Pretreatment with laccase and a phenolic mediator degrades lignin and enhances saccharification of Eucalyptus feedstock.
Pretreatment with laccase and a phenolic mediator degrades lignin and enhances saccharification of Eucalyptus feedstock.
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DOI：
10.1186/1754-6834-7-6
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发表时间：
2014-01-08
影响因子：
6.3
通讯作者：
Gutiérrez A
中科院分区：
文献类型：
--
作者：
Rico A;Rencoret J;Del Río JC;Martínez AT;Gutiérrez A
由于植物细胞壁的致密结构和木质素的存在，生物质对酶解的抵抗阻碍了木质纤维素材料的生物燃料生产。本研究的目的是研究工业上可用的漆酶介质系统在木材（桉木）原料预处理过程中修饰和去除木质素的能力，从而改善糖化，并分析整个材料中产生的化学修饰，特别是在顽固性木质素部分。以重组嗜热霉菌漆酶和紫丁香酸甲酯为介质预处理，再进行碱性过氧化物多阶段萃取，可使桉树木材中木质素的去除率达到50%。木质素的去除与酶解后葡萄糖和木糖产量的增加（约40%）直接相关。单独使用漆酶（无介质）预处理可从桉树木材中去除高达20%的木质素。预处理木材的热解-气相色谱/质谱分析显示木质素聚合物发生了修饰，木质素标记物侧链缩短，丁香基与愈创木酰的比例增加。通过对整个木材在二甲亚砜-d6中膨胀的二维核磁共振，获得了有关化学修饰的更多信息。得到的光谱结果显示，木素单元的愈木酰基和丁香基被去除，尽管前者优先被去除，并且每个苯丙烷单元的脂肪侧链数量较少（涉及主要的β- o -4′和β-β′单元间键），这与热解-气相色谱/质谱分析结果一致，而木多糖信号没有实质性变化。然而，光谱中观察到的最明显的修饰是在酶处理过程中形成的c α-氧化紫丁香基木质素单元。通过对酶预处理后从桉树原料中分离出的木质素进行核磁共振，进一步了解了木质素结构的修饰，影响了其他单元间键和氧化结构。这项工作显示了当直接应用于地面木质纤维素材料时，氧化酶预处理对硬木原料（桉树木）的脱木质素和改善纤维素酶糖化的潜力，并揭示了预处理材料的主要化学变化，以及在上述结果背后的顽固性木质素部分。
Biofuel production from lignocellulosic material is hampered by biomass recalcitrance towards enzymatic hydrolysis due to the compact architecture of the plant cell wall and the presence of lignin. The purpose of this work is to study the ability of an industrially available laccase-mediator system to modify and remove lignin during pretreatment of wood (Eucalyptus globulus) feedstock, thus improving saccharification, and to analyze the chemical modifications produced in the whole material and especially in the recalcitrant lignin moiety. Up to 50% lignin removal from ground eucalypt wood was attained by pretreatment with recombinant Myceliophthora thermophila laccase and methyl syringate as mediator, followed by alkaline peroxide extraction in a multistage sequence. The lignin removal directly correlated with increases (approximately 40%) in glucose and xylose yields after enzymatic hydrolysis. The pretreatment using laccase alone (without mediator) removed up to 20% of lignin from eucalypt wood. Pyrolysis-gas chromatography/mass spectrometry of the pretreated wood revealed modifications of the lignin polymer, as shown by lignin markers with shortened side chains and increased syringyl-to-guaiacyl ratio. Additional information on the chemical modifications produced was obtained by two-dimensional nuclear magnetic resonance of the whole wood swollen in dimethylsulfoxide-d6. The spectra obtained revealed the removal of guaiacyl and syringyl lignin units, although with a preferential removal of the former, and the lower number of aliphatic side-chains per phenylpropane unit (involved in main β-O-4ʹ and β-βʹ inter-unit linkages), in agreement with the pyrolysis-gas chromatography/mass spectrometry results, without a substantial change in the wood polysaccharide signals. However, the most noticeable modification observed in the spectra was the formation of Cα-oxidized syringyl lignin units during the enzymatic treatment. Further insight into the modifications of lignin structure, affecting other inter-unit linkages and oxidized structures, was attained by nuclear magnetic resonance of the lignins isolated from the eucalypt feedstock after the enzymatic pretreatments. This work shows the potential of an oxidative enzymatic pretreatment to delignify and improve cellulase saccharification of a hardwood feedstock (eucalypt wood) when applied directly on the ground lignocellulosic material, and reveals the main chemical changes in the pretreated material, and its recalcitrant lignin moiety, behind the above results.
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影响因子：
3.6
作者：
Kim, Hoon;Ralph, John;Akiyama, Takuya
通讯作者：
Akiyama, Takuya
影响因子：
6
作者：
Gonzalez, R.;Treasure, T.;Jameel, H.
通讯作者：
Jameel, H.
影响因子：
3.4
作者：
Kawai, S;Nakagawa, M;Ohashi, H
通讯作者：
Ohashi, H
影响因子：
6.2
作者：
Du, Xueyu;Li, Jiebing;Gutierrez, Ana
通讯作者：
Gutierrez, Ana
影响因子：
--
作者：
Cantarella, G;Galli, C;Gentili, P
通讯作者：
Gentili, P