1
|
Gacias-Amengual N, Wohlschlager L, Csarman F, Ludwig R. Fluorescent Imaging of Extracellular Fungal Enzymes Bound onto Plant Cell Walls. Int J Mol Sci 2022; 23:ijms23095216. [PMID: 35563607 PMCID: PMC9105846 DOI: 10.3390/ijms23095216] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2022] [Revised: 05/04/2022] [Accepted: 05/05/2022] [Indexed: 02/04/2023] Open
Abstract
Lignocelluloytic enzymes are industrially applied as biocatalysts for the deconstruction of recalcitrant plant biomass. To study their biocatalytic and physiological function, the assessment of their binding behavior and spatial distribution on lignocellulosic material is a crucial prerequisite. In this study, selected hydrolases and oxidoreductases from the white rot fungus Phanerochaete chrysosporium were localized on model substrates as well as poplar wood by confocal laser scanning microscopy. Two different detection approaches were investigated: direct tagging of the enzymes and tagging specific antibodies generated against the enzymes. Site-directed mutagenesis was employed to introduce a single surface-exposed cysteine residue for the maleimide site-specific conjugation. Specific polyclonal antibodies were produced against the enzymes and were labeled using N-hydroxysuccinimide (NHS) ester as a cross-linker. Both methods allowed the visualization of cell wall-bound enzymes but showed slightly different fluorescent yields. Using native poplar thin sections, we identified the innermost secondary cell wall layer as the preferential attack point for cellulose-degrading enzymes. Alkali pretreatment resulted in a partial delignification and promoted substrate accessibility and enzyme binding. The methods presented in this study are suitable for the visualization of enzymes during catalytic biomass degradation and can be further exploited for interaction studies of lignocellulolytic enzymes in biorefineries.
Collapse
|
2
|
Babi M, Fatona A, Li X, Cerson C, Jarvis VM, Abitbol T, Moran-Mirabal JM. Efficient Labeling of Nanocellulose for High-Resolution Fluorescence Microscopy Applications. Biomacromolecules 2022; 23:1981-1994. [PMID: 35442640 DOI: 10.1021/acs.biomac.1c01698] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The visualization of naturally derived cellulose nanofibrils (CNFs) and nanocrystals (CNCs) within nanocomposite materials is key to the development of packaging materials, tissue culture scaffolds, and emulsifying agents, among many other applications. In this work, we develop a versatile and efficient two-step approach based on triazine and azide-alkyne click-chemistry to fluorescently label nanocelluloses with a variety of commercially available dyes. We show that this method can be used to label bacterial cellulose fibrils, plant-derived CNFs, carboxymethylated CNFs, and CNCs with Cy5 and fluorescein derivatives to high degrees of labeling using minimal amounts of dye while preserving their native morphology and crystalline structure. The ability to tune the labeling density with this method allowed us to prepare optimized samples that were used to visualize nanostructural features of cellulose through super-resolution microscopy. The efficiency, cost-effectiveness, and versatility of this method make it ideal for labeling nanocelluloses and imaging them through advanced microscopy techniques for a broad range of applications.
Collapse
Affiliation(s)
- Mouhanad Babi
- Department of Chemistry and Chemical Biology, McMaster University, Hamilton, Ontario L8S 4M1, Canada
| | - Ayodele Fatona
- Department of Chemistry and Chemical Biology, McMaster University, Hamilton, Ontario L8S 4M1, Canada
| | - Xiang Li
- Department of Chemistry and Chemical Biology, McMaster University, Hamilton, Ontario L8S 4M1, Canada
| | - Christine Cerson
- Department of Chemistry and Chemical Biology, McMaster University, Hamilton, Ontario L8S 4M1, Canada
| | - Victoria M Jarvis
- McMaster Analytical X-ray Diffraction Facility, McMaster University, Hamilton, Ontario L8S 4M1, Canada
| | - Tiffany Abitbol
- RISE Research Institutes of Sweden, Stockholm 114 28, Sweden
| | - Jose M Moran-Mirabal
- Department of Chemistry and Chemical Biology, McMaster University, Hamilton, Ontario L8S 4M1, Canada.,Centre for Advanced Light Microscopy, McMaster University, Hamilton, Ontario L8S 4M1, Canada.,Brockhouse Institute for Materials Research, McMaster University, Hamilton, Ontario L8S 4M1, Canada
| |
Collapse
|
3
|
Rohrbach JC, Luterbacher JS. Investigating the effects of substrate morphology and experimental conditions on the enzymatic hydrolysis of lignocellulosic biomass through modeling. BIOTECHNOLOGY FOR BIOFUELS 2021; 14:103. [PMID: 33902675 PMCID: PMC8073973 DOI: 10.1186/s13068-021-01920-2] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 12/11/2020] [Accepted: 03/03/2021] [Indexed: 06/12/2023]
Abstract
BACKGROUND Understanding how the digestibility of lignocellulosic biomass is affected by its morphology is essential to design efficient processes for biomass deconstruction. In this study, we used a model based on a set of partial differential equations describing the evolution of the substrate morphology to investigate the interplay between experimental conditions and the physical characteristics of biomass particles as the reaction proceeds. Our model carefully considers the overall quantity of cellulase present in the hydrolysis mixture and explores its interplay with the available accessible cellulose surface. RESULTS Exploring the effect of various experimental and structural parameters highlighted the significant role of internal mass transfer as the substrate size increases and/or the enzyme loading decreases. In such cases, diffusion of cellulases to the available cellulose surface limits the rate of glucose release. We notably see that increasing biomass loading, while keeping enzyme loading constant should be favored for both small- (R < 300 [Formula: see text]) and middle-ranged (300 < R < 1000 [Formula: see text]) substrates to enhance enzyme diffusion while minimizing the use of enzymes. In such cases, working at enzyme loadings exceeding the full coverage of the cellulose surface (i.e. eI>1) does not bring a significant benefit. For larger particles (R > 1000 [Formula: see text]), increases in biomass loading do not offset the significant internal mass transfer limitations, but high enzyme loadings improve enzyme penetration by maintaining a high concentration gradient within the particle. We also confirm the well-known importance of cellulose accessibility, which increases with pretreatment. CONCLUSIONS Based on the developed model, we are able to propose several design criteria for deconstruction process. Importantly, we highlight the crucial role of adjusting the enzyme and biomass loading to the wood particle size and accessible cellulose surface to maintain a strong concentration gradient, while avoiding unnecessary excess in cellulase loading. Theory-based approaches that explicitly consider the entire lignocellulose particle structure can be used to clearly identify the relative importance of bottlenecks during the biomass deconstruction process, and serve as a framework to build on more detailed cellulase mechanisms.
Collapse
Affiliation(s)
- Jessica C Rohrbach
- Laboratory of Sustainable and Catalytic Processing, Institute of Chemical Sciences and Engineering, École Polytechnique Fédérale de Lausanne (EPFL), CH-1015, Lausanne, Switzerland
| | - Jeremy S Luterbacher
- Laboratory of Sustainable and Catalytic Processing, Institute of Chemical Sciences and Engineering, École Polytechnique Fédérale de Lausanne (EPFL), CH-1015, Lausanne, Switzerland.
| |
Collapse
|
4
|
Visootsat A, Nakamura A, Vignon P, Watanabe H, Uchihashi T, Iino R. Single-molecule imaging analysis reveals the mechanism of a high-catalytic-activity mutant of chitinase A from Serratia marcescens. J Biol Chem 2020; 295:1915-1925. [PMID: 31924658 PMCID: PMC7029130 DOI: 10.1074/jbc.ra119.012078] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2019] [Revised: 01/03/2020] [Indexed: 12/17/2022] Open
Abstract
Chitin degradation is important for biomass conversion and has potential applications for agriculture, biotechnology, and the pharmaceutical industry. Chitinase A from the Gram-negative bacterium Serratia marcescens (SmChiA) is a processive enzyme that hydrolyzes crystalline chitin as it moves linearly along the substrate surface. In a previous study, the catalytic activity of SmChiA against crystalline chitin was found to increase after the tryptophan substitution of two phenylalanine residues (F232W and F396W), located at the entrance and exit of the substrate binding cleft of the catalytic domain, respectively. However, the mechanism underlying this high catalytic activity remains elusive. In this study, single-molecule fluorescence imaging and high-speed atomic force microscopy were applied to understand the mechanism of this high-catalytic-activity mutant. A reaction scheme including processive catalysis was used to reproduce the properties of SmChiA WT and F232W/F396W, in which all of the kinetic parameters were experimentally determined. High activity of F232W/F396W mutant was caused by a high processivity and a low dissociation rate constant after productive binding. The turnover numbers for both WT and F232W/F396W, determined by the biochemical analysis, were well-replicated using the kinetic parameters obtained from single-molecule imaging analysis, indicating the validity of the reaction scheme. Furthermore, alignment of amino acid sequences of 258 SmChiA-like proteins revealed that tryptophan, not phenylalanine, is the predominant amino acid at the corresponding positions (Phe-232 and Phe-396 for SmChiA). Our study will be helpful for understanding the kinetic mechanisms and further improvement of crystalline chitin hydrolytic activity of SmChiA mutants.
Collapse
Affiliation(s)
- Akasit Visootsat
- Department of Functional Molecular Science, School of Physical Sciences, Graduate University for Advanced Studies (SOKENDAI), Hayama, Kanagawa 240-0193, Japan; Institute for Molecular Science, National Institutes of Natural Sciences, Okazaki, Aichi 444-8787, Japan
| | - Akihiko Nakamura
- Department of Functional Molecular Science, School of Physical Sciences, Graduate University for Advanced Studies (SOKENDAI), Hayama, Kanagawa 240-0193, Japan; Institute for Molecular Science, National Institutes of Natural Sciences, Okazaki, Aichi 444-8787, Japan
| | - Paul Vignon
- Institute for Molecular Science, National Institutes of Natural Sciences, Okazaki, Aichi 444-8787, Japan; Chimie ParisTech, Paris 75231, France
| | - Hiroki Watanabe
- Department of Physics, Nagoya University, Nagoya, Aichi 464-8601, Japan; Exploratory Research Center on Life and Living Systems (ExCELLS), National Institute of Natural Science, Okazaki, Aichi 444-8787, Japan
| | - Takayuki Uchihashi
- Department of Physics, Nagoya University, Nagoya, Aichi 464-8601, Japan; Exploratory Research Center on Life and Living Systems (ExCELLS), National Institute of Natural Science, Okazaki, Aichi 444-8787, Japan
| | - Ryota Iino
- Department of Functional Molecular Science, School of Physical Sciences, Graduate University for Advanced Studies (SOKENDAI), Hayama, Kanagawa 240-0193, Japan; Institute for Molecular Science, National Institutes of Natural Sciences, Okazaki, Aichi 444-8787, Japan.
| |
Collapse
|
5
|
Abstract
Cellulase enzymes deconstruct recalcitrant cellulose into soluble sugars, making them a biocatalyst of biotechnological interest for use in the nascent lignocellulosic bioeconomy. Cellobiohydrolases (CBHs) are cellulases capable of liberating many sugar molecules in a processive manner without dissociating from the substrate. Within the complete processive cycle of CBHs, dissociation from the cellulose substrate is rate limiting, but the molecular mechanism of this step is unknown. Here, we present a direct comparison of potential molecular mechanisms for dissociation via Hamiltonian replica exchange molecular dynamics of the model fungal CBH, Trichoderma reesei Cel7A. Computational rate estimates indicate that stepwise cellulose dethreading from the binding tunnel is 4 orders of magnitude faster than a clamshell mechanism, in which the substrate-enclosing loops open and release the substrate without reversing. We also present the crystal structure of a disulfide variant that covalently links substrate-enclosing loops on either side of the substrate-binding tunnel, which constitutes a CBH that can only dissociate via stepwise dethreading. Biochemical measurements indicate that this variant has a dissociation rate constant essentially equivalent to the wild type, implying that dethreading is likely the predominant mechanism for dissociation.
Collapse
|
6
|
Kari J, Christensen SJ, Andersen M, Baiget SS, Borch K, Westh P. A practical approach to steady-state kinetic analysis of cellulases acting on their natural insoluble substrate. Anal Biochem 2019; 586:113411. [PMID: 31520594 DOI: 10.1016/j.ab.2019.113411] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2019] [Revised: 08/26/2019] [Accepted: 08/28/2019] [Indexed: 10/26/2022]
Abstract
Measurement of steady-state rates (vSS) is straightforward in standard enzymology with soluble substrate, and it has been instrumental for comparative biochemical analyses within this area. For insoluble substrate, however, experimental values of vss remain controversial, and this has strongly limited the amount and quality of comparative analyses for cellulases and other enzymes that act on the surface of an insoluble substrate. In the current work, we have measured progress curves over a wide range of conditions for two cellulases, TrCel6A and TrCel7A from Trichoderma reesei, acting on their natural, insoluble substrate, cellulose. Based on this, we consider practical compromises for the determination of experimental vSS values, and propose a basic protocol that provides representative reaction rates and is experimentally simple so that larger groups of enzymes and conditions can be readily assayed with standard laboratory equipment. We surmise that the suggested experimental approach can be useful in comparative biochemical studies of cellulases; an area that remains poorly developed.
Collapse
Affiliation(s)
- Jeppe Kari
- Department of Biotechnology and Biomedicine, Technical University of Denmark, Søltofts Plads, Building 224, DK-2800, Kgs. Lyngby, Denmark
| | - Stefan Jarl Christensen
- Department of Science and Environment, Roskilde University, Universitetsvej, Build. 28.C, DK-4000, Roskilde, Denmark
| | - Morten Andersen
- Department of Science and Environment, Roskilde University, Universitetsvej, Build. 28.C, DK-4000, Roskilde, Denmark
| | | | - Kim Borch
- Novozymes A/S, Krogshøjvej 36, DK-2880, Bagsværd, Denmark
| | - Peter Westh
- Department of Biotechnology and Biomedicine, Technical University of Denmark, Søltofts Plads, Building 224, DK-2800, Kgs. Lyngby, Denmark.
| |
Collapse
|
7
|
Li T, Liu N, Ou X, Zhao X, Qi F, Huang J, Liu D. Visualizing cellulase adsorption and quantitatively determining cellulose accessibility with an updated fungal cellulose-binding module-based fluorescent probe protein. BIOTECHNOLOGY FOR BIOFUELS 2018; 11:105. [PMID: 29657580 PMCID: PMC5890345 DOI: 10.1186/s13068-018-1105-0] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 01/17/2018] [Accepted: 04/02/2018] [Indexed: 06/08/2023]
Abstract
BACKGROUND Cellulose accessibility to cellulases (CAC) is a direct factor determining the enzymatic digestibility of lignocellulosic cellulose. Improving CAC by pretreatment is a prerequisite step for the efficient release of fermentable sugars from biomass cell wall. However, conventional methods to study the porosimetry of solid materials showed some limitations to be used for investigating CAC. In this work, an updated novel fusion protein comprising a fungal cellulose-binding module (CBM) from Cel7A cellobiohydrolase I (CBH I) of Trichoderma reesei QM6 and a di-green fluorescent protein (GFP2) was constructed for quantitative determination of CAC. RESULTS The obtained probe protein had similar molecular size (e.g., weight) with that of Cel7A and could give detectable signal for quantitative analysis. Several construction strategies were compared with regard to the site of His-tag and order of CBM and GFP2 modules in the protein sequence, in order to achieve good expression quantity and usability of the probe protein. His6-CBM-GFP2 has been identified as the best probe protein for investigating the effects of structural features of cellulosic substrates on cellulose accessibility. Substrate samples with different contents of xylan, lignin, and degree of substitution of cellulose -OH by formyl group were obtained, respectively, by mild H2SO4 pre-hydrolysis, NaClO2 selective delignification, and treatment of filter paper cellulose with concentrated formic acid. The determined CAC was in a wide range of 0.6-20.4 m2/g depending on the contents of hemicelluloses, lignin, and formyl group as well as cellulose degree of crystallization. CONCLUSIONS The obtained fusion probe protein could be used as a versatile tool to quantitatively investigate the impacts of biomass structural features on CAC and hydrolyzability of cellulose substrates, as well as nonproductive adsorption of cellulase enzymes on lignin.
Collapse
Affiliation(s)
- Tian Li
- Key Laboratory for Industrial Biocatalysis, Ministry of Education of China, Institute of Applied Chemistry, Department of Chemical Engineering, Tsinghua University, Beijing, 100084 China
| | - Nan Liu
- Key Laboratory for Industrial Biocatalysis, Ministry of Education of China, Institute of Applied Chemistry, Department of Chemical Engineering, Tsinghua University, Beijing, 100084 China
- Engineering Research Center of Industrial Microbiology of Ministry of Education, College of Life Sciences, Fujian Normal University, Fuzhou, 350117 Fujian China
| | - Xianjin Ou
- Institute of Biophysics, Chinese Academy of Sciences, Beijing, 100101 China
| | - Xuebing Zhao
- Key Laboratory for Industrial Biocatalysis, Ministry of Education of China, Institute of Applied Chemistry, Department of Chemical Engineering, Tsinghua University, Beijing, 100084 China
| | - Feng Qi
- Engineering Research Center of Industrial Microbiology of Ministry of Education, College of Life Sciences, Fujian Normal University, Fuzhou, 350117 Fujian China
| | - Jianzhong Huang
- Engineering Research Center of Industrial Microbiology of Ministry of Education, College of Life Sciences, Fujian Normal University, Fuzhou, 350117 Fujian China
| | - Dehua Liu
- Key Laboratory for Industrial Biocatalysis, Ministry of Education of China, Institute of Applied Chemistry, Department of Chemical Engineering, Tsinghua University, Beijing, 100084 China
| |
Collapse
|
8
|
Rydahl MG, Hansen AR, Kračun SK, Mravec J. Report on the Current Inventory of the Toolbox for Plant Cell Wall Analysis: Proteinaceous and Small Molecular Probes. FRONTIERS IN PLANT SCIENCE 2018; 9:581. [PMID: 29774041 PMCID: PMC5943554 DOI: 10.3389/fpls.2018.00581] [Citation(s) in RCA: 38] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/11/2018] [Accepted: 04/13/2018] [Indexed: 05/18/2023]
Abstract
Plant cell walls are highly complex structures composed of diverse classes of polysaccharides, proteoglycans, and polyphenolics, which have numerous roles throughout the life of a plant. Significant research efforts aim to understand the biology of this cellular organelle and to facilitate cell-wall-based industrial applications. To accomplish this, researchers need to be provided with a variety of sensitive and specific detection methods for separate cell wall components, and their various molecular characteristics in vitro as well as in situ. Cell wall component-directed molecular detection probes (in short: cell wall probes, CWPs) are an essential asset to the plant glycobiology toolbox. To date, a relatively large set of CWPs has been produced-mainly consisting of monoclonal antibodies, carbohydrate-binding modules, synthetic antibodies produced by phage display, and small molecular probes. In this review, we summarize the state-of-the-art knowledge about these CWPs; their classification and their advantages and disadvantages in different applications. In particular, we elaborate on the recent advances in non-conventional approaches to the generation of novel CWPs, and identify the remaining gaps in terms of target recognition. This report also highlights the addition of new "compartments" to the probing toolbox, which is filled with novel chemical biology tools, such as metabolic labeling reagents and oligosaccharide conjugates. In the end, we also forecast future developments in this dynamic field.
Collapse
Affiliation(s)
- Maja G. Rydahl
- Department of Plant and Environmental Sciences, University of Copenhagen, Frederiksberg, Denmark
| | - Aleksander R. Hansen
- Department of Plant and Environmental Sciences, University of Copenhagen, Frederiksberg, Denmark
| | - Stjepan K. Kračun
- Department of Plant and Environmental Sciences, University of Copenhagen, Frederiksberg, Denmark
- GlycoSpot IVS, Frederiksberg, Denmark
| | - Jozef Mravec
- Department of Plant and Environmental Sciences, University of Copenhagen, Frederiksberg, Denmark
- *Correspondence: Jozef Mravec
| |
Collapse
|
9
|
Devaux MF, Jamme F, André W, Bouchet B, Alvarado C, Durand S, Robert P, Saulnier L, Bonnin E, Guillon F. Synchrotron Time-Lapse Imaging of Lignocellulosic Biomass Hydrolysis: Tracking Enzyme Localization by Protein Autofluorescence and Biochemical Modification of Cell Walls by Microfluidic Infrared Microspectroscopy. FRONTIERS IN PLANT SCIENCE 2018. [PMID: 29515611 PMCID: PMC5826215 DOI: 10.3389/fpls.2018.00200] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/05/2023]
Abstract
Tracking enzyme localization and following the local biochemical modification of the substrate should help explain the recalcitrance of lignocellulosic plant cell walls to enzymatic degradation. Time-lapse studies using conventional imaging require enzyme labeling and following the biochemical modifications of biopolymers found in plant cell walls, which cannot be easily achieved. In the present work, synchrotron facilities have been used to image the enzymatic degradation of lignocellulosic biomass without labeling the enzyme or the cell walls. Multichannel autofluorescence imaging of the protein and phenolic compounds after excitation at 275 nm highlighted the presence or absence of enzymes on cell walls and made it possible to track them during the reaction. Image analysis was used to quantify the fluorescence intensity variations. Consistent variations in the enzyme concentration were found locally for cell cavities and their surrounding cell walls. Microfluidic FT-IR microspectroscopy allowed for time-lapse tracking of local changes in the polysaccharides in cell walls during degradation. Hemicellulose degradation was found to occur prior to cellulose degradation using a Celluclast® preparation. Combining the fluorescence and FT-IR information yielded the conclusion that enzymes did not bind to lignified cell walls, which were consequently not degraded. Fluorescence multiscale imaging and FT-IR microspectroscopy showed an unexpected variability both in the initial biochemical composition and the degradation pattern, highlighting micro-domains in the cell wall of a given cell. Fluorescence intensity quantification showed that the enzymes were not evenly distributed, and their amount increased progressively on degradable cell walls. During degradation, adjacent cells were separated and the cell wall fragmented until complete degradation.
Collapse
Affiliation(s)
- Marie-Françoise Devaux
- UR1268 Biopolymères Interactions et Assemblages, Institut National de la Recherche Agronomique Pays de la Loire, Nantes, France
- *Correspondence: Marie-Françoise Devaux
| | | | | | - Brigitte Bouchet
- UR1268 Biopolymères Interactions et Assemblages, Institut National de la Recherche Agronomique Pays de la Loire, Nantes, France
| | - Camille Alvarado
- UR1268 Biopolymères Interactions et Assemblages, Institut National de la Recherche Agronomique Pays de la Loire, Nantes, France
| | - Sylvie Durand
- UR1268 Biopolymères Interactions et Assemblages, Institut National de la Recherche Agronomique Pays de la Loire, Nantes, France
| | - Paul Robert
- UR1268 Biopolymères Interactions et Assemblages, Institut National de la Recherche Agronomique Pays de la Loire, Nantes, France
| | - Luc Saulnier
- UR1268 Biopolymères Interactions et Assemblages, Institut National de la Recherche Agronomique Pays de la Loire, Nantes, France
| | - Estelle Bonnin
- UR1268 Biopolymères Interactions et Assemblages, Institut National de la Recherche Agronomique Pays de la Loire, Nantes, France
| | - Fabienne Guillon
- UR1268 Biopolymères Interactions et Assemblages, Institut National de la Recherche Agronomique Pays de la Loire, Nantes, France
| |
Collapse
|
10
|
Leng T, Jakubek ZJ, Mazloumi M, Leung ACW, Johnston LJ. Ensemble and Single Particle Fluorescence Characterization of Dye-Labeled Cellulose Nanocrystals. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2017; 33:8002-8011. [PMID: 28718649 DOI: 10.1021/acs.langmuir.7b01717] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
Cellulose nanocrystals (CNCs) have been covalently labeled with both fluorescein and rhodamine and studied by a combination of UV-vis absorption spectroscopy and ensemble and single molecule fluorescence spectroscopy. For all samples, the fluorescence anisotropy and lifetimes were consistent with effects expected for covalently bound dye molecules. Low dye loading levels (∼0.1 dye/particle) were estimated for the fluorescein-labeled CNC which coupled with the strong pH dependence make this a less suitable fluorophore for most applications. Rhodamine-labeled CNCs were prepared from both sulfated and carboxylated CNCs and had loading levels that varied from 0.25 to ∼15 dye molecules/CNC. For the sulfated samples, the absorption due to (nonfluorescent) dimeric dye increased with dye loading; in contrast, the carboxylated sample, which had the highest rhodamine content, had a low dimer yield. Single particle fluorescence studies for two of the rhodamine-labeled CNCs demonstrated that individual particles are readily detected by their stepwise blinking/bleaching behavior and by polarization effects. Overall, the results indicate the importance of understanding the effects of loading on dye photophysics to select an optimal dye concentration to maximize sensitivity while minimizing the effect of the dye on the CNC behavior. The results also demonstrate that CNCs with relatively low dye loadings (e.g., ∼1 dye/particle) are readily detectable by fluorescence and should be adequate for use in fluorescence-based biological assays or to probe the distribution of CNCs in composite materials.
Collapse
Affiliation(s)
- Tianyang Leng
- Measurement Science and Standards, National Research Council Canada , 100 Sussex Drive, Ottawa, ON K1A 0R6, Canada
- Department of Chemistry, University of Ottawa , Ottawa, ON K1N 6N5, Canada
| | - Zygmunt J Jakubek
- Measurement Science and Standards, National Research Council Canada , 100 Sussex Drive, Ottawa, ON K1A 0R6, Canada
| | - Mahyar Mazloumi
- Measurement Science and Standards, National Research Council Canada , 100 Sussex Drive, Ottawa, ON K1A 0R6, Canada
| | - Alfred C W Leung
- Aquatic and Crop Resource Development, National Research Council Canada , Montreal, QC H4P 2R2, Canada
| | - Linda J Johnston
- Measurement Science and Standards, National Research Council Canada , 100 Sussex Drive, Ottawa, ON K1A 0R6, Canada
- Department of Chemistry, University of Ottawa , Ottawa, ON K1N 6N5, Canada
| |
Collapse
|
11
|
Ezeilo UR, Zakaria II, Huyop F, Wahab RA. Enzymatic breakdown of lignocellulosic biomass: the role of glycosyl hydrolases and lytic polysaccharide monooxygenases. BIOTECHNOL BIOTEC EQ 2017. [DOI: 10.1080/13102818.2017.1330124] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022] Open
|
12
|
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.
Collapse
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
| |
Collapse
|
13
|
Paës G, Habrant A, Ossemond J, Chabbert B. Exploring accessibility of pretreated poplar cell walls by measuring dynamics of fluorescent probes. BIOTECHNOLOGY FOR BIOFUELS 2017; 10:15. [PMID: 28101142 PMCID: PMC5237506 DOI: 10.1186/s13068-017-0704-5] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/05/2016] [Accepted: 01/06/2017] [Indexed: 05/09/2023]
Abstract
BACKGROUND The lignocellulosic cell wall network is resistant to enzymatic degradation due to the complex chemical and structural features. Pretreatments are thus commonly used to overcome natural recalcitrance of lignocellulose. Characterization of their impact on architecture requires combinatory approaches. However, the accessibility of the lignocellulosic cell walls still needs further insights to provide relevant information. RESULTS Poplar specimens were pretreated using different conditions. Chemical, spectral, microscopic and immunolabeling analysis revealed that poplar cell walls were more altered by sodium chlorite-acetic acid and hydrothermal pretreatments but weakly modified by soaking in aqueous ammonium. In order to evaluate the accessibility of the pretreated poplar samples, two fluorescent probes (rhodamine B-isothiocyanate-dextrans of 20 and 70 kDa) were selected, and their mobility was measured by using the fluorescence recovery after photobleaching (FRAP) technique in a full factorial experiment. The mobility of the probes was dependent on the pretreatment type, the cell wall localization (secondary cell wall and cell corner middle lamella) and the probe size. Overall, combinatory analysis of pretreated poplar samples showed that even the partial removal of hemicellulose contributed to facilitate the accessibility to the fluorescent probes. On the contrary, nearly complete removal of lignin was detrimental to accessibility due to the possible cellulose-hemicellulose collapse. CONCLUSIONS Evaluation of plant cell wall accessibility through FRAP measurement brings further insights into the impact of physicochemical pretreatments on lignocellulosic samples in combination with chemical and histochemical analysis. This technique thus represents a relevant approach to better understand the effect of pretreatments on lignocellulose architecture, while considering different limitations as non-specific interactions and enzyme efficiency.
Collapse
Affiliation(s)
- Gabriel Paës
- FARE laboratory, INRA, Université de Reims Champagne-Ardenne, 51100 Reims, France
| | - Anouck Habrant
- FARE laboratory, INRA, Université de Reims Champagne-Ardenne, 51100 Reims, France
| | - Jordane Ossemond
- FARE laboratory, INRA, Université de Reims Champagne-Ardenne, 51100 Reims, France
| | - Brigitte Chabbert
- FARE laboratory, INRA, Université de Reims Champagne-Ardenne, 51100 Reims, France
| |
Collapse
|
14
|
Kont R, Kari J, Borch K, Westh P, Väljamäe P. Inter-domain Synergism Is Required for Efficient Feeding of Cellulose Chain into Active Site of Cellobiohydrolase Cel7A. J Biol Chem 2016; 291:26013-26023. [PMID: 27780868 DOI: 10.1074/jbc.m116.756007] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2016] [Revised: 10/21/2016] [Indexed: 01/27/2023] Open
Abstract
Structural polysaccharides like cellulose and chitin are abundant and their enzymatic degradation to soluble sugars is an important route in green chemistry. Processive glycoside hydrolases (GHs), like cellobiohydrolase Cel7A of Trichoderma reesei (TrCel7A) are key components of efficient enzyme systems. TrCel7A consists of a catalytic domain (CD) and a smaller carbohydrate-binding module (CBM) connected through the glycosylated linker peptide. A tunnel-shaped active site rests in the CD and contains 10 glucose unit binding sites. The active site of TrCel7A is lined with four Trp residues with two of them, Trp-40 and Trp-38, in the substrate binding sites near the tunnel entrance. Although addressed in numerous studies the elucidation of the role of CBM and active site aromatics has been obscured by a complex multistep mechanism of processive GHs. Here we studied the role of the CBM-linker and Trp-38 of TrCel7A with respect to binding affinity, on- and off-rates, processivity, and synergism with endoglucanase. The CBM-linker increased the on-rate and substrate affinity of the enzyme. The Trp-38 to Ala substitution resulted in increased off-rates and decreased processivity. The effect of the Trp-38 to Ala substitution on on-rates was strongly dependent on the presence of the CBM-linker. This compensation between CBM-linker and Trp-38 indicates synergism between CBM-linker and CD in feeding the cellulose chain into the active site. The inter-domain synergism was pre-requisite for the efficient degradation of cellulose in the presence of endoglucanase.
Collapse
Affiliation(s)
- Riin Kont
- From the Institute of Molecular and Cell Biology, University of Tartu, 51010 Tartu, Estonia
| | - Jeppe Kari
- the Department of Science and Environment, Roskilde University, DK-4000 Roskilde, Denmark, and
| | - Kim Borch
- Novozymes A/S, Bagsværd DK-2880, Denmark
| | - Peter Westh
- the Department of Science and Environment, Roskilde University, DK-4000 Roskilde, Denmark, and
| | - Priit Väljamäe
- From the Institute of Molecular and Cell Biology, University of Tartu, 51010 Tartu, Estonia,
| |
Collapse
|
15
|
Mechanisms employed by cellulase systems to gain access through the complex architecture of lignocellulosic substrates. Curr Opin Chem Biol 2015; 29:100-7. [DOI: 10.1016/j.cbpa.2015.08.014] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2015] [Revised: 08/19/2015] [Accepted: 08/20/2015] [Indexed: 01/27/2023]
|
16
|
Kurašin M, Kuusk S, Kuusk P, Sørlie M, Väljamäe P. Slow Off-rates and Strong Product Binding Are Required for Processivity and Efficient Degradation of Recalcitrant Chitin by Family 18 Chitinases. J Biol Chem 2015; 290:29074-85. [PMID: 26468285 DOI: 10.1074/jbc.m115.684977] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2015] [Indexed: 12/18/2022] Open
Abstract
Processive glycoside hydrolases are the key components of enzymatic machineries that decompose recalcitrant polysaccharides, such as chitin and cellulose. The intrinsic processivity (P(Intr)) of cellulases has been shown to be governed by the rate constant of dissociation from polymer chain (koff). However, the reported koff values of cellulases are strongly dependent on the method used for their measurement. Here, we developed a new method for determining koff, based on measuring the exchange rate of the enzyme between a non-labeled and a (14)C-labeled polymeric substrate. The method was applied to the study of the processive chitinase ChiA from Serratia marcescens. In parallel, ChiA variants with weaker binding of the N-acetylglucosamine unit either in substrate-binding site -3 (ChiA-W167A) or the product-binding site +1 (ChiA-W275A) were studied. Both ChiA variants showed increased off-rates and lower apparent processivity on α-chitin. The rate of the production of insoluble reducing groups on the reduced α-chitin was an order of magnitude higher than koff, suggesting that the enzyme can initiate several processive runs without leaving the substrate. On crystalline chitin, the general activity of the wild type enzyme was higher, and the difference was magnifying with hydrolysis time. On amorphous chitin, the variants clearly outperformed the wild type. A model is proposed whereby strong interactions with polymer in the substrate-binding sites (low off-rates) and strong binding of the product in the product-binding sites (high pushing potential) are required for the removal of obstacles, like disintegration of chitin microfibrils.
Collapse
Affiliation(s)
| | - Silja Kuusk
- From the Institutes of Molecular and Cell Biology and
| | - Piret Kuusk
- Physics, University of Tartu, 51010 Tartu, Estonia and
| | - Morten Sørlie
- the Department of Chemistry, Biotechnology and Food Science, Norwegian University of Life Sciences, Ås 1432, Norway
| | | |
Collapse
|
17
|
Payne CM, Knott BC, Mayes HB, Hansson H, Himmel ME, Sandgren M, Ståhlberg J, Beckham GT. Fungal Cellulases. Chem Rev 2015; 115:1308-448. [DOI: 10.1021/cr500351c] [Citation(s) in RCA: 533] [Impact Index Per Article: 59.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Affiliation(s)
- Christina M. Payne
- Department
of Chemical and Materials Engineering and Center for Computational
Sciences, University of Kentucky, 177 F. Paul Anderson Tower, Lexington, Kentucky 40506, United States
| | - Brandon C. Knott
- National
Bioenergy Center, National Renewable Energy Laboratory, 15013 Denver
West Parkway, Golden, Colorado 80401, United States
| | - Heather B. Mayes
- Department
of Chemical and Biological Engineering, Northwestern University, 2145 Sheridan Road, Evanston, Illinois 60208, United States
| | - Henrik Hansson
- Department
of Chemistry and Biotechnology, Swedish University of Agricultural Sciences, Uppsala BioCenter, Almas allé 5, SE-75651 Uppsala, Sweden
| | - Michael E. Himmel
- Biosciences
Center, National Renewable Energy Laboratory, 15013 Denver West Parkway, Golden, Colorado 80401, United States
| | - Mats Sandgren
- Department
of Chemistry and Biotechnology, Swedish University of Agricultural Sciences, Uppsala BioCenter, Almas allé 5, SE-75651 Uppsala, Sweden
| | - Jerry Ståhlberg
- Department
of Chemistry and Biotechnology, Swedish University of Agricultural Sciences, Uppsala BioCenter, Almas allé 5, SE-75651 Uppsala, Sweden
| | - Gregg T. Beckham
- National
Bioenergy Center, National Renewable Energy Laboratory, 15013 Denver
West Parkway, Golden, Colorado 80401, United States
| |
Collapse
|
18
|
Yang D, Parlange JY, Walker LP. Cellulases Significantly Alter the Nano-Scale Reaction Space for Pretreated Lignocellulosic Biomass. Ind Biotechnol (New Rochelle N Y) 2014. [DOI: 10.1089/ind.2014.0028] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Affiliation(s)
- Dong Yang
- Department of Biological and Environmental Engineering, Cornell University, Ithaca, NY
| | - Jean-Yves Parlange
- Department of Biological and Environmental Engineering, Cornell University, Ithaca, NY
| | - Larry P. Walker
- Department of Biological and Environmental Engineering, Cornell University, Ithaca, NY
| |
Collapse
|
19
|
Malinowska KH, Verdorfer T, Meinhold A, Milles LF, Funk V, Gaub HE, Nash MA. Redox-initiated hydrogel system for detection and real-time imaging of cellulolytic enzyme activity. CHEMSUSCHEM 2014; 7:2825-2831. [PMID: 25116339 DOI: 10.1002/cssc.201402428] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/16/2014] [Revised: 06/12/2014] [Indexed: 06/03/2023]
Abstract
Understanding the process of biomass degradation by cellulolytic enzymes is of urgent importance for biofuel and chemical production. Optimizing pretreatment conditions and improving enzyme formulations both require assays to quantify saccharification products on solid substrates. Typically, such assays are performed using freely diffusing fluorophores or dyes that measure reducing polysaccharide chain ends. These methods have thus far not allowed spatial localization of hydrolysis activity to specific substrate locations with identifiable morphological features. Here we describe a hydrogel reagent signaling (HyReS) system that amplifies saccharification products and initiates crosslinking of a hydrogel that localizes to locations of cellulose hydrolysis, allowing for imaging of the degradation process in real time. Optical detection of the gel in a rapid parallel format on synthetic and natural pretreated solid substrates was used to quantify activity of T. emersonii and T. reesei enzyme cocktails. When combined with total internal reflection fluorescence microscopy and AFM imaging, the reagent system provided a means to visualize enzyme activity in real-time with high spatial resolution (<2 μm). These results demonstrate the versatility of the HyReS system in detecting cellulolytic enzyme activity and suggest new opportunities in real-time chemical imaging of biomass depolymerization.
Collapse
Affiliation(s)
- Klara H Malinowska
- Lehrstuhl für Angewandte Physik and Center for Nanoscience, Ludwig-Maximilians-Universität, Amalienstrasse 54, 80799 Munich (Germany)
| | | | | | | | | | | | | |
Collapse
|
20
|
|
21
|
Bornscheuer U, Buchholz K, Seibel J. Enzymatic degradation of (ligno)cellulose. Angew Chem Int Ed Engl 2014; 53:10876-93. [PMID: 25136976 DOI: 10.1002/anie.201309953] [Citation(s) in RCA: 65] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2013] [Indexed: 11/06/2022]
Abstract
Glycoside-degrading enzymes play a dominant role in the biochemical conversion of cellulosic biomass into low-price biofuels and high-value-added chemicals. New insight into protein functions and substrate structures, the kinetics of recognition, and degradation events has resulted in a substantial improvement of our understanding of cellulose degradation.
Collapse
Affiliation(s)
- Uwe Bornscheuer
- Ernst-Moritz-Arndt-Universität Greifswald, Biotechnologie und Enzymkatalyse, Institut für Biochemie, Felix-Hausdorff-Strasse 4, 17487 Greifswald (Germany)
| | | | | |
Collapse
|
22
|
Paës G. Fluorescent probes for exploring plant cell wall deconstruction: a review. Molecules 2014; 19:9380-402. [PMID: 24995923 PMCID: PMC6271034 DOI: 10.3390/molecules19079380] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2014] [Revised: 06/27/2014] [Accepted: 06/27/2014] [Indexed: 11/16/2022] Open
Abstract
Plant biomass is a potential resource of chemicals, new materials and biofuels that could reduce our dependency on fossil carbon, thus decreasing the greenhouse effect. However, due to its chemical and structural complexity, plant biomass is recalcitrant to green biological transformation by enzymes, preventing the establishment of integrated bio-refineries. In order to gain more knowledge in the architecture of plant cell wall to facilitate their deconstruction, many fluorescent probes bearing various fluorophores have been devised and used successfully to reveal the changes in structural motifs during plant biomass deconstruction, and the molecular interactions between enzymes and plant cell wall polymers. Fluorescent probes are thus relevant tools to explore plant cell wall deconstruction.
Collapse
Affiliation(s)
- Gabriel Paës
- INRA (French National Institute for Agricultural Research), UMR0614 Fractionation of AgroResources and Environment, 2 esplanade Roland-Garros, 51100 Reims, France.
| |
Collapse
|
23
|
Goacher RE, Selig MJ, Master ER. Advancing lignocellulose bioconversion through direct assessment of enzyme action on insoluble substrates. Curr Opin Biotechnol 2014; 27:123-33. [PMID: 24525082 DOI: 10.1016/j.copbio.2014.01.009] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2013] [Revised: 01/16/2014] [Accepted: 01/17/2014] [Indexed: 11/26/2022]
Abstract
Microbial utilization of lignocellulose from plant cell walls is integral to carbon cycling on Earth. Correspondingly, secreted enzymes that initiate lignocellulose depolymerization serve a crucial step in the bioconversion of lignocellulosic biomass to fuels and chemicals. Genome and metagenome sequencing efforts that span the past decade reveal the diversity of enzymes that have evolved to transform lignocellulose from wood, herbaceous plants and grasses. Nevertheless, there are relatively few examples where 'omic' technologies have identified novel enzyme activities or combinations thereof that dramatically improve the economics of lignocellulose bioprocessing and utilization. A likely factor contributing to the discrepancy between sequence-based enzyme discovery and enzyme application is the common practice to screen enzyme candidates based on activity measurements using soluble model compounds. In this context, the development and application of imaging, physicochemical, and spectromicroscopic techniques that allow direct assessment of enzyme action on relevant lignocellulosic substrates is reviewed.
Collapse
Affiliation(s)
- Robyn E Goacher
- Department of Biochemistry, Chemistry and Physics, Niagara University, NY, USA
| | - Michael J Selig
- Department of Geoscience and Natural Resource Management, Faculty of Science, University of Copenhagen, Frederiksberg, Denmark; Department of Chemical Engineering and Applied Chemistry, University of Toronto, Toronto, Ontario, Canada
| | - Emma R Master
- Department of Chemical Engineering and Applied Chemistry, University of Toronto, Toronto, Ontario, Canada.
| |
Collapse
|
24
|
Eibinger M, Bubner P, Ganner T, Plank H, Nidetzky B. Surface structural dynamics of enzymatic cellulose degradation, revealed by combined kinetic and atomic force microscopy studies. FEBS J 2013; 281:275-90. [DOI: 10.1111/febs.12594] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2013] [Revised: 10/18/2013] [Accepted: 10/21/2013] [Indexed: 02/01/2023]
Affiliation(s)
- Manuel Eibinger
- Institute of Biotechnology and Biochemical Engineering; Graz University of Technology; Austria
| | - Patricia Bubner
- Institute of Biotechnology and Biochemical Engineering; Graz University of Technology; Austria
| | - Thomas Ganner
- Institute for Electron Microscopy and Fine Structure Research; Graz University of Technology; Austria
- Center for Electron Microscopy; Graz University of Technology; Austria
| | - Harald Plank
- Institute for Electron Microscopy and Fine Structure Research; Graz University of Technology; Austria
- Center for Electron Microscopy; Graz University of Technology; Austria
| | - Bernd Nidetzky
- Institute of Biotechnology and Biochemical Engineering; Graz University of Technology; Austria
| |
Collapse
|
25
|
Donaldson LA, Newman RH, Vaidya A. Nanoscale interactions of polyethylene glycol with thermo-mechanically pre-treatedPinus radiatabiofuel substrate. Biotechnol Bioeng 2013; 111:719-25. [DOI: 10.1002/bit.25138] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2013] [Revised: 10/10/2013] [Accepted: 10/21/2013] [Indexed: 11/11/2022]
Affiliation(s)
- Lloyd A. Donaldson
- Scion; Te Papa Tipu Innovation Park; 49 Sala Street Rotorua 3046 New Zealand
| | - Roger H. Newman
- Scion; Te Papa Tipu Innovation Park; 49 Sala Street Rotorua 3046 New Zealand
| | - Alankar Vaidya
- Scion; Te Papa Tipu Innovation Park; 49 Sala Street Rotorua 3046 New Zealand
| |
Collapse
|
26
|
Abitbol T, Palermo A, Moran-Mirabal JM, Cranston ED. Fluorescent labeling and characterization of cellulose nanocrystals with varying charge contents. Biomacromolecules 2013; 14:3278-84. [PMID: 23952644 DOI: 10.1021/bm400879x] [Citation(s) in RCA: 96] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
Cotton-source cellulose nanocrystals (CNCs) with a range of surface charge densities were fluorescently labeled with 5-(4, 6-dichlorotriazinyl) aminofluorescein (DTAF) in a facile, one-pot reaction under alkaline conditions. Three CNC samples were labeled: (I) anionic CNCs prepared by sulfuric acid hydrolysis with a sulfur content of 0.47 wt %, (II) a partially desulfated, sulfuric acid-hydrolyzed CNC sample, which was less anionic with an intermediate sulfur content of 0.21 wt %, and (III) uncharged CNCs prepared by HCl hydrolysis. The DTAF-labeled CNCs were characterized by dynamic light scattering, atomic force microscopy, fluorescence spectroscopy and microscopy, and polarized light microscopy. Fluorescent CNCs exhibited similar colloidal stability to the starting CNCs, with the exception of the HCl-hydrolyzed sample, which became less agglomerated after the labeling reaction. The degree of labeling depended on the sulfur content of the CNCs, indicating that the presence of sulfate half-ester groups on the CNC surfaces hindered labeling. The labeling reaction produced CNCs that had detectable fluorescence, without compromising the overall surface chemistry or behavior of the materials, an aspect relevant to studies that require a fluorescent cellulose substrate with intact native properties. The DTAF-labeled CNCs were proposed as optical markers for the dispersion quality of CNC-loaded polymer composites. Electrospun polyvinyl alcohol fibers loaded with DTAF-labeled CNCs appeared uniformly fluorescent by fluorescence microscopy, suggesting that the nanoparticles were well dispersed within the polymer matrix.
Collapse
Affiliation(s)
- Tiffany Abitbol
- Departments of Chemical Engineering, McMaster University, 1280 Main Street West, Hamilton, Ontario, Canada.
| | | | | | | |
Collapse
|
27
|
Yang D, Moran-Mirabal JM, Parlange JY, Walker LP. Investigation of the porous structure of cellulosic substrates through confocal laser scanning microscopy. Biotechnol Bioeng 2013; 110:2836-45. [PMID: 23737240 DOI: 10.1002/bit.24958] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2013] [Revised: 04/30/2013] [Accepted: 05/06/2013] [Indexed: 11/06/2022]
Abstract
At the most fundamental level, saccharification occurs when cell wall degrading enzymes (CWDEs) diffuse, bind to and react on readily accessible cellulose fibrils. Thus, the study of the diffusive behavior of solutes into and out of cellulosic substrates is important for understanding how biomass pore size distribution affects enzyme transport, binding, and catalysis. In this study, fluorescently labeled dextrans with molecular weights of 20, 70, and 150 kDa were used as probes to assess their diffusion into the porous structure of filter paper. Fluorescence microscopy with high numerical aperture objectives was used to generate high temporal and spatial resolution datasets of probe concentrations versus time. In addition, two diffusion models, including a simple transient diffusion and a pore grouping diffusion models, were developed. These models and the experimental datasets were used to investigate solute diffusion in macro- and micro-pores. Nonlinear least squares fitting of the datasets to the simple transient model yielded diffusion coefficient estimates that were inadequate for describing the initial fast diffusion and the later slow diffusion rates observed; on the other hand, nonlinear least squares fitting of the datasets to the pore grouping diffusion model yielded estimations of the micro-pore diffusion coefficient that described the inherently porous structure of plant-derived cellulose. In addition, modeling results show that on average 75% of the accessible pore volume is available for fast diffusion without any significant pore hindrance. The method developed can be applied to study the porous structure of plant-derived biomass and help assess the diffusion process for enzymes with known sizes.
Collapse
Affiliation(s)
- Dong Yang
- Department of Biological and Environmental Engineering, Cornell University, Ithaca, New York, 14853
| | | | | | | |
Collapse
|
28
|
Bubner P, Plank H, Nidetzky B. Visualizing cellulase activity. Biotechnol Bioeng 2013; 110:1529-49. [DOI: 10.1002/bit.24884] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2012] [Revised: 01/08/2013] [Accepted: 02/22/2013] [Indexed: 11/08/2022]
|