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Analysis of biopulping mechanism by Ceriporiopsis subvermispora

细孢角藻生物制浆机制分析

基本信息

批准号：
09660185
负责人：
WSTSNSBE Takashi
金额：
$ 2.11万
依托单位：
KYOTO UNIVERSITY
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
1997
资助国家：
日本
起止时间：
1997 至 1998
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-09660185/
关键词：
Lignin White-rotfungi Biopulping Lipid peroxidation リビッドペルオキシデーション木材腐朽

项目摘要

Ceriporiopsis subvermispora, a specific lignin-degrading fungus, has in recent years been used in delignifying treatments of plant biomass such as biomechanical pulping, biosulfite pulping and digestibility enhancement of forage grasses. This fungus is known to decompose lignin located in wood cell walls and middle lamellae without erosion of the wood cell walls even after fiber separation. Taking into account that hyphal growth and excretion of enzymes takes place in the lumen and that enzymes are too large to penetrate pores of wood cell Walls, it can be concluded that some kind of diffusible low molecular weight compounds are produced by the fungus, leading to the degradation of lignin at the site far from enzymes. In the biomechanical pulping with C.subvermispora, high energy saving effect was obtained with a short incubation period of 2 weeks, indicating that middle lamellae were damaged for the first 2 weeks. After 6 weeks cultivation, corresponding to 15-20 percent weight loss, … More fiber separation by the lignolysis of middle lamellae can be observed by microscopy. Thus, extensive damage of middle lamellae in the early stage of wood decay by C.subvermispora cannot be understood by the simple radical transfer system from cell lumina into wall regions. Based on this discussion, we focused on the free radical generation system inside of wood cell walls. In this study, peroxidizable low molecular mass compounds produced by C.subvermispora were analyzed by GC-MS, NMR and ESR spectroscopy. As a result, it has been found that C.subvermispora produced free unsaturated fatty acids (USFA), 9,12- octadecadienoic, 11-octadecenoic and 9-octadecenoic acids, together with saturated fatty acids (SFA) octadecanoic and hexadecanoic acids on wood meal cultures. The fractions containing USFA and SFA were oxidized with soybean lipoxygenase and the free radicals formed by the enzymatic peroxidation were analyzed by spin-trapping with 4-POBN.ESR spectra showed that strong radicals were generated from the extract obtained at the early stages of cultivation (8-12 days). However, signal intensities of the spin adducts did not increase after prolonged cultivation (16-28 days). Hyperfine coupling constant and g-value of the major spin adduct were identical to those of pentyl radical. These results strongly suggest that the free unsaturated fatty acids did not originate from fungal hypha but from extracellular metabolites of the fungus related to lignin biodegradation. Production of lipid hydroperoxide by this fungus was also demonstrated by DPPP assay. Less

Ceriporiopsis subvermispora是一种降解木质素的真菌，近年来在生物机械制浆、生物亚硫酸盐制浆和提高牧草消化率等方面得到了广泛的应用。已知这种真菌可以分解位于木材细胞壁和中间薄片的木质素，即使在纤维分离后也不会侵蚀木材细胞壁。考虑到菌丝的生长和酶的排泄是在管腔内进行的，而且酶的体积太大，无法穿透木材细胞壁的孔隙，可以得出结论，真菌产生了某种可扩散的低分子量化合物，导致木质素在远离酶的地方降解。在生物力学制浆过程中，利用颠覆孢霉进行生物力学制浆，在2周的孵育时间内获得了较高的节能效果，说明在前2周，中间薄片受到了破坏。经过6周的培养，在显微镜下可以观察到更多的纤维被木质素分解的中间薄片所分离。因此，从胞腔到壁区的简单自由基转移系统不能解释木霉在木材腐烂早期对中间片层的广泛破坏。在此基础上，我们重点研究了木材细胞壁内部的自由基生成系统。本研究采用气相色谱-质谱、核磁共振和ESR等方法对紫花菌产生的低分子质量过氧化物化合物进行了分析。结果发现，在木粕培养物上，黑孢霉可产生游离不饱和脂肪酸（USFA）、9、12-十八烯酸、11-十八烯酸和9-十八烯酸，以及饱和脂肪酸（SFA）十八烯酸和十六烯酸。用大豆脂氧合酶对含有USFA和SFA的组分进行氧化，用4-POBN自旋俘获法分析酶促过氧化反应形成的自由基。ESR光谱显示，培养初期（8 ~ 12 d）提取液产生了较强的自由基。然而，长时间培养（16-28天）后，自旋加合物的信号强度没有增加。主自旋加合物的超细偶联常数和g值与戊基自由基的超细偶联常数和g值相同。这些结果强烈表明游离不饱和脂肪酸不是来自真菌菌丝，而是来自木质素生物降解相关的真菌胞外代谢物。DPPP实验也证实了该真菌能产生过氧化脂。少