Production of Polygalacturonase and Increase of Longitudinal Gas Permeability in Southern Pine by Brown-Rot and White-Rot Fungi
Production of Polygalacturonase and Increase of Longitudinal Gas Permeability in Southern Pine by Brown-Rot and White-Rot Fungi
复制标题
褐腐病和白腐病真菌产生多聚半乳糖醛酸酶并提高南方松纵向透气性
DOI：
10.1515/hf.1999.093
复制
发表时间：
1999
期刊：
影响因子：
--
通讯作者：
C. Clausen
中科院分区：
文献类型：
--
作者：
F. Green;C. Clausen
边缘坑和松状坑的水解可能是腐烂真菌在木材定植过程中的一个关键事件。虽然有大量的果胶坑，但对木材腐烂真菌中果胶水解酶的研究很少，这可能是因为木材中果胶的含量相对较低（不到4%），而且主要集中在了解木质化成分的降解上。以聚羧酸钠为碳源，用杯板法测定了15种褐腐菌和8种白腐菌液体培养物中果胶的黏度，测定了内聚半乳糖醛酸酶（endo- PG）的活性。在液体培养中估计草酸，并与每种真菌的菌丝重量有关。在液体培养中，测定了南方松芯暴露于选定的腐烂真菌后纵向透气性的变化，以确定边缘坑的水解程度。15种褐腐菌中有12种，8种白腐菌中有6种对至少一种聚半乳糖醛酸酶测试方法呈阳性。15株褐腐菌中有13株检测到草酸积累，白腐菌中没有检测到草酸积累。棕腐菌对松芯透气性的影响增加了约4倍，白腐菌对松芯透气性的影响增加了约18倍。扫描电镜结果显示，白腐菌侵染下的果核有边缘坑膜水解，而褐腐菌侵染下的果核只有环面损伤、坑膜变弱和撕裂。我们得出结论，褐腐和白腐腐真菌都具有酶解果胶的能力，破坏有边界的窖膜，并在定植和早期腐烂期间增加木材的渗透性。
Summary Hydrolysis of bordered and pinoid pits may be a key event during colonization of wood by decay fungi. Although pits are numerous, studies of pectin-hydrolyzing enzymes in wood decay fungi are scarce, probably because of the relatively low content (less than 4 %) of pectin in wood and because of the primary focus on understanding the degradation of lignified components. Endopolygalacturonase (endo- PG) activity was estimated by cup-plate assay and viscosity reduction of pectin from liquid cultures of fifteen brown-rot and eight white-rot basidiomycetous fungi using sodium polypectate as the carbon source. Oxalic acid was estimated in liquid culture and related to mycelial weight of each fungus. Changes in longitudinal gas permeability of southern pine cores exposed to selected decay fungi in liquid culture were measured to determine the extent of hydrolysis of bordered pits. Twelve of fifteen brown-rot and six of eight white-rot fungi tested were positive for at least one of the polygalacturonase test methods. Accumulation of oxalic acid was detected in thirteen of fifteen brown-rot isolates and none of the white-rot fungi tested. Gas permeability of pine cores increased approximately fourfold among brown-rot fungi tested and eighteenfold among white-rot fungi tested. Scanning electron microscopy revealed bordered pit membrane hydrolysis in cores colonized by white-rot fungi, but only torus damage, weakening and tearing of the pit membranes, was observed in cores exposed to brown-rot fungi. We conclude that both brown- and white-rot decay fungi have the enzymatic capacity to hydrolyze pectin, damage bordered pit membranes, and increase wood permeability during colonization and incipient decay.