Alkaline peroxide pretreatment of corn stover: effects of biomass, peroxide, and enzyme loading and composition on yields of glucose and xylose.
Alkaline peroxide pretreatment of corn stover: effects of biomass, peroxide, and enzyme loading and composition on yields of glucose and xylose.
复制标题
DOI：
10.1186/1754-6834-4-16
复制
发表时间：
2011-06-09
影响因子：
6.3
通讯作者：
Walton JD
中科院分区：
文献类型：
--
作者：
Banerjee G;Car S;Scott-Craig JS;Hodge DB;Walton JD
预处理是木质纤维素转化为可发酵糖的关键步骤。虽然目前正在研究许多预处理工艺，但在有效性、成本或环境影响方面，没有一种工艺是完全令人满意的。Gould及其同事证明，在pH 11.5下使用过氧化氢（碱性过氧化氢（AHP））是在动物营养和乙醇生产的背景下对草秸杆和其他植物材料的有效预处理。我们早期的实验表明，AHP表现良好时，对其他两个碱性预处理。在这里，我们探讨了几个关键参数，以测试潜在的AHP进一步改进相关的木质纤维素乙醇生产。结合随后用商业酶制剂、四种商业酶的优化混合物或纯酶的优化合成混合物进行消化，测试生物质负载、过氧化氢负载、停留时间和pH控制的影响。在室温（23°C）和大气压下进行AHP预处理，并且在AHP预处理之后，用HCl中和生物质，但在酶消化之前不洗涤。标准酶消化条件为0.2%葡聚糖加载量、15 mg蛋白质/g葡聚糖和在50°C下消化48小时。更高的预处理生物质负载（10%至20%）比早期研究中使用的2%负载产生更高的单体葡萄糖（Glc）和木糖（Xyl）产率。0.25 g/g生物质的H2 O2负载几乎与0.5 g/g一样有效，但0.125 g/g的有效性显著降低。四种商业酶的优化混合物在所有H2 O2浓度下与任何单一商业酶相比大幅增加了后AHP预处理酶水解产率。在10%的预处理生物质负载和0.5 g/g生物质的H2 O2负载下，在8或15 mg/g葡聚糖的总蛋白质负载下的优化的商业混合物分别得到83%或95%的单体Glc产率。在低过氧化氢负荷（0.125 g H2 O2/g生物质）下预处理后，通过将预处理停留时间延长至48 h并在预处理期间每6 h将pH重新调节至11.5，可以提高Glc和Xyl的产率。使用15%的生物质负载，0.125克H2 O2/克生物质，和48小时的pH调节预处理，然后用优化的商业酶混合物在15毫克蛋白质/克葡聚糖的酶负载消化，获得77%的葡萄糖产率。碱性过氧化氢是一种有效的玉米秸秆预处理方法。特别的优势是使用对环境影响低的试剂和避免特殊反应室。单体葡萄糖的合理产量，可以得到在H2 O2浓度的四分之一，在以前的AHP研究中使用。AHP工艺的其他改进，如过氧化物稳定化、过氧化物回收和改进的pH控制，可能会导致AHP预处理的进一步改进。
Pretreatment is a critical step in the conversion of lignocellulose to fermentable sugars. Although many pretreatment processes are currently under investigation, none of them are entirely satisfactory in regard to effectiveness, cost, or environmental impact. The use of hydrogen peroxide at pH 11.5 (alkaline hydrogen peroxide (AHP)) was shown by Gould and coworkers to be an effective pretreatment of grass stovers and other plant materials in the context of animal nutrition and ethanol production. Our earlier experiments indicated that AHP performed well when compared against two other alkaline pretreatments. Here, we explored several key parameters to test the potential of AHP for further improvement relevant to lignocellulosic ethanol production. The effects of biomass loading, hydrogen peroxide loading, residence time, and pH control were tested in combination with subsequent digestion with a commercial enzyme preparation, optimized mixtures of four commercial enzymes, or optimized synthetic mixtures of pure enzymes. AHP pretreatment was performed at room temperature (23°C) and atmospheric pressure, and after AHP pretreatment the biomass was neutralized with HCl but not washed before enzyme digestion. Standard enzyme digestion conditions were 0.2% glucan loading, 15 mg protein/g glucan, and 48 h digestion at 50°C. Higher pretreatment biomass loadings (10% to 20%) gave higher monomeric glucose (Glc) and xylose (Xyl) yields than the 2% loading used in earlier studies. An H2O2 loading of 0.25 g/g biomass was almost as effective as 0.5 g/g, but 0.125 g/g was significantly less effective. Optimized mixtures of four commercial enzymes substantially increased post-AHP-pretreatment enzymatic hydrolysis yields at all H2O2 concentrations compared to any single commercial enzyme. At a pretreatment biomass loading of 10% and an H2O2 loading of 0.5 g/g biomass, an optimized commercial mixture at total protein loadings of 8 or 15 mg/g glucan gave monomeric Glc yields of 83% or 95%, respectively. Yields of Glc and Xyl after pretreatment at a low hydrogen peroxide loading (0.125 g H2O2/g biomass) could be improved by extending the pretreatment residence time to 48 h and readjusting the pH to 11.5 every 6 h during the pretreatment. A Glc yield of 77% was obtained using a pretreatment of 15% biomass loading, 0.125 g H2O2/g biomass, and 48 h with pH adjustment, followed by digestion with an optimized commercial enzyme mixture at an enzyme loading of 15 mg protein/g glucan. Alkaline peroxide is an effective pretreatment for corn stover. Particular advantages are the use of reagents with low environmental impact and avoidance of special reaction chambers. Reasonable yields of monomeric Glc can be obtained at an H2O2 concentration one-quarter of that used in previous AHP research. Additional improvements in the AHP process, such as peroxide stabilization, peroxide recycling, and improved pH control, could lead to further improvements in AHP pretreatment.
登录
查看更多内容
影响因子：
3.8
作者：
Chundawat, Shishir P. S.;Venkatesh, Balan;Dale, Bruce E.
通讯作者：
Dale, Bruce E.
影响因子：
5.4
作者：
Saha, Badal C.;Cotta, Michael A.
通讯作者：
Cotta, Michael A.
影响因子：
11.4
作者：
Banerjee, Goutami;Car, Suzana;Walton, Jonathan D.
通讯作者：
Walton, Jonathan D.
影响因子：
4.2
作者：
Qi, Benkun;Chen, Xiangrong;Wan, Yinhua
通讯作者：
Wan, Yinhua
影响因子：
3.8
作者：
Jeoh, Tina;Ishizawa, Claudia I.;Johnson, David K.
通讯作者：
Johnson, David K.