『Abstract
　In soils, mycorrhiza (microscopic fungal hypha) living in symbiosis with plant roots are the biological interface by which plants obtain, from rocks and organic matter, the nutrients necessary for their growth and maintenance. Despite their central role in soils, the mechanism and kinetics of mineral alteration by mycorrhiza are poorly constrained quantitatively. Here, we report in situ quantification of weathering rates from a mineral substrate, (001) basal plane of biotite, by a surface-bound hypha of Paxillus involutus, grown in association with the root system of a Scots pine, Pinus sylvestris. Four thin-sections were extracted by focused ion beam (FIB) milling along a single hypha grown over the biotite surface. Depth-profile of Si, O, K, Mg, Fe and Al concentrations were performed at the hypha-biotite interface by scanning transmission electron microscopy-energy dispersive X-ray spectroscopy (STEM-EDX). Large removals of K (50-65％), Mg (55-75％), Fe (80-85％) and Al (75-85％) were observed in the topmost 40 nm of biotite underneath the hypha while Si and O are preserved throughout the depth-profile. A quantitative model of alteration at the hypha-scale was developed based on solid-state diffusion fluxes of elements into the hypha and the break-down/mineralogical re-arrangement of biotite. A strong acidification was also observed with hypha bound to the biotite surface reaching pH＜4.6. When consistently compared with the abiotic biotite dissolution, we conclude that the surface-bound mycorrhiza accelerate the biotite alteration kinetics between pH 3.5 and 5.8 to 〜0.04μmol biotite m^-2 h^-1. Our current work reaffirms that fungal mineral alteration is a process that combines our previously documented bio-mechanical forcing with the μm-scale acidification mediated by surface-bound hypha and a subsequent chemical element removal due to the fungal action. A such, our study presents a first kinetic framework for mycorrhizal alteration at the hypha-scale under close-to-natural experimental conditions. 』

1. Introduction
2. Materials and methods
　2.1. Plant-mycorrhiza symbiosis and incubation with biotite
　2.2. Sampling and chemical analysis of hypha-biotite interface
　2.3. Hyphal pH measurements
　2.4. Abiotic dissolution of biotite
3. Results
　3.1. hyphae-biotite interfaces in the STEM elemental profiles
　3.2. Chemical composition of the biotite-hypha interface
　3.3. Abiotic dissolution of biotite
　3.4. pH of the hypha microenvironment
4. Model of the chemical weathering at the hypha-biotite interface
5. Discussion
　5.1. Mineral alteration underneath living hypha
　5.2. Quantification of elemental fluxes at the hypha-biotite interface
　5.3. Biotite alteration kinetics: mycorrhizal vs. abiotic
6. Conclusions
Acknowledgements
Appendix A. Supplementary data
References