Department of Chemistry, Umeå University, Umeå, Sweden.
J Biotechnol. 2011 Sep 10;155(2):244-50. doi: 10.1016/j.jbiotec.2011.06.026. Epub 2011 Jun 29.
Enzymatic hydrolysis of pretreated lignocellulosic substrates has emerged as an interesting option to produce sugars that can be converted to liquid biofuels and other commodities using microbial biocatalysts. Lignocellulosic substrates are pretreated to make them more accessible to cellulolytic enzymes, but the pretreatment liquid partially inhibits subsequent enzymatic hydrolysis. The presence of pretreatment liquid from Norway spruce resulted in a 63% decrease in the enzymatic saccharification of Avicel compared to when the reaction was performed in a buffered aqueous solution. The addition of 15mM of a reducing agent (hydrogen sulfite, dithionite, or dithiothreitol) to reaction mixtures with the pretreatment liquid resulted in up to 54% improvement of the saccharification efficiency. When the reducing agents were added to reaction mixtures without pretreatment liquid, there was a 13-39% decrease in saccharification efficiency. In the presence of pretreatment liquid, the addition of 15mM dithionite to Avicel, α-cellulose or filter cake of pretreated spruce wood resulted in improvements between 25 and 33%. Positive effects (6-17%) of reducing agents were also observed in experiments with carboxymethyl cellulose and 2-hydroxyethyl cellulose. The approach to add reducing agents appears useful for facilitating the utilization of enzymes to convert cellulosic substrates in industrial processes.
预处理木质纤维素底物的酶水解已成为一种很有前途的方法，可以生产可转化为液体生物燃料和其他商品的糖，使用微生物生物催化剂。木质纤维素底物经过预处理，使其更容易被纤维素酶分解，但预处理液会部分抑制随后的酶水解。与在缓冲水溶液中进行反应相比，来自挪威云杉的预处理液的存在导致 Avicel 的酶糖化率降低了 63%。向含有预处理液的反应混合物中添加 15mM 的还原剂（亚硫酸氢盐、连二亚硫酸盐或二硫苏糖醇）可将糖化效率提高高达 54%。当将还原剂添加到没有预处理液的反应混合物中时，糖化效率会降低 13-39%。在预处理液存在的情况下，向 Avicel、α-纤维素或预处理云杉木的滤饼中添加 15mM 的连二亚硫酸盐可提高 25-33%。在羧甲基纤维素和 2-羟乙基纤维素的实验中也观察到还原剂的积极影响（6-17%）。添加还原剂的方法似乎有助于促进酶的利用，以在工业过程中转化纤维素底物。
