Investigating plant cell wall components that affect biomass recalcitrance in poplar and switchgrass
Investigating plant cell wall components that affect biomass recalcitrance in poplar and switchgrass
复制标题
DOI：
10.1039/c3ee23801f
复制
发表时间：
2013-03-01
影响因子：
32.5
通讯作者：
Wyman, Charles E.
中科院分区：
文献类型：
--
作者：
DeMartini, Jaclyn D.;Pattathil, Sivakumar;Wyman, Charles E.
将纤维素生物质低成本生物转化为可再生燃料和化学品的关键障碍之一是植物不愿通过化学、酶和/或微生物途径进行解构。迫切需要更深入地了解生物量顽固性的来源，以便能够在不同的植物中识别限制糖释放的特定细胞壁化学和结构特征。本研究对两种系统发育不同的植物--单子叶柳枝菊(Panicum Virgata)和木本双子叶杨树(Pillius Trichcarpa)的生物量进行了研究。通过规定的化学和酶提取，从每一种原生生物量中产生在组成和结构上不同的几组样品。对两种天然生物量及其提取残留物进行了表征，并对所有样品的酶消化能力进行了测试，以揭示限制糖释放的底物相关特征。根据本研究的结果，木质素和半纤维素对杨树和柳枝菊的酶消化率都有影响，但影响程度有显著差异。从柳枝菊中去除木聚糖可以使材料在高酶负荷下获得接近100%的葡萄糖产率，而降低木质素含量的绿泥萃取物对杨树的影响最大。虽然木质素含量可能在生物量抗性中发挥重要作用，特别是在木质素含量较高的杨树等植物中，但本工作确定了半纤维素亚类，它们是导致柳枝菊抗性的关键因素。这项研究中提出的发现和研究方法强烈表明，当试图通过改造杨树和柳枝草来减少顽固性时，或者在设计加工条件以有效地将特定的生物质原料转化为糖时，需要采取不同的策略。
One of the key barriers to low cost biological conversion of cellulosic biomass into renewable fuels and chemicals is the recalcitrance of plants to deconstruction by chemical, enzymatic, and/or microbial routes. A deeper understanding of the source of biomass recalcitrance is sorely needed so that specific cell wall chemical and structural features that limit the release of sugars can be identified in different plants. In this study, biomass from two phylogenetically different plants, the monocot switchgrass (Panicum virgatum) and the woody dicot poplar (Populus trichocarpa) were studied. Sets of samples that varied in composition and structure were generated from each native biomass via defined chemical and enzymatic extractions. The two native biomasses, as well as their extracted residues, were characterized, and the enzymatic digestibility of all samples was tested to shed light on substrate-related features that limit sugar release. Based on the results from this study, lignin and hemicellulose were found to influence the enzymatic digestibility of both poplar and switchgrass, but the degree of influence varied significantly. Xylan removal from switchgrass resulted in materials that achieved nearly 100% glucose yields at high enzyme loading in subsequent enzymatic hydrolysis, whereas chlorite extractions that reduced the lignin content had the most beneficial effect in poplar. While lignin content likely plays an important role in biomass recalcitrance particularly in plants such as poplar that contain higher levels of lignin, this work identified subsets of hemicellulose that were key recalcitrance-causing factors in switchgrass. The findings and research approach presented in this study strongly suggest that different strategies will need to be adopted when trying to engineer poplar and switchgrass for reduced recalcitrance or when designing processing conditions to efficiently convert a specific biomass feedstock into sugars.