wAbstract
@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 (`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 namometer
scale. Specifically, the weathering process is initiated by physical
distortion of the lattice structure of biotite within 1 ƒÊm of
the attached fungal hypha. Only subsequently does the distorted
volume become chemically altered through dissolution and oxidation
reactions that lead to mineral neoformation.x
Introduction
Methods
Results
Discussion
Acknowledgments
References cited