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Effect of Lignin Chemistry on the Enzymatic Hydrolysis of Woody Biomass

Authors

  • Dr. Zhiying Yu,

    1. Department of Forest Biomaterials, North Carolina State University, 2820 Faucette Boulevard, Campus Box 8005, Raleigh, NC 27695-8005 (USA)
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  • Dr. Ki-Seob Gwak,

    1. Department of Forest Biomaterials, North Carolina State University, 2820 Faucette Boulevard, Campus Box 8005, Raleigh, NC 27695-8005 (USA)
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  • Trevor Treasure,

    1. Department of Forest Biomaterials, North Carolina State University, 2820 Faucette Boulevard, Campus Box 8005, Raleigh, NC 27695-8005 (USA)
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  • Dr. Hasan Jameel,

    1. Department of Forest Biomaterials, North Carolina State University, 2820 Faucette Boulevard, Campus Box 8005, Raleigh, NC 27695-8005 (USA)
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  • Dr. Hou-min Chang,

    1. Department of Forest Biomaterials, North Carolina State University, 2820 Faucette Boulevard, Campus Box 8005, Raleigh, NC 27695-8005 (USA)
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  • Dr. Sunkyu Park

    Corresponding author
    1. Department of Forest Biomaterials, North Carolina State University, 2820 Faucette Boulevard, Campus Box 8005, Raleigh, NC 27695-8005 (USA)
    • Department of Forest Biomaterials, North Carolina State University, 2820 Faucette Boulevard, Campus Box 8005, Raleigh, NC 27695-8005 (USA)===

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Abstract

The impact of lignin-derived inhibition on enzymatic hydrolysis is investigated by using lignins isolated from untreated woods and pretreated wood pulps. A new method, biomass reconstruction, for which isolated lignins are precipitated onto bleached pulps to mimic lignocellulosic biomass, is introduced, for the first time, to decouple the lignin distribution issue from lignin chemistry. Isolated lignins are physically mixed and reconstructed with bleached pulps. Lignins obtained from pretreated woods adsorb two to six times more cellulase than lignins obtained from untreated woods. The higher adsorption of enzymes on lignin correlates with decreased carbohydrate conversion in enzymatic hydrolysis. In addition, the reconstructed softwood substrate has a lower carbohydrate conversion than the reconstructed hardwood substrate. The degree of condensation of lignin increases significantly after pretreatment, especially with softwood lignins. In this study, the degree of condensation of lignin (0.02 to 0.64) and total OH groups in lignin (1.7 to 1.1) have a critical impact on cellulase adsorption (9 to 70 %) and enzymatic hydrolysis (83.2 to 58.2 %); this may provide insights into the more recalcitrant nature of softwood substrates.

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