Toward an understanding of the increase in enzymatic hydrolysis by mechanical refining.

Autor: de Assis T; 1Department of Forest Biomaterials, College of Natural Reseources, NC State University, Raleigh, NC USA., Huang S; 2Department of Chemical Engineering, Pennsylvania State University, University Park, PA USA., Driemeier CE; 3Brazilian Bioethanol Science and Technology Laboratory (CTBE), Brazilian Center for Research in Energy and Materials (CNPEM), Campinas, SP Brazil., Donohoe BS; 4Biosciences Center, National Renewable Energy Laboratory, Golden, CO USA., Kim C; 1Department of Forest Biomaterials, College of Natural Reseources, NC State University, Raleigh, NC USA., Kim SH; 2Department of Chemical Engineering, Pennsylvania State University, University Park, PA USA., Gonzalez R; 1Department of Forest Biomaterials, College of Natural Reseources, NC State University, Raleigh, NC USA., Jameel H; 1Department of Forest Biomaterials, College of Natural Reseources, NC State University, Raleigh, NC USA., Park S; 1Department of Forest Biomaterials, College of Natural Reseources, NC State University, Raleigh, NC USA.
Jazyk: angličtina
Zdroj: Biotechnology for biofuels [Biotechnol Biofuels] 2018 Oct 25; Vol. 11, pp. 289. Date of Electronic Publication: 2018 Oct 25 (Print Publication: 2018).
DOI: 10.1186/s13068-018-1289-3
Abstrakt: Background: Mechanical refining is a low-capital and well-established technology used in pulp and paper industry to improve fiber bonding for product strength. Refining can also be applied in a biorefinery context to overcome the recalcitrance of pretreated biomass by opening up the biomass structure and modifying substrate properties (e.g., morphology, particle size, porosity, crystallinity), which increases enzyme accessibility to substrate and improves carbohydrate conversion. Although several characterization methods have been used to identify the changes in substrate properties, there is no systematic approach to evaluate the extent of fiber cell wall disruption and what physical properties can explain the improvement in enzymatic digestibility when pretreated lignocellulosic biomass is mechanically refined. This is because the fiber cell wall is complex across multiple scales, including the molecular scale, nano- and meso-scale (microfibril), and microscale (tissue level). A combination of advanced characterization tools is used in this study to better understand the effect of mechanical refining on the meso-scale microfibril assembly and the relationship between those meso-scale modifications and enzymatic hydrolysis.
Results: Enzymatic conversion of autohydrolysis sugarcane bagasse was improved from 69.6 to 77.2% (11% relative increase) after applying mechanical refining and an increase in enzymatic digestibility is observed with an increase in refining intensity. Based on a combination of advanced characterizations employed in this study, it was found that the refining action caused fiber size reduction, internal delamination, and increase in pores and swellability.
Conclusions: A higher level of delamination and higher increase in porosity, analyzed by TEM and DSC, were clearly demonstrated, which explain the faster digestibility rate during the first 72 h of enzymatic hydrolysis for disc-refined samples when compared to the PFI-refined samples. In addition, an increased inter-fibrillar distance between cellulose microfibrils at the nano-meso-scale was also revealed by SFG analysis, while no evidence was found for a change in crystalline structure by XRD and solid-state NMR analysis.
Databáze: MEDLINE
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