Changes in Lignin Chemistry of Switchgrass due to Delignification by Sodium Hydroxide Pretreatment
Changes in Lignin Chemistry of Switchgrass due to Delignification by Sodium Hydroxide Pretreatment
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DOI：
10.3390/en11020376
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发表时间：
2018-02
期刊：
影响因子：
3.2
通讯作者：
Woochul Jung;D. Savithri;Ratna R. Sharma-Shivappa;P. Kolar
中科院分区：
文献类型：
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作者：
Woochul Jung;D. Savithri;Ratna R. Sharma-Shivappa;P. Kolar
以柳枝稷为原料，采用不同浓度的氢氧化钠（NaOH）对柳枝稷进行预处理，研究NaOH脱木素对柳枝稷木质素化学性质的影响。氢氧化钠导致显着的脱木质素作用，范围为44.0%至84.6%，具体取决于预处理强度。虽然由于NaOH预处理没有显著的葡聚糖损失，但较高的NaOH浓度去除了高达28.3%的木聚糖。采用硝基苯氧化（NBO）研究了木质素化学性质的变化，结果表明，在较高的NaOH浓度下，对羟基苯基丙醇（H）木质素单元降解的4-羟基苯甲醛（Hy）的量显著减少预处理15 min后，细胞凋亡率下降（P0.05），30 min和60 min后，细胞凋亡率分别上升至0.75和0.72（p 0.05）改变S/G比，但H/G比（=0.48生柳枝稷）显著降低至0.14，与预处理时间无关。总体而言，发现H单元比S和G单元单木质醇更容易受到NaOH的影响。虽然观察到由于NaOH浓度而引起的木质素化学变化，但它们在水解过程中对纤维素分解酶作用的影响不能完全理解。对木质素分离的进一步研究可能有助于确定NaOH对木质素化学的这些变化如何影响纤维素分解酶。
Switchgrass was pretreated with sodium hydroxide (NaOH) at various concentrations and pretreatment times to investigate how delignification caused by NaOH affects its lignin chemistry. NaOH resulted in significant delignification ranging from 44.0 to 84.6% depending on pretreatment intensity. While there was no significant glucan loss due to NaOH pretreatment, higher NaOH concentrations removed xylan by up to 28.3%. Nitrobenzene oxidation (NBO) was used to study changes in lignin chemistry, and indicated that at higher NaOH concentrations, the amount of 4-hydroxygenzaldehyde (Hy) degraded from p -hydroxyphenyl propanol (H) lignin units was significantly reduced ( p 0.05) change with 15 min pretreatment, but it increased to 0.75 and 0.72, respectively, with 30 and 60 min pretreatments ( p 0.05) change S/G ratio, but H/G ratio (=0.48 raw switchgrass) decreased significantly to 0.14 regardless of pretreatment times. Overall, the H unit was found to be more susceptible to NaOH than S and G unit monolignols. Though changes in lignin chemistry due to NaOH concentration were observed, their impact on cellulolytic enzyme action during hydrolysis could not be fully understood. Further studies on lignin isolation may help to determine how these changes in lignin chemistry by NaOH impact cellulolytic enzymes.