Enhanced enzymatic conversion of softwood lignocellulose by poly(ethylene glycol) addition
Enhanced enzymatic conversion of softwood lignocellulose by poly(ethylene glycol) addition
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DOI：
10.1016/j.enzmictec.2006.06.006
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发表时间：
2007-03-05
影响因子：
3.4
通讯作者：
Tjerneld, Folke
中科院分区：
文献类型：
--
作者：
Borjesson, Johan;Peterson, Ragna;Tjerneld, Folke
从木质纤维素生产乙醇具有巨大的潜力，是将燃料消耗转变为更环保的替代品的重要一步。木质纤维素是生物质的重要来源。然而，特别是对于木质纤维素和软木木质纤维素，纤维素向可发酵糖的高转化需要大量的酶。已知添加表面活性剂可提高酶转化率并降低所需酶的量。采用不同环氧乙烷（EO）含量的表面活性剂和聚合物对蒸汽预处理云杉木质纤维素的转化率进行了研究。非离子表面活性剂上的EO链越长，转化率越高。通过仅使用表面活性剂的亲水部分，即通过向水解混合物中加入环氧乙烷聚合物如聚（乙二醇）（PEG），获得了类似的结果。酶和PEG与底物的相互作用用C-14标记的PEG 4000和H-3标记的Cel 7A（CBH I）（来自里氏木霉的主要纤维素酶）监测。在木质纤维素的酶解过程中加入PEG，16 h内转化率由未加PEG时的42%提高到78%。Cel 7A的吸附从81%降低到59%。PEG对脱木质素底物没有影响。通过添加PEG，可以在50 ° C下进行水解，导致高纤维素转化率（80%）和较短的加工时间（48小时）。PEG在木质纤维素上的吸附存在两种不同的相互作用，即氢键和疏水作用。我们的结论是，从实验上的木质纤维素和脱木质素基板的EO含有表面活性剂和聚合物，如PEG，结合到木质素的疏水相互作用和氢键，并减少非生产性的结合酶。(c)2006年爱思唯尔公司All rights reserved.
Ethanol production from lignocellulose has great potential and is an important step in changing fuel consumption to a more environmentally friendly alternative. Lignocellulose is a large source of biomass. However, with lignocellulose and softwood lingocellulose in particular, high conversion of cellulose into fermentable sugars requires large amounts of enzymes. Addition of surfactants is known to increase the enzymatic conversion and decrease the amount of enzymes needed. Surfactants and polymers with various amount of ethylene oxide (EO) content were used to study the conversion of steam-pretreated spruce lignocellulose. Increasing conversion was obtained with longer EO chains on the non-ionic surfactants. Similar results were obtained by using only the hydrophilic part of the surfactant, i.e. by addition of ethylene oxide polymers such as poly(ethylene glycol) (PEG) to the hydrolysis mixture. Interactions of enzymes and PEG with substrate was monitored with C-14-labeled PEG 4000 and H-3-labeled Cel7A (CBH I), the dominating cellulase from Trichoderma reesei. Addition of PEG to enzyme hydrolysis of lignocellulose increased the conversion from 42% without addition to 78% in 16 h. Adsorption of Cel7A decreased from 81 to 59%. No effect of PEG was seen on a delignified substrate. By addition of PEG it was possible to perform hydrolysis at 50 degrees C leading to both high cellulose conversion (80%) and shorter process time (48 h). Two different interactions are proposed in PEG adsorption on lignocellulose, hydrogen bonding and hydrophobic interactions. Our conclusions from experiments on lignocellulose and delignified substrate are that EO containing surfactants and polymers, such as PEG, bind to lignin by hydrophobic interaction and hydrogen bonding and reduce the unproductive binding of enzymes. (c) 2006 Elsevier Inc. All rights reserved.