total sugar in GL-pretreated leaves was about 50% higher than that in GL-pretreated stems. The less content and lower S/G ratio of lignin are suggested to be the important factors for the better SED of GL-pretreated leaves.
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Affiliation(s)
- Bo Jiang
- Jiangsu Provincial Key Lab of Pulp and Paper Science and Technology, Nanjing Forestry University, Nanjing 210037, China
| | - Wangxia Wang
- Jiangsu Provincial Key Lab of Pulp and Paper Science and Technology, Nanjing Forestry University, Nanjing 210037, China
| | - Feng Gu
- Jiangsu Provincial Key Lab of Pulp and Paper Science and Technology, Nanjing Forestry University, Nanjing 210037, China
| | - Tingyue Cao
- Jiangsu Provincial Key Lab of Pulp and Paper Science and Technology, Nanjing Forestry University, Nanjing 210037, China
| | - Yongcan Jin
- Jiangsu Provincial Key Lab of Pulp and Paper Science and Technology, Nanjing Forestry University, Nanjing 210037, China.
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10
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Chandel AK, Antunes FAF, Anjos V, Bell MJV, Rodrigues LN, Polikarpov I, de Azevedo ER, Bernardinelli OD, Rosa CA, Pagnocca FC, da Silva SS. Multi-scale structural and chemical analysis of sugarcane bagasse in the process of sequential acid-base pretreatment and ethanol production by Scheffersomyces shehatae and Saccharomyces cerevisiae. BIOTECHNOLOGY FOR BIOFUELS 2014; 7:63. [PMID: 24739736 PMCID: PMC4005856 DOI: 10.1186/1754-6834-7-63] [Citation(s) in RCA: 66] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/09/2013] [Accepted: 02/04/2014] [Indexed: 05/04/2023]
Abstract
BACKGROUND Heavy usage of gasoline, burgeoning fuel prices, and environmental issues have paved the way for the exploration of cellulosic ethanol. Cellulosic ethanol production technologies are emerging and require continued technological advancements. One of the most challenging issues is the pretreatment of lignocellulosic biomass for the desired sugars yields after enzymatic hydrolysis. We hypothesized that consecutive dilute sulfuric acid-dilute sodium hydroxide pretreatment would overcome the native recalcitrance of sugarcane bagasse (SB) by enhancing cellulase accessibility of the embedded cellulosic microfibrils. RESULTS SB hemicellulosic hydrolysate after concentration by vacuum evaporation and detoxification showed 30.89 g/l xylose along with other products (0.32 g/l glucose, 2.31 g/l arabinose, and 1.26 g/l acetic acid). The recovered cellulignin was subsequently delignified by sodium hydroxide mediated pretreatment. The acid-base pretreated material released 48.50 g/l total reducing sugars (0.91 g sugars/g cellulose amount in SB) after enzymatic hydrolysis. Ultra-structural mapping of acid-base pretreated and enzyme hydrolyzed SB by microscopic analysis (scanning electron microcopy (SEM), transmitted light microscopy (TLM), and spectroscopic analysis (X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy, Fourier transform near-infrared (FT-NIR) spectroscopy, and nuclear magnetic resonance (NMR) spectroscopy) elucidated the molecular changes in hemicellulose, cellulose, and lignin components of bagasse. The detoxified hemicellulosic hydrolysate was fermented by Scheffersomyces shehatae (syn. Candida shehatae UFMG HM 52.2) and resulted in 9.11 g/l ethanol production (yield 0.38 g/g) after 48 hours of fermentation. Enzymatic hydrolysate when fermented by Saccharomyces cerevisiae 174 revealed 8.13 g/l ethanol (yield 0.22 g/g) after 72 hours of fermentation. CONCLUSIONS Multi-scale structural studies of SB after sequential acid-base pretreatment and enzymatic hydrolysis showed marked changes in hemicellulose and lignin removal at molecular level. The cellulosic material showed high saccharification efficiency after enzymatic hydrolysis. Hemicellulosic and cellulosic hydrolysates revealed moderate ethanol production by S. shehatae and S. cerevisiae under batch fermentation conditions.
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Affiliation(s)
- Anuj K Chandel
- Department of Biotechnology, School of Engineering of Lorena, Estrada Municipal do Campinho, University of São Paulo, Caixa Postal 116 12.602.810, Lorena, São Paulo, Brazil
| | - Felipe AF Antunes
- Department of Biotechnology, School of Engineering of Lorena, Estrada Municipal do Campinho, University of São Paulo, Caixa Postal 116 12.602.810, Lorena, São Paulo, Brazil
| | - Virgilio Anjos
- Materials Spectroscopy Laboratory, Department of Physics, Federal University of Juiz de Fora, Juiz de Fora 36036-330 Minas Gerais, Brazil
| | - Maria JV Bell
- Materials Spectroscopy Laboratory, Department of Physics, Federal University of Juiz de Fora, Juiz de Fora 36036-330 Minas Gerais, Brazil
| | - Leonarde N Rodrigues
- Materials Spectroscopy Laboratory, Department of Physics, Federal University of Juiz de Fora, Juiz de Fora 36036-330 Minas Gerais, Brazil
| | - Igor Polikarpov
- Instituto de Física de São Carlos, Universidade de São Paulo, Caixa Postal 369, São Carlos, São Paulo CEP 13560-970, Brazil
| | - Eduardo R de Azevedo
- Instituto de Física de São Carlos, Universidade de São Paulo, Caixa Postal 369, São Carlos, São Paulo CEP 13560-970, Brazil
| | - Oigres D Bernardinelli
- Instituto de Física de São Carlos, Universidade de São Paulo, Caixa Postal 369, São Carlos, São Paulo CEP 13560-970, Brazil
| | - Carlos A Rosa
- Departmento de Microbiologia, Instituto de Ciências Biológicas, Universidade Federal de Minas Gerais, Belo Horizonte, Minas Gerais, Brazil
| | - Fernando C Pagnocca
- Department of Biochemistry and Microbiology, Institute of Biosciences, CIES/UNESP, Rio Claro, São Paulo, Brazil
| | - Silvio S da Silva
- Department of Biotechnology, School of Engineering of Lorena, Estrada Municipal do Campinho, University of São Paulo, Caixa Postal 116 12.602.810, Lorena, São Paulo, Brazil
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Zhang H, Thygesen LG, Mortensen K, Kádár Z, Lindedam J, Jørgensen H, Felby C. Structure and enzymatic accessibility of leaf and stem from wheat straw before and after hydrothermal pretreatment. BIOTECHNOLOGY FOR BIOFUELS 2014; 7:74. [PMID: 24860617 PMCID: PMC4031911 DOI: 10.1186/1754-6834-7-74] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/22/2014] [Accepted: 05/08/2014] [Indexed: 05/04/2023]
Abstract
BACKGROUND Biomass recalcitrance is affected by a number of chemical, physical and biological factors. In this study we looked into the differences in recalcitrance between two major anatomical fractions of wheat straw biomass, leaf and stem. A set of twenty-one wheat cultivars was fractionated and illustrated the substantial variation in leaf-to-stem ratio between cultivars. The two fractions were compared in terms of chemical composition, enzymatic convertibility, cellulose crystallinity and glucan accessibility. The use of water as a probe for assessing glucan accessibility was explored using low field nuclear magnetic resonance and infrared spectroscopy in combination with hydrogen-deuterium exchange. RESULTS Leaves were clearly more degradable by lignocellulolytic enzymes than stems, and it was demonstrated that xylose removal was more linked to glucose yield for stems than for leaves. Comparing the locations of water in leaf and stem by low field NMR and FT-IR revealed that the glucan hydroxyl groups in leaves were more accessible to water than glucan hydroxyl groups in stems. No difference in crystallinity between leaf and stem was observed using wide angle x-ray diffraction. Hydrothermal pretreatment increased the accessibility towards water in stems but not in leaves. The results in this study indicate a correlation between the accessibility of glucan to water and to enzymes. CONCLUSIONS Enzymatic degradability of wheat straw anatomical fractions can be indicated by the accessibility of the hydroxyl groups to water. This suggests that water may be used to assess glucan accessibility in biomass samples.
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Affiliation(s)
- Heng Zhang
- Department of Geosciences and Natural Resource Management, Faculty of Sciences, University of Copenhagen, Rolighedsvej 23, DK-1958 Frederiksberg C, Denmark
| | - Lisbeth G Thygesen
- Department of Geosciences and Natural Resource Management, Faculty of Sciences, University of Copenhagen, Rolighedsvej 23, DK-1958 Frederiksberg C, Denmark
| | - Kell Mortensen
- Niels Bohr Institute, University of Copenhagen, Universitetsparken 5, D-03-3-06, DK-2100 Copenhagen Ø, Denmark
| | - Zsófia Kádár
- Center for BioProcess Engineering, Department of Chemical and Biochemical Engineering, Technical University of Denmark, DTU, DK-2800, Kgs, Lyngby, Denmark
| | - Jane Lindedam
- Department of Plant and Environmental Sciences, University of Copenhagen, Thorvaldsensvej 40, DK-1871 Frederiksberg C, Denmark
| | - Henning Jørgensen
- Department of Chemical and Biochemical Engineering, Technical University of Denmark, 2800 Kgs, Lyngby, Denmark
| | - Claus Felby
- Department of Geosciences and Natural Resource Management, Faculty of Sciences, University of Copenhagen, Rolighedsvej 23, DK-1958 Frederiksberg C, Denmark
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12
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Kont R, Kurašin M, Teugjas H, Väljamäe P. Strong cellulase inhibitors from the hydrothermal pretreatment of wheat straw. BIOTECHNOLOGY FOR BIOFUELS 2013; 6:135. [PMID: 24053778 PMCID: PMC3849272 DOI: 10.1186/1754-6834-6-135] [Citation(s) in RCA: 60] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/03/2013] [Accepted: 09/13/2013] [Indexed: 05/03/2023]
Abstract
BACKGROUND The use of the enzymatic hydrolysis of lignocellulose with subsequent fermentation to ethanol provides a green alternative for the production of transportation fuels. Because of its recalcitrant nature, the lignocellulosic biomass must be pretreated before enzymatic hydrolysis. However, the pretreatment often results in the formation of compounds that are inhibitory for the enzymes or fermenting organism. Although well recognized, little quantitative information on the inhibition of individual cellulase components by identified inhibitors is available. RESULTS Strong cellulase inhibitors were separated from the liquid fraction of the hydrothermal pretreatment of wheat straw. HPLC and mass-spectroscopy analyses confirmed that the inhibitors were oligosaccharides (inhibitory oligosaccharides, IOS) with a degree of polymerization from 7 to 16. The IOS are composed of a mixture of xylo- (XOS) and gluco-oligosaccharides (GOS). We propose that XOS and GOS are the fragments of the xylan backbone and mixed-linkage β-glucans, respectively. The IOS were approximately 100 times stronger inhibitors for Trichoderma reesei cellobiohydrolases (CBHs) than cellobiose, which is one of the strongest inhibitors of these enzymes reported to date. Inhibition of endoglucanases (EGs) by IOS was weaker than that of CBHs. Most of the tested cellulases and hemicellulases were able to slowly degrade IOS and reduce the inhibitory power of the liquid fraction to some extent. The most efficient single enzyme component here was T. reesei EG TrCel7B. Although reduced by the enzyme treatment, the residual inhibitory power of IOS and the liquid fraction was strong enough to silence the major component of the T. reesei cellulase system, CBH TrCel7A. CONCLUSIONS The cellulase inhibitors described here may be responsible for the poor yields from the enzymatic conversion of the whole slurries from lignocellulose pretreatment under conditions that do not favor complete degradation of hemicellulose. Identification of the inhibitory compounds helps to design better enzyme mixtures for their degradation and to optimize the pretreatment regimes to minimize their formation.
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Affiliation(s)
- Riin Kont
- Institute of Molecular and Cell Biology, University of Tartu, Riia 23b - 202, 51010 Tartu, Estonia
| | - Mihhail Kurašin
- Institute of Molecular and Cell Biology, University of Tartu, Riia 23b - 202, 51010 Tartu, Estonia
| | - Hele Teugjas
- Institute of Molecular and Cell Biology, University of Tartu, Riia 23b - 202, 51010 Tartu, Estonia
| | - Priit Väljamäe
- Institute of Molecular and Cell Biology, University of Tartu, Riia 23b - 202, 51010 Tartu, Estonia
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