土生空团菌对白云母的风化作用及解钾特性

K-release and weathering of muscovite by Cenococcum geophilum

摘要:

摘要:【目的】为了提高森林土壤含钾硅酸盐矿物利用率和改善树木钾素营养，探讨外生菌根真菌对白云母矿物的解钾及风化效应。【方法】通过5种外生菌根真菌在贫钾条件下与白云母的相互作用，考察了3种常用培养基对菌株解钾能力的影响;采用解钾效果最高的土生空团菌在Modified Melin-Norkrans(MMN)培养基条件下，进一步研究了21d浸出过程中主要矿质元素的释放量、生物量、剩余葡萄糖量、产生的小分子有机酸种类及含量、菌丝-矿物微环境的改变，利用扫描电子显微镜观测白云母被风化的痕迹。【结果】培养基对不同外生菌根真菌解钾能力的影响各异，其中土生空团菌在MMN培养基条件下解钾能力最强，其解钾量与生物量、剩余葡萄糖量、pH值显著相关。土生空团菌能够分泌有助于菌丝-矿物粘附的胞外多糖以形成菌丝-矿物微环境，并富集有机酸，促进微环境内钾的释放;菌丝不仅能够粘附在白云母表面产生刻蚀作用，还能破坏矿物深入其内部。【结论】外生菌根真菌具有促进白云母风化并释放钾素的能力，这种能力可能与菌丝、有机酸、多糖的协同作用有关。

Abstract:

Abstract:［Objective］To use efficiently the insoluble K-bearing minerals in forest soil as nutrients for plant growth，we studied the weathering mechanism of muscovite by ectomycorrhizal fungi．［Methods］Cenococcum geophilum，Paxillus involutus，Laccaria bicolor，Pisolithus tinctorius，and Suillus tomentosus were used to dissolve muscovite in three culture mediums． Furthermore，K release from muscovite，biomass，remaining glucose，pH value andorganic acids were measured during the 21-day incubation of C．geophilum in Modified Melin-Norkrans (MMN) culture medium．We also compared K release amounts，organic acids and polysaccharides in external environment with those in micro-environment after 15-day and 21-day bioleaching．The weathering phenomenon on muscovite surface was observed by Scanning Electron Microscope (SEM).［Results］Among five ectomycorrhizal fungi，C．geophilum showed the best K-releasing ability in MMN culture medium．Fungal biomass，remaining glucose and pH value had significantly effects on K release．With the aid of exopolysaccharides，the hypha adhered to the mineral surface forming the micro-environment．In the microenvironment，organic acids were concentrated to promote K-release from muscovite，and obvious weathering marks on muscovite surface were found by SEM image．［Conclusion］Ectomycorrhizal fungi could weather muscovite to provide Ksolubilizing microbial resource for plant growth，and the synergism action of hyphae，organic acids and polysaccharides would accelerate K mobilization.