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(Reference retrieved automatically from Web of Science through information on FAPESP grant and its corresponding number as mentioned in the publication by the authors.)

Nuclear magnetic resonance investigation of water accessibility in cellulose of pretreated sugarcane bagasse

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Tsuchida, Jefferson Esquina [1] ; Rezende, Camila Alves [1] ; de Oliveira-Silva, Rodrigo [1] ; Lima, Marisa Aparecida [1] ; d'Eurydice, Marcel Nogueira [1] ; Polikarpov, Igor [1] ; Bonagamba, Tito Jose [1]
Total Authors: 7
[1] Univ Sao Paulo, Inst Fis Sao Carlos, BR-13560970 Sao Carlos, SP - Brazil
Total Affiliations: 1
Document type: Journal article
Web of Science Citations: 23

Background: Enzymatic hydrolysis is a crucial step of biomass conversion into biofuels and different pretreatments have been proposed to improve the process efficiency. Amongst the various factors affecting hydrolysis yields of biomass samples, porosity and water accessibility stand out due to their intimate relation with enzymes accessibility to the cellulose and hemicellulose fractions of the biomass. In this work, sugarcane bagasse was subjected to acid and alkali pretreatments. The changes in the total surface area, hydrophilicity, porosity and water accessibility of cellulose were investigated by scanning electron microscopy (SEM) and nuclear magnetic resonance (NMR). Results: Changes in chemical and physical properties of the samples, caused by the partial removal of hemicellulose and lignin, led to the increase in porosity of the cell walls and unwinding of the cellulose bundles, as observed by SEM. H-1 NMR relaxation data revealed the existence of water molecules occupying the cores of wide and narrow vessels as well as the cell wall internal structure. Upon drying, the water molecules associated with the structure of the cell wall did not undergo significant dynamical and partial moisture changes, while those located in the cores of wide and narrow vessels kept continuously evaporating until reaching approximately 20% of relative humidity. This indicates that water is first removed from the cores of lumens and, in the dry sample, the only remaining water molecules are those bound to the cell walls. The stronger interaction of water with pretreated bagasse is consistent with better enzymes accessibility to cellulose and higher efficiency of the enzymatic hydrolysis. Conclusions: We were able to identify that sugarcane bagasse modification under acid and basic pretreatments change the water accessibility to different sites of the sample, associated with both bagasse structure (lumens and cell walls) and hydrophilicity (lignin removal). Furthermore, we show that the substrates with increased water accessibility correspond to those with higher hydrolysis yields and that there is a correlation between experimentally NMR-measured transverse relaxation times and the efficiency of enzymatic hydrolysis. This might allow for semiquantitative estimates of the enzymatic hydrolysis efficiency of biomass samples using inexpensive and non-destructive low-field H-1 NMR relaxometry methods. (AU)

FAPESP's process: 12/22119-7 - Study of the decomposition mechanisms of the plant cell wall
Grantee:Camila Alves de Rezende
Support type: Regular Research Grants
FAPESP's process: 09/18354-8 - Dynamics and structure of polymer systems as studied by nuclear magnetic resonance
Grantee:Eduardo Ribeiro de Azevedo
Support type: Regular Research Grants
FAPESP's process: 10/08370-3 - Biophysical and biochemical studies of exoglucanases from Trichoderma harzianum involved in the biodegradation of cellulose
Grantee:Wanius José Garcia da Silva
Support type: Regular Research Grants
FAPESP's process: 10/11135-6 - Structural and morphological aspects of the cell-wall degradation and its biopolymers
Grantee:Camila Alves de Rezende
Support type: Scholarships in Brazil - Post-Doctorate
FAPESP's process: 09/54880-6 - Manipulation of nuclear spins by magnetic and quadrupole resonance techniques
Grantee:Tito José Bonagamba
Support type: Regular Research Grants
FAPESP's process: 08/56255-9 - Structure and function of enzymes and auxiliary proteins from Trichoderma, active in cell-wall hydrolysis
Grantee:Igor Polikarpov
Support type: Program for Research on Bioenergy (BIOEN) - Thematic Grants