酶解木质素的分离与结构研究

酶解木质素的分离与结构研究

刘晓玲1,程贤甦﹡1,2

（1．福州大学材料科学与工程学院，福建福州，350002；

2．闽江学院化学与化学工程系，福建福州，350011）

酶解木质素是从微生物酶解玉米杆制备能源酒精的残渣中提取得到的木质素[1]。酶解玉米杆制备能源酒精既节省粮食又能充分利用资源，因此受到国内外学者的关注，南京林业大学余世袁教授培育优良菌种发酵玉米秸秆制备能源酒精，项目中试工艺过程取得了成功，但由于没有对残渣进行综合利用，成本过高而无法工业化生产。

本文采用两种不同的分离、提取方法，从酶解玉米秸杆制备酒精的残渣中提取酶解木质素，并结合多种分析手段，研究其结构特征，为酶解木质素的制备及应用奠定基础。 称取研磨至100目的酶解玉米秸杆残渣，和溶剂在0.1-1.0MPa 压力条件下，加热至70-95℃,维持50-180分钟,过滤。根据不同的溶剂种类，采用不同的后续处理方法。氢氧化钠氨水等碱性萃取液，用稀盐酸中和，再加入3-6倍体积的水，酶解木质素以沉淀析出，离心分离，冷冻干燥则得到酶解木质素；有机溶剂萃取液采用减压蒸去有机溶剂得到酶解木质素。将所得到的粗木质素溶于二氧六环，并用乙醚使之沉淀提纯[2]。

应用FT-IR 、UV 、GPC 和13C-NMR 研究了不同分离方法的酶解木质素的结构，结果表明，酶解木质素的分子量小于磨木木质素[3]，与木质素磺酸盐相比较，酶解木质素在结构上较好地保留了各种活性基团，酶解木质素的红外图谱中还多了1700cm -1和1328cm -1峰，说明酶解木质素中存在非共轭羰基。紫外图谱在210nm ，280nm 和310nm 附近有吸收峰出现，证明其具有木质素的基本结构，且不饱和性较大。由13C-NMR 图谱解析可知，所提取酶解木质素为GSH 型木质素，主要以β-O-4，β-5，β-1的结构存在[4]。以氢氧化钠作为萃取剂获得的酶解木质素提取率比较高。

Tab.1 Molecular weight distribution of EH lignin from different solvents

酶解木质素

溶剂 Mn M P Mw Mz Poly Dispersity SL

氢氧化钠 939 1047 1124 1338 1.20 BL

1，4-丁二醇 1167 1284 1544 1995 1.32 40003500300025002000

1500100050020

40

60

80100BL

SL

%T r a n s m i t t a n c e

Wavenumber(cm -1) 200250300350400450500SL BL

A b s o r p t i o n c o e f f i c i e n t Wavelength(nm)

Fig1 FT-IR spectra of EH lignin from Fig2 UV spectra of EH lignin from

different solvents different solvents

Fig3 13C-NMR spectra of EH lignin from different solvents

参考文献:

[1] 徐勇，勇强，余世袁等. 汽喷玉米秸秆纤维素酶水解的研究.林产化工通讯，1999，33（6）：15

[2] 中野準三编，高洁等译. 木质素的化学—基础与应用. 北京：轻工业出版社，1988：45

[3] 蒋挺大. 木质素. 北京：化学工业出版社，2001：42

[4] Lawther J. Mark，Sun R.-C，Banks W.B. Rapid isolation and structural characterization of

alkali-soluble lignins during alkaline treatment and atmospheric refining of wheat straw.

Industrial Crops and Products，1996，5（2）：97

Separation and Study on Structure of Enzymatic Hydrolysis Lignin

Liu Xiaoling1, Cheng Xiansu﹡1, 2

(1.College of Material Science and Engineering, Fuzhou University, Fuzhou 350002;

2.Department of Chemistry and Chemical Engineering, Minjiang University, Fuzhou 350011) Abstract: EH lignin from the cornstalks residue was separated by two methods. The EH lignin was analyzed with respect to molecular weights, IR, UV spectra and 13C-NMR spectroscopy. The results indicated that EH lignin had lower molecular weight than the milled wood lignin and contained many active chemical groups. There were different absorbance peaks at 1700cm-1 and 1328cm-1 on the IR spectra of EH lignin. It is showed that the non-conjugated carbonyls were existed in the EH lignin. The absorbance appeared in 210 nm, 280 nm and 310 nm in UV spectra of the EH lignin, the fact indicate the EH lignin is an unsaturated polymer. According to the 13C-NMR, the separated EH lignin belongs to “GSH”-lignin, and it is composed mainly of β-O-4 ether bonds together withβ-5 andβ-1 carbon-carbon linkages between the lignin structural units. The yield of EH lignin, extracted with NaOH was higher with organic solvents. The effective application of EH lignin will rise the beneficial result of enzymatic hydrolysis.

Key words:enzymatic hydrolysis of cornstalks enzymatic hydrolysis lignin(EH lignin)

structure of EH lignin