Endoglucanase effects on energy consumption in the mechanical fibrillation of cellulose fibers into nanocelluloses

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A1 Alkuperäisartikkeli tieteellisessä aikakauslehdessä
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Date
2023-07-15
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en
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International Journal of Biological Macromolecules, Volume 243
Abstract
Enzymatic processing is considered a promising approach for advancing environmentally friendly industrial processes, such as the use of endoglucanase (EG) enzyme in the production of nanocellulose. However, there is ongoing debate regarding the specific properties that make EG pretreatment effective in isolating fibrillated cellulose. To address this issue, we investigated EGs from four glycosyl hydrolase (GH) families (5, 6, 7, and 12) and examined the roles of the three-dimensional structure and catalytic features, with a focus on the presence of a carbohydrate binding module (CBM). Using eucalyptus Kraft wood fibers, we produced cellulose nanofibrils (CNFs) through mild enzymatic pretreatment, followed by disc ultra-refining. Comparing the results with the control (without pretreatment), we observed that GH5 and GH12 enzymes (without CBM) reduced fibrillation energy by approximately 15 %. The most significant energy reduction, 25 and 32 %, was achieved with GH5 and GH6 linked to CBM, respectively. Notably, these CBM-linked EGs improved the rheological properties of CNF suspensions without releasing soluble products. In contrast, GH7-CBM exhibited significant hydrolytic activity, resulting in the release of soluble products, but did not contribute to a reduction in fibrillation energy. This discrepancy can be attributed to the large molecular weight and wide cleft of GH7-CBM, which led to the release of soluble sugars but had little impact on fibrillation. Our findings suggest that the improved fibrillation observed with EG pretreatment is primarily driven by efficient enzyme adsorption on the substrate and modification of the surface viscoelasticity (amorphogenesis), rather than hydrolytic activity or release of products.
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| openaire: EC/H2020/788489/EU//BioELCell Funding Information: The authors thank the São Paulo Research Foundation (FAPESP, grant numbers 2015/02862-5 , 2014/18784-2 , 2019/22284-7 , 2021/06679-1 and 21/07023-2 ) for financial support. This study was financed in part by the Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - Brasil ( CAPES ) – Finance Code 001 . The authors also acknowledge support from the Canada Excellence Research Chair Program ( CERC-2018-00006 ), and Canada Foundation for Innovation (Project number 38623 ) and the European Research Council under the European Union's Horizon 2020 research and innovation program (ERC Advanced Grant No. 788489 , “BioElCell”). Publisher Copyright: © 2023 Elsevier B.V.
Keywords
Amorphogenesis, Carbohydrate binding module, Cellulases, Cellulose nanofibrils, Enzymatic pretreatment, Enzyme-substrate interaction, Fibrillation
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Citation
Berto, G L, Mattos, B D, Velasco, J, Zhao, B, Segato, F, Rojas, O J & Arantes, V 2023, ' Endoglucanase effects on energy consumption in the mechanical fibrillation of cellulose fibers into nanocelluloses ', International Journal of Biological Macromolecules, vol. 243, 125002 . https://doi.org/10.1016/j.ijbiomac.2023.125002