摘要
用定量(13)C－NMR技术研究了稻草经白腐菌Panusconchatus降解后木素的高分子部分的结构特征变化。与未经生物作用的木素相比较，发现发酵稻草木素的13C－NMR谱图出现新的吸收峰以及某些吸收峰的强度有明显变化。这些变化证实了在生物作用过程木素大分子中形成了醌类以及α-羟基酸的结构，这些类型的结构特别有利于木素进一步降解。并同时证实木素生物降解过程中发生β-O－4；Cα-Cβ及Cβ-Cγ键的断裂及Cγ的氧化。定量分析结果表明，经生物降解后木素大分子的甲氧基和羧基含量增加，愈疮木基和对羟基苯基结构单元优先降解，推断出此白腐菌对稻草的作用首先进攻纤维胞间层，其结果与电子显微镜所得的结果相一致。分析结果同时表明，生物降解优先发生于木索非缩聚结构单元。
The fraction of decayed rice straw lignin with high molecular weight was caracterizedby quantitative 13 C-NMP spectroscopy.The signals of the spectra of decayed and undecayed lignin were assigned.Theresults showed that the structure of quinone and a-hydroxyl acid ap-peared and the content of total carbonyl group increased after biodegradation.It was concludedthat oxidation as a main reaction occurred in li\gnin biodegradation and rice straw lignin underwentfungal degradation probably via oxidation cleavage of C a-C bond,Cb-Cbond and oxidation of Cr.The results in quantitative 13C-NMR spectra also showed that the contents of methoxylgroup and ester-linked coumaric acid in lignin increased and decreased respectively,and the ra-tion of syringyl(S),guaiacyl(G)and p-hydroxyl-phenyl(H)units and the ratio of non-con-densed S and G in rice straw lignin were obviously changed after the fungal degradation was ester-linkedcomaric acid unit,guaiacyl unit and syringyl unit,and the fungal attack occurred in the middlelamella at first wich is rich in guaiacyl-type lignin.This conclusion was in accordance with ourprevious results obtained by eletromicroscopy.
出处
《纤维素科学与技术》
CAS
CSCD
1998年第4期41-49,共9页
Journal of Cellulose Science and Technology
基金
国家自然科学基金
广东省科学基金
