Mapping out the structural changes of natural and pretreated plant cell wall surfaces by atomic force microscopy single molecular recognition imaging

BACKGROUND: Enzymatic hydrolysis of lignocellulosic biomass (mainly plant cell walls) is a critical process for biofuel production. This process is greatly hindered by the natural complexity of plant cell walls and limited accessibility of surface cellulose by enzymes. Little is known about the plan...

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Autores principales: Zhang, Mengmeng, Chen, Guojun, Kumar, Rajeev, Xu, Bingqian
Formato: Online Artículo Texto
Lenguaje:English
Publicado: BioMed Central 2013
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3852143/
https://www.ncbi.nlm.nih.gov/pubmed/24119447
http://dx.doi.org/10.1186/1754-6834-6-147
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author Zhang, Mengmeng
Chen, Guojun
Kumar, Rajeev
Xu, Bingqian
author_facet Zhang, Mengmeng
Chen, Guojun
Kumar, Rajeev
Xu, Bingqian
author_sort Zhang, Mengmeng
collection PubMed
description BACKGROUND: Enzymatic hydrolysis of lignocellulosic biomass (mainly plant cell walls) is a critical process for biofuel production. This process is greatly hindered by the natural complexity of plant cell walls and limited accessibility of surface cellulose by enzymes. Little is known about the plant cell wall structural and molecular level component changes after pretreatments, especially on the outer surface. Therefore, a more profound understanding of surface cellulose distributions before and after pretreatments at single-molecule level is in great need. In this study, we determined the structural changes, specifically on crystalline cellulose, of natural, dilute sulfuric acid pretreated and delignified cell wall surfaces of poplar, switchgrass, and corn stover using single molecular atomic force microscopy (AFM) recognition imaging. RESULTS: The AFM tip was first functionalized by a family 3 carbohydrate-binding module (CBM3a) (Clostridium thermocellum Scaffoldin) which specifically recognizes crystalline cellulose by selectively binding to it. The surface structural changes were studied at single molecule level based on the recognition area percentage (RAP) of exposed crystalline cellulose over the imaged cell wall surface. Our results show that the cell wall surface crystalline cellulose coverage increased from 17-20% to 18-40% after dilute acid pretreatment at 135°C under different acid concentrations and reached to 40-70% after delignification. Pretreated with 0.5% sulfuric acid, the crystalline cellulose surface distributions of 23% on poplar, 28% on switchgrass and, 38% on corn stover were determined as an optimized result. Corn stover cell walls also show less recalcitrance due to more effective pretreatments and delignification compared to poplar and switchgrass. CONCLUSIONS: The dilute acid pretreatment can effectively increase the cellulose accessibility on plant cell wall surfaces. The optimal acid concentration was determined to be 0.5% acid at 135°C, especially for corn stover. This study provides a better understanding of surface structural changes after pretreatment such as lignin relocation, re-precipitation, and crystalline cellulose distribution, and can lead to potential improvements of biomass pretreatment.
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spelling pubmed-38521432013-12-06 Mapping out the structural changes of natural and pretreated plant cell wall surfaces by atomic force microscopy single molecular recognition imaging Zhang, Mengmeng Chen, Guojun Kumar, Rajeev Xu, Bingqian Biotechnol Biofuels Research BACKGROUND: Enzymatic hydrolysis of lignocellulosic biomass (mainly plant cell walls) is a critical process for biofuel production. This process is greatly hindered by the natural complexity of plant cell walls and limited accessibility of surface cellulose by enzymes. Little is known about the plant cell wall structural and molecular level component changes after pretreatments, especially on the outer surface. Therefore, a more profound understanding of surface cellulose distributions before and after pretreatments at single-molecule level is in great need. In this study, we determined the structural changes, specifically on crystalline cellulose, of natural, dilute sulfuric acid pretreated and delignified cell wall surfaces of poplar, switchgrass, and corn stover using single molecular atomic force microscopy (AFM) recognition imaging. RESULTS: The AFM tip was first functionalized by a family 3 carbohydrate-binding module (CBM3a) (Clostridium thermocellum Scaffoldin) which specifically recognizes crystalline cellulose by selectively binding to it. The surface structural changes were studied at single molecule level based on the recognition area percentage (RAP) of exposed crystalline cellulose over the imaged cell wall surface. Our results show that the cell wall surface crystalline cellulose coverage increased from 17-20% to 18-40% after dilute acid pretreatment at 135°C under different acid concentrations and reached to 40-70% after delignification. Pretreated with 0.5% sulfuric acid, the crystalline cellulose surface distributions of 23% on poplar, 28% on switchgrass and, 38% on corn stover were determined as an optimized result. Corn stover cell walls also show less recalcitrance due to more effective pretreatments and delignification compared to poplar and switchgrass. CONCLUSIONS: The dilute acid pretreatment can effectively increase the cellulose accessibility on plant cell wall surfaces. The optimal acid concentration was determined to be 0.5% acid at 135°C, especially for corn stover. This study provides a better understanding of surface structural changes after pretreatment such as lignin relocation, re-precipitation, and crystalline cellulose distribution, and can lead to potential improvements of biomass pretreatment. BioMed Central 2013-10-11 /pmc/articles/PMC3852143/ /pubmed/24119447 http://dx.doi.org/10.1186/1754-6834-6-147 Text en Copyright © 2013 Zhang et al.; licensee BioMed Central Ltd. http://creativecommons.org/licenses/by/2.0 This is an open access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/2.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
spellingShingle Research
Zhang, Mengmeng
Chen, Guojun
Kumar, Rajeev
Xu, Bingqian
Mapping out the structural changes of natural and pretreated plant cell wall surfaces by atomic force microscopy single molecular recognition imaging
title Mapping out the structural changes of natural and pretreated plant cell wall surfaces by atomic force microscopy single molecular recognition imaging
title_full Mapping out the structural changes of natural and pretreated plant cell wall surfaces by atomic force microscopy single molecular recognition imaging
title_fullStr Mapping out the structural changes of natural and pretreated plant cell wall surfaces by atomic force microscopy single molecular recognition imaging
title_full_unstemmed Mapping out the structural changes of natural and pretreated plant cell wall surfaces by atomic force microscopy single molecular recognition imaging
title_short Mapping out the structural changes of natural and pretreated plant cell wall surfaces by atomic force microscopy single molecular recognition imaging
title_sort mapping out the structural changes of natural and pretreated plant cell wall surfaces by atomic force microscopy single molecular recognition imaging
topic Research
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3852143/
https://www.ncbi.nlm.nih.gov/pubmed/24119447
http://dx.doi.org/10.1186/1754-6834-6-147
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