Plant-driven fungal weathering: Early stages of mineral alteration at the nanometer scale
Plant-driven fungal weathering: Early stages of mineral alteration at the nanometer scale
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DOI：
10.1130/g25699a.1
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发表时间：
2009-07-01
期刊：
影响因子：
5.8
通讯作者：
Benning, Liane G.
中科院分区：
文献类型：
--
作者：
Bonneville, Steeve;Smits, Mark M.;Benning, Liane G.
植物驱动的真菌风化是土壤形成的主要途径，但菌根改变矿物质的确切机制尚不清楚。在这里，我们报道了第一次在对照实验中对土壤真菌对其生长的矿物表面的影响的直接原位观察。一种外生菌根真菌与一棵树苗共生生长，使单个菌丝在三个月的时间里扩展到黑云母片的表面。对真菌-黑云母界面的超微结构和光谱分析表明，真菌与矿物的紧密结合、生物力学的强迫、层间距的改变、钾的大量贫化(约50 nm深度)、黑云母Fe(II)的氧化、蚯蚓石和Fe(III)氧化物簇的形成。我们的研究在纳米尺度上证明了真菌-黑云母界面的生物力学-化学变化的相互作用。具体地说，风化过程是由附着的真菌菌丝1微米范围内的黑云母晶格结构的物理扭曲引起的。只有随后，扭曲的体积才会通过溶解和氧化反应而发生化学变化，从而导致矿物新形成。
Plant-driven fungal weathering is a major pathway of soil formation, yet the precise mechanism by which mycorrhiza alter minerals is poorly understood. Here we report the first direct in situ observations of the effects of a soil fungus on the surface of a mineral over which it grew in a controlled experiment. An ectomycorrhizal fungus was grown in symbiosis with a tree seedling so that individual hyphae expanded across the surface of a biotite flake over a period of three months. Ultramicroscopic and spectroscopic analysis of the fungus-biotite interfaces revealed intimate fungal-mineral attachment, biomechanical forcing, altered interlayer spacings, substantial depletion of potassium (similar to 50 nm depth), oxidation of the biotite Fe(II), and the formation of vermiculite and clusters of Fe(III) oxides. Our study demonstrates the biomechanical-chemical alteration interplay at the fungus-biotite interface at the nanometer scale. Specifically, the weathering process is initiated by physical distortion of the lattice structure of biotite within 1 mu m of the attached fungal hypha. Only subsequently does the distorted volume become chemically altered through dissolution and oxidation reactions that lead to mineral neoformation.